From f9221e2cf5049805d9151b3db6a5eef07b1cc92e Mon Sep 17 00:00:00 2001 From: Taylor Blau Date: Wed, 23 Jun 2021 14:39:07 -0400 Subject: [PATCH] csum-file: introduce checksum_valid() 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 Signed-off-by: Jeff King Signed-off-by: Taylor Blau Signed-off-by: Junio C Hamano --- 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 7510950fa3e..60f58f662ae 100644 --- a/csum-file.c +++ b/csum-file.c @@ -187,3 +187,19 @@ 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 e54d53d1d0b..87e3879f1cc 100644 --- a/csum-file.h +++ b/csum-file.h @@ -42,6 +42,9 @@ 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 4b089fe8ec0..c8e560d71ab 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;