{"thread":{"id":"55472","subject":"[PATCH 00/15] SHA-256 / SHA-1 interop, part 1","startedAt":"2021-04-10T15:22:35Z","lastAt":"2022-02-21T16:05:39Z","messageCount":71,"participants":["brian m. carlson","Chris Torek","Ævar Arnfjörð Bjarmason","Junio C Hamano","Bagas Sanjaya","Jeff King","Derrick Stolee","Denton Liu","Jonathan Nieder"],"isPatch":true,"patchVersion":1,"patchTotal":15},"messages":[{"id":"421535","messageId":"20210410152140.3525040-1-sandals@crustytoothpaste.net","threadId":"55472","inReplyTo":null,"subject":"[PATCH 00/15] SHA-256 / SHA-1 interop, part 1","fromName":"brian m. carlson","fromEmail":"sandals@crustytoothpaste.net","sentAt":"2021-04-10T15:21:25Z","receivedAt":"2021-04-10T15:22:35Z","isPatch":true,"sender":{"key":"sandals@crustytoothpaste.net","avatar":"https://avatars.githubusercontent.com/u/497054?v=4"},"body":"Because I know the first twenty-something weren't enough, here's another\nseries of SHA-256-related patches. This is the beginning of the work to\nmake SHA-256 and SHA-1 repositories interoperate, which of course is\npart of the transition plan.\n\nThis series introduces code to make struct object_id take a hash\nalgorithm member and use that for printing the object ID. This is the\nfirst step to handling multiple hash algorithms in the same binary,\nwhich we'll need if we're going to process both SHA-1 and SHA-256\nversions of objects.\n\nThe major contributor to the size of this series is the patch to switch\nto per-algorithm null OIDs via a null_oid function. It's certainly\npossible there are conflicts with topics in flight, but those should be\neasy to resolve (just change \"&null_oid\" to \"null_oid()\").\n\nIn addition, there's an initial set of patches to allow hashing an\nobject literally with any algorithm. Such objects cannot be written\ninto the object store, but their values can be printed.\n\nThis series is available as transition-interop-part-1 from the usual\nplaces and is part of the transition-interop branch (the entirety of the\nwork) as well. Be aware that the latter is very, very broken and its\nuse is not advised at this time.\n\nFuture series will likely include some fixes to our testsuite and code\nto map objects across hash algorithms.\n\nbrian m. carlson (15):\n sha1-file: allow hashing objects literally with any algorithm\n builtin/hash-object: allow literally hashing with a given algorithm\n cache: add an algo member to struct object_id\n Always use oidread to read into struct object_id\n hash: add a function to finalize object IDs\n Use the final_oid_fn to finalize hashing of object IDs\n builtin/pack-redundant: avoid casting buffers to struct object_id\n cache: compare the entire buffer for struct object_id\n hash: set and copy algo field in struct object_id\n hash: provide per-algorithm null OIDs\n builtin/show-index: set the algorithm for object IDs\n commit-graph: don't store file hashes as struct object_id\n builtin/pack-objects: avoid using struct object_id for pack hash\n hex: default to the_hash_algo on zero algorithm value\n hex: print objects using the hash algorithm member\n\n archive.c | 6 +-\n blame.c | 2 +-\n branch.c | 2 +-\n builtin/checkout.c | 6 +-\n builtin/clone.c | 2 +-\n builtin/describe.c | 2 +-\n builtin/diff.c | 2 +-\n builtin/fast-export.c | 10 +--\n builtin/fast-import.c | 8 +-\n builtin/grep.c | 2 +-\n builtin/hash-object.c | 47 ++++++++----\n builtin/index-pack.c | 6 +-\n builtin/ls-files.c | 2 +-\n builtin/pack-objects.c | 20 ++---\n builtin/pack-redundant.c | 28 +++----\n builtin/rebase.c | 4 +-\n builtin/receive-pack.c | 2 +-\n builtin/show-index.c | 4 +-\n builtin/submodule--helper.c | 29 +++----\n builtin/unpack-objects.c | 7 +-\n builtin/worktree.c | 4 +-\n bulk-checkin.c | 2 +-\n combine-diff.c | 2 +-\n commit-graph.c | 25 ++++---\n connect.c | 2 +-\n diff-lib.c | 6 +-\n diff-no-index.c | 2 +-\n diff.c | 6 +-\n dir.c | 6 +-\n grep.c | 2 +-\n hash.h | 73 +++++++++++-------\n hex.c | 20 +++--\n http-walker.c | 2 +-\n http.c | 2 +-\n log-tree.c | 2 +-\n match-trees.c | 2 +-\n merge-ort.c | 20 ++---\n merge-recursive.c | 10 +--\n midx.c | 2 +-\n notes-merge.c | 2 +-\n notes.c | 9 ++-\n object-file.c | 79 +++++++++++++++++---\n object-store.h | 3 +\n parse-options-cb.c | 2 +-\n range-diff.c | 2 +-\n read-cache.c | 4 +-\n refs.c | 4 +-\n refs/debug.c | 2 +-\n refs/files-backend.c | 2 +-\n reset.c | 2 +-\n sequencer.c | 4 +-\n split-index.c | 2 +-\n submodule-config.c | 2 +-\n submodule.c | 26 ++++---\n t/helper/test-submodule-nested-repo-config.c | 2 +-\n t/t1007-hash-object.sh | 10 +++\n tree-diff.c | 4 +-\n tree-walk.c | 2 +-\n wt-status.c | 4 +-\n xdiff-interface.c | 2 +-\n 60 files changed, 341 insertions(+), 209 deletions(-)\n\n"},{"id":"421536","messageId":"20210410152140.3525040-2-sandals@crustytoothpaste.net","threadId":"55472","inReplyTo":"20210410152140.3525040-1-sandals@crustytoothpaste.net","subject":"[PATCH 01/15] sha1-file: allow hashing objects literally with any algorithm","fromName":"brian m. carlson","fromEmail":"sandals@crustytoothpaste.net","sentAt":"2021-04-10T15:21:26Z","receivedAt":"2021-04-10T15:22:36Z","isPatch":true,"sender":{"key":"sandals@crustytoothpaste.net","avatar":"https://avatars.githubusercontent.com/u/497054?v=4"},"body":"In order to perform suitable testing with multiple algorithms and\ninteroperability, we'll need the ability to hash an object with a given\nalgorithm. Introduce this capability for now only for objects which are\nhashed literally by adding a function which does this and changing a\nstatic function to accept an algorithm pointer.\n\nSigned-off-by: brian m. carlson \n---\n object-file.c | 16 ++++++++++++++--\n object-store.h | 3 +++\n 2 files changed, 17 insertions(+), 2 deletions(-)\n\ndiff --git a/object-file.c b/object-file.c\nindex 624af408cd..f5847ee20f 100644\n--- a/object-file.c\n+++ b/object-file.c\n@@ -1957,6 +1957,15 @@ int write_object_file(const void *buf, unsigned long len, const char *type,\n int hash_object_file_literally(const void *buf, unsigned long len,\n \t\t\t const char *type, struct object_id *oid,\n \t\t\t unsigned flags)\n+{\n+\treturn hash_object_file_literally_algop(buf, len, type, oid, flags,\n+\t\t\t\t\t\tthe_hash_algo);\n+}\n+\n+int hash_object_file_literally_algop(const void *buf, unsigned long len,\n+\t\t\t\t const char *type, struct object_id *oid,\n+\t\t\t\t unsigned flags,\n+\t\t\t\t const struct git_hash_algo *algo)\n {\n \tchar *header;\n \tint hdrlen, status = 0;\n@@ -1964,11 +1973,14 @@ int hash_object_file_literally(const void *buf, unsigned long len,\n \t/* type string, SP, %lu of the length plus NUL must fit this */\n \thdrlen = strlen(type) + MAX_HEADER_LEN;\n \theader = xmalloc(hdrlen);\n-\twrite_object_file_prepare(the_hash_algo, buf, len, type, oid, header,\n-\t\t\t\t &hdrlen);\n+\twrite_object_file_prepare(algo, buf, len, type, oid, header, &hdrlen);\n \n \tif (!(flags & HASH_WRITE_OBJECT))\n \t\tgoto cleanup;\n+\tif (algo->format_id != the_hash_algo->format_id) {\n+\t\tstatus = -1;\n+\t\tgoto cleanup;\n+\t}\n \tif (freshen_packed_object(oid) || freshen_loose_object(oid))\n \t\tgoto cleanup;\n \tstatus = write_loose_object(oid, header, hdrlen, buf, len, 0);\ndiff --git a/object-store.h b/object-store.h\nindex ec32c23dcb..f95d03a7f5 100644\n--- a/object-store.h\n+++ b/object-store.h\n@@ -221,6 +221,9 @@ int hash_object_file_literally(const void *buf, unsigned long len,\n \t\t\t const char *type, struct object_id *oid,\n \t\t\t unsigned flags);\n \n+int hash_object_file_literally_algop(const void *buf, unsigned long len,\n+\t\t\t\t const char *type, struct object_id *oid,\n+\t\t\t\t unsigned flags, const struct git_hash_algo *algo);\n /*\n * Add an object file to the in-memory object store, without writing it\n * to disk.\n"},{"id":"421537","messageId":"20210410152140.3525040-5-sandals@crustytoothpaste.net","threadId":"55472","inReplyTo":"20210410152140.3525040-1-sandals@crustytoothpaste.net","subject":"[PATCH 04/15] Always use oidread to read into struct object_id","fromName":"brian m. carlson","fromEmail":"sandals@crustytoothpaste.net","sentAt":"2021-04-10T15:21:29Z","receivedAt":"2021-04-10T15:22:36Z","isPatch":true,"sender":{"key":"sandals@crustytoothpaste.net","avatar":"https://avatars.githubusercontent.com/u/497054?v=4"},"body":"In the future, we'll want oidread to automatically set the hash\nalgorithm member for an object ID we read into it, so ensure we use\noidread instead of hashcpy everywhere we're copying a hash value into a\nstruct object_id.\n\nSigned-off-by: brian m. carlson \n---\n archive.c | 2 +-\n builtin/fast-import.c | 4 ++--\n builtin/index-pack.c | 4 ++--\n builtin/unpack-objects.c | 2 +-\n commit-graph.c | 12 ++++++------\n dir.c | 4 ++--\n http-walker.c | 2 +-\n match-trees.c | 2 +-\n midx.c | 2 +-\n notes.c | 4 ++--\n read-cache.c | 4 ++--\n split-index.c | 2 +-\n tree-walk.c | 2 +-\n 13 files changed, 23 insertions(+), 23 deletions(-)\n\ndiff --git a/archive.c b/archive.c\nindex 295615580d..6cfb9e42d6 100644\n--- a/archive.c\n+++ b/archive.c\n@@ -203,7 +203,7 @@ static void queue_directory(const unsigned char *sha1,\n \td->mode\t = mode;\n \tc->bottom = d;\n \td->len = xsnprintf(d->path, len, \"%.*s%s/\", (int)base->len, base->buf, filename);\n-\thashcpy(d->oid.hash, sha1);\n+\toidread(&d->oid, sha1);\n }\n \n static int write_directory(struct archiver_context *c)\ndiff --git a/builtin/fast-import.c b/builtin/fast-import.c\nindex 3afa81cf9a..9d2a058a66 100644\n--- a/builtin/fast-import.c\n+++ b/builtin/fast-import.c\n@@ -1276,8 +1276,8 @@ static void load_tree(struct tree_entry *root)\n \t\te->versions[0].mode = e->versions[1].mode;\n \t\te->name = to_atom(c, strlen(c));\n \t\tc += e->name->str_len + 1;\n-\t\thashcpy(e->versions[0].oid.hash, (unsigned char *)c);\n-\t\thashcpy(e->versions[1].oid.hash, (unsigned char *)c);\n+\t\toidread(&e->versions[0].oid, (unsigned char *)c);\n+\t\toidread(&e->versions[1].oid, (unsigned char *)c);\n \t\tc += the_hash_algo->rawsz;\n \t}\n \tfree(buf);\ndiff --git a/builtin/index-pack.c b/builtin/index-pack.c\nindex 15507b5cff..41e2c240b8 100644\n--- a/builtin/index-pack.c\n+++ b/builtin/index-pack.c\n@@ -524,7 +524,7 @@ static void *unpack_raw_entry(struct object_entry *obj,\n \n \tswitch (obj->type) {\n \tcase OBJ_REF_DELTA:\n-\t\thashcpy(ref_oid->hash, fill(the_hash_algo->rawsz));\n+\t\toidread(ref_oid, fill(the_hash_algo->rawsz));\n \t\tuse(the_hash_algo->rawsz);\n \t\tbreak;\n \tcase OBJ_OFS_DELTA:\n@@ -1358,7 +1358,7 @@ static struct object_entry *append_obj_to_pack(struct hashfile *f,\n \tobj[1].idx.offset += write_compressed(f, buf, size);\n \tobj[0].idx.crc32 = crc32_end(f);\n \thashflush(f);\n-\thashcpy(obj->idx.oid.hash, sha1);\n+\toidread(&obj->idx.oid, sha1);\n \treturn obj;\n }\n \ndiff --git a/builtin/unpack-objects.c b/builtin/unpack-objects.c\nindex 4a70b17f8f..a8b73ecf43 100644\n--- a/builtin/unpack-objects.c\n+++ b/builtin/unpack-objects.c\n@@ -355,7 +355,7 @@ static void unpack_delta_entry(enum object_type type, unsigned long delta_size,\n \tstruct object_id base_oid;\n \n \tif (type == OBJ_REF_DELTA) {\n-\t\thashcpy(base_oid.hash, fill(the_hash_algo->rawsz));\n+\t\toidread(&base_oid, fill(the_hash_algo->rawsz));\n \t\tuse(the_hash_algo->rawsz);\n \t\tdelta_data = get_data(delta_size);\n \t\tif (dry_run || !delta_data) {\ndiff --git a/commit-graph.c b/commit-graph.c\nindex f18380b922..23fef56d31 100644\n--- a/commit-graph.c\n+++ b/commit-graph.c\n@@ -425,7 +425,7 @@ struct commit_graph *parse_commit_graph(struct repository *r,\n \t\tFREE_AND_NULL(graph->bloom_filter_settings);\n \t}\n \n-\thashcpy(graph->oid.hash, graph->data + graph->data_len - graph->hash_len);\n+\toidread(&graph->oid, graph->data + graph->data_len - graph->hash_len);\n \n \tif (verify_commit_graph_lite(graph))\n \t\tgoto free_and_return;\n@@ -746,7 +746,7 @@ static void load_oid_from_graph(struct commit_graph *g,\n \n \tlex_index = pos - g->num_commits_in_base;\n \n-\thashcpy(oid->hash, g->chunk_oid_lookup + g->hash_len * lex_index);\n+\toidread(oid, g->chunk_oid_lookup + g->hash_len * lex_index);\n }\n \n static struct commit_list **insert_parent_or_die(struct repository *r,\n@@ -939,7 +939,7 @@ static struct tree *load_tree_for_commit(struct repository *r,\n \tcommit_data = g->chunk_commit_data +\n \t\t\tGRAPH_DATA_WIDTH * (graph_pos - g->num_commits_in_base);\n \n-\thashcpy(oid.hash, commit_data);\n+\toidread(&oid, commit_data);\n \tset_commit_tree(c, lookup_tree(r, &oid));\n \n \treturn c->maybe_tree;\n@@ -2322,7 +2322,7 @@ int write_commit_graph(struct object_directory *odb,\n \t\tstruct commit_graph *g = ctx->r->objects->commit_graph;\n \t\tfor (i = 0; i < g->num_commits; i++) {\n \t\t\tstruct object_id oid;\n-\t\t\thashcpy(oid.hash, g->chunk_oid_lookup + g->hash_len * i);\n+\t\t\toidread(&oid, g->chunk_oid_lookup + g->hash_len * i);\n \t\t\toid_array_append(&ctx->oids, &oid);\n \t\t}\n \t}\n@@ -2453,7 +2453,7 @@ int verify_commit_graph(struct repository *r, struct commit_graph *g, int flags)\n \tfor (i = 0; i < g->num_commits; i++) {\n \t\tstruct commit *graph_commit;\n \n-\t\thashcpy(cur_oid.hash, g->chunk_oid_lookup + g->hash_len * i);\n+\t\toidread(&cur_oid, g->chunk_oid_lookup + g->hash_len * i);\n \n \t\tif (i && oidcmp(&prev_oid, &cur_oid) >= 0)\n \t\t\tgraph_report(_(\"commit-graph has incorrect OID order: %s then %s\"),\n@@ -2501,7 +2501,7 @@ int verify_commit_graph(struct repository *r, struct commit_graph *g, int flags)\n \t\ttimestamp_t generation;\n \n \t\tdisplay_progress(progress, i + 1);\n-\t\thashcpy(cur_oid.hash, g->chunk_oid_lookup + g->hash_len * i);\n+\t\toidread(&cur_oid, g->chunk_oid_lookup + g->hash_len * i);\n \n \t\tgraph_commit = lookup_commit(r, &cur_oid);\n \t\todb_commit = (struct commit *)create_object(r, &cur_oid, alloc_commit_node(r));\ndiff --git a/dir.c b/dir.c\nindex 3474e67e8f..813dd7ba53 100644\n--- a/dir.c\n+++ b/dir.c\n@@ -3344,7 +3344,7 @@ static void read_oid(size_t pos, void *cb)\n \t\trd->data = rd->end + 1;\n \t\treturn;\n \t}\n-\thashcpy(ud->exclude_oid.hash, rd->data);\n+\toidread(&ud->exclude_oid, rd->data);\n \trd->data += the_hash_algo->rawsz;\n }\n \n@@ -3352,7 +3352,7 @@ static void load_oid_stat(struct oid_stat *oid_stat, const unsigned char *data,\n \t\t\t const unsigned char *sha1)\n {\n \tstat_data_from_disk(&oid_stat->stat, data);\n-\thashcpy(oid_stat->oid.hash, sha1);\n+\toidread(&oid_stat->oid, sha1);\n \toid_stat->valid = 1;\n }\n \ndiff --git a/http-walker.c b/http-walker.c\nindex 4fb1235cd4..90d8ecb57e 100644\n--- a/http-walker.c\n+++ b/http-walker.c\n@@ -155,7 +155,7 @@ static void prefetch(struct walker *walker, unsigned char *sha1)\n \n \tnewreq = xmalloc(sizeof(*newreq));\n \tnewreq->walker = walker;\n-\thashcpy(newreq->oid.hash, sha1);\n+\toidread(&newreq->oid, sha1);\n \tnewreq->repo = data->alt;\n \tnewreq->state = WAITING;\n \tnewreq->req = NULL;\ndiff --git a/match-trees.c b/match-trees.c\nindex f6c194c1cc..df413989fa 100644\n--- a/match-trees.c\n+++ b/match-trees.c\n@@ -226,7 +226,7 @@ static int splice_tree(const struct object_id *oid1, const char *prefix,\n \t\t oid_to_hex(oid1));\n \tif (*subpath) {\n \t\tstruct object_id tree_oid;\n-\t\thashcpy(tree_oid.hash, rewrite_here);\n+\t\toidread(&tree_oid, rewrite_here);\n \t\tstatus = splice_tree(&tree_oid, subpath, oid2, &subtree);\n \t\tif (status)\n \t\t\treturn status;\ndiff --git a/midx.c b/midx.c\nindex 9e86583172..21d6a05e88 100644\n--- a/midx.c\n+++ b/midx.c\n@@ -247,7 +247,7 @@ struct object_id *nth_midxed_object_oid(struct object_id *oid,\n \tif (n >= m->num_objects)\n \t\treturn NULL;\n \n-\thashcpy(oid->hash, m->chunk_oid_lookup + m->hash_len * n);\n+\toidread(oid, m->chunk_oid_lookup + m->hash_len * n);\n \treturn oid;\n }\n \ndiff --git a/notes.c b/notes.c\nindex a19e4ad794..a44b25858f 100644\n--- a/notes.c\n+++ b/notes.c\n@@ -352,7 +352,7 @@ static void add_non_note(struct notes_tree *t, char *path,\n \tn->next = NULL;\n \tn->path = path;\n \tn->mode = mode;\n-\thashcpy(n->oid.hash, sha1);\n+\toidread(&n->oid, sha1);\n \tt->prev_non_note = n;\n \n \tif (!t->first_non_note) {\n@@ -1134,7 +1134,7 @@ int remove_note(struct notes_tree *t, const unsigned char *object_sha1)\n \tif (!t)\n \t\tt = &default_notes_tree;\n \tassert(t->initialized);\n-\thashcpy(l.key_oid.hash, object_sha1);\n+\toidread(&l.key_oid, object_sha1);\n \toidclr(&l.val_oid);\n \tnote_tree_remove(t, t->root, 0, &l);\n \tif (is_null_oid(&l.val_oid)) /* no note was removed */\ndiff --git a/read-cache.c b/read-cache.c\nindex 5a907af2fb..2944146545 100644\n--- a/read-cache.c\n+++ b/read-cache.c\n@@ -1845,7 +1845,7 @@ static struct cache_entry *create_from_disk(struct mem_pool *ce_mem_pool,\n \tce->ce_flags = flags & ~CE_NAMEMASK;\n \tce->ce_namelen = len;\n \tce->index = 0;\n-\thashcpy(ce->oid.hash, ondisk->data);\n+\toidread(&ce->oid, ondisk->data);\n \tmemcpy(ce->name, name, len);\n \tce->name[len] = '\\0';\n \n@@ -2195,7 +2195,7 @@ int do_read_index(struct index_state *istate, const char *path, int must_exist)\n \tif (verify_hdr(hdr, mmap_size) < 0)\n \t\tgoto unmap;\n \n-\thashcpy(istate->oid.hash, (const unsigned char *)hdr + mmap_size - the_hash_algo->rawsz);\n+\toidread(&istate->oid, (const unsigned char *)hdr + mmap_size - the_hash_algo->rawsz);\n \tistate->version = ntohl(hdr->hdr_version);\n \tistate->cache_nr = ntohl(hdr->hdr_entries);\n \tistate->cache_alloc = alloc_nr(istate->cache_nr);\ndiff --git a/split-index.c b/split-index.c\nindex 94937d21a3..4d6e52d46f 100644\n--- a/split-index.c\n+++ b/split-index.c\n@@ -21,7 +21,7 @@ int read_link_extension(struct index_state *istate,\n \tif (sz < the_hash_algo->rawsz)\n \t\treturn error(\"corrupt link extension (too short)\");\n \tsi = init_split_index(istate);\n-\thashcpy(si->base_oid.hash, data);\n+\toidread(&si->base_oid, data);\n \tdata += the_hash_algo->rawsz;\n \tsz -= the_hash_algo->rawsz;\n \tif (!sz)\ndiff --git a/tree-walk.c b/tree-walk.c\nindex 2d6226d5f1..3a94959d64 100644\n--- a/tree-walk.c\n+++ b/tree-walk.c\n@@ -49,7 +49,7 @@ static int decode_tree_entry(struct tree_desc *desc, const char *buf, unsigned l\n \tdesc->entry.path = path;\n \tdesc->entry.mode = canon_mode(mode);\n \tdesc->entry.pathlen = len - 1;\n-\thashcpy(desc->entry.oid.hash, (const unsigned char *)path + len);\n+\toidread(&desc->entry.oid, (const unsigned char *)path + len);\n \n \treturn 0;\n }\n"},{"id":"421538","messageId":"20210410152140.3525040-6-sandals@crustytoothpaste.net","threadId":"55472","inReplyTo":"20210410152140.3525040-1-sandals@crustytoothpaste.net","subject":"[PATCH 05/15] hash: add a function to finalize object IDs","fromName":"brian m. carlson","fromEmail":"sandals@crustytoothpaste.net","sentAt":"2021-04-10T15:21:30Z","receivedAt":"2021-04-10T15:22:37Z","isPatch":true,"sender":{"key":"sandals@crustytoothpaste.net","avatar":"https://avatars.githubusercontent.com/u/497054?v=4"},"body":"To avoid the penalty of having to branch in hash comparison functions,\nwe'll want to always compare the full hash member in a struct object_id,\nwhich will require that SHA-1 object IDs be zero-padded. To do so, add\na function which finalizes a hash context and writes it into an object\nID that performs this padding.\n\nMove the definition of struct object_id and the constant definitions\nhigher up so we they are available for us to use.