[PATCH 08/15] get_sha1_with_context: dynamically allocate oc->path
- From
Jeff King <peff@peff.net>
- Date
- May 19, 2017, 12:54 UTC
- Message-ID
- <20170519125443.7fknotkezbpfwdht@sigill.intra.peff.net>
- In-Reply-To
- <20170519124651.4q7waz75rmzfopgn@sigill.intra.peff.net>
When a sha1 lookup returns the tree path via "struct object_context", it just copies it into a fixed-size buffer. This means the result can be truncated, and it means our "struct object_context" consumes a lot of stack space.
Instead, let's allocate a string on the heap. Because most callers don't care about this information, we'll avoid doing it by default (so they don't all have to start calling free() on the result). There are basically two options for the caller to signal to us that it's interested:
1. By setting a pointer to storage in the object_context.
2. By passing a flag in another parameter.
Doing (1) would match the way that sha1_object_info_extended() works. But it would mean that every caller would have to initialize the object_context, which they don't currently have to do.
This patch does (2), and adds a new bit to the function's flags field. All of the callers that look at the "path" field are updated to pass the new flag.
Signed-off-by: Jeff King <peff@peff.net> --- If there's a topic in flight that adds a new call without the flag, note that it will stop filling the "path" field (which is what most calls would want). And you won't get a compile error, because the pointer can be used in largely the same way as the array.
I find it unlikely that there's a case that would care, but if we wanted to be really paranoid, we could change the name of oc->path (at the cost of making this diff much noisier).
builtin/cat-file.c | 4 +++- builtin/grep.c | 4 +++- builtin/log.c | 10 +++++++--- cache.h | 8 +++++++- sha1_name.c | 6 ++++-- 5 files changed, 24 insertions(+), 8 deletions(-)
diff --git a/builtin/cat-file.c b/builtin/cat-file.c index 1890d7a63..421709517 100644 --- a/builtin/cat-file.c +++ b/builtin/cat-file.c @@ -61,7 +61,8 @@ static int cat_one_file(int opt, const char *exp_type, const char *obj_name, if (unknown_type) flags |= LOOKUP_UNKNOWN_OBJECT; - if (get_sha1_with_context(obj_name, 0, oid.hash, &obj_context)) + if (get_sha1_with_context(obj_name, GET_SHA1_RECORD_PATH, + oid.hash, &obj_context)) die("Not a valid object name %s", obj_name); if (!path) @@ -165,6 +166,7 @@ static int cat_one_file(int opt, const char *exp_type, const char *obj_name, die("git cat-file %s: bad file", obj_name); write_or_die(1, buf, size); + free(obj_context.path); return 0; } diff --git a/builtin/grep.c b/builtin/grep.c index 3ffb5b4e8..254c1c784 100644 --- a/builtin/grep.c +++ b/builtin/grep.c @@ -1190,7 +1190,8 @@ int cmd_grep(int argc, const char **argv, const char *prefix) break; } - if (get_sha1_with_context(arg, 0, oid.hash, &oc)) { + if (get_sha1_with_context(arg, GET_SHA1_RECORD_PATH, + oid.hash, &oc)) { if (seen_dashdash) die(_("unable to resolve revision: %s"), arg); break; @@ -1200,6 +1201,7 @@ int cmd_grep(int argc, const char **argv, const char *prefix) if (!seen_dashdash) verify_non_filename(prefix, arg); add_object_array_with_path(object, arg, &list, oc.mode, oc.path); + free(oc.path); } /* diff --git a/builtin/log.c b/builtin/log.c index fd3d10ec2..a0d5233dc 100644 --- a/builtin/log.c +++ b/builtin/log.c @@ -483,16 +483,20 @@ static int show_blob_object(const struct object_id *oid, struct rev_info *rev, c !DIFF_OPT_TST(&rev->diffopt, ALLOW_TEXTCONV)) return stream_blob_to_fd(1, oid, NULL, 0); - if (get_sha1_with_context(obj_name, 0, oidc.hash, &obj_context)) + if (get_sha1_with_context(obj_name, GET_SHA1_RECORD_PATH, + oidc.hash, &obj_context)) die(_("Not a valid object name %s"), obj_name); - if (!obj_context.path[0] || - !textconv_object(obj_context.path, obj_context.mode, &oidc, 1, &buf, &size)) + if (!obj_context.path || + !textconv_object(obj_context.path, obj_context.mode, &oidc, 1, &buf, &size)) { + free(obj_context.path); return stream_blob_to_fd(1, oid, NULL, 0); + } if (!buf) die(_("git show %s: bad file"), obj_name); write_or_die(1, buf, size); + free(obj_context.path); return 0; } diff --git a/cache.h b/cache.h index 656341b8e..e219c45ed 100644 --- a/cache.h +++ b/cache.h @@ -1333,13 +1333,18 @@ static inline int hex2chr(const char *s) struct object_context { unsigned char tree[20]; - char path[PATH_MAX]; unsigned mode; /* * symlink_path is only used by get_tree_entry_follow_symlinks, * and only for symlinks that point outside the repository. */ struct strbuf symlink_path; + /* + * If GET_SHA1_RECORD_PATH is set, this will record path (if any) + * found when resolving the name. The caller is responsible for + * releasing the memory. + */ + char *path; }; #define GET_SHA1_QUIETLY 01 @@ -1349,6 +1354,7 @@ struct object_context { #define GET_SHA1_TREEISH 020 #define GET_SHA1_BLOB 040 #define GET_SHA1_FOLLOW_SYMLINKS 0100 +#define GET_SHA1_RECORD_PATH 0200 #define GET_SHA1_ONLY_TO_DIE 04000 #define GET_SHA1_DISAMBIGUATORS \ diff --git a/sha1_name.c b/sha1_name.c index 35b16efc6..70f096749 100644 --- a/sha1_name.c +++ b/sha1_name.c @@ -1550,7 +1550,8 @@ static int get_sha1_with_context_1(const char *name, namelen = strlen(cp); } - strlcpy(oc->path, cp, sizeof(oc->path)); + if (flags & GET_SHA1_RECORD_PATH) + oc->path = xstrdup(cp); if (!active_cache) read_cache(); @@ -1613,7 +1614,8 @@ static int get_sha1_with_context_1(const char *name, } } hashcpy(oc->tree, tree_sha1); - strlcpy(oc->path, filename, sizeof(oc->path)); + if (flags & GET_SHA1_RECORD_PATH) + oc->path = xstrdup(filename); free(new_filename); return ret;
-- 2.13.0.219.g63f6bc368