[PATCH v5 31/39] bundle: add new version for use with SHA-256
- From
brian m. carlson <sandals@crustytoothpaste.net>
- Date
- Jul 28, 2020, 23:34 UTC
- Message-ID
- <20200728233446.3066485-32-sandals@crustytoothpaste.net>
- In-Reply-To
- <20200728233446.3066485-1-sandals@crustytoothpaste.net>
Currently we detect the hash algorithm in use by the length of the object ID. This is inelegant and prevents us from using a different hash algorithm that is also 256 bits in length.
Since we cannot extend the v2 format in a backward-compatible way, let's add a v3 format, which is identical, except for the addition of capabilities, which are prefixed by an at sign. We add "object-format" as the only capability and reject unknown capabilities, since we do not have a network connection and therefore cannot negotiate with the other side.
For compatibility, default to the v2 format for SHA-1 and require v3 for SHA-256.
In t5510, always use format v3 so we can be sure we produce consistent results across hash algorithms. Since head -n N lists the top N lines instead of the Nth line, let's run our output through sed to normalize it and compare it against a fixed value, which will make sure we get exactly what we're expecting.
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net> --- Documentation/git-bundle.txt | 9 ++- Documentation/technical/bundle-format.txt | 30 +++++++- builtin/bundle.c | 5 +- bundle.c | 83 +++++++++++++++++------ bundle.h | 4 +- t/t5510-fetch.sh | 16 +++-- t/t5607-clone-bundle.sh | 31 +++++++++ 7 files changed, 147 insertions(+), 31 deletions(-)
diff --git a/Documentation/git-bundle.txt b/Documentation/git-bundle.txt index d34b0964be..53804cad4b 100644 --- a/Documentation/git-bundle.txt +++ b/Documentation/git-bundle.txt @@ -9,7 +9,8 @@ git-bundle - Move objects and refs by archive SYNOPSIS -------- [verse] -'git bundle' create [-q | --quiet | --progress | --all-progress] [--all-progress-implied] <file> <git-rev-list-args> +'git bundle' create [-q | --quiet | --progress | --all-progress] [--all-progress-implied] + [--version=<version>] <file> <git-rev-list-args> 'git bundle' verify [-q | --quiet] <file> 'git bundle' list-heads <file> [<refname>...] 'git bundle' unbundle <file> [<refname>...] @@ -102,6 +103,12 @@ unbundle <file>:: is activated. Unlike --all-progress this flag doesn't actually force any progress display by itself. +--version=<version>:: + Specify the bundle version. Version 2 is the older format and can only be + used with SHA-1 repositories; the newer version 3 contains capabilities that + permit extensions. The default is the oldest supported format, based on the + hash algorithm in use. + -q:: --quiet:: This flag makes the command not to report its progress diff --git a/Documentation/technical/bundle-format.txt b/Documentation/technical/bundle-format.txt index 0e828151a5..bac558d049 100644 --- a/Documentation/technical/bundle-format.txt +++ b/Documentation/technical/bundle-format.txt @@ -7,6 +7,8 @@ The Git bundle format is a format that represents both refs and Git objects. We will use ABNF notation to define the Git bundle format. See protocol-common.txt for the details. +A v2 bundle looks like this: + ---- bundle = signature *prerequisite *reference LF pack signature = "# v2 git bundle" LF @@ -18,9 +20,28 @@ reference = obj-id SP refname LF pack = ... ; packfile ---- +A v3 bundle looks like this: + +---- +bundle = signature *capability *prerequisite *reference LF pack +signature = "# v3 git bundle" LF + +capability = "@" key ["=" value] LF +prerequisite = "-" obj-id SP comment LF +comment = *CHAR +reference = obj-id SP refname LF +key = 1*(ALPHA / DIGIT / "-") +value = *(%01-09 / %0b-FF) + +pack = ... ; packfile +---- + == Semantics -A Git bundle consists of three parts. +A Git bundle consists of several parts. + +* "Capabilities", which are only in the v3 format, indicate functionality that + the bundle requires to be read properly. * "Prerequisites" lists the objects that are NOT included in the bundle and the reader of the bundle MUST already have, in order to use the data in the @@ -46,3 +67,10 @@ put any string here. The reader of the bundle MUST ignore the comment. Note that the prerequisites does not represent a shallow-clone boundary. The semantics of the prerequisites and the shallow-clone boundaries are different, and the Git bundle v2 format cannot represent a shallow clone repository. + +== Capabilities + +Because