\n\nSigned-off-by: brian m. carlson \n---\n hash.h | 50 +++++++++++++++++++++++++++-----------------------\n object-file.c | 25 +++++++++++++++++++++++++\n 2 files changed, 52 insertions(+), 23 deletions(-)\n\ndiff --git a/hash.h b/hash.h\nindex dafdcb3335..c8f03d8aee 100644\n--- a/hash.h\n+++ b/hash.h\n@@ -95,6 +95,29 @@ static inline void git_SHA256_Clone(git_SHA256_CTX *dst, const git_SHA256_CTX *s\n /* Number of algorithms supported (including unknown). */\n #define GIT_HASH_NALGOS (GIT_HASH_SHA256 + 1)\n \n+/* The length in bytes and in hex digits of an object name (SHA-1 value). */\n+#define GIT_SHA1_RAWSZ 20\n+#define GIT_SHA1_HEXSZ (2 * GIT_SHA1_RAWSZ)\n+/* The block size of SHA-1. */\n+#define GIT_SHA1_BLKSZ 64\n+\n+/* The length in bytes and in hex digits of an object name (SHA-256 value). */\n+#define GIT_SHA256_RAWSZ 32\n+#define GIT_SHA256_HEXSZ (2 * GIT_SHA256_RAWSZ)\n+/* The block size of SHA-256. */\n+#define GIT_SHA256_BLKSZ 64\n+\n+/* The length in byte and in hex digits of the largest possible hash value. */\n+#define GIT_MAX_RAWSZ GIT_SHA256_RAWSZ\n+#define GIT_MAX_HEXSZ GIT_SHA256_HEXSZ\n+/* The largest possible block size for any supported hash. */\n+#define GIT_MAX_BLKSZ GIT_SHA256_BLKSZ\n+\n+struct object_id {\n+\tunsigned char hash[GIT_MAX_RAWSZ];\n+\tint algo;\n+};\n+\n /* A suitably aligned type for stack allocations of hash contexts. */\n union git_hash_ctx {\n \tgit_SHA_CTX sha1;\n@@ -106,6 +129,7 @@ typedef void (*git_hash_init_fn)(git_hash_ctx *ctx);\n typedef void (*git_hash_clone_fn)(git_hash_ctx *dst, const git_hash_ctx *src);\n typedef void (*git_hash_update_fn)(git_hash_ctx *ctx, const void *in, size_t len);\n typedef void (*git_hash_final_fn)(unsigned char *hash, git_hash_ctx *ctx);\n+typedef void (*git_hash_final_oid_fn)(struct object_id *oid, git_hash_ctx *ctx);\n \n struct git_hash_algo {\n \t/*\n@@ -138,6 +162,9 @@ struct git_hash_algo {\n \t/* The hash finalization function. */\n \tgit_hash_final_fn final_fn;\n \n+\t/* The hash finalization function for object IDs. */\n+\tgit_hash_final_oid_fn final_oid_fn;\n+\n \t/* The OID of the empty tree. */\n \tconst struct object_id *empty_tree;\n \n@@ -161,29 +188,6 @@ static inline int hash_algo_by_ptr(const struct git_hash_algo *p)\n \treturn p - hash_algos;\n }\n \n-/* The length in bytes and in hex digits of an object name (SHA-1 value). */\n-#define GIT_SHA1_RAWSZ 20\n-#define GIT_SHA1_HEXSZ (2 * GIT_SHA1_RAWSZ)\n-/* The block size of SHA-1. */\n-#define GIT_SHA1_BLKSZ 64\n-\n-/* The length in bytes and in hex digits of an object name (SHA-256 value). */\n-#define GIT_SHA256_RAWSZ 32\n-#define GIT_SHA256_HEXSZ (2 * GIT_SHA256_RAWSZ)\n-/* The block size of SHA-256. */\n-#define GIT_SHA256_BLKSZ 64\n-\n-/* The length in byte and in hex digits of the largest possible hash value. */\n-#define GIT_MAX_RAWSZ GIT_SHA256_RAWSZ\n-#define GIT_MAX_HEXSZ GIT_SHA256_HEXSZ\n-/* The largest possible block size for any supported hash. */\n-#define GIT_MAX_BLKSZ GIT_SHA256_BLKSZ\n-\n-struct object_id {\n-\tunsigned char hash[GIT_MAX_RAWSZ];\n-\tint algo;\n-};\n-\n #define the_hash_algo the_repository->hash_algo\n \n extern const struct object_id null_oid;\ndiff --git a/object-file.c b/object-file.c\nindex f5847ee20f..58d31452d8 100644\n--- a/object-file.c\n+++ b/object-file.c\n@@ -89,6 +89,12 @@ static void git_hash_sha1_final(unsigned char *hash, git_hash_ctx *ctx)\n \tgit_SHA1_Final(hash, &ctx->sha1);\n }\n \n+static void git_hash_sha1_final_oid(struct object_id *oid, git_hash_ctx *ctx)\n+{\n+\tgit_SHA1_Final(oid->hash, &ctx->sha1);\n+\tmemset(oid->hash + GIT_SHA1_RAWSZ, 0, GIT_MAX_RAWSZ - GIT_SHA1_RAWSZ);\n+}\n+\n \n static void git_hash_sha256_init(git_hash_ctx *ctx)\n {\n@@ -110,6 +116,16 @@ static void git_hash_sha256_final(unsigned char *hash, git_hash_ctx *ctx)\n \tgit_SHA256_Final(hash, &ctx->sha256);\n }\n \n+static void git_hash_sha256_final_oid(struct object_id *oid, git_hash_ctx *ctx)\n+{\n+\tgit_SHA256_Final(oid->hash, &ctx->sha256);\n+\t/*\n+\t * This currently does nothing, so the compiler should optimize it out,\n+\t * but keep it in case we extend the hash size again.\n+\t */\n+\tmemset(oid->hash + GIT_SHA256_RAWSZ, 0, GIT_MAX_RAWSZ - GIT_SHA256_RAWSZ);\n+}\n+\n static void git_hash_unknown_init(git_hash_ctx *ctx)\n {\n \tBUG(\"trying to init unknown hash\");\n@@ -130,6 +146,12 @@ static void git_hash_unknown_final(unsigned char *hash, git_hash_ctx *ctx)\n \tBUG(\"trying to finalize unknown hash\");\n }\n \n+static void git_hash_unknown_final_oid(struct object_id *oid, git_hash_ctx *ctx)\n+{\n+\tBUG(\"trying to finalize unknown hash\");\n+}\n+\n+\n const struct git_hash_algo hash_algos[GIT_HASH_NALGOS] = {\n \t{\n \t\tNULL,\n@@ -141,6 +163,7 @@ const struct git_hash_algo hash_algos[GIT_HASH_NALGOS] = {\n \t\tgit_hash_unknown_clone,\n \t\tgit_hash_unknown_update,\n \t\tgit_hash_unknown_final,\n+\t\tgit_hash_unknown_final_oid,\n \t\tNULL,\n \t\tNULL,\n \t},\n@@ -155,6 +178,7 @@ const struct git_hash_algo hash_algos[GIT_HASH_NALGOS] = {\n \t\tgit_hash_sha1_clone,\n \t\tgit_hash_sha1_update,\n \t\tgit_hash_sha1_final,\n+\t\tgit_hash_sha1_final_oid,\n \t\t&empty_tree_oid,\n \t\t&empty_blob_oid,\n \t},\n@@ -169,6 +193,7 @@ const struct git_hash_algo hash_algos[GIT_HASH_NALGOS] = {\n \t\tgit_hash_sha256_clone,\n \t\tgit_hash_sha256_update,\n \t\tgit_hash_sha256_final,\n+\t\tgit_hash_sha256_final_oid,\n \t\t&empty_tree_oid_sha256,\n \t\t&empty_blob_oid_sha256,\n \t}\n"},{"id":"421539","messageId":"20210410152140.3525040-8-sandals@crustytoothpaste.net","threadId":"55472","inReplyTo":"20210410152140.3525040-1-sandals@crustytoothpaste.net","subject":"[PATCH 07/15] builtin/pack-redundant: avoid casting buffers to struct object_id","fromName":"brian m. carlson","fromEmail":"sandals@crustytoothpaste.net","sentAt":"2021-04-10T15:21:32Z","receivedAt":"2021-04-10T15:22:38Z","isPatch":true,"sender":{"key":"sandals@crustytoothpaste.net","avatar":"https://avatars.githubusercontent.com/u/497054?v=4"},"body":"Now that we need our instances of struct object_id to be zero padded, we\ncan no longer cast unsigned char buffers to be pointers to struct\nobject_id. This file reads data out of the pack objects and then\ninserts it directly into a linked list item which is a pointer to struct\nobject_id. Instead, let's have the linked list item hold its own struct\nobject_id and copy the data into it.\n\nIn addition, since these are not really pointers to struct object_id,\nstop passing them around as such, and call them what they really are:\npointers to unsigned char.\n\nSigned-off-by: brian m. carlson \n---\n builtin/pack-redundant.c | 28 ++++++++++++++--------------\n 1 file changed, 14 insertions(+), 14 deletions(-)\n\ndiff --git a/builtin/pack-redundant.c b/builtin/pack-redundant.c\nindex 7102996c75..8bf5c0acad 100644\n--- a/builtin/pack-redundant.c\n+++ b/builtin/pack-redundant.c\n@@ -20,7 +20,7 @@ static int load_all_packs, verbose, alt_odb;\n \n struct llist_item {\n \tstruct llist_item *next;\n-\tconst struct object_id *oid;\n+\tstruct object_id oid;\n };\n static struct llist {\n \tstruct llist_item *front;\n@@ -95,10 +95,10 @@ static struct llist * llist_copy(struct llist *list)\n \n static inline struct llist_item *llist_insert(struct llist *list,\n \t\t\t\t\t struct llist_item *after,\n-\t\t\t\t\t const struct object_id *oid)\n+\t\t\t\t\t const unsigned char *oid)\n {\n \tstruct llist_item *new_item = llist_item_get();\n-\tnew_item->oid = oid;\n+\toidread(&new_item->oid, oid);\n \tnew_item->next = NULL;\n \n \tif (after != NULL) {\n@@ -118,7 +118,7 @@ static inline struct llist_item *llist_insert(struct llist *list,\n }\n \n static inline struct llist_item *llist_insert_back(struct llist *list,\n-\t\t\t\t\t\t const struct object_id *oid)\n+\t\t\t\t\t\t const unsigned char *oid)\n {\n \treturn llist_insert(list, list->back, oid);\n }\n@@ -130,9 +130,9 @@ static inline struct llist_item *llist_insert_sorted_unique(struct llist *list,\n \n \tl = (hint == NULL) ? list->front : hint;\n \twhile (l) {\n-\t\tint cmp = oidcmp(l->oid, oid);\n+\t\tint cmp = oidcmp(&l->oid, oid);\n \t\tif (cmp > 0) { /* we insert before this entry */\n-\t\t\treturn llist_insert(list, prev, oid);\n+\t\t\treturn llist_insert(list, prev, oid->hash);\n \t\t}\n \t\tif (!cmp) { /* already exists */\n \t\t\treturn l;\n@@ -141,11 +141,11 @@ static inline struct llist_item *llist_insert_sorted_unique(struct llist *list,\n \t\tl = l->next;\n \t}\n \t/* insert at the end */\n-\treturn llist_insert_back(list, oid);\n+\treturn llist_insert_back(list, oid->hash);\n }\n \n /* returns a pointer to an item in front of sha1 */\n-static inline struct llist_item * llist_sorted_remove(struct llist *list, const struct object_id *oid, struct llist_item *hint)\n+static inline struct llist_item * llist_sorted_remove(struct llist *list, const unsigned char *oid, struct llist_item *hint)\n {\n \tstruct llist_item *prev, *l;\n \n@@ -153,7 +153,7 @@ static inline struct llist_item * llist_sorted_remove(struct llist *list, const\n \tl = (hint == NULL) ? list->front : hint;\n \tprev = NULL;\n \twhile (l) {\n-\t\tconst int cmp = oidcmp(l->oid, oid);\n+\t\tconst int cmp = hashcmp(l->oid.hash, oid);\n \t\tif (cmp > 0) /* not in list, since sorted */\n \t\t\treturn prev;\n \t\tif (!cmp) { /* found */\n@@ -188,7 +188,7 @@ static void llist_sorted_difference_inplace(struct llist *A,\n \tb = B->front;\n \n \twhile (b) {\n-\t\thint = llist_sorted_remove(A, b->oid, hint);\n+\t\thint = llist_sorted_remove(A, b->oid.hash, hint);\n \t\tb = b->next;\n \t}\n }\n@@ -260,10 +260,10 @@ static void cmp_two_packs(struct pack_list *p1, struct pack_list *p2)\n \t\t/* cmp ~ p1 - p2 */\n \t\tif (cmp == 0) {\n \t\t\tp1_hint = llist_sorted_remove(p1->unique_objects,\n-\t\t\t\t\t(const struct object_id *)(p1_base + p1_off),\n+\t\t\t\t\tp1_base + p1_off,\n \t\t\t\t\tp1_hint);\n \t\t\tp2_hint = llist_sorted_remove(p2->unique_objects,\n-\t\t\t\t\t(const struct object_id *)(p1_base + p1_off),\n+\t\t\t\t\tp1_base + p1_off,\n \t\t\t\t\tp2_hint);\n \t\t\tp1_off += p1_step;\n \t\t\tp2_off += p2_step;\n@@ -455,7 +455,7 @@ static void load_all_objects(void)\n \t\tl = pl->remaining_objects->front;\n \t\twhile (l) {\n \t\t\thint = llist_insert_sorted_unique(all_objects,\n-\t\t\t\t\t\t\t l->oid, hint);\n+\t\t\t\t\t\t\t &l->oid, hint);\n \t\t\tl = l->next;\n \t\t}\n \t\tpl = pl->next;\n@@ -521,7 +521,7 @@ static struct pack_list * add_pack(struct packed_git *p)\n \tbase += 256 * 4 + ((p->index_version < 2) ? 4 : 8);\n \tstep = the_hash_algo->rawsz + ((p->index_version < 2) ? 4 : 0);\n \twhile (off < p->num_objects * step) {\n-\t\tllist_insert_back(l.remaining_objects, (const struct object_id *)(base + off));\n+\t\tllist_insert_back(l.remaining_objects, base + off);\n \t\toff += step;\n \t}\n \tl.all_objects_size = l.remaining_objects->size;\n"},{"id":"421540","messageId":"20210410152140.3525040-9-sandals@crustytoothpaste.net","threadId":"55472","inReplyTo":"20210410152140.3525040-1-sandals@crustytoothpaste.net","subject":"[PATCH 08/15] cache: compare the entire buffer for struct object_id","fromName":"brian m. carlson","fromEmail":"sandals@crustytoothpaste.net","sentAt":"2021-04-10T15:21:33Z","receivedAt":"2021-04-10T15:22:39Z","isPatch":true,"sender":{"key":"sandals@crustytoothpaste.net","avatar":"https://avatars.githubusercontent.com/u/497054?v=4"},"body":"Currently, when we compare two object IDs, we have to take a branch to\ndetermine what the hash size is supposed to be. The compiler can\noptimize well for a single length, but has trouble when there are two\npossible lengths.\n\nThere is, however, an alternative: we can ensure that we always compare\nthe full length of the hash buffer, but in turn we must zero the\nremainder of the buffer when using SHA-1; otherwise, we'll end up with\nincompatible junk at the end of otherwise equivalent object IDs that\nwill prevent them from matching. This is an acceptable tradeoff,\nbecause we generally read an object ID in once, but then compare it\nagainst others multiple times.\n\nThis latter approach also has some benefits as well: since we will have\nannotated every location in which we load an object ID into an instance\nof struct object_id, if we want to set the hash algorithm for the object\nID, we can do so at the same time.\n\nAdopt this latter approach, since it provides us greater flexibility and\nlets us read and store object IDs for multiple algorithms at once.\n\nSigned-off-by: brian m. carlson \n---\n hash.h | 13 ++++++++++---\n hex.c | 9 ++++++---\n notes.c | 3 +++\n object-file.c | 1 +\n 4 files changed, 20 insertions(+), 6 deletions(-)\n\ndiff --git a/hash.h b/hash.h\nindex c8f03d8aee..04eba5c56b 100644\n--- a/hash.h\n+++ b/hash.h\n@@ -205,7 +205,7 @@ static inline int hashcmp(const unsigned char *sha1, const unsigned char *sha2)\n \n static inline int oidcmp(const struct object_id *oid1, const struct object_id *oid2)\n {\n-\treturn hashcmp(oid1->hash, oid2->hash);\n+\treturn memcmp(oid1->hash, oid2->hash, GIT_MAX_RAWSZ);\n }\n \n static inline int hasheq(const unsigned char *sha1, const unsigned char *sha2)\n@@ -221,7 +221,7 @@ static inline int hasheq(const unsigned char *sha1, const unsigned char *sha2)\n \n static inline int oideq(const struct object_id *oid1, const struct object_id *oid2)\n {\n-\treturn hasheq(oid1->hash, oid2->hash);\n+\treturn !memcmp(oid1->hash, oid2->hash, GIT_MAX_RAWSZ);\n }\n \n static inline int is_null_oid(const struct object_id *oid)\n@@ -258,7 +258,9 @@ static inline void oidclr(struct object_id *oid)\n \n static inline void oidread(struct object_id *oid, const unsigned char *hash)\n {\n-\tmemcpy(oid->hash, hash, the_hash_algo->rawsz);\n+\tsize_t rawsz = the_hash_algo->rawsz;\n+\tmemcpy(oid->hash, hash, rawsz);\n+\tmemset(oid->hash + rawsz, 0, GIT_MAX_RAWSZ - rawsz);\n }\n \n static inline int is_empty_blob_sha1(const unsigned char *sha1)\n@@ -281,6 +283,11 @@ static inline int is_empty_tree_oid(const struct object_id *oid)\n \treturn oideq(oid, the_hash_algo->empty_tree);\n }\n \n+static inline void oid_pad_buffer(struct object_id *oid, const struct git_hash_algo *algop)\n+{\n+\tmemset(oid->hash + algop->rawsz, 0, GIT_MAX_RAWSZ - algop->rawsz);\n+}\n+\n const char *empty_tree_oid_hex(void);\n const char *empty_blob_oid_hex(void);\n \ndiff --git a/hex.c b/hex.c\nindex da51e64929..5fa3e71cb9 100644\n--- a/hex.c\n+++ b/hex.c\n@@ -69,7 +69,10 @@ int get_sha1_hex(const char *hex, unsigned char *sha1)\n int get_oid_hex_algop(const char *hex, struct object_id *oid,\n \t\t const struct git_hash_algo *algop)\n {\n-\treturn get_hash_hex_algop(hex, oid->hash, algop);\n+\tint ret = get_hash_hex_algop(hex, oid->hash, algop);\n+\tif (!ret)\n+\t\toid_pad_buffer(oid, algop);\n+\treturn ret;\n }\n \n /*\n@@ -80,7 +83,7 @@ int get_oid_hex_any(const char *hex, struct object_id *oid)\n {\n \tint i;\n \tfor (i = GIT_HASH_NALGOS - 1; i > 0; i--) {\n-\t\tif (!get_hash_hex_algop(hex, oid->hash, &hash_algos[i]))\n+\t\tif (!get_oid_hex_algop(hex, oid, &hash_algos[i]))\n \t\t\treturn i;\n \t}\n \treturn GIT_HASH_UNKNOWN;\n@@ -95,7 +98,7 @@ int parse_oid_hex_algop(const char *hex, struct object_id *oid,\n \t\t\tconst char **end,\n \t\t\tconst struct git_hash_algo *algop)\n {\n-\tint ret = get_hash_hex_algop(hex, oid->hash, algop);\n+\tint ret = get_oid_hex_algop(hex, oid, algop);\n \tif (!ret)\n \t\t*end = hex + algop->hexsz;\n \treturn ret;\ndiff --git a/notes.c b/notes.c\nindex a44b25858f..1dfe9e2b9f 100644\n--- a/notes.c\n+++ b/notes.c\n@@ -455,6 +455,8 @@ static void load_subtree(struct notes_tree *t, struct leaf_node *subtree,\n \t\tCALLOC_ARRAY(l, 1);\n \t\toidcpy(&l->key_oid, &object_oid);\n \t\toidcpy(&l->val_oid, &entry.oid);\n+\t\toid_pad_buffer(&l->key_oid, the_hash_algo);\n+\t\toid_pad_buffer(&l->val_oid, the_hash_algo);\n \t\tif (note_tree_insert(t, node, n, l, type,\n \t\t\t\t combine_notes_concatenate))\n \t\t\tdie(\"Failed to load %s %s into notes tree \"\n@@ -484,6 +486,7 @@ static void load_subtree(struct notes_tree *t, struct leaf_node *subtree,\n \t\t\t\tstrbuf_addch(&non_note_path, '/');\n \t\t\t}\n \t\t\tstrbuf_addstr(&non_note_path, entry.path);\n+\t\t\toid_pad_buffer(&entry.oid, the_hash_algo);\n \t\t\tadd_non_note(t, strbuf_detach(&non_note_path, NULL),\n \t\t\t\t entry.mode, entry.oid.hash);\n \t\t}\ndiff --git a/object-file.c b/object-file.c\nindex 3f43c376e7..8e338247cc 100644\n--- a/object-file.c\n+++ b/object-file.c\n@@ -2352,6 +2352,7 @@ int for_each_file_in_obj_subdir(unsigned int subdir_nr,\n \t\tif (namelen == the_hash_algo->hexsz - 2 &&\n \t\t !hex_to_bytes(oid.hash + 1, de->d_name,\n \t\t\t\t the_hash_algo->rawsz - 1)) {\n+\t\t\toid_pad_buffer(&oid, the_hash_algo);\n \t\t\tif (obj_cb) {\n \t\t\t\tr = obj_cb(&oid, path->buf, data);\n \t\t\t\tif (r)\n"},{"id":"421542","messageId":"20210410152140.3525040-11-sandals@crustytoothpaste.net","threadId":"55472","inReplyTo":"20210410152140.3525040-1-sandals@crustytoothpaste.net","subject":"[PATCH 10/15] hash: provide per-algorithm null OIDs","fromName":"brian m. carlson","fromEmail":"sandals@crustytoothpaste.net","sentAt":"2021-04-10T15:21:35Z","receivedAt":"2021-04-10T15:22:40Z","isPatch":true,"sender":{"key":"sandals@crustytoothpaste.net","avatar":"https://avatars.githubusercontent.com/u/497054?v=4"},"body":"Up until recently, object IDs did not have an algorithm member, only a\nhash. Consequently, it was possible to share one null (all-zeros)\nobject ID among all hash algorithms. Now that we're going to be\nhandling objects from multiple hash algorithms, it's important to make\nsure that all object IDs have a correct algorithm field.\n\nIntroduce a per-algorithm null OID, and add it to struct hash_algo.\nIntroduce a wrapper function as well, and use it everywhere we used to\nuse the null_oid constant.