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.h b/csum-file.h
index e54d53d..87e3879 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).
