[2/4] commit-graph: rewrite to use checksum_valid()

Commit Message

Taylor Blau June 23, 2021, 6:39 p.m. UTC

Rewrite an existing caller in `git commit-graph verify` to take
advantage of checksum_valid().

Note that the replacement isn't a verbatim cut-and-paste, since the new
function avoids using hashfile at all and instead talks to the_hash_algo
directly, but it is functionally equivalent.

Signed-off-by: Taylor Blau <[e-mail]>
---
 commit-graph.c | 14 ++++++--------
 1 file changed, 6 insertions(+), 8 deletions(-)

Comments

Jeff King June 24, 2021, 7:42 p.m. UTC | #1

On Wed, Jun 23, 2021 at 02:39:09PM -0400, Taylor Blau wrote:

> Rewrite an existing caller in `git commit-graph verify` to take
> advantage of checksum_valid().
> 
> Note that the replacement isn't a verbatim cut-and-paste, since the new
> function avoids using hashfile at all and instead talks to the_hash_algo
> directly, but it is functionally equivalent.

Yay. IMHO the result is much nicer, as we do not have to wonder about
open() returning an error.

-Peff

Patch

diff --git a/commit-graph.c b/commit-graph.c
index 2bcb4e0f89..1a2602da61 100644
--- a/commit-graph.c
+++ b/commit-graph.c
@@ -2422,14 +2422,16 @@  static void graph_report(const char *fmt, ...)
 #define GENERATION_ZERO_EXISTS 1
 #define GENERATION_NUMBER_EXISTS 2
 
+static int commit_graph_checksum_valid(struct commit_graph *g)
+{
+	return hashfile_checksum_valid(g->data, g->data_len);
+}
+
 int verify_commit_graph(struct repository *r, struct commit_graph *g, int flags)
 {
 	uint32_t i, cur_fanout_pos = 0;
 	struct object_id prev_oid, cur_oid;
-	unsigned char checksum[GIT_MAX_HEXSZ];
 	int generation_zero = 0;
-	struct hashfile *f;
-	int devnull;
 	struct progress *progress = NULL;
 	int local_error = 0;
 
@@ -2442,11 +2444,7 @@  int verify_commit_graph(struct repository *r, struct commit_graph *g, int flags)
 	if (verify_commit_graph_error)
 		return verify_commit_graph_error;
 
-	devnull = open("/dev/null", O_WRONLY);
-	f = hashfd(devnull, NULL);
-	hashwrite(f, g->data, g->data_len - g->hash_len);
-	finalize_hashfile(f, checksum, CSUM_CLOSE);
-	if (!hasheq(checksum, g->data + g->data_len - g->hash_len)) {
+	if (!commit_graph_checksum_valid(g)) {
 		graph_report(_("the commit-graph file has incorrect checksum and is likely corrupt"));
 		verify_commit_graph_error = VERIFY_COMMIT_GRAPH_ERROR_HASH;
 	}