\n\nSigned-off-by: brian m. carlson \n---\n archive.c | 4 ++-\n blame.c | 2 +-\n branch.c | 2 +-\n builtin/checkout.c | 6 ++--\n builtin/clone.c | 2 +-\n builtin/describe.c | 2 +-\n builtin/diff.c | 2 +-\n builtin/fast-export.c | 10 +++----\n builtin/grep.c | 2 +-\n builtin/ls-files.c | 2 +-\n builtin/rebase.c | 4 +--\n builtin/receive-pack.c | 2 +-\n builtin/submodule--helper.c | 29 ++++++++++----------\n builtin/unpack-objects.c | 3 +-\n builtin/worktree.c | 4 +--\n combine-diff.c | 2 +-\n connect.c | 2 +-\n diff-lib.c | 6 ++--\n diff-no-index.c | 2 +-\n diff.c | 4 +--\n dir.c | 2 +-\n grep.c | 2 +-\n hash.h | 7 +++--\n log-tree.c | 2 +-\n merge-ort.c | 20 +++++++-------\n merge-recursive.c | 10 +++----\n notes-merge.c | 2 +-\n notes.c | 2 +-\n object-file.c | 15 +++++++++-\n parse-options-cb.c | 2 +-\n range-diff.c | 2 +-\n refs.c | 4 +--\n refs/debug.c | 2 +-\n refs/files-backend.c | 2 +-\n reset.c | 2 +-\n sequencer.c | 4 +--\n submodule-config.c | 2 +-\n submodule.c | 26 ++++++++++--------\n t/helper/test-submodule-nested-repo-config.c | 2 +-\n tree-diff.c | 4 +--\n wt-status.c | 4 +--\n xdiff-interface.c | 2 +-\n 42 files changed, 117 insertions(+), 95 deletions(-)\n\ndiff --git a/archive.c b/archive.c\nindex 6cfb9e42d6..ff2bb54f62 100644\n--- a/archive.c\n+++ b/archive.c\n@@ -275,9 +275,11 @@ int write_archive_entries(struct archiver_args *args,\n \tint err;\n \tstruct strbuf path_in_archive = STRBUF_INIT;\n \tstruct strbuf content = STRBUF_INIT;\n-\tstruct object_id fake_oid = null_oid;\n+\tstruct object_id fake_oid;\n \tint i;\n \n+\toidcpy(&fake_oid, null_oid());\n+\n \tif (args->baselen > 0 && args->base[args->baselen - 1] == '/') {\n \t\tsize_t len = args->baselen;\n \ndiff --git a/blame.c b/blame.c\nindex 5018bb8fb2..206c295660 100644\n--- a/blame.c\n+++ b/blame.c\n@@ -242,7 +242,7 @@ static struct commit *fake_working_tree_commit(struct repository *r,\n \t\tswitch (st.st_mode & S_IFMT) {\n \t\tcase S_IFREG:\n \t\t\tif (opt->flags.allow_textconv &&\n-\t\t\t textconv_object(r, read_from, mode, &null_oid, 0, &buf_ptr, &buf_len))\n+\t\t\t textconv_object(r, read_from, mode, null_oid(), 0, &buf_ptr, &buf_len))\n \t\t\t\tstrbuf_attach(&buf, buf_ptr, buf_len, buf_len + 1);\n \t\t\telse if (strbuf_read_file(&buf, read_from, st.st_size) != st.st_size)\n \t\t\t\tdie_errno(\"cannot open or read '%s'\", read_from);\ndiff --git a/branch.c b/branch.c\nindex 9c9dae1eae..8db10f8496 100644\n--- a/branch.c\n+++ b/branch.c\n@@ -322,7 +322,7 @@ void create_branch(struct repository *r,\n \t\ttransaction = ref_transaction_begin(&err);\n \t\tif (!transaction ||\n \t\t ref_transaction_update(transaction, ref.buf,\n-\t\t\t\t\t &oid, forcing ? NULL : &null_oid,\n+\t\t\t\t\t &oid, forcing ? NULL : null_oid(),\n \t\t\t\t\t 0, msg, &err) ||\n \t\t ref_transaction_commit(transaction, &err))\n \t\t\tdie(\"%s\", err.buf);\ndiff --git a/builtin/checkout.c b/builtin/checkout.c\nindex 4c696ef480..8a12b92c5f 100644\n--- a/builtin/checkout.c\n+++ b/builtin/checkout.c\n@@ -106,8 +106,8 @@ static int post_checkout_hook(struct commit *old_commit, struct commit *new_comm\n \t\t\t int changed)\n {\n \treturn run_hook_le(NULL, \"post-checkout\",\n-\t\t\t oid_to_hex(old_commit ? &old_commit->object.oid : &null_oid),\n-\t\t\t oid_to_hex(new_commit ? &new_commit->object.oid : &null_oid),\n+\t\t\t oid_to_hex(old_commit ? &old_commit->object.oid : null_oid()),\n+\t\t\t oid_to_hex(new_commit ? &new_commit->object.oid : null_oid()),\n \t\t\t changed ? \"1\" : \"0\", NULL);\n \t/* \"new_commit\" can be NULL when checking out from the index before\n \t a commit exists. */\n@@ -638,7 +638,7 @@ static int reset_tree(struct tree *tree, const struct checkout_opts *o,\n \topts.src_index = &the_index;\n \topts.dst_index = &the_index;\n \tinit_checkout_metadata(&opts.meta, info->refname,\n-\t\t\t info->commit ? &info->commit->object.oid : &null_oid,\n+\t\t\t info->commit ? &info->commit->object.oid : null_oid(),\n \t\t\t NULL);\n \tparse_tree(tree);\n \tinit_tree_desc(&tree_desc, tree->buffer, tree->size);\ndiff --git a/builtin/clone.c b/builtin/clone.c\nindex f6b0c48bed..eeb74c0217 100644\n--- a/builtin/clone.c\n+++ b/builtin/clone.c\n@@ -820,7 +820,7 @@ static int checkout(int submodule_progress)\n \tif (write_locked_index(&the_index, &lock_file, COMMIT_LOCK))\n \t\tdie(_(\"unable to write new index file\"));\n \n-\terr |= run_hook_le(NULL, \"post-checkout\", oid_to_hex(&null_oid),\n+\terr |= run_hook_le(NULL, \"post-checkout\", oid_to_hex(null_oid()),\n \t\t\t oid_to_hex(&oid), \"1\", NULL);\n \n \tif (!err && (option_recurse_submodules.nr > 0)) {\ndiff --git a/builtin/describe.c b/builtin/describe.c\nindex 40482d8e9f..e912ba50d7 100644\n--- a/builtin/describe.c\n+++ b/builtin/describe.c\n@@ -502,7 +502,7 @@ static void describe_blob(struct object_id oid, struct strbuf *dst)\n {\n \tstruct rev_info revs;\n \tstruct strvec args = STRVEC_INIT;\n-\tstruct process_commit_data pcd = { null_oid, oid, dst, &revs};\n+\tstruct process_commit_data pcd = { *null_oid(), oid, dst, &revs};\n \n \tstrvec_pushl(&args, \"internal: The first arg is not parsed\",\n \t\t \"--objects\", \"--in-commit-order\", \"--reverse\", \"HEAD\",\ndiff --git a/builtin/diff.c b/builtin/diff.c\nindex 617b9a4101..2d87c37a17 100644\n--- a/builtin/diff.c\n+++ b/builtin/diff.c\n@@ -98,7 +98,7 @@ static int builtin_diff_b_f(struct rev_info *revs,\n \n \tstuff_change(&revs->diffopt,\n \t\t blob[0]->mode, canon_mode(st.st_mode),\n-\t\t &blob[0]->item->oid, &null_oid,\n+\t\t &blob[0]->item->oid, null_oid(),\n \t\t 1, 0,\n \t\t blob[0]->path ? blob[0]->path : path,\n \t\t path);\ndiff --git a/builtin/fast-export.c b/builtin/fast-export.c\nindex 85a76e0ef8..3c20f164f0 100644\n--- a/builtin/fast-export.c\n+++ b/builtin/fast-export.c\n@@ -870,7 +870,7 @@ static void handle_tag(const char *name, struct tag *tag)\n \t\t\t\tp = rewrite_commit((struct commit *)tagged);\n \t\t\t\tif (!p) {\n \t\t\t\t\tprintf(\"reset %s\\nfrom %s\\n\\n\",\n-\t\t\t\t\t name, oid_to_hex(&null_oid));\n+\t\t\t\t\t name, oid_to_hex(null_oid()));\n \t\t\t\t\tfree(buf);\n \t\t\t\t\treturn;\n \t\t\t\t}\n@@ -884,7 +884,7 @@ static void handle_tag(const char *name, struct tag *tag)\n \n \tif (tagged->type == OBJ_TAG) {\n \t\tprintf(\"reset %s\\nfrom %s\\n\\n\",\n-\t\t name, oid_to_hex(&null_oid));\n+\t\t name, oid_to_hex(null_oid()));\n \t}\n \tskip_prefix(name, \"refs/tags/\", &name);\n \tprintf(\"tag %s\\n\", name);\n@@ -1016,7 +1016,7 @@ static void handle_tags_and_duplicates(struct string_list *extras)\n \t\t\t\t * it.\n \t\t\t\t */\n \t\t\t\tprintf(\"reset %s\\nfrom %s\\n\\n\",\n-\t\t\t\t name, oid_to_hex(&null_oid));\n+\t\t\t\t name, oid_to_hex(null_oid()));\n \t\t\t\tcontinue;\n \t\t\t}\n \n@@ -1035,7 +1035,7 @@ static void handle_tags_and_duplicates(struct string_list *extras)\n \t\t\t\tif (!reference_excluded_commits) {\n \t\t\t\t\t/* delete the ref */\n \t\t\t\t\tprintf(\"reset %s\\nfrom %s\\n\\n\",\n-\t\t\t\t\t name, oid_to_hex(&null_oid));\n+\t\t\t\t\t name, oid_to_hex(null_oid()));\n \t\t\t\t\tcontinue;\n \t\t\t\t}\n \t\t\t\t/* set ref to commit using oid, not mark */\n@@ -1146,7 +1146,7 @@ static void handle_deletes(void)\n \t\t\tcontinue;\n \n \t\tprintf(\"reset %s\\nfrom %s\\n\\n\",\n-\t\t\t\trefspec->dst, oid_to_hex(&null_oid));\n+\t\t\t\trefspec->dst, oid_to_hex(null_oid()));\n \t}\n }\n \ndiff --git a/builtin/grep.c b/builtin/grep.c\nindex 5de725f904..e0e326004e 100644\n--- a/builtin/grep.c\n+++ b/builtin/grep.c\n@@ -421,7 +421,7 @@ static int grep_submodule(struct grep_opt *opt,\n \tstruct grep_opt subopt;\n \tint hit;\n \n-\tsub = submodule_from_path(superproject, &null_oid, path);\n+\tsub = submodule_from_path(superproject, null_oid(), path);\n \n \tif (!is_submodule_active(superproject, path))\n \t\treturn 0;\ndiff --git a/builtin/ls-files.c b/builtin/ls-files.c\nindex 60a2913a01..c589eb7f89 100644\n--- a/builtin/ls-files.c\n+++ b/builtin/ls-files.c\n@@ -210,7 +210,7 @@ static void show_submodule(struct repository *superproject,\n {\n \tstruct repository subrepo;\n \tconst struct submodule *sub = submodule_from_path(superproject,\n-\t\t\t\t\t\t\t &null_oid, path);\n+\t\t\t\t\t\t\t null_oid(), path);\n \n \tif (repo_submodule_init(&subrepo, superproject, sub))\n \t\treturn;\ndiff --git a/builtin/rebase.c b/builtin/rebase.c\nindex 783b526f6e..c9206b40ea 100644\n--- a/builtin/rebase.c\n+++ b/builtin/rebase.c\n@@ -485,7 +485,7 @@ static const char * const builtin_rebase_interactive_usage[] = {\n int cmd_rebase__interactive(int argc, const char **argv, const char *prefix)\n {\n \tstruct rebase_options opts = REBASE_OPTIONS_INIT;\n-\tstruct object_id squash_onto = null_oid;\n+\tstruct object_id squash_onto = *null_oid();\n \tenum action command = ACTION_NONE;\n \tstruct option options[] = {\n \t\tOPT_NEGBIT(0, \"ff\", &opts.flags, N_(\"allow fast-forward\"),\n@@ -1139,7 +1139,7 @@ static int can_fast_forward(struct commit *onto, struct commit *upstream,\n \n \tmerge_bases = get_merge_bases(onto, head);\n \tif (!merge_bases || merge_bases->next) {\n-\t\toidcpy(merge_base, &null_oid);\n+\t\toidcpy(merge_base, null_oid());\n \t\tgoto done;\n \t}\n \ndiff --git a/builtin/receive-pack.c b/builtin/receive-pack.c\nindex 6bc12c828a..a34742513a 100644\n--- a/builtin/receive-pack.c\n+++ b/builtin/receive-pack.c\n@@ -329,7 +329,7 @@ static void write_head_info(void)\n \tfor_each_alternate_ref(show_one_alternate_ref, &seen);\n \toidset_clear(&seen);\n \tif (!sent_capabilities)\n-\t\tshow_ref(\"capabilities^{}\", &null_oid);\n+\t\tshow_ref(\"capabilities^{}\", null_oid());\n \n \tadvertise_shallow_grafts(1);\n \ndiff --git a/builtin/submodule--helper.c b/builtin/submodule--helper.c\nindex 9d505a6329..d55f6262e9 100644\n--- a/builtin/submodule--helper.c\n+++ b/builtin/submodule--helper.c\n@@ -426,7 +426,8 @@ static int module_list(int argc, const char **argv, const char *prefix)\n \t\tconst struct cache_entry *ce = list.entries[i];\n \n \t\tif (ce_stage(ce))\n-\t\t\tprintf(\"%06o %s U\\t\", ce->ce_mode, oid_to_hex(&null_oid));\n+\t\t\tprintf(\"%06o %s U\\t\", ce->ce_mode,\n+\t\t\t oid_to_hex(null_oid()));\n \t\telse\n \t\t\tprintf(\"%06o %s %d\\t\", ce->ce_mode,\n \t\t\t oid_to_hex(&ce->oid), ce_stage(ce));\n@@ -466,7 +467,7 @@ static void runcommand_in_submodule_cb(const struct cache_entry *list_item,\n \n \tdisplaypath = get_submodule_displaypath(path, info->prefix);\n \n-\tsub = submodule_from_path(the_repository, &null_oid, path);\n+\tsub = submodule_from_path(the_repository, null_oid(), path);\n \n \tif (!sub)\n \t\tdie(_(\"No url found for submodule path '%s' in .gitmodules\"),\n@@ -623,7 +624,7 @@ static void init_submodule(const char *path, const char *prefix,\n \n \tdisplaypath = get_submodule_displaypath(path, prefix);\n \n-\tsub = submodule_from_path(the_repository, &null_oid, path);\n+\tsub = submodule_from_path(the_repository, null_oid(), path);\n \n \tif (!sub)\n \t\tdie(_(\"No url found for submodule path '%s' in .gitmodules\"),\n@@ -783,14 +784,14 @@ static void status_submodule(const char *path, const struct object_id *ce_oid,\n \tstruct strbuf buf = STRBUF_INIT;\n \tconst char *git_dir;\n \n-\tif (!submodule_from_path(the_repository, &null_oid, path))\n+\tif (!submodule_from_path(the_repository, null_oid(), path))\n \t\tdie(_(\"no submodule mapping found in .gitmodules for path '%s'\"),\n \t\t path);\n \n \tdisplaypath = get_submodule_displaypath(path, prefix);\n \n \tif ((CE_STAGEMASK & ce_flags) >> CE_STAGESHIFT) {\n-\t\tprint_status(flags, 'U', path, &null_oid, displaypath);\n+\t\tprint_status(flags, 'U', path, null_oid(), displaypath);\n \t\tgoto cleanup;\n \t}\n \n@@ -916,7 +917,7 @@ static int module_name(int argc, const char **argv, const char *prefix)\n \tif (argc != 2)\n \t\tusage(_(\"git submodule--helper name \"));\n \n-\tsub = submodule_from_path(the_repository, &null_oid, argv[1]);\n+\tsub = submodule_from_path(the_repository, null_oid(), argv[1]);\n \n \tif (!sub)\n \t\tdie(_(\"no submodule mapping found in .gitmodules for path '%s'\"),\n@@ -1040,7 +1041,7 @@ static void generate_submodule_summary(struct summary_cb *info,\n \tchar *errmsg = NULL;\n \tint total_commits = -1;\n \n-\tif (!info->cached && oideq(&p->oid_dst, &null_oid)) {\n+\tif (!info->cached && oideq(&p->oid_dst, null_oid())) {\n \t\tif (S_ISGITLINK(p->mod_dst)) {\n \t\t\tstruct ref_store *refs = get_submodule_ref_store(p->sm_path);\n \t\t\tif (refs)\n@@ -1177,7 +1178,7 @@ static void prepare_submodule_summary(struct summary_cb *info,\n \n \t\tif (info->for_status && p->status != 'A' &&\n \t\t (sub = submodule_from_path(the_repository,\n-\t\t\t\t\t &null_oid, p->sm_path))) {\n+\t\t\t\t\t null_oid(), p->sm_path))) {\n \t\t\tchar *config_key = NULL;\n \t\t\tconst char *value;\n \t\t\tint ignore_all = 0;\n@@ -1373,7 +1374,7 @@ static void sync_submodule(const char *path, const char *prefix,\n \tif (!is_submodule_active(the_repository, path))\n \t\treturn;\n \n-\tsub = submodule_from_path(the_repository, &null_oid, path);\n+\tsub = submodule_from_path(the_repository, null_oid(), path);\n \n \tif (sub && sub->url) {\n \t\tif (starts_with_dot_dot_slash(sub->url) ||\n@@ -1525,7 +1526,7 @@ static void deinit_submodule(const char *path, const char *prefix,\n \tstruct strbuf sb_config = STRBUF_INIT;\n \tchar *sub_git_dir = xstrfmt(\"%s/.git\", path);\n \n-\tsub = submodule_from_path(the_repository, &null_oid, path);\n+\tsub = submodule_from_path(the_repository, null_oid(), path);\n \n \tif (!sub || !sub->name)\n \t\tgoto cleanup;\n@@ -1925,7 +1926,7 @@ static void determine_submodule_update_strategy(struct repository *r,\n \t\t\t\t\t\tconst char *update,\n \t\t\t\t\t\tstruct submodule_update_strategy *out)\n {\n-\tconst struct submodule *sub = submodule_from_path(r, &null_oid, path);\n+\tconst struct submodule *sub = submodule_from_path(r, null_oid(), path);\n \tchar *key;\n \tconst char *val;\n \n@@ -2077,7 +2078,7 @@ static int prepare_to_clone_next_submodule(const struct cache_entry *ce,\n \t\tgoto cleanup;\n \t}\n \n-\tsub = submodule_from_path(the_repository, &null_oid, ce->name);\n+\tsub = submodule_from_path(the_repository, null_oid(), ce->name);\n \n \tif (suc->recursive_prefix)\n \t\tdisplaypath = relative_path(suc->recursive_prefix,\n@@ -2395,7 +2396,7 @@ static const char *remote_submodule_branch(const char *path)\n \tconst char *branch = NULL;\n \tchar *key;\n \n-\tsub = submodule_from_path(the_repository, &null_oid, path);\n+\tsub = submodule_from_path(the_repository, null_oid(), path);\n \tif (!sub)\n \t\treturn NULL;\n \n@@ -2533,7 +2534,7 @@ static int ensure_core_worktree(int argc, const char **argv, const char *prefix)\n \n \tpath = argv[1];\n \n-\tsub = submodule_from_path(the_repository, &null_oid, path);\n+\tsub = submodule_from_path(the_repository, null_oid(), path);\n \tif (!sub)\n \t\tBUG(\"We could get the submodule handle before?\");\n \ndiff --git a/builtin/unpack-objects.c b/builtin/unpack-objects.c\nindex 6ac90dc5f7..4a9466295b 100644\n--- a/builtin/unpack-objects.c\n+++ b/builtin/unpack-objects.c\n@@ -421,7 +421,8 @@ static void unpack_delta_entry(enum object_type type, unsigned long delta_size,\n \t\t\t * has not been resolved yet.\n \t\t\t */\n \t\t\toidclr(&obj_list[nr].oid);\n-\t\t\tadd_delta_to_list(nr, &null_oid, base_offset, delta_data, delta_size);\n+\t\t\tadd_delta_to_list(nr, null_oid(), base_offset,\n+\t\t\t\t\t delta_data, delta_size);\n \t\t\treturn;\n \t\t}\n \t}\ndiff --git a/builtin/worktree.c b/builtin/worktree.c\nindex 8771453493..f754978e47 100644\n--- a/builtin/worktree.c\n+++ b/builtin/worktree.c\n@@ -331,7 +331,7 @@ static int add_worktree(const char *path, const char *refname,\n \t */\n \tstrbuf_reset(&sb);\n \tstrbuf_addf(&sb, \"%s/HEAD\", sb_repo.buf);\n-\twrite_file(sb.buf, \"%s\", oid_to_hex(&null_oid));\n+\twrite_file(sb.buf, \"%s\", oid_to_hex(null_oid()));\n \tstrbuf_reset(&sb);\n \tstrbuf_addf(&sb, \"%s/commondir\", sb_repo.buf);\n \twrite_file(sb.buf, \"../..\");\n@@ -394,7 +394,7 @@ static int add_worktree(const char *path, const char *refname,\n \t\t\tcp.argv = NULL;\n \t\t\tcp.trace2_hook_name = \"post-checkout\";\n \t\t\tstrvec_pushl(&cp.args, absolute_path(hook),\n-\t\t\t\t oid_to_hex(&null_oid),\n+\t\t\t\t oid_to_hex(null_oid()),\n \t\t\t\t oid_to_hex(&commit->object.oid),\n \t\t\t\t \"1\", NULL);\n \t\t\tret = run_command(&cp);\ndiff --git a/combine-diff.c b/combine-diff.c\nindex 06635f91bc..7d925ce9ce 100644\n--- a/combine-diff.c\n+++ b/combine-diff.c\n@@ -1068,7 +1068,7 @@ static void show_patch_diff(struct combine_diff_path *elem, int num_parent,\n \t\t\t\t\t\t &result_size, NULL, NULL);\n \t\t} else if (textconv) {\n \t\t\tstruct diff_filespec *df = alloc_filespec(elem->path);\n-\t\t\tfill_filespec(df, &null_oid, 0, st.st_mode);\n+\t\t\tfill_filespec(df, null_oid(), 0, st.st_mode);\n \t\t\tresult_size = fill_textconv(opt->repo, textconv, df, &result);\n \t\t\tfree_filespec(df);\n \t\t} else if (0 <= (fd = open(elem->path, O_RDONLY))) {\ndiff --git a/connect.c b/connect.c\nindex 40b5c15f81..70b13389ba 100644\n--- a/connect.c\n+++ b/connect.c\n@@ -254,7 +254,7 @@ static int process_dummy_ref(const struct packet_reader *reader)\n \t\treturn 0;\n \tname++;\n \n-\treturn oideq(&null_oid, &oid) && !strcmp(name, \"capabilities^{}\");\n+\treturn oideq(null_oid(), &oid) && !strcmp(name, \"capabilities^{}\");\n }\n \n static void check_no_capabilities(const char *line, int len)\ndiff --git a/diff-lib.c b/diff-lib.c\nindex e5a58c9259..c2ac9250fe 100644\n--- a/diff-lib.c\n+++ b/diff-lib.c\n@@ -232,7 +232,7 @@ int run_diff_files(struct rev_info *revs, unsigned int option)\n \t\t\t\t ce_intent_to_add(ce)) {\n \t\t\t\tnewmode = ce_mode_from_stat(ce, st.st_mode);\n \t\t\t\tdiff_addremove(&revs->diffopt, '+', newmode,\n-\t\t\t\t\t &null_oid, 0, ce->name, 0);\n+\t\t\t\t\t null_oid(), 0, ce->name, 0);\n \t\t\t\tcontinue;\n \t\t\t}\n \n@@ -249,7 +249,7 @@ int run_diff_files(struct rev_info *revs, unsigned int option)\n \t\t}\n \t\toldmode = ce->ce_mode;\n \t\told_oid = &ce->oid;\n-\t\tnew_oid = changed ? &null_oid : &ce->oid;\n+\t\tnew_oid = changed ? null_oid() : &ce->oid;\n \t\tdiff_change(&revs->diffopt, oldmode, newmode,\n \t\t\t old_oid, new_oid,\n \t\t\t !is_null_oid(old_oid),\n@@ -307,7 +307,7 @@ static int get_stat_data(const struct index_state *istate,\n \t\t\t\t\t\t 0, dirty_submodule);\n \t\tif (changed) {\n \t\t\tmode = ce_mode_from_stat(ce, st.st_mode);\n-\t\t\toid = &null_oid;\n+\t\t\toid = null_oid();\n \t\t}\n \t}\n \ndiff --git a/diff-no-index.c b/diff-no-index.c\nindex 7814eabfe0..308922e2b3 100644\n--- a/diff-no-index.c\n+++ b/diff-no-index.c\n@@ -83,7 +83,7 @@ static struct diff_filespec *noindex_filespec(const char *name, int mode)\n \tif (!name)\n \t\tname = \"/dev/null\";\n \ts = alloc_filespec(name);\n-\tfill_filespec(s, &null_oid, 0, mode);\n+\tfill_filespec(s, null_oid(), 0, mode);\n \tif (name == file_from_standard_input)\n \t\tpopulate_from_stdin(s);\n \treturn s;\ndiff --git a/diff.c b/diff.c\nindex 97c62f47df..7c730fe644 100644\n--- a/diff.c\n+++ b/diff.c\n@@ -4190,7 +4190,7 @@ static struct diff_tempfile *prepare_temp_file(struct repository *r,\n \t\t\t\tdie_errno(\"readlink(%s)\", name);\n \t\t\tprep_temp_blob(r->index, name, temp, sb.buf, sb.len,\n \t\t\t\t (one->oid_valid ?\n-\t\t\t\t\t&one->oid : &null_oid),\n+\t\t\t\t\t&one->oid : null_oid()),\n \t\t\t\t (one->oid_valid ?\n \t\t\t\t\tone->mode : S_IFLNK));\n \t\t\tstrbuf_release(&sb);\n@@ -4199,7 +4199,7 @@ static struct diff_tempfile *prepare_temp_file(struct repository *r,\n \t\t\t/* we can borrow from the file in the work tree */\n \t\t\ttemp->name = name;\n \t\t\tif (!one->oid_valid)\n-\t\t\t\toid_to_hex_r(temp->hex, &null_oid);\n+\t\t\t\toid_to_hex_r(temp->hex, null_oid());\n \t\t\telse\n \t\t\t\toid_to_hex_r(temp->hex, &one->oid);\n \t\t\t/* Even though we may sometimes borrow the\ndiff --git a/dir.c b/dir.c\nindex 813dd7ba53..037474337f 100644\n--- a/dir.c\n+++ b/dir.c\n@@ -3556,7 +3556,7 @@ static void connect_wt_gitdir_in_nested(const char *sub_worktree,\n \t\t\t */\n \t\t\ti++;\n \n-\t\tsub = submodule_from_path(&subrepo, &null_oid, ce->name);\n+\t\tsub = submodule_from_path(&subrepo, null_oid(), ce->name);\n \t\tif (!sub || !is_submodule_active(&subrepo, ce->name))\n \t\t\t/* .gitmodules broken or inactive sub */\n \t\t\tcontinue;\ndiff --git a/grep.c b/grep.c\nindex c5c348be55..8f91af1cb0 100644\n--- a/grep.c\n+++ b/grep.c\n@@ -1494,7 +1494,7 @@ static int fill_textconv_grep(struct repository *r,\n \t\tfill_filespec(df, gs->identifier, 1, 0100644);\n \t\tbreak;\n \tcase GREP_SOURCE_FILE:\n-\t\tfill_filespec(df, &null_oid, 0, 0100644);\n+\t\tfill_filespec(df, null_oid(), 0, 0100644);\n \t\tbreak;\n \tdefault:\n \t\tBUG(\"attempt to textconv something without a path?