csum-file: store the hash algorithm as a struct field

Throughout the hashfile API, we rely on a reference to 'the_hash_algo',
and call its _unsafe function variants directly.

Prepare for a future change where we may use a different 'git_hash_algo'
pointer (instead of just relying on 'the_hash_algo' throughout) by
making the 'git_hash_algo' pointer a member of the 'hashfile' structure
itself.

Signed-off-by: Taylor Blau <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: ttaylorr

csum-file.c

@@ -50,7 +50,7 @@ void hashflush(struct hashfile *f)
 
 	if (offset) {
 		if (!f->skip_hash)
-			the_hash_algo->unsafe_update_fn(&f->ctx, f->buffer, offset);
+			f->algop->unsafe_update_fn(&f->ctx, f->buffer, offset);
 		flush(f, f->buffer, offset);
 		f->offset = 0;
 	}
@@ -71,14 +71,14 @@ int finalize_hashfile(struct hashfile *f, unsigned char *result,
 	hashflush(f);
 
 	if (f->skip_hash)
-		hashclr(f->buffer, the_repository->hash_algo);
+		hashclr(f->buffer, f->algop);
 	else
-		the_hash_algo->unsafe_final_fn(f->buffer, &f->ctx);
+		f->algop->unsafe_final_fn(f->buffer, &f->ctx);
 
 	if (result)
-		hashcpy(result, f->buffer, the_repository->hash_algo);
+		hashcpy(result, f->buffer, f->algop);
 	if (flags & CSUM_HASH_IN_STREAM)
-		flush(f, f->buffer, the_hash_algo->rawsz);
+		flush(f, f->buffer, f->algop->rawsz);
 	if (flags & CSUM_FSYNC)
 		fsync_component_or_die(component, f->fd, f->name);
 	if (flags & CSUM_CLOSE) {
@@ -128,7 +128,7 @@ void hashwrite(struct hashfile *f, const void *buf, unsigned int count)
 			 * f->offset is necessarily zero.
 			 */
 			if (!f->skip_hash)
-				the_hash_algo->unsafe_update_fn(&f->ctx, buf, nr);
+				f->algop->unsafe_update_fn(&f->ctx, buf, nr);
 			flush(f, buf, nr);
 		} else {
 			/*
@@ -174,7 +174,9 @@ static struct hashfile *hashfd_internal(int fd, const char *name,
 	f->name = name;
 	f->do_crc = 0;
 	f->skip_hash = 0;
-	the_hash_algo->unsafe_init_fn(&f->ctx);
+
+	f->algop = the_hash_algo;
+	f->algop->unsafe_init_fn(&f->ctx);
 
 	f->buffer_len = buffer_len;
 	f->buffer = xmalloc(buffer_len);
@@ -208,7 +210,7 @@ void hashfile_checkpoint(struct hashfile *f, struct hashfile_checkpoint *checkpo
 {
 	hashflush(f);
 	checkpoint->offset = f->total;
-	the_hash_algo->unsafe_clone_fn(&checkpoint->ctx, &f->ctx);
+	f->algop->unsafe_clone_fn(&checkpoint->ctx, &f->ctx);
 }
 
 int hashfile_truncate(struct hashfile *f, struct hashfile_checkpoint *checkpoint)
@@ -219,7 +221,7 @@ int hashfile_truncate(struct hashfile *f, struct hashfile_checkpoint *checkpoint
 	    lseek(f->fd, offset, SEEK_SET) != offset)
 		return -1;
 	f->total = offset;
-	the_hash_algo->unsafe_clone_fn(&f->ctx, &checkpoint->ctx);
+	f->algop->unsafe_clone_fn(&f->ctx, &checkpoint->ctx);
 	f->offset = 0; /* hashflush() was called in checkpoint */
 	return 0;
 }

csum-file.h

@@ -20,6 +20,7 @@ struct hashfile {
 	size_t buffer_len;
 	unsigned char *buffer;
 	unsigned char *check_buffer;
+	const struct git_hash_algo *algop;
 
 	/**
 	 * If non-zero, skip_hash indicates that we should