object-file API: return "void", not "int" from hash_object_file()

The hash_object_file() function added in abdc3fc842 (Add
hash_sha1_file(), 2006-10-14) did not have a meaningful return value,
and it never has.

One was seemingly added to avoid adding braces to the "ret = "
assignments being modified here. Let's instead assign "0" to the "ret"
variables at the beginning of the relevant functions, and have them
return "void".

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

object-file.c

@@ -1836,14 +1836,13 @@ static int write_buffer(int fd, const void *buf, size_t len)
 	return 0;
 }
 
-int hash_object_file(const struct git_hash_algo *algo, const void *buf,
+void hash_object_file(const struct git_hash_algo *algo, const void *buf,
 		     unsigned long len, const char *type,
 		     struct object_id *oid)
 {
 	char hdr[MAX_HEADER_LEN];
 	int hdrlen = sizeof(hdr);
 	write_object_file_prepare(algo, buf, len, type, oid, hdr, &hdrlen);
-	return 0;
 }
 
 /* Finalize a file on disk, and close it. */
@@ -2118,7 +2117,7 @@ static int index_mem(struct index_state *istate,
 		     enum object_type type,
 		     const char *path, unsigned flags)
 {
-	int ret;
+	int ret = 0;
 	int re_allocated = 0;
 	int write_object = flags & HASH_WRITE_OBJECT;
 
@@ -2148,8 +2147,9 @@ static int index_mem(struct index_state *istate,
 	if (write_object)
 		ret = write_object_file(buf, size, type_name(type), oid);
 	else
-		ret = hash_object_file(the_hash_algo, buf, size,
-				       type_name(type), oid);
+		hash_object_file(the_hash_algo, buf, size, type_name(type),
+				 oid);
+
 	if (re_allocated)
 		free(buf);
 	return ret;
@@ -2161,7 +2161,7 @@ static int index_stream_convert_blob(struct index_state *istate,
 				     const char *path,
 				     unsigned flags)
 {
-	int ret;
+	int ret = 0;
 	const int write_object = flags & HASH_WRITE_OBJECT;
 	struct strbuf sbuf = STRBUF_INIT;
 
@@ -2175,7 +2175,7 @@ static int index_stream_convert_blob(struct index_state *istate,
 		ret = write_object_file(sbuf.buf, sbuf.len, type_name(OBJ_BLOB),
 					oid);
 	else
-		ret = hash_object_file(the_hash_algo, sbuf.buf, sbuf.len,
+		hash_object_file(the_hash_algo, sbuf.buf, sbuf.len,
 				 type_name(OBJ_BLOB), oid);
 	strbuf_release(&sbuf);
 	return ret;

object-store.h

@@ -245,7 +245,7 @@ static inline void *repo_read_object_file(struct repository *r,
 /* Read and unpack an object file into memory, write memory to an object file */
 int oid_object_info(struct repository *r, const struct object_id *, unsigned long *);
 
-int hash_object_file(const struct git_hash_algo *algo, const void *buf,
+void hash_object_file(const struct git_hash_algo *algo, const void *buf,
 		      unsigned long len, const char *type,
 		      struct object_id *oid);