\");\ndiff --git a/hash.h b/hash.h\nindex 3b114f053e..5fabf6e1ec 100644\n--- a/hash.h\n+++ b/hash.h\n@@ -170,6 +170,9 @@ struct git_hash_algo {\n \n \t/* The OID of the empty blob. */\n \tconst struct object_id *empty_blob;\n+\n+\t/* The all-zeros OID. */\n+\tconst struct object_id *null_oid;\n };\n extern const struct git_hash_algo hash_algos[GIT_HASH_NALGOS];\n \n@@ -190,7 +193,7 @@ static inline int hash_algo_by_ptr(const struct git_hash_algo *p)\n \n #define the_hash_algo the_repository->hash_algo\n \n-extern const struct object_id null_oid;\n+const struct object_id *null_oid(void);\n \n static inline int hashcmp(const unsigned char *sha1, const unsigned char *sha2)\n {\n@@ -226,7 +229,7 @@ static inline int oideq(const struct object_id *oid1, const struct object_id *oi\n \n static inline int is_null_oid(const struct object_id *oid)\n {\n-\treturn oideq(oid, &null_oid);\n+\treturn oideq(oid, null_oid());\n }\n \n static inline void hashcpy(unsigned char *sha_dst, const unsigned char *sha_src)\ndiff --git a/log-tree.c b/log-tree.c\nindex f3178a66a9..7b823786c2 100644\n--- a/log-tree.c\n+++ b/log-tree.c\n@@ -419,7 +419,7 @@ void log_write_email_headers(struct rev_info *opt, struct commit *commit,\n {\n \tconst char *extra_headers = opt->extra_headers;\n \tconst char *name = oid_to_hex(opt->zero_commit ?\n-\t\t\t\t &null_oid : &commit->object.oid);\n+\t\t\t\t null_oid() : &commit->object.oid);\n \n \t*need_8bit_cte_p = 0; /* unknown */\n \ndiff --git a/merge-ort.c b/merge-ort.c\nindex 5e118a85ee..3e552cfd21 100644\n--- a/merge-ort.c\n+++ b/merge-ort.c\n@@ -1291,7 +1291,7 @@ static int handle_content_merge(struct merge_options *opt,\n \t\ttwo_way = ((S_IFMT & o->mode) != (S_IFMT & a->mode));\n \n \t\tmerge_status = merge_3way(opt, path,\n-\t\t\t\t\t two_way ? &null_oid : &o->oid,\n+\t\t\t\t\t two_way ? null_oid() : &o->oid,\n \t\t\t\t\t &a->oid, &b->oid,\n \t\t\t\t\t pathnames, extra_marker_size,\n \t\t\t\t\t &result_buf);\n@@ -1313,7 +1313,7 @@ static int handle_content_merge(struct merge_options *opt,\n \t} else if (S_ISGITLINK(a->mode)) {\n \t\tint two_way = ((S_IFMT & o->mode) != (S_IFMT & a->mode));\n \t\tclean = merge_submodule(opt, pathnames[0],\n-\t\t\t\t\ttwo_way ? &null_oid : &o->oid,\n+\t\t\t\t\ttwo_way ? null_oid() : &o->oid,\n \t\t\t\t\t&a->oid, &b->oid, &result->oid);\n \t\tif (opt->priv->call_depth && two_way && !clean) {\n \t\t\tresult->mode = o->mode;\n@@ -2123,7 +2123,7 @@ static int process_renames(struct merge_options *opt,\n \t\t\tif (type_changed) {\n \t\t\t\t/* rename vs. typechange */\n \t\t\t\t/* Mark the original as resolved by removal */\n-\t\t\t\tmemcpy(&oldinfo->stages[0].oid, &null_oid,\n+\t\t\t\tmemcpy(&oldinfo->stages[0].oid, null_oid(),\n \t\t\t\t sizeof(oldinfo->stages[0].oid));\n \t\t\t\toldinfo->stages[0].mode = 0;\n \t\t\t\toldinfo->filemask &= 0x06;\n@@ -2762,7 +2762,7 @@ static void process_entry(struct merge_options *opt,\n \t\t\tif (ci->filemask & (1 << i))\n \t\t\t\tcontinue;\n \t\t\tci->stages[i].mode = 0;\n-\t\t\toidcpy(&ci->stages[i].oid, &null_oid);\n+\t\t\toidcpy(&ci->stages[i].oid, null_oid());\n \t\t}\n \t} else if (ci->df_conflict && ci->merged.result.mode != 0) {\n \t\t/*\n@@ -2808,7 +2808,7 @@ static void process_entry(struct merge_options *opt,\n \t\t\t\tcontinue;\n \t\t\t/* zero out any entries related to directories */\n \t\t\tnew_ci->stages[i].mode = 0;\n-\t\t\toidcpy(&new_ci->stages[i].oid, &null_oid);\n+\t\t\toidcpy(&new_ci->stages[i].oid, null_oid());\n \t\t}\n \n \t\t/*\n@@ -2909,11 +2909,11 @@ static void process_entry(struct merge_options *opt,\n \t\t\tnew_ci->merged.result.mode = ci->stages[2].mode;\n \t\t\toidcpy(&new_ci->merged.result.oid, &ci->stages[2].oid);\n \t\t\tnew_ci->stages[1].mode = 0;\n-\t\t\toidcpy(&new_ci->stages[1].oid, &null_oid);\n+\t\t\toidcpy(&new_ci->stages[1].oid, null_oid());\n \t\t\tnew_ci->filemask = 5;\n \t\t\tif ((S_IFMT & b_mode) != (S_IFMT & o_mode)) {\n \t\t\t\tnew_ci->stages[0].mode = 0;\n-\t\t\t\toidcpy(&new_ci->stages[0].oid, &null_oid);\n+\t\t\t\toidcpy(&new_ci->stages[0].oid, null_oid());\n \t\t\t\tnew_ci->filemask = 4;\n \t\t\t}\n \n@@ -2921,11 +2921,11 @@ static void process_entry(struct merge_options *opt,\n \t\t\tci->merged.result.mode = ci->stages[1].mode;\n \t\t\toidcpy(&ci->merged.result.oid, &ci->stages[1].oid);\n \t\t\tci->stages[2].mode = 0;\n-\t\t\toidcpy(&ci->stages[2].oid, &null_oid);\n+\t\t\toidcpy(&ci->stages[2].oid, null_oid());\n \t\t\tci->filemask = 3;\n \t\t\tif ((S_IFMT & a_mode) != (S_IFMT & o_mode)) {\n \t\t\t\tci->stages[0].mode = 0;\n-\t\t\t\toidcpy(&ci->stages[0].oid, &null_oid);\n+\t\t\t\toidcpy(&ci->stages[0].oid, null_oid());\n \t\t\t\tci->filemask = 2;\n \t\t\t}\n \n@@ -3042,7 +3042,7 @@ static void process_entry(struct merge_options *opt,\n \t\t/* Deleted on both sides */\n \t\tci->merged.is_null = 1;\n \t\tci->merged.result.mode = 0;\n-\t\toidcpy(&ci->merged.result.oid, &null_oid);\n+\t\toidcpy(&ci->merged.result.oid, null_oid());\n \t\tci->merged.clean = !ci->path_conflict;\n \t}\n \ndiff --git a/merge-recursive.c b/merge-recursive.c\nindex ed31f9496c..03f5c0769e 100644\n--- a/merge-recursive.c\n+++ b/merge-recursive.c\n@@ -486,7 +486,7 @@ static int get_tree_entry_if_blob(struct repository *r,\n \n \tret = get_tree_entry(r, tree, path, &dfs->oid, &dfs->mode);\n \tif (S_ISDIR(dfs->mode)) {\n-\t\toidcpy(&dfs->oid, &null_oid);\n+\t\toidcpy(&dfs->oid, null_oid());\n \t\tdfs->mode = 0;\n \t}\n \treturn ret;\n@@ -1604,7 +1604,7 @@ static int handle_file_collision(struct merge_options *opt,\n \n \t/* Store things in diff_filespecs for functions that need it */\n \tnull.path = (char *)collide_path;\n-\toidcpy(&null.oid, &null_oid);\n+\toidcpy(&null.oid, null_oid());\n \tnull.mode = 0;\n \n \tif (merge_mode_and_contents(opt, &null, a, b, collide_path,\n@@ -2789,11 +2789,11 @@ static int process_renames(struct merge_options *opt,\n \t\t\tdst_other.mode = ren1->dst_entry->stages[other_stage].mode;\n \t\t\ttry_merge = 0;\n \n-\t\t\tif (oideq(&src_other.oid, &null_oid) &&\n+\t\t\tif (oideq(&src_other.oid, null_oid()) &&\n \t\t\t ren1->dir_rename_original_type == 'A') {\n \t\t\t\tsetup_rename_conflict_info(RENAME_VIA_DIR,\n \t\t\t\t\t\t\t opt, ren1, NULL);\n-\t\t\t} else if (oideq(&src_other.oid, &null_oid)) {\n+\t\t\t} else if (oideq(&src_other.oid, null_oid())) {\n \t\t\t\tsetup_rename_conflict_info(RENAME_DELETE,\n \t\t\t\t\t\t\t opt, ren1, NULL);\n \t\t\t} else if ((dst_other.mode == ren1->pair->two->mode) &&\n@@ -2812,7 +2812,7 @@ static int process_renames(struct merge_options *opt,\n \t\t\t\t\t\t 1, /* update_cache */\n \t\t\t\t\t\t 0 /* update_wd */))\n \t\t\t\t\tclean_merge = -1;\n-\t\t\t} else if (!oideq(&dst_other.oid, &null_oid)) {\n+\t\t\t} else if (!oideq(&dst_other.oid, null_oid())) {\n \t\t\t\t/*\n \t\t\t\t * Probably not a clean merge, but it's\n \t\t\t\t * premature to set clean_merge to 0 here,\ndiff --git a/notes-merge.c b/notes-merge.c\nindex d2771fa3d4..53c587f750 100644\n--- a/notes-merge.c\n+++ b/notes-merge.c\n@@ -600,7 +600,7 @@ int notes_merge(struct notes_merge_options *o,\n \t/* Find merge bases */\n \tbases = get_merge_bases(local, remote);\n \tif (!bases) {\n-\t\tbase_oid = &null_oid;\n+\t\tbase_oid = null_oid();\n \t\tbase_tree_oid = the_hash_algo->empty_tree;\n \t\tif (o->verbosity >= 4)\n \t\t\tprintf(\"No merge base found; doing history-less merge\\n\");\ndiff --git a/notes.c b/notes.c\nindex 1dfe9e2b9f..3f48a2aac3 100644\n--- a/notes.c\n+++ b/notes.c\n@@ -1327,7 +1327,7 @@ int copy_note(struct notes_tree *t,\n \tif (note)\n \t\treturn add_note(t, to_obj, note, combine_notes);\n \telse if (existing_note)\n-\t\treturn add_note(t, to_obj, &null_oid, combine_notes);\n+\t\treturn add_note(t, to_obj, null_oid(), combine_notes);\n \n \treturn 0;\n }\ndiff --git a/object-file.c b/object-file.c\nindex 5f1fa05c4e..50bb5b6ca4 100644\n--- a/object-file.c\n+++ b/object-file.c\n@@ -55,7 +55,6 @@\n \t\"\\x6f\\xe1\\x41\\xf7\\x74\\x91\\x20\\xa3\\x03\\x72\" \\\n \t\"\\x18\\x13\"\n \n-const struct object_id null_oid;\n static const struct object_id empty_tree_oid = {\n \tEMPTY_TREE_SHA1_BIN_LITERAL,\n \tGIT_HASH_SHA1,\n@@ -64,6 +63,9 @@ static const struct object_id empty_blob_oid = {\n \tEMPTY_BLOB_SHA1_BIN_LITERAL,\n \tGIT_HASH_SHA1,\n };\n+const struct object_id null_oid_sha1 = {\n+\t{0}, GIT_HASH_SHA1,\n+};\n static const struct object_id empty_tree_oid_sha256 = {\n \tEMPTY_TREE_SHA256_BIN_LITERAL,\n \tGIT_HASH_SHA256,\n@@ -72,6 +74,9 @@ static const struct object_id empty_blob_oid_sha256 = {\n \tEMPTY_BLOB_SHA256_BIN_LITERAL,\n \tGIT_HASH_SHA256,\n };\n+static const struct object_id null_oid_sha256 = {\n+\t{0}, GIT_HASH_SHA256,\n+};\n \n static void git_hash_sha1_init(git_hash_ctx *ctx)\n {\n@@ -172,6 +177,7 @@ const struct git_hash_algo hash_algos[GIT_HASH_NALGOS] = {\n \t\tgit_hash_unknown_final_oid,\n \t\tNULL,\n \t\tNULL,\n+\t\tNULL,\n \t},\n \t{\n \t\t\"sha1\",\n@@ -187,6 +193,7 @@ const struct git_hash_algo hash_algos[GIT_HASH_NALGOS] = {\n \t\tgit_hash_sha1_final_oid,\n \t\t&empty_tree_oid,\n \t\t&empty_blob_oid,\n+\t\t&null_oid_sha1,\n \t},\n \t{\n \t\t\"sha256\",\n@@ -202,9 +209,15 @@ const struct git_hash_algo hash_algos[GIT_HASH_NALGOS] = {\n \t\tgit_hash_sha256_final_oid,\n \t\t&empty_tree_oid_sha256,\n \t\t&empty_blob_oid_sha256,\n+\t\t&null_oid_sha256,\n \t}\n };\n \n+const struct object_id *null_oid(void)\n+{\n+\treturn the_hash_algo->null_oid;\n+}\n+\n const char *empty_tree_oid_hex(void)\n {\n \tstatic char buf[GIT_MAX_HEXSZ + 1];\ndiff --git a/parse-options-cb.c b/parse-options-cb.c\nindex 4542d4d3f9..3c811e1e4a 100644\n--- a/parse-options-cb.c\n+++ b/parse-options-cb.c\n@@ -140,7 +140,7 @@ int parse_opt_object_id(const struct option *opt, const char *arg, int unset)\n \tstruct object_id *target = opt->value;\n \n \tif (unset) {\n-\t\t*target = null_oid;\n+\t\toidcpy(target, null_oid());\n \t\treturn 0;\n \t}\n \tif (!arg)\ndiff --git a/range-diff.c b/range-diff.c\nindex 116fb0735c..1a4471fe4c 100644\n--- a/range-diff.c\n+++ b/range-diff.c\n@@ -445,7 +445,7 @@ static struct diff_filespec *get_filespec(const char *name, const char *p)\n {\n \tstruct diff_filespec *spec = alloc_filespec(name);\n \n-\tfill_filespec(spec, &null_oid, 0, 0100644);\n+\tfill_filespec(spec, null_oid(), 0, 0100644);\n \tspec->data = (char *)p;\n \tspec->size = strlen(p);\n \tspec->should_munmap = 0;\ndiff --git a/refs.c b/refs.c\nindex 261fd82beb..996063fdf4 100644\n--- a/refs.c\n+++ b/refs.c\n@@ -1107,7 +1107,7 @@ int ref_transaction_create(struct ref_transaction *transaction,\n \tif (!new_oid || is_null_oid(new_oid))\n \t\tBUG(\"create called without valid new_oid\");\n \treturn ref_transaction_update(transaction, refname, new_oid,\n-\t\t\t\t &null_oid, flags, msg, err);\n+\t\t\t\t null_oid(), flags, msg, err);\n }\n \n int ref_transaction_delete(struct ref_transaction *transaction,\n@@ -1119,7 +1119,7 @@ int ref_transaction_delete(struct ref_transaction *transaction,\n \tif (old_oid && is_null_oid(old_oid))\n \t\tBUG(\"delete called with old_oid set to zeros\");\n \treturn ref_transaction_update(transaction, refname,\n-\t\t\t\t &null_oid, old_oid,\n+\t\t\t\t null_oid(), old_oid,\n \t\t\t\t flags, msg, err);\n }\n \ndiff --git a/refs/debug.c b/refs/debug.c\nindex 922e64fa6a..2665f94309 100644\n--- a/refs/debug.c\n+++ b/refs/debug.c\n@@ -243,7 +243,7 @@ static int debug_read_raw_ref(struct ref_store *ref_store, const char *refname,\n \tstruct debug_ref_store *drefs = (struct debug_ref_store *)ref_store;\n \tint res = 0;\n \n-\toidcpy(oid, &null_oid);\n+\toidcpy(oid, null_oid());\n \tres = drefs->refs->be->read_raw_ref(drefs->refs, refname, oid, referent,\n \t\t\t\t\t type);\n \ndiff --git a/refs/files-backend.c b/refs/files-backend.c\nindex 119972ee16..3f29f8c143 100644\n--- a/refs/files-backend.c\n+++ b/refs/files-backend.c\n@@ -1084,7 +1084,7 @@ static void prune_ref(struct files_ref_store *refs, struct ref_to_prune *r)\n \tref_transaction_add_update(\n \t\t\ttransaction, r->name,\n \t\t\tREF_NO_DEREF | REF_HAVE_NEW | REF_HAVE_OLD | REF_IS_PRUNING,\n-\t\t\t&null_oid, &r->oid, NULL);\n+\t\t\tnull_oid(), &r->oid, NULL);\n \tif (ref_transaction_commit(transaction, &err))\n \t\tgoto cleanup;\n \ndiff --git a/reset.c b/reset.c\nindex 2f4fbd07c5..4bea758053 100644\n--- a/reset.c\n+++ b/reset.c\n@@ -128,7 +128,7 @@ int reset_head(struct repository *r, struct object_id *oid, const char *action,\n \t}\n \tif (run_hook)\n \t\trun_hook_le(NULL, \"post-checkout\",\n-\t\t\t oid_to_hex(orig ? orig : &null_oid),\n+\t\t\t oid_to_hex(orig ? orig : null_oid()),\n \t\t\t oid_to_hex(oid), \"1\", NULL);\n \n leave_reset_head:\ndiff --git a/sequencer.c b/sequencer.c\nindex fd183b5593..dbee779243 100644\n--- a/sequencer.c\n+++ b/sequencer.c\n@@ -524,7 +524,7 @@ static int fast_forward_to(struct repository *r,\n \tif (!transaction ||\n \t ref_transaction_update(transaction, \"HEAD\",\n \t\t\t\t to, unborn && !is_rebase_i(opts) ?\n-\t\t\t\t &null_oid : from,\n+\t\t\t\t null_oid() : from,\n \t\t\t\t 0, sb.buf, &err) ||\n \t ref_transaction_commit(transaction, &err)) {\n \t\tref_transaction_free(transaction);\n@@ -1131,7 +1131,7 @@ int update_head_with_reflog(const struct commit *old_head,\n \ttransaction = ref_transaction_begin(err);\n \tif (!transaction ||\n \t ref_transaction_update(transaction, \"HEAD\", new_head,\n-\t\t\t\t old_head ? &old_head->object.oid : &null_oid,\n+\t\t\t\t old_head ? &old_head->object.oid : null_oid(),\n \t\t\t\t 0, sb.buf, err) ||\n \t ref_transaction_commit(transaction, err)) {\n \t\tret = -1;\ndiff --git a/submodule-config.c b/submodule-config.c\nindex f502505566..2026120fb3 100644\n--- a/submodule-config.c\n+++ b/submodule-config.c\n@@ -671,7 +671,7 @@ static int gitmodules_cb(const char *var, const char *value, void *data)\n \n \tparameter.cache = repo->submodule_cache;\n \tparameter.treeish_name = NULL;\n-\tparameter.gitmodules_oid = &null_oid;\n+\tparameter.gitmodules_oid = null_oid();\n \tparameter.overwrite = 1;\n \n \treturn parse_config(var, value, ¶meter);\ndiff --git a/submodule.c b/submodule.c\nindex 9767ba9893..7eeaf7d203 100644\n--- a/submodule.c\n+++ b/submodule.c\n@@ -113,7 +113,7 @@ int update_path_in_gitmodules(const char *oldpath, const char *newpath)\n \tif (is_gitmodules_unmerged(the_repository->index))\n \t\tdie(_(\"Cannot change unmerged .gitmodules, resolve merge conflicts first\"));\n \n-\tsubmodule = submodule_from_path(the_repository, &null_oid, oldpath);\n+\tsubmodule = submodule_from_path(the_repository, null_oid(), oldpath);\n \tif (!submodule || !submodule->name) {\n \t\twarning(_(\"Could not find section in .gitmodules where path=%s\"), oldpath);\n \t\treturn -1;\n@@ -142,7 +142,7 @@ int remove_path_from_gitmodules(const char *path)\n \tif (is_gitmodules_unmerged(the_repository->index))\n \t\tdie(_(\"Cannot change unmerged .gitmodules, resolve merge conflicts first\"));\n \n-\tsubmodule = submodule_from_path(the_repository, &null_oid, path);\n+\tsubmodule = submodule_from_path(the_repository, null_oid(), path);\n \tif (!submodule || !submodule->name) {\n \t\twarning(_(\"Could not find section in .gitmodules where path=%s\"), path);\n \t\treturn -1;\n@@ -188,7 +188,8 @@ void set_diffopt_flags_from_submodule_config(struct diff_options *diffopt,\n \t\t\t\t\t const char *path)\n {\n \tconst struct submodule *submodule = submodule_from_path(the_repository,\n-\t\t\t\t\t\t\t\t&null_oid, path);\n+\t\t\t\t\t\t\t\tnull_oid(),\n+\t\t\t\t\t\t\t\tpath);\n \tif (submodule) {\n \t\tconst char *ignore;\n \t\tchar *key;\n@@ -244,7 +245,7 @@ int is_submodule_active(struct repository *repo, const char *path)\n \tconst struct string_list *sl;\n \tconst struct submodule *module;\n \n-\tmodule = submodule_from_path(repo, &null_oid, path);\n+\tmodule = submodule_from_path(repo, null_oid(), path);\n \n \t/* early return if there isn't a path->module mapping */\n \tif (!module)\n@@ -745,7 +746,7 @@ const struct submodule *submodule_from_ce(const struct cache_entry *ce)\n \tif (!should_update_submodules())\n \t\treturn NULL;\n \n-\treturn submodule_from_path(the_repository, &null_oid, ce->name);\n+\treturn submodule_from_path(the_repository, null_oid(), ce->name);\n }\n \n static struct oid_array *submodule_commits(struct string_list *submodules,\n@@ -1037,7 +1038,7 @@ int find_unpushed_submodules(struct repository *r,\n \t\tconst struct submodule *submodule;\n \t\tconst char *path = NULL;\n \n-\t\tsubmodule = submodule_from_name(r, &null_oid, name->string);\n+\t\tsubmodule = submodule_from_name(r, null_oid(), name->string);\n \t\tif (submodule)\n \t\t\tpath = submodule->path;\n \t\telse\n@@ -1224,7 +1225,7 @@ static void calculate_changed_submodule_paths(struct repository *r,\n \t\tconst struct submodule *submodule;\n \t\tconst char *path = NULL;\n \n-\t\tsubmodule = submodule_from_name(r, &null_oid, name->string);\n+\t\tsubmodule = submodule_from_name(r, null_oid(), name->string);\n \t\tif (submodule)\n \t\t\tpath = submodule->path;\n \t\telse\n@@ -1361,7 +1362,7 @@ static struct fetch_task *fetch_task_create(struct repository *r,\n \tstruct fetch_task *task = xmalloc(sizeof(*task));\n \tmemset(task, 0, sizeof(*task));\n \n-\ttask->sub = submodule_from_path(r, &null_oid, path);\n+\ttask->sub = submodule_from_path(r, null_oid(), path);\n \tif (!task->sub) {\n \t\t/*\n \t\t * No entry in .gitmodules? Technically not a submodule,\n@@ -1917,7 +1918,7 @@ int submodule_move_head(const char *path,\n \tif (old_head && !is_submodule_populated_gently(path, error_code_ptr))\n \t\treturn 0;\n \n-\tsub = submodule_from_path(the_repository, &null_oid, path);\n+\tsub = submodule_from_path(the_repository, null_oid(), path);\n \n \tif (!sub)\n \t\tBUG(\"could not get submodule information for '%s'\", path);\n@@ -2076,7 +2077,7 @@ static void relocate_single_git_dir_into_superproject(const char *path)\n \n \treal_old_git_dir = real_pathdup(old_git_dir, 1);\n \n-\tsub = submodule_from_path(the_repository, &null_oid, path);\n+\tsub = submodule_from_path(the_repository, null_oid(), path);\n \tif (!sub)\n \t\tdie(_(\"could not lookup name for submodule '%s'\"), path);\n \n@@ -2135,7 +2136,7 @@ void absorb_git_dir_into_superproject(const char *path,\n \t\t* superproject did not rewrite the git file links yet,\n \t\t* fix it now.\n \t\t*/\n-\t\tsub = submodule_from_path(the_repository, &null_oid, path);\n+\t\tsub = submodule_from_path(the_repository, null_oid(), path);\n \t\tif (!sub)\n \t\t\tdie(_(\"could not lookup name for submodule '%s'\"), path);\n \t\tconnect_work_tree_and_git_dir(path,\n@@ -2283,7 +2284,8 @@ int submodule_to_gitdir(struct strbuf *buf, const char *submodule)\n \t\tstrbuf_addstr(buf, git_dir);\n \t}\n \tif (!is_git_directory(buf->buf)) {\n-\t\tsub = submodule_from_path(the_repository, &null_oid, submodule);\n+\t\tsub = submodule_from_path(the_repository, null_oid(),\n+\t\t\t\t\t submodule);\n \t\tif (!sub) {\n \t\t\tret = -1;\n \t\t\tgoto cleanup;\ndiff --git a/t/helper/test-submodule-nested-repo-config.c b/t/helper/test-submodule-nested-repo-config.c\nindex c5fd4527dc..e3f11ff5a7 100644\n--- a/t/helper/test-submodule-nested-repo-config.c\n+++ b/t/helper/test-submodule-nested-repo-config.c\n@@ -18,7 +18,7 @@ int cmd__submodule_nested_repo_config(int argc, const char **argv)\n \n \tsetup_git_directory();\n \n-\tsub = submodule_from_path(the_repository, &null_oid, argv[1]);\n+\tsub = submodule_from_path(the_repository, null_oid(), argv[1]);\n \tif (repo_submodule_init(&subrepo, the_repository, sub)) {\n \t\tdie_usage(argv, \"Submodule not found.