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 <peff@peff.net>
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/csum-file.c b/csum-file.c
index 7510950..60f58f6 100644
--- a/csum-file.c
+++ b/csum-file.c
@@ -187,3 +187,19 @@
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 e54d53d..87e3879 100644
--- a/csum-file.h
+++ b/csum-file.h
@@ -42,6 +42,9 @@
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 4b089fe..c8e560d 100644
--- a/pack-check.c
+++ b/pack-check.c
@@ -164,22 +164,13 @@
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;
