[PATCH 4/9] csum-file: provide a function to release checkpoints

[Jeff King <peff@peff.net>]

A hashfile_checkpoint struct is basically just a copy of the hash_ctx
state at a given point in the file. As such, it contains its own
git_hash_ctx which may (depending on the underlying hash implementation)
need to be discarded when we're done with it.

Let's add a "release" function which cleans up the hash context it
holds. I chose "release" here and not "discard" because you'd use this
to clean up every checkpoint, whether you used it or not. As opposed to
git_hash_discard(), which is needed only if you didn't call
git_hash_final().

There are only two callers which use hashfile_checkpoints, and we can
add release calls to both. When built with "SANITIZE=leak
OPENSSL_SHA1_UNSAFE=1", this makes both t1050 and t9300 leak-free.

Signed-off-by: Jeff King <peff@peff.net>
---
 builtin/fast-import.c | 1 +
 csum-file.c           | 5 +++++
 csum-file.h           | 1 +
 object-file.c         | 2 ++
 4 files changed, 9 insertions(+)

diff --git a/builtin/fast-import.c b/builtin/fast-import.c
index aa656c5195..f6473dcc8e 100644
--- a/builtin/fast-import.c
+++ b/builtin/fast-import.c
@@ -1216,6 +1216,7 @@ static void stream_blob(uintmax_t len, struct object_id *oidout, uintmax_t mark)
 out:
 	free(in_buf);
 	free(out_buf);
+	hashfile_checkpoint_release(&checkpoint);
 }
 
 /* All calls must be guarded by find_object() or find_mark() to
diff --git a/csum-file.c b/csum-file.c
index 44ff460692..b166f89624 100644
--- a/csum-file.c
+++ b/csum-file.c
@@ -223,6 +223,11 @@ int hashfile_truncate(struct hashfile *f, struct hashfile_checkpoint *checkpoint
 	return 0;
 }
 
+void hashfile_checkpoint_release(struct hashfile_checkpoint *checkpoint)
+{
+	git_hash_discard(&checkpoint->ctx);
+}
+
 void crc32_begin(struct hashfile *f)
 {
 	f->crc32 = crc32(0, NULL, 0);
diff --git a/csum-file.h b/csum-file.h
index d1a0ff29cd..6ed74d1637 100644
--- a/csum-file.h
+++ b/csum-file.h
@@ -39,6 +39,7 @@ struct hashfile_checkpoint {
 void hashfile_checkpoint_init(struct hashfile *, struct hashfile_checkpoint *);
 void hashfile_checkpoint(struct hashfile *, struct hashfile_checkpoint *);
 int hashfile_truncate(struct hashfile *, struct hashfile_checkpoint *);
+void hashfile_checkpoint_release(struct hashfile_checkpoint *);
 
 /* finalize_hashfile flags */
 #define CSUM_CLOSE		1
diff --git a/object-file.c b/object-file.c
index e3d92bbda2..32a0d6d237 100644
--- a/object-file.c
+++ b/object-file.c
@@ -1352,6 +1352,8 @@ static int odb_transaction_files_write_object_stream(struct odb_transaction *bas
 			   state->alloc_written);
 		state->written[state->nr_written++] = idx;
 	}
+
+	hashfile_checkpoint_release(&checkpoint);
 	return 0;
 }
 
-- 
2.55.0.418.g37da59dd42