\");\n \t}\ndiff --git a/tree-diff.c b/tree-diff.c\nindex 7cebbb327e..1572615bd9 100644\n--- a/tree-diff.c\n+++ b/tree-diff.c\n@@ -161,7 +161,7 @@ static struct combine_diff_path *path_appendnew(struct combine_diff_path *last,\n \tmemcpy(p->path + base->len, path, pathlen);\n \tp->path[len] = 0;\n \tp->mode = mode;\n-\toidcpy(&p->oid, oid ? oid : &null_oid);\n+\toidcpy(&p->oid, oid ? oid : null_oid());\n \n \treturn p;\n }\n@@ -243,7 +243,7 @@ static struct combine_diff_path *emit_path(struct combine_diff_path *p,\n \t\t\t\tmode_i = tp[i].entry.mode;\n \t\t\t}\n \t\t\telse {\n-\t\t\t\toid_i = &null_oid;\n+\t\t\t\toid_i = null_oid();\n \t\t\t\tmode_i = 0;\n \t\t\t}\n \ndiff --git a/wt-status.c b/wt-status.c\nindex 1aed68c43c..7603c1b198 100644\n--- a/wt-status.c\n+++ b/wt-status.c\n@@ -1687,10 +1687,10 @@ void wt_status_get_state(struct repository *r,\n \tif (!sequencer_get_last_command(r, &action)) {\n \t\tif (action == REPLAY_PICK) {\n \t\t\tstate->cherry_pick_in_progress = 1;\n-\t\t\toidcpy(&state->cherry_pick_head_oid, &null_oid);\n+\t\t\toidcpy(&state->cherry_pick_head_oid, null_oid());\n \t\t} else {\n \t\t\tstate->revert_in_progress = 1;\n-\t\t\toidcpy(&state->revert_head_oid, &null_oid);\n+\t\t\toidcpy(&state->revert_head_oid, null_oid());\n \t\t}\n \t}\n \tif (get_detached_from)\ndiff --git a/xdiff-interface.c b/xdiff-interface.c\nindex 4d20069302..609615db2c 100644\n--- a/xdiff-interface.c\n+++ b/xdiff-interface.c\n@@ -172,7 +172,7 @@ void read_mmblob(mmfile_t *ptr, const struct object_id *oid)\n \tunsigned long size;\n \tenum object_type type;\n \n-\tif (oideq(oid, &null_oid)) {\n+\tif (oideq(oid, null_oid())) {\n \t\tptr->ptr = xstrdup(\"\");\n \t\tptr->size = 0;\n \t\treturn;\n"},{"id":"421541","messageId":"20210410152140.3525040-10-sandals@crustytoothpaste.net","threadId":"55472","inReplyTo":"20210410152140.3525040-1-sandals@crustytoothpaste.net","subject":"[PATCH 09/15] hash: set and copy algo field in struct object_id","fromName":"brian m. carlson","fromEmail":"sandals@crustytoothpaste.net","sentAt":"2021-04-10T15:21:34Z","receivedAt":"2021-04-10T15:22:41Z","isPatch":true,"sender":{"key":"sandals@crustytoothpaste.net","avatar":"https://avatars.githubusercontent.com/u/497054?v=4"},"body":"Now that struct object_id has an algorithm field, we should populate it.\nThis will allow us to handle object IDs in any supported algorithm and\ndistinguish between them. Ensure that the field is written whenever we\nwrite an object ID by storing it explicitly every time we write an\nobject. Set values for the empty blob and tree values as well.\n\nSigned-off-by: brian m. carlson \n---\n hash.h | 4 ++++\n object-file.c | 14 ++++++++++----\n 2 files changed, 14 insertions(+), 4 deletions(-)\n\ndiff --git a/hash.h b/hash.h\nindex 04eba5c56b..3b114f053e 100644\n--- a/hash.h\n+++ b/hash.h\n@@ -237,6 +237,7 @@ static inline void hashcpy(unsigned char *sha_dst, const unsigned char *sha_src)\n static inline void oidcpy(struct object_id *dst, const struct object_id *src)\n {\n \tmemcpy(dst->hash, src->hash, GIT_MAX_RAWSZ);\n+\tdst->algo = src->algo;\n }\n \n static inline struct object_id *oiddup(const struct object_id *src)\n@@ -254,6 +255,7 @@ static inline void hashclr(unsigned char *hash)\n static inline void oidclr(struct object_id *oid)\n {\n \tmemset(oid->hash, 0, GIT_MAX_RAWSZ);\n+\toid->algo = hash_algo_by_ptr(the_hash_algo);\n }\n \n static inline void oidread(struct object_id *oid, const unsigned char *hash)\n@@ -261,6 +263,7 @@ static inline void oidread(struct object_id *oid, const unsigned char *hash)\n \tsize_t rawsz = the_hash_algo->rawsz;\n \tmemcpy(oid->hash, hash, rawsz);\n \tmemset(oid->hash + rawsz, 0, GIT_MAX_RAWSZ - rawsz);\n+\toid->algo = hash_algo_by_ptr(the_hash_algo);\n }\n \n static inline int is_empty_blob_sha1(const unsigned char *sha1)\n@@ -286,6 +289,7 @@ static inline int is_empty_tree_oid(const struct object_id *oid)\n static inline void oid_pad_buffer(struct object_id *oid, const struct git_hash_algo *algop)\n {\n \tmemset(oid->hash + algop->rawsz, 0, GIT_MAX_RAWSZ - algop->rawsz);\n+\toid->algo = hash_algo_by_ptr(algop);\n }\n \n const char *empty_tree_oid_hex(void);\ndiff --git a/object-file.c b/object-file.c\nindex 8e338247cc..5f1fa05c4e 100644\n--- a/object-file.c\n+++ b/object-file.c\n@@ -57,16 +57,20 @@\n \n const struct object_id null_oid;\n static const struct object_id empty_tree_oid = {\n-\tEMPTY_TREE_SHA1_BIN_LITERAL\n+\tEMPTY_TREE_SHA1_BIN_LITERAL,\n+\tGIT_HASH_SHA1,\n };\n static const struct object_id empty_blob_oid = {\n-\tEMPTY_BLOB_SHA1_BIN_LITERAL\n+\tEMPTY_BLOB_SHA1_BIN_LITERAL,\n+\tGIT_HASH_SHA1,\n };\n static const struct object_id empty_tree_oid_sha256 = {\n-\tEMPTY_TREE_SHA256_BIN_LITERAL\n+\tEMPTY_TREE_SHA256_BIN_LITERAL,\n+\tGIT_HASH_SHA256,\n };\n static const struct object_id empty_blob_oid_sha256 = {\n-\tEMPTY_BLOB_SHA256_BIN_LITERAL\n+\tEMPTY_BLOB_SHA256_BIN_LITERAL,\n+\tGIT_HASH_SHA256,\n };\n \n static void git_hash_sha1_init(git_hash_ctx *ctx)\n@@ -93,6 +97,7 @@ static void git_hash_sha1_final_oid(struct object_id *oid, git_hash_ctx *ctx)\n {\n \tgit_SHA1_Final(oid->hash, &ctx->sha1);\n \tmemset(oid->hash + GIT_SHA1_RAWSZ, 0, GIT_MAX_RAWSZ - GIT_SHA1_RAWSZ);\n+\toid->algo = GIT_HASH_SHA1;\n }\n \n \n@@ -124,6 +129,7 @@ static void git_hash_sha256_final_oid(struct object_id *oid, git_hash_ctx *ctx)\n \t * but keep it in case we extend the hash size again.\n \t */\n \tmemset(oid->hash + GIT_SHA256_RAWSZ, 0, GIT_MAX_RAWSZ - GIT_SHA256_RAWSZ);\n+\toid->algo = GIT_HASH_SHA256;\n }\n \n static void git_hash_unknown_init(git_hash_ctx *ctx)\n"},{"id":"421543","messageId":"20210410152140.3525040-12-sandals@crustytoothpaste.net","threadId":"55472","inReplyTo":"20210410152140.3525040-1-sandals@crustytoothpaste.net","subject":"[PATCH 11/15] builtin/show-index: set the algorithm for object IDs","fromName":"brian m. carlson","fromEmail":"sandals@crustytoothpaste.net","sentAt":"2021-04-10T15:21:36Z","receivedAt":"2021-04-10T15:22:41Z","isPatch":true,"sender":{"key":"sandals@crustytoothpaste.net","avatar":"https://avatars.githubusercontent.com/u/497054?v=4"},"body":"In most cases, when we load the hash of an object into a struct\nobject_id, we load it using one of the oid* or *_oid_hex functions.\nHowever, for git show-index, we read it in directly using fread. As a\nconsequence, set the algorithm correctly so the objects can be used\ncorrectly both now and in the future.\n\nSigned-off-by: brian m. carlson \n---\n builtin/show-index.c | 4 +++-\n 1 file changed, 3 insertions(+), 1 deletion(-)\n\ndiff --git a/builtin/show-index.c b/builtin/show-index.c\nindex 8106b03a6b..0e0b9fb95b 100644\n--- a/builtin/show-index.c\n+++ b/builtin/show-index.c\n@@ -71,9 +71,11 @@ int cmd_show_index(int argc, const char **argv, const char *prefix)\n \t\t\tuint32_t off;\n \t\t} *entries;\n \t\tALLOC_ARRAY(entries, nr);\n-\t\tfor (i = 0; i < nr; i++)\n+\t\tfor (i = 0; i < nr; i++) {\n \t\t\tif (fread(entries[i].oid.hash, hashsz, 1, stdin) != 1)\n \t\t\t\tdie(\"unable to read sha1 %u/%u\", i, nr);\n+\t\t\tentries[i].oid.algo = hash_algo_by_ptr(the_hash_algo);\n+\t\t}\n \t\tfor (i = 0; i < nr; i++)\n \t\t\tif (fread(&entries[i].crc, 4, 1, stdin) != 1)\n \t\t\t\tdie(\"unable to read crc %u/%u\", i, nr);\n"},{"id":"421544","messageId":"20210410152140.3525040-13-sandals@crustytoothpaste.net","threadId":"55472","inReplyTo":"20210410152140.3525040-1-sandals@crustytoothpaste.net","subject":"[PATCH 12/15] commit-graph: don't store file hashes as struct object_id","fromName":"brian m. carlson","fromEmail":"sandals@crustytoothpaste.net","sentAt":"2021-04-10T15:21:37Z","receivedAt":"2021-04-10T15:22:42Z","isPatch":true,"sender":{"key":"sandals@crustytoothpaste.net","avatar":"https://avatars.githubusercontent.com/u/497054?v=4"},"body":"The idea behind struct object_id is that it is supposed to represent the\nidentifier of a standard Git object or a special pseudo-object like the\nall-zeros object ID. In this case, we have file hashes, which, while\nsimilar, are distinct from the identifiers of objects.\n\nSwitch these code paths to use an unsigned char array. This is both\nmore logically consistent and it means that we need not set the\nalgorithm identifier for the struct object_id.\n\nSigned-off-by: brian m. carlson \n---\n commit-graph.c | 13 +++++++------\n 1 file changed, 7 insertions(+), 6 deletions(-)\n\ndiff --git a/commit-graph.c b/commit-graph.c\nindex 23fef56d31..2bcb4e0f89 100644\n--- a/commit-graph.c\n+++ b/commit-graph.c\n@@ -1793,8 +1793,8 @@ static int write_commit_graph_file(struct write_commit_graph_context *ctx)\n \tstruct lock_file lk = LOCK_INIT;\n \tconst unsigned hashsz = the_hash_algo->rawsz;\n \tstruct strbuf progress_title = STRBUF_INIT;\n-\tstruct object_id file_hash;\n \tstruct chunkfile *cf;\n+\tunsigned char file_hash[GIT_MAX_RAWSZ];\n \n \tif (ctx->split) {\n \t\tstruct strbuf tmp_file = STRBUF_INIT;\n@@ -1909,7 +1909,7 @@ static int write_commit_graph_file(struct write_commit_graph_context *ctx)\n \t}\n \n \tclose_commit_graph(ctx->r->objects);\n-\tfinalize_hashfile(f, file_hash.hash, CSUM_HASH_IN_STREAM | CSUM_FSYNC);\n+\tfinalize_hashfile(f, file_hash, CSUM_HASH_IN_STREAM | CSUM_FSYNC);\n \tfree_chunkfile(cf);\n \n \tif (ctx->split) {\n@@ -1945,7 +1945,7 @@ static int write_commit_graph_file(struct write_commit_graph_context *ctx)\n \t\t\tunlink(graph_name);\n \t\t}\n \n-\t\tctx->commit_graph_hash_after[ctx->num_commit_graphs_after - 1] = xstrdup(oid_to_hex(&file_hash));\n+\t\tctx->commit_graph_hash_after[ctx->num_commit_graphs_after - 1] = xstrdup(hash_to_hex(file_hash));\n \t\tfinal_graph_name = get_split_graph_filename(ctx->odb,\n \t\t\t\t\tctx->commit_graph_hash_after[ctx->num_commit_graphs_after - 1]);\n \t\tctx->commit_graph_filenames_after[ctx->num_commit_graphs_after - 1] = final_graph_name;\n@@ -2425,7 +2425,8 @@ static void graph_report(const char *fmt, ...)\n int verify_commit_graph(struct repository *r, struct commit_graph *g, int flags)\n {\n \tuint32_t i, cur_fanout_pos = 0;\n-\tstruct object_id prev_oid, cur_oid, checksum;\n+\tstruct object_id prev_oid, cur_oid;\n+\tunsigned char checksum[GIT_MAX_HEXSZ];\n \tint generation_zero = 0;\n \tstruct hashfile *f;\n \tint devnull;\n@@ -2444,8 +2445,8 @@ int verify_commit_graph(struct repository *r, struct commit_graph *g, int flags)\n \tdevnull = open(\"/dev/null\", O_WRONLY);\n \tf = hashfd(devnull, NULL);\n \thashwrite(f, g->data, g->data_len - g->hash_len);\n-\tfinalize_hashfile(f, checksum.hash, CSUM_CLOSE);\n-\tif (!hasheq(checksum.hash, g->data + g->data_len - g->hash_len)) {\n+\tfinalize_hashfile(f, checksum, CSUM_CLOSE);\n+\tif (!hasheq(checksum, g->data + g->data_len - g->hash_len)) {\n \t\tgraph_report(_(\"the commit-graph file has incorrect checksum and is likely corrupt\"));\n \t\tverify_commit_graph_error = VERIFY_COMMIT_GRAPH_ERROR_HASH;\n \t}\n"},{"id":"421545","messageId":"20210410152140.3525040-16-sandals@crustytoothpaste.net","threadId":"55472","inReplyTo":"20210410152140.3525040-1-sandals@crustytoothpaste.net","subject":"[PATCH 15/15] hex: print objects using the hash algorithm member","fromName":"brian m. carlson","fromEmail":"sandals@crustytoothpaste.net","sentAt":"2021-04-10T15:21:40Z","receivedAt":"2021-04-10T15:22:44Z","isPatch":true,"sender":{"key":"sandals@crustytoothpaste.net","avatar":"https://avatars.githubusercontent.com/u/497054?v=4"},"body":"Now that all code paths correctly set the hash algorithm member of\nstruct object_id, write an object's hex representation using the hash\nalgorithm member embedded in it.\n\nSigned-off-by: brian m. carlson \n---\n hex.c | 4 ++--\n 1 file changed, 2 insertions(+), 2 deletions(-)\n\ndiff --git a/hex.c b/hex.c\nindex 43597b2dbb..4537e79d3c 100644\n--- a/hex.c\n+++ b/hex.c\n@@ -143,7 +143,7 @@ char *hash_to_hex_algop_r(char *buffer, const unsigned char *hash,\n \n char *oid_to_hex_r(char *buffer, const struct object_id *oid)\n {\n-\treturn hash_to_hex_algop_r(buffer, oid->hash, the_hash_algo);\n+\treturn hash_to_hex_algop_r(buffer, oid->hash, &hash_algos[oid->algo]);\n }\n \n char *hash_to_hex_algop(const unsigned char *hash, const struct git_hash_algo *algop)\n@@ -161,5 +161,5 @@ char *hash_to_hex(const unsigned char *hash)\n \n char *oid_to_hex(const struct object_id *oid)\n {\n-\treturn hash_to_hex_algop(oid->hash, the_hash_algo);\n+\treturn hash_to_hex_algop(oid->hash, &hash_algos[oid->algo]);\n }\n"},{"id":"421546","messageId":"20210410152140.3525040-3-sandals@crustytoothpaste.net","threadId":"55472","inReplyTo":"20210410152140.3525040-1-sandals@crustytoothpaste.net","subject":"[PATCH 02/15] builtin/hash-object: allow literally hashing with a given algorithm","fromName":"brian m. carlson","fromEmail":"sandals@crustytoothpaste.net","sentAt":"2021-04-10T15:21:27Z","receivedAt":"2021-04-10T15:23:04Z","isPatch":true,"sender":{"key":"sandals@crustytoothpaste.net","avatar":"https://avatars.githubusercontent.com/u/497054?v=4"},"body":"Add an --object-format argument to git hash-object that allows hashing\nan object with a given algorithm. Currently this options is limited to\nuse with --literally, since the index_* functions do not yet handle\nmultiple hash algorithms.\n\nSigned-off-by: brian m. carlson \n---\n builtin/hash-object.c | 47 ++++++++++++++++++++++++++++++------------\n t/t1007-hash-object.sh | 10 +++++++++\n 2 files changed, 44 insertions(+), 13 deletions(-)\n\ndiff --git a/builtin/hash-object.c b/builtin/hash-object.c\nindex 640ef4ded5..0203cfbe9a 100644\n--- a/builtin/hash-object.c\n+++ b/builtin/hash-object.c\n@@ -17,7 +17,8 @@\n * needs to bypass the data conversion performed by, and the type\n * limitation imposed by, index_fd() and its callees.\n */\n-static int hash_literally(struct object_id *oid, int fd, const char *type, unsigned flags)\n+static int hash_literally(struct object_id *oid, int fd, const char *type,\n+\t\t\t unsigned flags, const struct git_hash_algo *algo)\n {\n \tstruct strbuf buf = STRBUF_INIT;\n \tint ret;\n@@ -25,42 +26,46 @@ static int hash_literally(struct object_id *oid, int fd, const char *type, unsig\n \tif (strbuf_read(&buf, fd, 4096) < 0)\n \t\tret = -1;\n \telse\n-\t\tret = hash_object_file_literally(buf.buf, buf.len, type, oid,\n-\t\t\t\t\t\t flags);\n+\t\tret = hash_object_file_literally_algop(buf.buf, buf.len, type, oid,\n+\t\t\t\t\t\t flags, algo);\n \tstrbuf_release(&buf);\n \treturn ret;\n }\n \n static void hash_fd(int fd, const char *type, const char *path, unsigned flags,\n-\t\t int literally)\n+\t\t int literally, const struct git_hash_algo *algo)\n {\n \tstruct stat st;\n \tstruct object_id oid;\n \n+\tif (!literally && algo != the_hash_algo)\n+\t\tdie(_(\"Can't use hash algo %s except literally yet\"), algo->name);\n+\n \tif (fstat(fd, &st) < 0 ||\n \t (literally\n-\t ? hash_literally(&oid, fd, type, flags)\n+\t ? hash_literally(&oid, fd, type, flags, algo)\n \t : index_fd(the_repository->index, &oid, fd, &st,\n \t\t\ttype_from_string(type), path, flags)))\n \t\tdie((flags & HASH_WRITE_OBJECT)\n \t\t ? \"Unable to add %s to database\"\n \t\t : \"Unable to hash %s\", path);\n-\tprintf(\"%s\\n\", oid_to_hex(&oid));\n+\tprintf(\"%s\\n\", hash_to_hex_algop(oid.hash, algo));\n \tmaybe_flush_or_die(stdout, \"hash to stdout\");\n }\n \n static void hash_object(const char *path, const char *type, const char *vpath,\n-\t\t\tunsigned flags, int literally)\n+\t\t\tunsigned flags, int literally,\n+\t\t\tconst struct git_hash_algo *algo)\n {\n \tint fd;\n \tfd = open(path, O_RDONLY);\n \tif (fd < 0)\n \t\tdie_errno(\"Cannot open '%s'\", path);\n-\thash_fd(fd, type, vpath, flags, literally);\n+\thash_fd(fd, type, vpath, flags, literally, algo);\n }\n \n static void hash_stdin_paths(const char *type, int no_filters, unsigned flags,\n-\t\t\t int literally)\n+\t\t\t int literally, const struct git_hash_algo *algo)\n {\n \tstruct strbuf buf = STRBUF_INIT;\n \tstruct strbuf unquoted = STRBUF_INIT;\n@@ -73,7 +78,7 @@ static void hash_stdin_paths(const char *type, int no_filters, unsigned flags,\n \t\t\tstrbuf_swap(&buf, &unquoted);\n \t\t}\n \t\thash_object(buf.buf, type, no_filters ? NULL : buf.buf, flags,\n-\t\t\t literally);\n+\t\t\t literally, algo);\n \t}\n \tstrbuf_release(&buf);\n \tstrbuf_release(&unquoted);\n@@ -94,6 +99,8 @@ int cmd_hash_object(int argc, const char **argv, const char *prefix)\n \tint nongit = 0;\n \tunsigned flags = HASH_FORMAT_CHECK;\n \tconst char *vpath = NULL;\n+\tconst char *object_format = NULL;\n+\tconst struct git_hash_algo *algo;\n \tconst struct option hash_object_options[] = {\n \t\tOPT_STRING('t', NULL, &type, N_(\"type\"), N_(\"object type\")),\n \t\tOPT_BIT('w', NULL, &flags, N_(\"write the object into the object database\"),\n@@ -103,6 +110,7 @@ int cmd_hash_object(int argc, const char **argv, const char *prefix)\n \t\tOPT_BOOL( 0 , \"no-filters\", &no_filters, N_(\"store file as is without filters\")),\n \t\tOPT_BOOL( 0, \"literally\", &literally, N_(\"just hash any random garbage to create corrupt objects for debugging Git\")),\n \t\tOPT_STRING( 0 , \"path\", &vpath, N_(\"file\"), N_(\"process file as it were from this path\")),\n+\t\tOPT_STRING( 0 , \"object-format\", &object_format, N_(\"object-format\"), N_(\"Use this hash algorithm\")),\n \t\tOPT_END()\n \t};\n \tint i;\n@@ -121,6 +129,19 @@ int cmd_hash_object(int argc, const char **argv, const char *prefix)\n \n \tgit_config(git_default_config, NULL);\n \n+\talgo = the_hash_algo;\n+\tif (object_format) {\n+\t\tif (flags & HASH_WRITE_OBJECT)\n+\t\t\terrstr = \"Can't use -w with --object-format\";\n+\t\telse {\n+\t\t\tint id = hash_algo_by_name(object_format);\n+\t\t\tif (id == GIT_HASH_UNKNOWN)\n+\t\t\t\terrstr = \"Unknown object format\";\n+\t\t\telse\n+\t\t\t\talgo = &hash_algos[id];\n+\t\t}\n+\t}\n+\n \tif (stdin_paths) {\n \t\tif (hashstdin)\n \t\t\terrstr = \"Can't use --stdin-paths with --stdin\";\n@@ -142,7 +163,7 @@ int cmd_hash_object(int argc, const char **argv, const char *prefix)\n \t}\n \n \tif (hashstdin)\n-\t\thash_fd(0, type, vpath, flags, literally);\n+\t\thash_fd(0, type, vpath, flags, literally, algo);\n \n \tfor (i = 0 ; i < argc; i++) {\n \t\tconst char *arg = argv[i];\n@@ -151,12 +172,12 @@ int cmd_hash_object(int argc, const char **argv, const char *prefix)\n \t\tif (prefix)\n \t\t\targ = to_free = prefix_filename(prefix, arg);\n \t\thash_object(arg, type, no_filters ? NULL : vpath ? vpath : arg,\n-\t\t\t flags, literally);\n+\t\t\t flags, literally, algo);\n \t\tfree(to_free);\n \t}\n \n \tif (stdin_paths)\n-\t\thash_stdin_paths(type, no_filters, flags, literally);\n+\t\thash_stdin_paths(type, no_filters, flags, literally, algo);\n \n \treturn 0;\n }\ndiff --git a/t/t1007-hash-object.sh b/t/t1007-hash-object.sh\nindex 64b340f227..ea4b3d2bda 100755\n--- a/t/t1007-hash-object.sh\n+++ b/t/t1007-hash-object.sh\n@@ -83,6 +83,11 @@ test_expect_success 'hash a file' '\n \ttest \"$(test_oid hello)\" = $(git hash-object hello)\n '\n \n+test_expect_failure 'hash a file with a given algorithm' '\n+\ttest \"$(test_oid --hash=sha1 hello)\" = $(git hash-object --object-format=sha1 hello) &&\n+\ttest \"$(test_oid --hash=sha256 hello)\" = $(git hash-object --object-format=sha256 hello)\n+'\n+\n test_blob_does_not_exist \"$(test_oid hello)\"\n \n test_expect_success 'hash from stdin' '\n@@ -248,4 +253,9 @@ test_expect_success '--literally with extra-long type' '\n \techo example | git hash-object -t $t --literally --stdin\n '\n \n+test_expect_success '--literally with --object-format' '\n+\ttest $(test_oid --hash=sha1 hello) = $(git hash-object -t blob --literally --object-format=sha1 hello) &&\n+\ttest $(test_oid --hash=sha256 hello) = $(git hash-object -t blob --literally --object-format=sha256 hello)\n+'\n+\n test_done\n"},{"id":"421547","messageId":"20210410152140.3525040-4-sandals@crustytoothpaste.net","threadId":"55472","inReplyTo":"20210410152140.3525040-1-sandals@crustytoothpaste.net","subject":"[PATCH 03/15] cache: add an algo member to struct object_id","fromName":"brian m. carlson","fromEmail":"sandals@crustytoothpaste.net","sentAt":"2021-04-10T15:21:28Z","receivedAt":"2021-04-10T15:23:06Z","isPatch":true,"sender":{"key":"sandals@crustytoothpaste.net","avatar":"https://avatars.githubusercontent.com/u/497054?v=4"},"body":"Now that we're working with multiple hash algorithms in the same repo,\nit's best if we label each object ID with its algorithm so we can\ndetermine how to format a given object ID. Add a member called algo to\nstruct object_id.