there is no opportunity for negotiation, unknown capabilities cause 'git +bundle' to abort. The only known capability is `object-format`, which specifies +the hash algorithm in use, and can take the same values as the +`extensions.objectFormat` configuration value. diff --git a/builtin/bundle.c b/builtin/bundle.c index f049d27a14..e1a85e7dcc 100644 --- a/builtin/bundle.c +++ b/builtin/bundle.c @@ -60,6 +60,7 @@ static int cmd_bundle_create(int argc, const char **argv, const char *prefix) { int all_progress_implied = 0; int progress = isatty(STDERR_FILENO); struct argv_array pack_opts; + int version = -1; struct option options[] = { OPT_SET_INT('q', "quiet", &progress, @@ -71,6 +72,8 @@ static int cmd_bundle_create(int argc, const char **argv, const char *prefix) { OPT_BOOL(0, "all-progress-implied", &all_progress_implied, N_("similar to --all-progress when progress meter is shown")), + OPT_INTEGER(0, "version", &version, + N_("specify bundle format version")), OPT_END() }; const char* bundle_file; @@ -91,7 +94,7 @@ static int cmd_bundle_create(int argc, const char **argv, const char *prefix) { if (!startup_info->have_repository) die(_("Need a repository to create a bundle.")); - return !!create_bundle(the_repository, bundle_file, argc, argv, &pack_opts); + return !!create_bundle(the_repository, bundle_file, argc, argv, &pack_opts, version); } static int cmd_bundle_verify(int argc, const char **argv, const char *prefix) { diff --git a/bundle.c b/bundle.c index 2a0d744d3f..35585f237c 100644 --- a/bundle.c +++ b/bundle.c @@ -12,7 +12,16 @@ #include "refs.h" #include "argv-array.h" -static const char bundle_signature[] = "# v2 git bundle\n"; + +static const char v2_bundle_signature[] = "# v2 git bundle\n"; +static const char v3_bundle_signature[] = "# v3 git bundle\n"; +static struct { + int version; + const char *signature; +} bundle_sigs[] = { + { 2, v2_bundle_signature }, + { 3, v3_bundle_signature }, +}; static void add_to_ref_list(const struct object_id *oid, const char *name, struct ref_list *list) @@ -23,15 +32,30 @@ static void add_to_ref_list(const struct object_id *oid, const char *name, list->nr++; } -static const struct git_hash_algo *detect_hash_algo(struct strbuf *buf) +static int parse_capability(struct bundle_header *header, const char *capability) { - size_t len = strcspn(buf->buf, " \n"); - int algo; + const char *arg; + if (skip_prefix(capability, "object-format=", &arg)) { + int algo = hash_algo_by_name(arg); + if (algo == GIT_HASH_UNKNOWN) + return error(_("unrecognized bundle hash algorithm: %s"), arg); + header->hash_algo = &hash_algos[algo]; + return 0; + } + return error(_("unknown capability '%s'"), capability); +} - algo = hash_algo_by_length(len / 2); - if (algo == GIT_HASH_UNKNOWN) - return NULL; - return &hash_algos[algo]; +static int parse_bundle_signature(struct bundle_header *header, const char *line) +{ + int i; + + for (i = 0; i < ARRAY_SIZE(bundle_sigs); i++) { + if (!strcmp(line, bundle_sigs[i].signature)) { + header->version = bundle_sigs[i].version; + return 0; + } + } + return -1; } static int parse_bundle_header(int fd, struct bundle_header *header, @@ -42,14 +66,16 @@ static int parse_bundle_header(int fd, struct bundle_header *header, /* The bundle header begins with the signature */ if (strbuf_getwholeline_fd(&buf, fd, '\n') || - strcmp(buf.buf, bundle_signature)) { + parse_bundle_signature(header, buf.buf)) { if (report_path) - error(_("'%s' does not look like a v2 bundle file"), + error(_("'%s' does not look like a v2 or v3 bundle file"), report_path); status = -1; goto abort; } + header->hash_algo = the_hash_algo; + /* The bundle header ends with an empty line */ while (!strbuf_getwholeline_fd(&buf, fd, '\n') && buf.len && buf.buf[0] != '\n') { @@ -57,19 +83,19 @@ static int parse_bundle_header(int fd, struct bundle_header *header, int is_prereq = 0; const char *p; - if (*buf.buf == '-') { - is_prereq = 1; - strbuf_remove(&buf, 0, 1); - } strbuf_rtrim(&buf); - if (!header->hash_algo) { - header->hash_algo = detect_hash_algo(&buf); - if (!header->hash_algo) { - error(_("unknown hash algorithm length")); + if (header->version == 3 && *buf.buf == '@') { + if (parse_capability(header, buf.buf + 1)) { status = -1; break; } + continue; + } + + if (*buf.buf == '-') { + is_prereq = 1; + strbuf_remove(&buf, 0, 1); } /* @@ -449,13 +475,14 @@ static int write_bundle_refs(int bundle_fd, struct rev_info *revs) } int create_bundle(struct repository *r, const char *path, - int argc, const char **argv, struct argv_array *pack_options) + int argc, const char **argv, struct argv_array *pack_options, int version) { struct lock_file lock = LOCK_INIT; int bundle_fd = -1; int bundle_to_stdout; int ref_count = 0; struct rev_info revs; + int min_version = the_hash_algo == &hash_algos[GIT_HASH_SHA1] ? 