[PATCH 1/4] csum-file: introduce checksum_valid()
- From
Taylor Blau <me@ttaylorr.com>
- Date
- Jun 23, 2021, 18:39 UTC
- Message-ID
- <3f1fcf348473d7320d46e3df6fe97c482b9888f2.1624473543.git.me@ttaylorr.com>
- In-Reply-To
- <cover.1624473543.git.me@ttaylorr.com>
Introduce a new function which checks the validity of a file's trailing checksum. This is similar to hashfd_check(), but different since it is intended to be used by callers who aren't writing the same data (like `git index-pack --verify`), but who instead want to validate the integrity of data that they are reading.
Rewrite the first of two callers which could benefit from this new function in pack-check.c. Subsequent callers will be added in the following patches.
Helped-by: Jeff King <peff@peff.net> Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Taylor Blau <me@ttaylorr.com> --- csum-file.c | 16 ++++++++++++++++ csum-file.h | 3 +++ pack-check.c | 11 +---------- 3 files changed, 20 insertions(+), 10 deletions(-)
diff --git a/csum-file.c b/csum-file.c index 3487d28ed7..c951cf8277 100644 --- a/csum-file.c +++ b/csum-file.c @@ -217,3 +217,19 @@ uint32_t crc32_end(struct hashfile *f) f->do_crc = 0; return f->crc32; } + +int hashfile_checksum_valid(const unsigned char *data, size_t total_len) +{ + unsigned char got[GIT_MAX_RAWSZ]; + git_hash_ctx ctx; + size_t data_len = total_len - the_hash_algo->rawsz; + + if (total_len < the_hash_algo->rawsz) + return 0; /* say "too short"? */ + + the_hash_algo->init_fn(&ctx); + the_hash_algo->update_fn(&ctx, data, data_len); + the_hash_algo->final_fn(got, &ctx); + + return hasheq(got, data + data_len); +} diff --git a/csum-file.h b/csum-file.h index 3044bd19ab..291215b34e 100644 --- a/csum-file.h +++ b/csum-file.h @@ -44,6 +44,9 @@ void hashflush(struct hashfile *f); void crc32_begin(struct hashfile *); uint32_t crc32_end(struct hashfile *); +/* Verify checksum validity while reading. Returns non-zero on success. */ +int hashfile_checksum_valid(const unsigned char *data, size_t len); + /* * Returns the total number of bytes fed to the hashfile so far (including ones * that have not been written out to the descriptor yet). diff --git a/pack-check.c b/pack-check.c index 4b089fe8ec..c8e560d71a 100644 --- a/pack-check.c +++ b/pack-check.c @@ -164,22 +164,13 @@ static int verify_packfile(struct repository *r, int verify_pack_index(struct packed_git *p) { - size_t len; - const unsigned char *index_base; - git_hash_ctx ctx; - unsigned char hash[GIT_MAX_RAWSZ]; int err = 0; if (open_pack_index(p)) return error("packfile %s index not opened", p->pack_name); - index_base = p->index_data; - len = p->index_size - the_hash_algo->rawsz; /* Verify SHA1 sum of the index file */ - the_hash_algo->init_fn(&ctx); - the_hash_algo->update_fn(&ctx, index_base, len); - the_hash_algo->final_fn(hash, &ctx); - if (!hasheq(hash, index_base + len)) + if (!hashfile_checksum_valid(p->index_data, p->index_size)) err = error("Packfile index for %s hash mismatch", p->pack_name); return err;
-- 2.31.1.163.ga65ce7f831