\n\nSigned-off-by: brian m. carlson \n---\n hash.h | 1 +\n 1 file changed, 1 insertion(+)\n\ndiff --git a/hash.h b/hash.h\nindex 3fb0c3d400..dafdcb3335 100644\n--- a/hash.h\n+++ b/hash.h\n@@ -181,6 +181,7 @@ static inline int hash_algo_by_ptr(const struct git_hash_algo *p)\n \n struct object_id {\n \tunsigned char hash[GIT_MAX_RAWSZ];\n+\tint algo;\n };\n \n #define the_hash_algo the_repository->hash_algo\n"},{"id":"421548","messageId":"20210410152140.3525040-7-sandals@crustytoothpaste.net","threadId":"55472","inReplyTo":"20210410152140.3525040-1-sandals@crustytoothpaste.net","subject":"[PATCH 06/15] Use the final_oid_fn to finalize hashing of object IDs","fromName":"brian m. carlson","fromEmail":"sandals@crustytoothpaste.net","sentAt":"2021-04-10T15:21:31Z","receivedAt":"2021-04-10T15:23:06Z","isPatch":true,"sender":{"key":"sandals@crustytoothpaste.net","avatar":"https://avatars.githubusercontent.com/u/497054?v=4"},"body":"When we're hashing a value which is going to be an object ID, we want to\nzero-pad that value if necessary. To do so, use the final_oid_fn\ninstead of the final_fn anytime we're going to create an object ID to\nensure we perform this operation.\n\nSigned-off-by: brian m. carlson \n---\n builtin/fast-import.c | 4 ++--\n builtin/index-pack.c | 2 +-\n builtin/unpack-objects.c | 2 +-\n bulk-checkin.c | 2 +-\n diff.c | 2 +-\n http.c | 2 +-\n object-file.c | 8 ++++----\n 7 files changed, 11 insertions(+), 11 deletions(-)\n\ndiff --git a/builtin/fast-import.c b/builtin/fast-import.c\nindex 9d2a058a66..20406f6775 100644\n--- a/builtin/fast-import.c\n+++ b/builtin/fast-import.c\n@@ -940,7 +940,7 @@ static int store_object(\n \tthe_hash_algo->init_fn(&c);\n \tthe_hash_algo->update_fn(&c, hdr, hdrlen);\n \tthe_hash_algo->update_fn(&c, dat->buf, dat->len);\n-\tthe_hash_algo->final_fn(oid.hash, &c);\n+\tthe_hash_algo->final_oid_fn(&oid, &c);\n \tif (oidout)\n \t\toidcpy(oidout, &oid);\n \n@@ -1136,7 +1136,7 @@ static void stream_blob(uintmax_t len, struct object_id *oidout, uintmax_t mark)\n \t\t}\n \t}\n \tgit_deflate_end(&s);\n-\tthe_hash_algo->final_fn(oid.hash, &c);\n+\tthe_hash_algo->final_oid_fn(&oid, &c);\n \n \tif (oidout)\n \t\toidcpy(oidout, &oid);\ndiff --git a/builtin/index-pack.c b/builtin/index-pack.c\nindex 41e2c240b8..3fbc5d7077 100644\n--- a/builtin/index-pack.c\n+++ b/builtin/index-pack.c\n@@ -489,7 +489,7 @@ static void *unpack_entry_data(off_t offset, unsigned long size,\n \t\tbad_object(offset, _(\"inflate returned %d\"), status);\n \tgit_inflate_end(&stream);\n \tif (oid)\n-\t\tthe_hash_algo->final_fn(oid->hash, &c);\n+\t\tthe_hash_algo->final_oid_fn(oid, &c);\n \treturn buf == fixed_buf ? NULL : buf;\n }\n \ndiff --git a/builtin/unpack-objects.c b/builtin/unpack-objects.c\nindex a8b73ecf43..6ac90dc5f7 100644\n--- a/builtin/unpack-objects.c\n+++ b/builtin/unpack-objects.c\n@@ -576,7 +576,7 @@ int cmd_unpack_objects(int argc, const char **argv, const char *prefix)\n \tthe_hash_algo->init_fn(&ctx);\n \tunpack_all();\n \tthe_hash_algo->update_fn(&ctx, buffer, offset);\n-\tthe_hash_algo->final_fn(oid.hash, &ctx);\n+\tthe_hash_algo->final_oid_fn(&oid, &ctx);\n \tif (strict) {\n \t\twrite_rest();\n \t\tif (fsck_finish(&fsck_options))\ndiff --git a/bulk-checkin.c b/bulk-checkin.c\nindex 6f3c97cd34..127312acd1 100644\n--- a/bulk-checkin.c\n+++ b/bulk-checkin.c\n@@ -238,7 +238,7 @@ static int deflate_to_pack(struct bulk_checkin_state *state,\n \t\tif (lseek(fd, seekback, SEEK_SET) == (off_t) -1)\n \t\t\treturn error(\"cannot seek back\");\n \t}\n-\tthe_hash_algo->final_fn(result_oid->hash, &ctx);\n+\tthe_hash_algo->final_oid_fn(result_oid, &ctx);\n \tif (!idx)\n \t\treturn 0;\n \ndiff --git a/diff.c b/diff.c\nindex 4acccd9d7e..97c62f47df 100644\n--- a/diff.c\n+++ b/diff.c\n@@ -6234,7 +6234,7 @@ static int diff_get_patch_id(struct diff_options *options, struct object_id *oid\n \t}\n \n \tif (!stable)\n-\t\tthe_hash_algo->final_fn(oid->hash, &ctx);\n+\t\tthe_hash_algo->final_oid_fn(oid, &ctx);\n \n \treturn 0;\n }\ndiff --git a/http.c b/http.c\nindex 406410f884..c83bc33a5f 100644\n--- a/http.c\n+++ b/http.c\n@@ -2576,7 +2576,7 @@ int finish_http_object_request(struct http_object_request *freq)\n \t}\n \n \tgit_inflate_end(&freq->stream);\n-\tthe_hash_algo->final_fn(freq->real_oid.hash, &freq->c);\n+\tthe_hash_algo->final_oid_fn(&freq->real_oid, &freq->c);\n \tif (freq->zret != Z_STREAM_END) {\n \t\tunlink_or_warn(freq->tmpfile.buf);\n \t\treturn -1;\ndiff --git a/object-file.c b/object-file.c\nindex 58d31452d8..3f43c376e7 100644\n--- a/object-file.c\n+++ b/object-file.c\n@@ -1054,7 +1054,7 @@ int check_object_signature(struct repository *r, const struct object_id *oid,\n \t\t\tbreak;\n \t\tr->hash_algo->update_fn(&c, buf, readlen);\n \t}\n-\tr->hash_algo->final_fn(real_oid.hash, &c);\n+\tr->hash_algo->final_oid_fn(&real_oid, &c);\n \tclose_istream(st);\n \treturn !oideq(oid, &real_oid) ? -1 : 0;\n }\n@@ -1755,7 +1755,7 @@ static void write_object_file_prepare(const struct git_hash_algo *algo,\n \talgo->init_fn(&c);\n \talgo->update_fn(&c, hdr, *hdrlen);\n \talgo->update_fn(&c, buf, len);\n-\talgo->final_fn(oid->hash, &c);\n+\talgo->final_oid_fn(oid, &c);\n }\n \n /*\n@@ -1927,7 +1927,7 @@ static int write_loose_object(const struct object_id *oid, char *hdr,\n \tif (ret != Z_OK)\n \t\tdie(_(\"deflateEnd on object %s failed (%d)\"), oid_to_hex(oid),\n \t\t ret);\n-\tthe_hash_algo->final_fn(parano_oid.hash, &c);\n+\tthe_hash_algo->final_oid_fn(¶no_oid, &c);\n \tif (!oideq(oid, ¶no_oid))\n \t\tdie(_(\"confused by unstable object source data for %s\"),\n \t\t oid_to_hex(oid));\n@@ -2520,7 +2520,7 @@ static int check_stream_oid(git_zstream *stream,\n \t\treturn -1;\n \t}\n \n-\tthe_hash_algo->final_fn(real_oid.hash, &c);\n+\tthe_hash_algo->final_oid_fn(&real_oid, &c);\n \tif (!oideq(expected_oid, &real_oid)) {\n \t\terror(_(\"hash mismatch for %s (expected %s)\"), path,\n \t\t oid_to_hex(expected_oid));\n"},{"id":"421549","messageId":"20210410152140.3525040-14-sandals@crustytoothpaste.net","threadId":"55472","inReplyTo":"20210410152140.3525040-1-sandals@crustytoothpaste.net","subject":"[PATCH 13/15] builtin/pack-objects: avoid using struct object_id for pack hash","fromName":"brian m. carlson","fromEmail":"sandals@crustytoothpaste.net","sentAt":"2021-04-10T15:21:38Z","receivedAt":"2021-04-10T15:23:09Z","isPatch":true,"sender":{"key":"sandals@crustytoothpaste.net","avatar":"https://avatars.githubusercontent.com/u/497054?v=4"},"body":"We use struct object_id for the names of objects. It isn't intended to\nbe used for other hash values that don't name objects such as the pack\nhash.\n\nBecause struct object_id will soon need to have its algorithm member\nset, using it in this code path would mean that we didn't set that\nmember, only the hash member, which would result in a crash. For both\nof these reasons, switch to using an unsigned char array of size\nGIT_MAX_RAWSZ.\n\nSigned-off-by: brian m. carlson \n---\n builtin/pack-objects.c | 20 ++++++++++----------\n 1 file changed, 10 insertions(+), 10 deletions(-)\n\ndiff --git a/builtin/pack-objects.c b/builtin/pack-objects.c\nindex 525c2d8552..5b25382204 100644\n--- a/builtin/pack-objects.c\n+++ b/builtin/pack-objects.c\n@@ -1030,7 +1030,7 @@ static void write_pack_file(void)\n \twrite_order = compute_write_order();\n \n \tdo {\n-\t\tstruct object_id oid;\n+\t\tunsigned char hash[GIT_MAX_RAWSZ];\n \t\tchar *pack_tmp_name = NULL;\n \n \t\tif (pack_to_stdout)\n@@ -1059,13 +1059,13 @@ static void write_pack_file(void)\n \t\t * If so, rewrite it like in fast-import\n \t\t */\n \t\tif (pack_to_stdout) {\n-\t\t\tfinalize_hashfile(f, oid.hash, CSUM_HASH_IN_STREAM | CSUM_CLOSE);\n+\t\t\tfinalize_hashfile(f, hash, CSUM_HASH_IN_STREAM | CSUM_CLOSE);\n \t\t} else if (nr_written == nr_remaining) {\n-\t\t\tfinalize_hashfile(f, oid.hash, CSUM_HASH_IN_STREAM | CSUM_FSYNC | CSUM_CLOSE);\n+\t\t\tfinalize_hashfile(f, hash, CSUM_HASH_IN_STREAM | CSUM_FSYNC | CSUM_CLOSE);\n \t\t} else {\n-\t\t\tint fd = finalize_hashfile(f, oid.hash, 0);\n-\t\t\tfixup_pack_header_footer(fd, oid.hash, pack_tmp_name,\n-\t\t\t\t\t\t nr_written, oid.hash, offset);\n+\t\t\tint fd = finalize_hashfile(f, hash, 0);\n+\t\t\tfixup_pack_header_footer(fd, hash, pack_tmp_name,\n+\t\t\t\t\t\t nr_written, hash, offset);\n \t\t\tclose(fd);\n \t\t\tif (write_bitmap_index) {\n \t\t\t\tif (write_bitmap_index != WRITE_BITMAP_QUIET)\n@@ -1100,17 +1100,17 @@ static void write_pack_file(void)\n \t\t\tstrbuf_addf(&tmpname, \"%s-\", base_name);\n \n \t\t\tif (write_bitmap_index) {\n-\t\t\t\tbitmap_writer_set_checksum(oid.hash);\n+\t\t\t\tbitmap_writer_set_checksum(hash);\n \t\t\t\tbitmap_writer_build_type_index(\n \t\t\t\t\t&to_pack, written_list, nr_written);\n \t\t\t}\n \n \t\t\tfinish_tmp_packfile(&tmpname, pack_tmp_name,\n \t\t\t\t\t written_list, nr_written,\n-\t\t\t\t\t &pack_idx_opts, oid.hash);\n+\t\t\t\t\t &pack_idx_opts, hash);\n \n \t\t\tif (write_bitmap_index) {\n-\t\t\t\tstrbuf_addf(&tmpname, \"%s.bitmap\", oid_to_hex(&oid));\n+\t\t\t\tstrbuf_addf(&tmpname, \"%s.bitmap\", hash_to_hex(hash));\n \n \t\t\t\tstop_progress(&progress_state);\n \n@@ -1124,7 +1124,7 @@ static void write_pack_file(void)\n \n \t\t\tstrbuf_release(&tmpname);\n \t\t\tfree(pack_tmp_name);\n-\t\t\tputs(oid_to_hex(&oid));\n+\t\t\tputs(hash_to_hex(hash));\n \t\t}\n \n \t\t/* mark written objects as written to previous pack */\n"},{"id":"421550","messageId":"20210410152140.3525040-15-sandals@crustytoothpaste.net","threadId":"55472","inReplyTo":"20210410152140.3525040-1-sandals@crustytoothpaste.net","subject":"[PATCH 14/15] hex: default to the_hash_algo on zero algorithm value","fromName":"brian m. carlson","fromEmail":"sandals@crustytoothpaste.net","sentAt":"2021-04-10T15:21:39Z","receivedAt":"2021-04-10T15:23:10Z","isPatch":true,"sender":{"key":"sandals@crustytoothpaste.net","avatar":"https://avatars.githubusercontent.com/u/497054?v=4"},"body":"There are numerous places in the codebase where we assume we can\ninitialize data by zeroing all its bytes. However, when we do that with\na struct object_id, it leaves the structure with a zero value for the\nalgorithm, which is invalid.\n\nWe could forbid this pattern and require that all struct object_id\ninstances be initialized using oidclr, but this seems burdensome and\nit's unnatural to most C programmers. Instead, if the algorithm is\nzero, assume we wanted to use the default hash algorithm instead.\n\nSigned-off-by: brian m. carlson \n---\n hex.c | 7 +++++++\n 1 file changed, 7 insertions(+)\n\ndiff --git a/hex.c b/hex.c\nindex 5fa3e71cb9..43597b2dbb 100644\n--- a/hex.c\n+++ b/hex.c\n@@ -124,6 +124,13 @@ char *hash_to_hex_algop_r(char *buffer, const unsigned char *hash,\n \tchar *buf = buffer;\n \tint i;\n \n+\t/*\n+\t * Our struct object_id has been memset to 0, so default to printing\n+\t * using the default hash.\n+\t */\n+\tif (algop == &hash_algos[0])\n+\t\talgop = the_hash_algo;\n+\n \tfor (i = 0; i < algop->rawsz; i++) {\n \t\tunsigned int val = *hash++;\n \t\t*buf++ = hex[val >> 4];\n"},{"id":"421571","messageId":"CAPx1GvfiG9AzYJi2PqhEW2d1n1ghn4Jnna4QR0cJSgNXvaEXQg@mail.gmail.com","threadId":"55472","inReplyTo":"20210410152140.3525040-9-sandals@crustytoothpaste.net","subject":"Re: [PATCH 08/15] cache: compare the entire buffer for struct object_id","fromName":"Chris Torek","fromEmail":"chris.torek@gmail.com","sentAt":"2021-04-11T08:17:10Z","receivedAt":"2021-04-11T08:17:25Z","isPatch":true,"sender":{"key":"chris.torek@gmail.com","avatar":"https://avatars.githubusercontent.com/u/16826774?v=4"},"body":"Just an observation here: comparing 256 bytes every time\nwould seem to have one nice bonus side effect and one\npotentially bad, but vanishingly unlikely, side effect: a 160\nbyte null hash will now compare equal to a 256 byte null\nhash (good), but a 160 byte hash extended to 256 bytes\nwill compare equal to a 256 byte hash that just happens to\nend in 96 bytes of zero (bad, but I would guess, will never\nactually happen).\n\nChris\n\nOn Sat, Apr 10, 2021 at 8:23 AM brian m. carlson\n wrote:\n>\n> Currently, when we compare two object IDs, we have to take a branch to\n> determine what the hash size is supposed to be. The compiler can\n> optimize well for a single length, but has trouble when there are two\n> possible lengths.\n>\n> There is, however, an alternative: we can ensure that we always compare\n> the full length of the hash buffer, but in turn we must zero the\n> remainder of the buffer when using SHA-1; otherwise, we'll end up with\n> incompatible junk at the end of otherwise equivalent object IDs that\n> will prevent them from matching. This is an acceptable tradeoff,\n> because we generally read an object ID in once, but then compare it\n> against others multiple times.\n>\n> This latter approach also has some benefits as well: since we will have\n> annotated every location in which we load an object ID into an instance\n> of struct object_id, if we want to set the hash algorithm for the object\n> ID, we can do so at the same time.\n>\n> Adopt this latter approach, since it provides us greater flexibility and\n> lets us read and store object IDs for multiple algorithms at once.\n>\n> Signed-off-by: brian m. carlson \n> ---\n> hash.h | 13 ++++++++++---\n> hex.c | 9 ++++++---\n> notes.c | 3 +++\n> object-file.c | 1 +\n> 4 files changed, 20 insertions(+), 6 deletions(-)\n>\n> diff --git a/hash.h b/hash.h\n> index c8f03d8aee..04eba5c56b 100644\n> --- a/hash.h\n> +++ b/hash.h\n> @@ -205,7 +205,7 @@ static inline int hashcmp(const unsigned char *sha1, const unsigned char *sha2)\n>\n> static inline int oidcmp(const struct object_id *oid1, const struct object_id *oid2)\n> {\n> - return hashcmp(oid1->hash, oid2->hash);\n> + return memcmp(oid1->hash, oid2->hash, GIT_MAX_RAWSZ);\n> }\n>\n> static inline int hasheq(const unsigned char *sha1, const unsigned char *sha2)\n> @@ -221,7 +221,7 @@ static inline int hasheq(const unsigned char *sha1, const unsigned char *sha2)\n>\n> static inline int oideq(const struct object_id *oid1, const struct object_id *oid2)\n> {\n> - return hasheq(oid1->hash, oid2->hash);\n> + return !memcmp(oid1->hash, oid2->hash, GIT_MAX_RAWSZ);\n> }\n>\n> static inline int is_null_oid(const struct object_id *oid)\n> @@ -258,7 +258,9 @@ static inline void oidclr(struct object_id *oid)\n>\n> static inline void oidread(struct object_id *oid, const unsigned char *hash)\n> {\n> - memcpy(oid->hash, hash, the_hash_algo->rawsz);\n> + size_t rawsz = the_hash_algo->rawsz;\n> + memcpy(oid->hash, hash, rawsz);\n> + memset(oid->hash + rawsz, 0, GIT_MAX_RAWSZ - rawsz);\n> }\n>\n> static inline int is_empty_blob_sha1(const unsigned char *sha1)\n> @@ -281,6 +283,11 @@ static inline int is_empty_tree_oid(const struct object_id *oid)\n> return oideq(oid, the_hash_algo->empty_tree);\n> }\n>\n> +static inline void oid_pad_buffer(struct object_id *oid, const struct git_hash_algo *algop)\n> +{\n> + memset(oid->hash + algop->rawsz, 0, GIT_MAX_RAWSZ - algop->rawsz);\n> +}\n> +\n> const char *empty_tree_oid_hex(void);\n> const char *empty_blob_oid_hex(void);\n>\n> diff --git a/hex.c b/hex.c\n> index da51e64929..5fa3e71cb9 100644\n> --- a/hex.c\n> +++ b/hex.c\n> @@ -69,7 +69,10 @@ int get_sha1_hex(const char *hex, unsigned char *sha1)\n> int get_oid_hex_algop(const char *hex, struct object_id *oid,\n> const struct git_hash_algo *algop)\n> {\n> - return get_hash_hex_algop(hex, oid->hash, algop);\n> + int ret = get_hash_hex_algop(hex, oid->hash, algop);\n> + if (!ret)\n> + oid_pad_buffer(oid, algop);\n> + return ret;\n> }\n>\n> /*\n> @@ -80,7 +83,7 @@ int get_oid_hex_any(const char *hex, struct object_id *oid)\n> {\n> int i;\n> for (i = GIT_HASH_NALGOS - 1; i > 0; i--) {\n> - if (!get_hash_hex_algop(hex, oid->hash, &hash_algos[i]))\n> + if (!get_oid_hex_algop(hex, oid, &hash_algos[i]))\n> return i;\n> }\n> return GIT_HASH_UNKNOWN;\n> @@ -95,7 +98,7 @@ int parse_oid_hex_algop(const char *hex, struct object_id *oid,\n> const char **end,\n> const struct git_hash_algo *algop)\n> {\n> - int ret = get_hash_hex_algop(hex, oid->hash, algop);\n> + int ret = get_oid_hex_algop(hex, oid, algop);\n> if (!ret)\n> *end = hex + algop->hexsz;\n> return ret;\n> diff --git a/notes.c b/notes.c\n> index a44b25858f..1dfe9e2b9f 100644\n> --- a/notes.c\n> +++ b/notes.c\n> @@ -455,6 +455,8 @@ static void load_subtree(struct notes_tree *t, struct leaf_node *subtree,\n> CALLOC_ARRAY(l, 1);\n> oidcpy(&l->key_oid, &object_oid);\n> oidcpy(&l->val_oid, &entry.oid);\n> + oid_pad_buffer(&l->key_oid, the_hash_algo);\n> + oid_pad_buffer(&l->val_oid, the_hash_algo);\n> if (note_tree_insert(t, node, n, l, type,\n> combine_notes_concatenate))\n> die(\"Failed to load %s %s into notes tree \"\n> @@ -484,6 +486,7 @@ static void load_subtree(struct notes_tree *t, struct leaf_node *subtree,\n> strbuf_addch(&non_note_path, '/');\n> }\n> strbuf_addstr(&non_note_path, entry.path);\n> + oid_pad_buffer(&entry.oid, the_hash_algo);\n> add_non_note(t, strbuf_detach(&non_note_path, NULL),\n> entry.mode, entry.oid.hash);\n> }\n> diff --git a/object-file.c b/object-file.c\n> index 3f43c376e7..8e338247cc 100644\n> --- a/object-file.c\n> +++ b/object-file.c\n> @@ -2352,6 +2352,7 @@ int for_each_file_in_obj_subdir(unsigned int subdir_nr,\n> if (namelen == the_hash_algo->hexsz - 2 &&\n> !hex_to_bytes(oid.hash + 1, de->d_name,\n> the_hash_algo->rawsz - 1)) {\n> + oid_pad_buffer(&oid, the_hash_algo);\n> if (obj_cb) {\n> r = obj_cb(&oid, path->buf, data);\n> if (r)\n"},{"id":"421572","messageId":"87sg3xfbkd.fsf@evledraar.gmail.com","threadId":"55472","inReplyTo":"20210410152140.3525040-3-sandals@crustytoothpaste.net","subject":"Re: [PATCH 02/15] builtin/hash-object: allow literally hashing with a given algorithm","fromName":"Ævar Arnfjörð Bjarmason","fromEmail":"avarab@gmail.com","sentAt":"2021-04-11T08:52:02Z","receivedAt":"2021-04-11T08:52:09Z","isPatch":true,"sender":{"key":"avarab@gmail.com","avatar":"https://avatars.githubusercontent.com/u/45301?v=4"},"body":"\nOn Sat, Apr 10 2021, brian m. carlson wrote:\n\n> +\talgo = the_hash_algo;\n> +\tif (object_format) {\n> +\t\tif (flags & HASH_WRITE_OBJECT)\n> +\t\t\terrstr = \"Can't use -w with --object-format\";\n> +\t\telse {\n> +\t\t\tint id = hash_algo_by_name(object_format);\n> +\t\t\tif (id == GIT_HASH_UNKNOWN)\n> +\t\t\t\terrstr = \"Unknown object format\";\n\nAn established pattern, but shouldn't these be N_()'d while we're at it?