2 : 3; bundle_to_stdout = !strcmp(path, "-"); if (bundle_to_stdout) @@ -464,8 +491,22 @@ int create_bundle(struct repository *r, const char *path, bundle_fd = hold_lock_file_for_update(&lock, path, LOCK_DIE_ON_ERROR); - /* write signature */ - write_or_die(bundle_fd, bundle_signature, strlen(bundle_signature)); + if (version == -1) + version = min_version; + + if (version < 2 || version > 3) { + die(_("unsupported bundle version %d"), version); + } else if (version < min_version) { + die(_("cannot write bundle version %d with algorithm %s"), version, the_hash_algo->name); + } else if (version == 2) { + write_or_die(bundle_fd, v2_bundle_signature, strlen(v2_bundle_signature)); + } else { + const char *capability = "@object-format="; + write_or_die(bundle_fd, v3_bundle_signature, strlen(v3_bundle_signature)); + write_or_die(bundle_fd, capability, strlen(capability)); + write_or_die(bundle_fd, the_hash_algo->name, strlen(the_hash_algo->name)); + write_or_die(bundle_fd, "\n", 1); + } /* init revs to list objects for pack-objects later */ save_commit_buffer = 0; diff --git a/bundle.h b/bundle.h index 2dc9442024..70c84cab08 100644 --- a/bundle.h +++ b/bundle.h @@ -13,6 +13,7 @@ struct ref_list { }; struct bundle_header { + unsigned version; struct ref_list prerequisites; struct ref_list references; const struct git_hash_algo *hash_algo; @@ -21,7 +22,8 @@ struct bundle_header { int is_bundle(const char *path, int quiet); int read_bundle_header(const char *path, struct bundle_header *header); int create_bundle(struct repository *r, const char *path, - int argc, const char **argv, struct argv_array *pack_options); + int argc, const char **argv, struct argv_array *pack_options, + int version); int verify_bundle(struct repository *r, struct bundle_header *header, int verbose); #define BUNDLE_VERBOSE 1 int unbundle(struct repository *r, struct bundle_header *header, diff --git a/t/t5510-fetch.sh b/t/t5510-fetch.sh index a66dbe0bde..9243335ab0 100755 --- a/t/t5510-fetch.sh +++ b/t/t5510-fetch.sh @@ -281,15 +281,19 @@ test_expect_success 'create bundle 1' ' cd "$D" && echo >file updated again by origin && git commit -a -m "tip" && - git bundle create bundle1 master^..master + git bundle create --version=3 bundle1 master^..master ' test_expect_success 'header of bundle looks right' ' - head -n 4 "$D"/bundle1 && - head -n 1 "$D"/bundle1 | grep "^#" && - head -n 2 "$D"/bundle1 | grep "^-$OID_REGEX " && - head -n 3 "$D"/bundle1 | grep "^$OID_REGEX " && - head -n 4 "$D"/bundle1 | grep "^$" + cat >expect <<-EOF && + # v3 git bundle + @object-format=$(test_oid algo) + -OID updated by origin + OID refs/heads/master + + EOF + sed -e "s/$OID_REGEX/OID/g" -e "5q" "$D"/bundle1 >actual && + test_cmp expect actual ' test_expect_success 'create bundle 2' ' diff --git a/t/t5607-clone-bundle.sh b/t/t5607-clone-bundle.sh index 6d5a977fcb..26985f4b44 100755 --- a/t/t5607-clone-bundle.sh +++ b/t/t5607-clone-bundle.sh @@ -4,6 +4,10 @@ test_description='some bundle related tests' . ./test-lib.sh test_expect_success 'setup' ' + test_oid_cache <<-EOF && + version sha1:2 + version sha256:3 + EOF test_commit initial && test_tick && git tag -m tag tag && @@ -94,4 +98,31 @@ test_expect_success 'fetch SHA-1 from bundle' ' git fetch --no-tags foo/tip.bundle "$(cat hash)" ' +test_expect_success 'git bundle uses expected default format' ' + git bundle create bundle HEAD^.. && + head -n1 bundle | grep "^# v$(test_oid version) git bundle$" +' + +test_expect_success 'git bundle v3 has expected contents' ' + git branch side HEAD && + git bundle create --version=3 bundle HEAD^..side && + head -n2 bundle >actual && + cat >expect <<-EOF && + # v3 git bundle + @object-format=$(test_oid algo) + EOF + test_cmp expect actual && + git bundle verify bundle +' + +test_expect_success 'git bundle v3 rejects unknown capabilities' ' + cat >new <<-EOF && + # v3 git bundle + @object-format=$(test_oid algo) + @unknown=silly + EOF + test_must_fail git bundle verify new 2>output && + test_i18ngrep "unknown capability .unknown=silly." output +' + test_done