\nAt least for new strings.\n\n> +\t\t\telse\n> +\t\t\t\talgo = &hash_algos[id];\n> +\t\t}\n> +\t}\n\nStyle nit: if .. {} else {} not if .. else {}.\n\n> +test_expect_success '--literally with --object-format' '\n> +\ttest $(test_oid --hash=sha1 hello) = $(git hash-object -t blob --literally --object-format=sha1 hello) &&\n> +\ttest $(test_oid --hash=sha256 hello) = $(git hash-object -t blob --literally --object-format=sha256 hello)\n> +'\n\nThis would be more readable and easier to debug with 4x tempfiles and 2x\ntest_cmp.\n"},{"id":"421586","messageId":"87pmz1f3y6.fsf@evledraar.gmail.com","threadId":"55472","inReplyTo":"20210410152140.3525040-9-sandals@crustytoothpaste.net","subject":"Re: [PATCH 08/15] cache: compare the entire buffer for struct object_id","fromName":"Ævar Arnfjörð Bjarmason","fromEmail":"avarab@gmail.com","sentAt":"2021-04-11T11:36:33Z","receivedAt":"2021-04-11T11:36:37Z","isPatch":true,"sender":{"key":"avarab@gmail.com","avatar":"https://avatars.githubusercontent.com/u/45301?v=4"},"body":"\nOn Sat, Apr 10 2021, brian m. carlson wrote:\n\n> Currently, when we compare two object IDs, we have to take a branch to\n> determine what the hash size is supposed to be. The compiler can\n> optimize well for a single length, but has trouble when there are two\n> possible lengths.\n\nThis would benefit from some performance/perf numbers. When this code\nwas first changed like this in 183a638b7da (hashcmp: assert constant\nhash size, 2018-08-23) we had:\n\n Test v2.18.0 v2.19.0-rc0 HEAD\n ------------------------------------------------------------------------------\n 0001.2: 34.24(33.81+0.43) 34.83(34.42+0.40) +1.7% 33.90(33.47+0.42) -1.0%\n\nThen it was later modified in 0dab7129ab1 (cache: make hashcmp and\nhasheq work with larger hashes, 2018-11-14).\n\n> @@ -205,7 +205,7 @@ static inline int hashcmp(const unsigned char *sha1, const unsigned char *sha2)\n> \n> static inline int oidcmp(const struct object_id *oid1, const struct object_id *oid2)\n> {\n> -\treturn hashcmp(oid1->hash, oid2->hash);\n> +\treturn memcmp(oid1->hash, oid2->hash, GIT_MAX_RAWSZ);\n> }\n\nhashcmp is now:\n\n if (the_hash_algo->rawsz == GIT_MAX_RAWSZ)\n return memcmp(sha1, sha2, GIT_MAX_RAWSZ);\n return memcmp(sha1, sha2, GIT_SHA1_RAWSZ);\n\nWouldn't it make more sense to amend it to just be a memcmp\nwrapper/macro if we're going to not make this conditional on the hash\nalgorithm, or are there other callsites where we still want the old way\nof doing it?\n\n> \n> static inline int hasheq(const unsigned char *sha1, const unsigned char *sha2)\n> @@ -221,7 +221,7 @@ static inline int hasheq(const unsigned char *sha1, const unsigned char *sha2)\n> \n> static inline int oideq(const struct object_id *oid1, const struct object_id *oid2)\n> {\n> -\treturn hasheq(oid1->hash, oid2->hash);\n> +\treturn !memcmp(oid1->hash, oid2->hash, GIT_MAX_RAWSZ);\n> }\n\nDitto hasheq v.s. !memcmp:\n\n if (the_hash_algo->rawsz == GIT_MAX_RAWSZ)\n return !memcmp(sha1, sha2, GIT_MAX_RAWSZ);\n return !memcmp(sha1, sha2, GIT_SHA1_RAWSZ);\n"},{"id":"421588","messageId":"87mtu5f31u.fsf@evledraar.gmail.com","threadId":"55472","inReplyTo":"20210410152140.3525040-4-sandals@crustytoothpaste.net","subject":"Re: [PATCH 03/15] cache: add an algo member to struct object_id","fromName":"Ævar Arnfjörð Bjarmason","fromEmail":"avarab@gmail.com","sentAt":"2021-04-11T11:55:57Z","receivedAt":"2021-04-11T11:56:01Z","isPatch":true,"sender":{"key":"avarab@gmail.com","avatar":"https://avatars.githubusercontent.com/u/45301?v=4"},"body":"\nOn Sat, Apr 10 2021, brian m. carlson wrote:\n\n> Now that we're working with multiple hash algorithms in the same repo,\n> it's best if we label each object ID with its algorithm so we can\n> determine how to format a given object ID. Add a member called algo to\n> struct object_id.\n>\n> Signed-off-by: brian m. carlson \n> ---\n> hash.h | 1 +\n> 1 file changed, 1 insertion(+)\n>\n> diff --git a/hash.h b/hash.h\n> index 3fb0c3d400..dafdcb3335 100644\n> --- a/hash.h\n> +++ b/hash.h\n> @@ -181,6 +181,7 @@ static inline int hash_algo_by_ptr(const struct git_hash_algo *p)\n> \n> struct object_id {\n> \tunsigned char hash[GIT_MAX_RAWSZ];\n> +\tint algo;\n\nCuriosity since I'm not as familiar as you with the multi-hash support\nby far:\n\nSo struct object_id is GIT_MAX_RAWSZ, not two types of structs for\nGIT_SHA1_RAWSZ and GIT_SHA256_RAWSZ. That pre-dates this series because\nwe'd like to not deal with two types of objects everywhere for SHA-1 and\nSHA-256. Makes sense.\n\nBefore this series we'd memcmp them up to their actual length, but the\nlast GIT_MAX_RAWSZ-GIT_SHA1_RAWSZ would be uninitialized\n\nNow we pad them out, so the last 96 bits of every SHA1 are 0000...;\nCouldn't we also tell which hash an object is by memcmp-ing those last N\nbits and see if they're all zero'd?\n\nFeels a bit hackish, and we'd need to reconsider that method if we'd\never support other same-length hashes.\n\nBut OTOH having these objects all padded out in memory to the same\nlength, but having to carry around a \"what hash algo\" is it yields the\narguably weird hack of having a per-hash NULL_OID, which has never been\nan actual object of any hash type, but just a pseudo-object.\n\nAs another aside I had some local patches (just for playing around) to\nimplement SHA-256/160, i.e. a SHA-256-to-SHA-1-length that doesn't\nofficially exist. We'd store things as full-length SHA-256 internally,\nbut on anything that would format them (including plumbing output) we'd\nemit the truncated version(s).\n\nThe idea was to support Git/SHA-256 when combined with legacy systems\nwho'd all need DB column changes to have different length hashes.\n\nI abandoned it as insany sillyness after playing with it for about a\nday, but it did reveal that much of the hash code now can assume\ninternal length == formatting length, which is why I'm 3 paragraphs into\nthis digression, i.e. maybe some of the code structure also makes having\na NULL_OID always be 256-bits when we want to format it as 160/256\npainful...\n"},{"id":"421589","messageId":"87k0p9f2z9.fsf@evledraar.gmail.com","threadId":"55472","inReplyTo":"20210410152140.3525040-10-sandals@crustytoothpaste.net","subject":"Re: [PATCH 09/15] hash: set and copy algo field in struct object_id","fromName":"Ævar Arnfjörð Bjarmason","fromEmail":"avarab@gmail.com","sentAt":"2021-04-11T11:57:30Z","receivedAt":"2021-04-11T11:57:35Z","isPatch":true,"sender":{"key":"avarab@gmail.com","avatar":"https://avatars.githubusercontent.com/u/45301?v=4"},"body":"\nOn Sat, Apr 10 2021, brian m. carlson wrote:\n\n> const struct object_id null_oid;\n> static const struct object_id empty_tree_oid = {\n> -\tEMPTY_TREE_SHA1_BIN_LITERAL\n> +\tEMPTY_TREE_SHA1_BIN_LITERAL,\n> +\tGIT_HASH_SHA1,\n> };\n> static const struct object_id empty_blob_oid = {\n> -\tEMPTY_BLOB_SHA1_BIN_LITERAL\n> +\tEMPTY_BLOB_SHA1_BIN_LITERAL,\n> +\tGIT_HASH_SHA1,\n> };\n> static const struct object_id empty_tree_oid_sha256 = {\n> -\tEMPTY_TREE_SHA256_BIN_LITERAL\n> +\tEMPTY_TREE_SHA256_BIN_LITERAL,\n> +\tGIT_HASH_SHA256,\n> };\n> static const struct object_id empty_blob_oid_sha256 = {\n> -\tEMPTY_BLOB_SHA256_BIN_LITERAL\n> +\tEMPTY_BLOB_SHA256_BIN_LITERAL,\n> +\tGIT_HASH_SHA256,\n> };\n\nIn this and some other patches we're continuing to add new fields to\nstructs without using designated initializers.\n\nNot a new problem at all, just a note that if you re-roll I for one\nwould very much appreciate starting by migrating over to that. It makes\nfor much easier reading in subsequent patches in this series, and in\nfuture ones.\n"},{"id":"421594","messageId":"xmqqy2dohqau.fsf@gitster.g","threadId":"55472","inReplyTo":"20210410152140.3525040-11-sandals@crustytoothpaste.net","subject":"Re: [PATCH 10/15] hash: provide per-algorithm null OIDs","fromName":"Junio C Hamano","fromEmail":"gitster@pobox.com","sentAt":"2021-04-11T14:03:05Z","receivedAt":"2021-04-11T14:03:12Z","isPatch":true,"sender":{"key":"gitster@pobox.com","avatar":"https://avatars.githubusercontent.com/u/54884?v=4"},"body":"\"brian m. carlson\" writes:\n\n> diff --git a/object-file.c b/object-file.c\n> index 5f1fa05c4e..50bb5b6ca4 100644\n> --- a/object-file.c\n> +++ b/object-file.c\n> @@ -55,7 +55,6 @@\n> \t\"\\x6f\\xe1\\x41\\xf7\\x74\\x91\\x20\\xa3\\x03\\x72\" \\\n> \t\"\\x18\\x13\"\n> \n> -const struct object_id null_oid;\n> static const struct object_id empty_tree_oid = {\n> \tEMPTY_TREE_SHA1_BIN_LITERAL,\n> \tGIT_HASH_SHA1,\n> @@ -64,6 +63,9 @@ static const struct object_id empty_blob_oid = {\n> \tEMPTY_BLOB_SHA1_BIN_LITERAL,\n> \tGIT_HASH_SHA1,\n> };\n> +const struct object_id null_oid_sha1 = {\n> +\t{0}, GIT_HASH_SHA1,\n> +};\n\nsparse wants this to be a file-scope static.\n"},{"id":"421623","messageId":"YHNkrnid7sJh5RSh@camp.crustytoothpaste.net","threadId":"55472","inReplyTo":"87pmz1f3y6.fsf@evledraar.gmail.com","subject":"Re: [PATCH 08/15] cache: compare the entire buffer for struct object_id","fromName":"brian m. carlson","fromEmail":"sandals@crustytoothpaste.net","sentAt":"2021-04-11T21:05:50Z","receivedAt":"2021-04-11T21:05:57Z","isPatch":true,"sender":{"key":"sandals@crustytoothpaste.net","avatar":"https://avatars.githubusercontent.com/u/497054?v=4"},"body":"On 2021-04-11 at 11:36:33, Ævar Arnfjörð Bjarmason wrote:\n> \n> On Sat, Apr 10 2021, brian m. carlson wrote:\n> \n> > Currently, when we compare two object IDs, we have to take a branch to\n> > determine what the hash size is supposed to be. The compiler can\n> > optimize well for a single length, but has trouble when there are two\n> > possible lengths.\n> \n> This would benefit from some performance/perf numbers. When this code\n> was first changed like this in 183a638b7da (hashcmp: assert constant\n> hash size, 2018-08-23) we had:\n> \n> Test v2.18.0 v2.19.0-rc0 HEAD\n> ------------------------------------------------------------------------------\n> 0001.2: 34.24(33.81+0.43) 34.83(34.42+0.40) +1.7% 33.90(33.47+0.42) -1.0%\n> \n> Then it was later modified in 0dab7129ab1 (cache: make hashcmp and\n> hasheq work with larger hashes, 2018-11-14).\n\nI can do some perf numbers.\n\n> > @@ -205,7 +205,7 @@ static inline int hashcmp(const unsigned char *sha1, const unsigned char *sha2)\n> > \n> > static inline int oidcmp(const struct object_id *oid1, const struct object_id *oid2)\n> > {\n> > -\treturn hashcmp(oid1->hash, oid2->hash);\n> > +\treturn memcmp(oid1->hash, oid2->hash, GIT_MAX_RAWSZ);\n> > }\n> \n> hashcmp is now:\n> \n> if (the_hash_algo->rawsz == GIT_MAX_RAWSZ)\n> return memcmp(sha1, sha2, GIT_MAX_RAWSZ);\n> return memcmp(sha1, sha2, GIT_SHA1_RAWSZ);\n> \n> Wouldn't it make more sense to amend it to just be a memcmp\n> wrapper/macro if we're going to not make this conditional on the hash\n> algorithm, or are there other callsites where we still want the old way\n> of doing it?\n\nNo, we can't do that. With oidcmp, we know the buffer is large enough.\nHowever, in some cases, the buffer in hashcmp is not large enough. For\nexample, we may be at the end of a SHA-1 tree object and we'd segfault.\nI did try that and I quickly found that it was totally broken.\n-- \nbrian m. carlson (he/him or they/them)\nHouston, Texas, US\n"},{"id":"421624","messageId":"YHNlFmpQa3Qlgh9g@camp.crustytoothpaste.net","threadId":"55472","inReplyTo":"87sg3xfbkd.fsf@evledraar.gmail.com","subject":"Re: [PATCH 02/15] builtin/hash-object: allow literally hashing with a given algorithm","fromName":"brian m. carlson","fromEmail":"sandals@crustytoothpaste.net","sentAt":"2021-04-11T21:07:34Z","receivedAt":"2021-04-11T21:07:42Z","isPatch":true,"sender":{"key":"sandals@crustytoothpaste.net","avatar":"https://avatars.githubusercontent.com/u/497054?v=4"},"body":"On 2021-04-11 at 08:52:02, Ævar Arnfjörð Bjarmason wrote:\n> \n> On Sat, Apr 10 2021, brian m. carlson wrote:\n> \n> > +\talgo = the_hash_algo;\n> > +\tif (object_format) {\n> > +\t\tif (flags & HASH_WRITE_OBJECT)\n> > +\t\t\terrstr = \"Can't use -w with --object-format\";\n> > +\t\telse {\n> > +\t\t\tint id = hash_algo_by_name(object_format);\n> > +\t\t\tif (id == GIT_HASH_UNKNOWN)\n> > +\t\t\t\terrstr = \"Unknown object format\";\n> \n> An established pattern, but shouldn't these be N_()'d while we're at it?\n> At least for new strings.\n\nSure, I can do that.\n\n> > +\t\t\telse\n> > +\t\t\t\talgo = &hash_algos[id];\n> > +\t\t}\n> > +\t}\n> \n> Style nit: if .. {} else {} not if .. else {}.\n\nWill fix.\n\n> > +test_expect_success '--literally with --object-format' '\n> > +\ttest $(test_oid --hash=sha1 hello) = $(git hash-object -t blob --literally --object-format=sha1 hello) &&\n> > +\ttest $(test_oid --hash=sha256 hello) = $(git hash-object -t blob --literally --object-format=sha256 hello)\n> > +'\n> \n> This would be more readable and easier to debug with 4x tempfiles and 2x\n> test_cmp.\n\nOkay, I can go for that.\n-- \nbrian m. carlson (he/him or they/them)\nHouston, Texas, US\n"},{"id":"421626","messageId":"YHNsEVMs2lRmycOx@camp.crustytoothpaste.net","threadId":"55472","inReplyTo":"87mtu5f31u.fsf@evledraar.gmail.com","subject":"Re: [PATCH 03/15] cache: add an algo member to struct object_id","fromName":"brian m. carlson","fromEmail":"sandals@crustytoothpaste.net","sentAt":"2021-04-11T21:37:21Z","receivedAt":"2021-04-11T21:38:00Z","isPatch":true,"sender":{"key":"sandals@crustytoothpaste.net","avatar":"https://avatars.githubusercontent.com/u/497054?v=4"},"body":"On 2021-04-11 at 11:55:57, Ævar Arnfjörð Bjarmason wrote:\n> \n> On Sat, Apr 10 2021, brian m. carlson wrote:\n> \n> > Now that we're working with multiple hash algorithms in the same repo,\n> > it's best if we label each object ID with its algorithm so we can\n> > determine how to format a given object ID. Add a member called algo to\n> > struct object_id.\n> >\n> > Signed-off-by: brian m. carlson \n> > ---\n> > hash.h | 1 +\n> > 1 file changed, 1 insertion(+)\n> >\n> > diff --git a/hash.h b/hash.h\n> > index 3fb0c3d400..dafdcb3335 100644\n> > --- a/hash.h\n> > +++ b/hash.h\n> > @@ -181,6 +181,7 @@ static inline int hash_algo_by_ptr(const struct git_hash_algo *p)\n> > \n> > struct object_id {\n> > \tunsigned char hash[GIT_MAX_RAWSZ];\n> > +\tint algo;\n> \n> Curiosity since I'm not as familiar as you with the multi-hash support\n> by far:\n> \n> So struct object_id is GIT_MAX_RAWSZ, not two types of structs for\n> GIT_SHA1_RAWSZ and GIT_SHA256_RAWSZ. That pre-dates this series because\n> we'd like to not deal with two types of objects everywhere for SHA-1 and\n> SHA-256. Makes sense.\n> \n> Before this series we'd memcmp them up to their actual length, but the\n> last GIT_MAX_RAWSZ-GIT_SHA1_RAWSZ would be uninitialized\n> \n> Now we pad them out, so the last 96 bits of every SHA1 are 0000...;\n> Couldn't we also tell which hash an object is by memcmp-ing those last N\n> bits and see if they're all zero'd?\n\nThat makes a lot of assumptions about the security of the hash\nalgorithm that I don't want to make here. If anyone can ever find a\nSHA-256 hash with trailing 96 bits zero, then they can confuse it with a\nSHA-1 hash. That means that our security level goes from 128 bits to 96\nbits. It's also a nonstandard construction.\n\nMore importantly, it results in the null OID being treated as a SHA-1\nOID. Because we do print the null OID in some cases, we're going to\nbreak a lot of output formats if we print all the rest of the OIDs with\n64 characters and then the null OID with 40. That's to say nothing of\nthe problems in binary formats.\n\nThe reason we pad these objects is because our hashmaps are broken if we\ndon't. I don't remember all the gory details, but it was obvious to me\nthat if they weren't consistently equal, things were going to be broken.\nThat's the only reason, not theoretical purity.\n\n> Feels a bit hackish, and we'd need to reconsider that method if we'd\n> ever support other same-length hashes.\n\nMy hope is that we don't need to do this, but we do have SHA-3 to serve\nas a backup for SHA-2. If quantum computers don't progress\nsubstantially, SHA-3-256 is definitely a viable candidate for\nreplacement if anything ever happens to SHA-256.\n\n> But OTOH having these objects all padded out in memory to the same\n> length, but having to carry around a \"what hash algo\" is it yields the\n> arguably weird hack of having a per-hash NULL_OID, which has never been\n> an actual object of any hash type, but just a pseudo-object.\n\nUnfortunately, as I mentioned above, we need to have two null OIDs to\nhandle printing things out. It's inconvenient, I agree.\n\n> I abandoned it as insany sillyness after playing with it for about a\n> day, but it did reveal that much of the hash code now can assume\n> internal length == formatting length, which is why I'm 3 paragraphs into\n> this digression, i.e. maybe some of the code structure also makes having\n> a NULL_OID always be 256-bits when we want to format it as 160/256\n> painful...\n\nWe'll always format based on the algorithm in the OID. That's the\nsimplest way to make things work because unfortunately we may end up\nwith both types of OIDs in the same code paths (as we're converting one\nto the other) and otherwise our printing functions need a lot of special\nhandling and even more variants than they have today.\n-- \nbrian m. carlson (he/him or they/them)\nHouston, Texas, US\n"},{"id":"421627","messageId":"YHNusqcmwv75P6Ck@camp.crustytoothpaste.net","threadId":"55472","inReplyTo":"87k0p9f2z9.fsf@evledraar.gmail.com","subject":"Re: [PATCH 09/15] hash: set and copy algo field in struct object_id","fromName":"brian m. carlson","fromEmail":"sandals@crustytoothpaste.net","sentAt":"2021-04-11T21:48:34Z","receivedAt":"2021-04-11T21:48:44Z","isPatch":true,"sender":{"key":"sandals@crustytoothpaste.net","avatar":"https://avatars.githubusercontent.com/u/497054?v=4"},"body":"On 2021-04-11 at 11:57:30, Ævar Arnfjörð Bjarmason wrote:\n> \n> On Sat, Apr 10 2021, brian m. carlson wrote:\n> \n> > const struct object_id null_oid;\n> > static const struct object_id empty_tree_oid = {\n> > -\tEMPTY_TREE_SHA1_BIN_LITERAL\n> > +\tEMPTY_TREE_SHA1_BIN_LITERAL,\n> > +\tGIT_HASH_SHA1,\n> > };\n> > static const struct object_id empty_blob_oid = {\n> > -\tEMPTY_BLOB_SHA1_BIN_LITERAL\n> > +\tEMPTY_BLOB_SHA1_BIN_LITERAL,\n> > +\tGIT_HASH_SHA1,\n> > };\n> > static const struct object_id empty_tree_oid_sha256 = {\n> > -\tEMPTY_TREE_SHA256_BIN_LITERAL\n> > +\tEMPTY_TREE_SHA256_BIN_LITERAL,\n> > +\tGIT_HASH_SHA256,\n> > };\n> > static const struct object_id empty_blob_oid_sha256 = {\n> > -\tEMPTY_BLOB_SHA256_BIN_LITERAL\n> > +\tEMPTY_BLOB_SHA256_BIN_LITERAL,\n> > +\tGIT_HASH_SHA256,\n> > };\n> \n> In this and some other patches we're continuing to add new fields to\n> structs without using designated initializers.\n> \n> Not a new problem at all, just a note that if you re-roll I for one\n> would very much appreciate starting by migrating over to that. It makes\n> for much easier reading in subsequent patches in this series, and in\n> future ones.\n\nI'm happy to do that. I thought we were not allowed to use C99 features\nbecause only recent versions of MSVC support modern C. I was previously\nunder the impression that MSVC didn't support anything but C89, but they\nnow support C11 and C17 in their latest release[0], much to my surprise.\n\nIf we're willing to require C99 features, then I'm happy to add those.\nI'll also send a follow-up series to require C99 support, which I think\nis overdue considering the standard is 22 years old.\n\n[0] https://devblogs.microsoft.com/cppblog/c11-and-c17-standard-support-arriving-in-msvc/\n-- \nbrian m. carlson (he/him or they/them)\nHouston, Texas, US\n"},{"id":"421628","messageId":"YHNvVWyRK3bfS/ZL@camp.crustytoothpaste.net","threadId":"55472","inReplyTo":"xmqqy2dohqau.fsf@gitster.g","subject":"Re: [PATCH 10/15] hash: provide per-algorithm null OIDs","fromName":"brian m. carlson","fromEmail":"sandals@crustytoothpaste.net","sentAt":"2021-04-11T21:51:17Z","receivedAt":"2021-04-11T21:51:53Z","isPatch":true,"sender":{"key":"sandals@crustytoothpaste.net","avatar":"https://avatars.githubusercontent.com/u/497054?v=4"},"body":"On 2021-04-11 at 14:03:05, Junio C Hamano wrote:\n> \"brian m. carlson\" writes:\n> \n> > diff --git a/object-file.c b/object-file.c\n> > index 5f1fa05c4e..50bb5b6ca4 100644\n> > --- a/object-file.c\n> > +++ b/object-file.c\n> > @@ -55,7 +55,6 @@\n> > \t\"\\x6f\\xe1\\x41\\xf7\\x74\\x91\\x20\\xa3\\x03\\x72\" \\\n> > \t\"\\x18\\x13\"\n> > \n> > -const struct object_id null_oid;\n> > static const struct object_id empty_tree_oid = {\n> > \tEMPTY_TREE_SHA1_BIN_LITERAL,\n> > \tGIT_HASH_SHA1,\n> > @@ -64,6 +63,9 @@ static const struct object_id empty_blob_oid = {\n> > \tEMPTY_BLOB_SHA1_BIN_LITERAL,\n> > \tGIT_HASH_SHA1,\n> > };\n> > +const struct object_id null_oid_sha1 = {\n> > +\t{0}, GIT_HASH_SHA1,\n> > +};\n> \n> sparse wants this to be a file-scope static.\n\nCan do.\n-- \nbrian m. carlson (he/him or they/them)\nHouston, Texas, US\n"},{"id":"421630","messageId":"87wnt8eai1.fsf@evledraar.gmail.com","threadId":"55472","inReplyTo":"YHNusqcmwv75P6Ck@camp.crustytoothpaste.net","subject":"Re: [PATCH 09/15] hash: set and copy algo field in struct object_id","fromName":"Ævar Arnfjörð Bjarmason","fromEmail":"avarab@gmail.com","sentAt":"2021-04-11T22:12:38Z","receivedAt":"2021-04-11T22:12:46Z","isPatch":true,"sender":{"key":"avarab@gmail.com","avatar":"https://avatars.githubusercontent.com/u/45301?v=4"},"body":"\nOn Sun, Apr 11 2021, brian m. carlson wrote:\n\n> On 2021-04-11 at 11:57:30, Ævar Arnfjörð Bjarmason wrote:\n>> \n>> On Sat, Apr 10 2021, brian m. carlson wrote:\n>> \n>> > const struct object_id null_oid;\n>> > static const struct object_id empty_tree_oid = {\n>> > -\tEMPTY_TREE_SHA1_BIN_LITERAL\n>> > +\tEMPTY_TREE_SHA1_BIN_LITERAL,\n>> > +\tGIT_HASH_SHA1,\n>> > };\n>> > static const struct object_id empty_blob_oid = {\n>> > -\tEMPTY_BLOB_SHA1_BIN_LITERAL\n>> > +\tEMPTY_BLOB_SHA1_BIN_LITERAL,\n>> > +\tGIT_HASH_SHA1,\n>> > };\n>> > static const struct object_id empty_tree_oid_sha256 = {\n>> > -\tEMPTY_TREE_SHA256_BIN_LITERAL\n>> > +\tEMPTY_TREE_SHA256_BIN_LITERAL,\n>> > +\tGIT_HASH_SHA256,\n>> > };\n>> > static const struct object_id empty_blob_oid_sha256 = {\n>> > -\tEMPTY_BLOB_SHA256_BIN_LITERAL\n>> > +\tEMPTY_BLOB_SHA256_BIN_LITERAL,\n>> > +\tGIT_HASH_SHA256,\n>> > };\n>> \n>> In this and some other patches we're continuing to add new fields to\n>> structs without using designated initializers.\n>> \n>> Not a new problem at all, just a note that if you re-roll I for one\n>> would very much appreciate starting by migrating over to that. It makes\n>> for much easier reading in subsequent patches in this series, and in\n>> future ones.\n>\n> I'm happy to do that. I thought we were not allowed to use C99 features\n> because only recent versions of MSVC support modern C. I was previously\n> under the impression that MSVC didn't support anything but C89, but they\n> now support C11 and C17 in their latest release[0], much to my surprise.\n>\n> If we're willing to require C99 features, then I'm happy to add those.\n> I'll also send a follow-up series to require C99 support, which I think\n> is overdue considering the standard is 22 years old.\n>\n> [0] https://devblogs.microsoft.com/cppblog/c11-and-c17-standard-support-arriving-in-msvc/\n\nI don't think we can in general require C99, e.g. I found just the other\nday that our CI's MSVC will fail on %zu (to print size_t without %lu & a\ncast).\n\nBut we can use some subset of C99 features, and happily designated\ninitializers is one of those, see cbc0f81d96f (strbuf: use designated\ninitializers in STRBUF_INIT, 2017-07-10). It's been used all over the\nplace since then.\n\nSee e.g.: git grep -P '^\\s+\\.\\S+ = ' -- '*.[ch]'\n"},{"id":"421634","messageId":"YHOLo36MfuTj6YeD@camp.crustytoothpaste.net","threadId":"55472","inReplyTo":"87wnt8eai1.fsf@evledraar.gmail.com","subject":"Re: [PATCH 09/15] hash: set and copy algo field in struct object_id","fromName":"brian m. carlson","fromEmail":"sandals@crustytoothpaste.net","sentAt":"2021-04-11T23:52:03Z","receivedAt":"2021-04-11T23:52:42Z","isPatch":true,"sender":{"key":"sandals@crustytoothpaste.net","avatar":"https://avatars.githubusercontent.com/u/497054?v=4"},"body":"On 2021-04-11 at 22:12:38, Ævar Arnfjörð Bjarmason wrote:\n> \n> On Sun, Apr 11 2021, brian m. carlson wrote:\n> \n> > On 2021-04-11 at 11:57:30, Ævar Arnfjörð Bjarmason wrote:\n> >> \n> >> In this and some other patches we're continuing to add new fields to\n> >> structs without using designated initializers.\n> >> \n> >> Not a new problem at all, just a note that if you re-roll I for one\n> >> would very much appreciate starting by migrating over to that. It makes\n> >> for much easier reading in subsequent patches in this series, and in\n> >> future ones.\n> >\n> > I'm happy to do that. I thought we were not allowed to use C99 features\n> > because only recent versions of MSVC support modern C. I was previously\n> > under the impression that MSVC didn't support anything but C89, but they\n> > now support C11 and C17 in their latest release[0], much to my surprise.\n> >\n> > If we're willing to require C99 features, then I'm happy to add those.\n> > I'll also send a follow-up series to require C99 support, which I think\n> > is overdue considering the standard is 22 years old.\n> >\n> > [0] https://devblogs.microsoft.com/cppblog/c11-and-c17-standard-support-arriving-in-msvc/\n> \n> I don't think we can in general require C99, e.g. I found just the other\n> day that our CI's MSVC will fail on %zu (to print size_t without %lu & a\n> cast).\n\nThat's a shame. I think I'd like to try, though, and ask people to\nupgrade MSVC to a suitable version if we're going to continue to support\nit. It's not like there aren't alternatives. So I'm going to send out\nthat series anyway, I think. That's independent of this series, though,\nso I'll add the designated initializers in v2.\n-- \nbrian m. carlson (he/him or they/them)\nHouston, Texas, US\n"},{"id":"421643","messageId":"xmqqeeffg4fi.fsf@gitster.g","threadId":"55472","inReplyTo":"87wnt8eai1.fsf@evledraar.gmail.com","subject":"Re: [PATCH 09/15] hash: set and copy algo field in struct object_id","fromName":"Junio C Hamano","fromEmail":"gitster@pobox.com","sentAt":"2021-04-12T10:53:05Z","receivedAt":"2021-04-12T10:53:12Z","isPatch":true,"sender":{"key":"gitster@pobox.com","avatar":"https://avatars.githubusercontent.com/u/54884?v=4"},"body":"Ævar Arnfjörð Bjarmason writes:\n\n> But we can use some subset of C99 features, and happily designated\n> initializers is one of those, see cbc0f81d96f (strbuf: use designated\n> initializers in STRBUF_INIT, 2017-07-10). It's been used all over the\n> place since then.\n\nGood advice to cite a commit that on purpose used a feature and\ndocumented that it is allowed.\n\nAlso see Documentation/CodingGuidelines ;-) The document should\ngive the authoritative blessing for features allowed to be used (add\nany missing with a proposed patch).\n\nThanks.\n\n"},{"id":"421644","messageId":"patch-2.2-f12e3cad57d-20210412T105422Z-avarab@gmail.com","threadId":"55472","inReplyTo":"cover-0.2-00000000000-20210412T105422Z-avarab@gmail.com","subject":"[PATCH 2/2] C99 support: remove non-HAVE_VARIADIC_MACROS code","fromName":"Ævar Arnfjörð Bjarmason","fromEmail":"avarab@gmail.com","sentAt":"2021-04-12T11:02:18Z","receivedAt":"2021-04-12T11:02:32Z","isPatch":true,"sender":{"key":"avarab@gmail.com","avatar":"https://avatars.githubusercontent.com/u/45301?v=4"},"body":"Remove code that depend on HAVE_VARIADIC_MACROS not being set. Since\n765dc168882 (git-compat-util: always enable variadic macros,\n2021-01-28) we've unconditionally defined it to be true, and that\nchange went out with v2.31.0. This should have given packagers enough\ntime to discover whether variadic macros were an issue.\n\nIt seems that they weren't, so let's update the coding guidelines and\nremove all the fallback code for the non-HAVE_VARIADIC_MACROS case.\n\nSigned-off-by: Ævar Arnfjörð Bjarmason \n---\n Documentation/CodingGuidelines | 3 ++\n banned.h | 5 ---\n git-compat-util.h | 12 ------\n trace.c | 73 ----------------------------------\n trace.h | 62 -----------------------------\n trace2.c | 39 ------------------\n trace2.h | 25 ------------\n usage.c | 10 -----\n 8 files changed, 3 insertions(+), 226 deletions(-)\n\ndiff --git a/Documentation/CodingGuidelines b/Documentation/CodingGuidelines\nindex 45465bc0c98..7eafb1758e6 100644\n--- a/Documentation/CodingGuidelines\n+++ b/Documentation/CodingGuidelines\n@@ -205,6 +205,9 @@ For C programs:\n . since mid 2017 with 512f41cf, we have been using designated\n initializers for array (e.g. \"int array[10] = { [5] = 2 }\").\n \n+ . since early 2021 with 765dc168882, we have been using variadic\n+ macros, mostly for printf-like trace and debug macros.\n+\n These used to be forbidden, but we have not heard any breakage\n report, and they are assumed to be safe.\n \ndiff --git a/banned.h b/banned.h\nindex 7ab4f2e4921..6ccf46bc197 100644\n--- a/banned.h\n+++ b/banned.h\n@@ -21,13 +21,8 @@\n \n #undef sprintf\n #undef vsprintf\n-#ifdef HAVE_VARIADIC_MACROS\n #define sprintf(...) BANNED(sprintf)\n #define vsprintf(...) BANNED(vsprintf)\n-#else\n-#define sprintf(buf,fmt,arg) BANNED(sprintf)\n-#define vsprintf(buf,fmt,arg) BANNED(vsprintf)\n-#endif\n \n #undef gmtime\n #define gmtime(t) BANNED(gmtime)\ndiff --git a/git-compat-util.h b/git-compat-util.h\nindex 540aba22a4d..da7ab91335f 100644\n--- a/git-compat-util.h\n+++ b/git-compat-util.h\n@@ -1192,24 +1192,12 @@ static inline int regexec_buf(const regex_t *preg, const char *buf, size_t size,\n #endif\n #endif\n \n-/*\n- * This is always defined as a first step towards making the use of variadic\n- * macros unconditional. If it causes compilation problems on your platform,\n- * please report it to the Git mailing list at git@vger.kernel.org.\n- */\n-#define HAVE_VARIADIC_MACROS 1\n-\n /* usage.c: only to be used for testing BUG() implementation (see test-tool) */\n extern int BUG_exit_code;\n \n-#ifdef HAVE_VARIADIC_MACROS\n __attribute__((format (printf, 3, 4))) NORETURN\n void BUG_fl(const char *file, int line, const char *fmt, ...);\n #define BUG(...) BUG_fl(__FILE__, __LINE__, __VA_ARGS__)\n-#else\n-__attribute__((format (printf, 1, 2))) NORETURN\n-void BUG(const char *fmt, ...);\n-#endif\n \n /*\n * Preserves errno, prints a message, but gives no warning for ENOENT.\ndiff --git a/trace.c b/trace.c\nindex f726686fd92..43173301f59 100644\n--- a/trace.c\n+++ b/trace.c\n@@ -111,13 +111,11 @@ static int prepare_trace_line(const char *file, int line,\n \tstrbuf_addf(buf, \"%02d:%02d:%02d.%06ld \", tm.tm_hour, tm.tm_min,\n \t\t tm.tm_sec, (long) tv.tv_usec);\n \n-#ifdef HAVE_VARIADIC_MACROS\n \t/* print file:line */\n \tstrbuf_addf(buf, \"%s:%d \", file, line);\n \t/* align trace output (column 40 catches most files names in git) */\n \twhile (buf->len < 40)\n \t\tstrbuf_addch(buf, ' ');\n-#endif\n \n \treturn 1;\n }\n@@ -229,74 +227,6 @@ static void trace_performance_vprintf_fl(const char *file, int line,\n \tstrbuf_release(&buf);\n }\n \n-#ifndef HAVE_VARIADIC_MACROS\n-\n-void trace_printf(const char *format, ...)\n-{\n-\tva_list ap;\n-\tva_start(ap, format);\n-\ttrace_vprintf_fl(NULL, 0, &trace_default_key, format, ap);\n-\tva_end(ap);\n-}\n-\n-void trace_printf_key(struct trace_key *key, const char *format, ...)\n-{\n-\tva_list ap;\n-\tva_start(ap, format);\n-\ttrace_vprintf_fl(NULL, 0, key, format, ap);\n-\tva_end(ap);\n-}\n-\n-void trace_argv_printf(const char **argv, const char *format, ...)\n-{\n-\tva_list ap;\n-\tva_start(ap, format);\n-\ttrace_argv_vprintf_fl(NULL, 0, argv, format, ap);\n-\tva_end(ap);\n-}\n-\n-void trace_strbuf(struct trace_key *key, const struct strbuf *data)\n-{\n-\ttrace_strbuf_fl(NULL, 0, key, data);\n-}\n-\n-void trace_performance(uint64_t nanos, const char *format, ...)\n-{\n-\tva_list ap;\n-\tva_start(ap, format);\n-\ttrace_performance_vprintf_fl(NULL, 0, nanos, format, ap);\n-\tva_end(ap);\n-}\n-\n-void trace_performance_since(uint64_t start, const char *format, ...)\n-{\n-\tva_list ap;\n-\tva_start(ap, format);\n-\ttrace_performance_vprintf_fl(NULL, 0, getnanotime() - start,\n-\t\t\t\t format, ap);\n-\tva_end(ap);\n-}\n-\n-void trace_performance_leave(const char *format, ...)\n-{\n-\tva_list ap;\n-\tuint64_t since;\n-\n-\tif (perf_indent)\n-\t\tperf_indent--;\n-\n-\tif (!format) /* Allow callers to leave without tracing anything */\n-\t\treturn;\n-\n-\tsince = perf_start_times[perf_indent];\n-\tva_start(ap, format);\n-\ttrace_performance_vprintf_fl(NULL, 0, getnanotime() - since,\n-\t\t\t\t format, ap);\n-\tva_end(ap);\n-}\n-\n-#else\n-\n void trace_printf_key_fl(const char *file, int line, struct trace_key *key,\n \t\t\t const char *format, ...)\n {\n@@ -342,9 +272,6 @@ void trace_performance_leave_fl(const char *file, int line,\n \tva_end(ap);\n }\n \n-#endif /* HAVE_VARIADIC_MACROS */\n-\n-\n static const char *quote_crnl(const char *path)\n {\n \tstatic struct strbuf new_path = STRBUF_INIT;\ndiff --git a/trace.h b/trace.h\nindex 0dbbad0e41c..c6b3f6ce889 100644\n--- a/trace.h\n+++ b/trace.h\n@@ -126,66 +126,6 @@ void trace_command_performance(const char **argv);\n void trace_verbatim(struct trace_key *key, const void *buf, unsigned len);\n uint64_t trace_performance_enter(void);\n \n-#ifndef HAVE_VARIADIC_MACROS\n-\n-/**\n- * Prints a formatted message, similar to printf.\n- */\n-__attribute__((format (printf, 1, 2)))\n-void trace_printf(const char *format, ...);\n-\n-__attribute__((format (printf, 2, 3)))\n-void trace_printf_key(struct trace_key *key, const char *format, ...);\n-\n-/**\n- * Prints a formatted message, followed by a quoted list of arguments.\n- */\n-__attribute__((format (printf, 2, 3)))\n-void trace_argv_printf(const char **argv, const char *format, ...);\n-\n-/**\n- * Prints the strbuf, without additional formatting (i.e. doesn't\n- * choke on `%` or even `\\0`).\n- */\n-void trace_strbuf(struct trace_key *key, const struct strbuf *data);\n-\n-/**\n- * Prints elapsed time (in nanoseconds) if GIT_TRACE_PERFORMANCE is enabled.\n- *\n- * Example:\n- * ------------\n- * uint64_t t = 0;\n- * for (;;) {\n- * \t// ignore\n- * t -= getnanotime();\n- * // code section to measure\n- * t += getnanotime();\n- * // ignore\n- * }\n- * trace_performance(t, \"frotz\");\n- * ------------\n- */\n-__attribute__((format (printf, 2, 3)))\n-void trace_performance(uint64_t nanos, const char *format, ...);\n-\n-/**\n- * Prints elapsed time since 'start' if GIT_TRACE_PERFORMANCE is enabled.\n- *\n- * Example:\n- * ------------\n- * uint64_t start = getnanotime();\n- * // code section to measure\n- * trace_performance_since(start, \"foobar\");\n- * ------------\n- */\n-__attribute__((format (printf, 2, 3)))\n-void trace_performance_since(uint64_t start, const char *format, ...);\n-\n-__attribute__((format (printf, 1, 2)))\n-void trace_performance_leave(const char *format, ...);\n-\n-#else\n-\n /*\n * Macros to add file:line - see above for C-style declarations of how these\n * should be used.\n@@ -285,6 +225,4 @@ static inline int trace_pass_fl(struct trace_key *key)\n \treturn key->fd || !key->initialized;\n }\n \n-#endif /* HAVE_VARIADIC_MACROS */\n-\n #endif /* TRACE_H */\ndiff --git a/trace2.c b/trace2.c\nindex 256120c7fd5..51d0e6cbd5e 100644\n--- a/trace2.c\n+++ b/trace2.c\n@@ -597,20 +597,6 @@ void trace2_region_enter_printf_fl(const char *file, int line,\n \tva_end(ap);\n }\n \n-#ifndef HAVE_VARIADIC_MACROS\n-void trace2_region_enter_printf(const char *category, const char *label,\n-\t\t\t\tconst struct repository *repo, const char *fmt,\n-\t\t\t\t...)\n-{\n-\tva_list ap;\n-\n-\tva_start(ap, fmt);\n-\ttrace2_region_enter_printf_va_fl(NULL, 0, category, label, repo, fmt,\n-\t\t\t\t\t ap);\n-\tva_end(ap);\n-}\n-#endif\n-\n void trace2_region_leave_printf_va_fl(const char *file, int line,\n \t\t\t\t const char *category, const char *label,\n \t\t\t\t const struct repository *repo,\n@@ -673,20 +659,6 @@ void trace2_region_leave_printf_fl(const char *file, int line,\n \tva_end(ap);\n }\n \n-#ifndef HAVE_VARIADIC_MACROS\n-void trace2_region_leave_printf(const char *category, const char *label,\n-\t\t\t\tconst struct repository *repo, const char *fmt,\n-\t\t\t\t...)\n-{\n-\tva_list ap;\n-\n-\tva_start(ap, fmt);\n-\ttrace2_region_leave_printf_va_fl(NULL, 0, category, label, repo, fmt,\n-\t\t\t\t\t ap);\n-\tva_end(ap);\n-}\n-#endif\n-\n void trace2_data_string_fl(const char *file, int line, const char *category,\n \t\t\t const struct repository *repo, const char *key,\n \t\t\t const char *value)\n@@ -782,17 +754,6 @@ void trace2_printf_fl(const char *file, int line, const char *fmt, ...)\n \tva_end(ap);\n }\n \n-#ifndef HAVE_VARIADIC_MACROS\n-void trace2_printf(const char *fmt, ...)\n-{\n-\tva_list ap;\n-\n-\tva_start(ap, fmt);\n-\ttrace2_printf_va_fl(NULL, 0, fmt, ap);\n-\tva_end(ap);\n-}\n-#endif\n-\n const char *trace2_session_id(void)\n {\n \treturn tr2_sid_get();\ndiff --git a/trace2.h b/trace2.h\nindex ede18c2e063..5d85826f23d 100644\n--- a/trace2.h\n+++ b/trace2.h\n@@ -362,18 +362,9 @@ void trace2_region_enter_printf_fl(const char *file, int line,\n \t\t\t\t const struct repository *repo,\n \t\t\t\t const char *fmt, ...);\n \n-#ifdef HAVE_VARIADIC_MACROS\n #define trace2_region_enter_printf(category, label, repo, ...) \\\n \ttrace2_region_enter_printf_fl(__FILE__, __LINE__, (category), (label), \\\n \t\t\t\t (repo), __VA_ARGS__)\n-#else\n-/* clang-format off */\n-__attribute__((format (region_enter_printf, 4, 5)))\n-void trace2_region_enter_printf(const char *category, const char *label,\n-\t\t\t\tconst struct repository *repo, const char *fmt,\n-\t\t\t\t...);\n-/* clang-format on */\n-#endif\n \n /**\n * Emit a 'region_leave' event for .