packfile: drop nth_packed_object_sha1()

Once upon a time, nth_packed_object_sha1() was the primary way to get
the oid of a packfile's index position. But these days we have the more
type-safe nth_packed_object_id() wrapper, and all callers have been
converted.

Let's drop the "sha1" version (turning the safer wrapper into a single
function) so that nobody is tempted to introduce new callers.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: peff

packfile.c

@@ -1867,35 +1867,26 @@ int bsearch_pack(const struct object_id *oid, const struct packed_git *p, uint32
 			    index_lookup, index_lookup_width, result);
 }
 
-const unsigned char *nth_packed_object_sha1(struct packed_git *p,
-					    uint32_t n)
+int nth_packed_object_id(struct object_id *oid,
+			 struct packed_git *p,
+			 uint32_t n)
 {
 	const unsigned char *index = p->index_data;
 	const unsigned int hashsz = the_hash_algo->rawsz;
 	if (!index) {
 		if (open_pack_index(p))
-			return NULL;
+			return -1;
 		index = p->index_data;
 	}
 	if (n >= p->num_objects)
-		return NULL;
+		return -1;
 	index += 4 * 256;
 	if (p->index_version == 1) {
-		return index + (hashsz + 4) * n + 4;
+		oidread(oid, index + (hashsz + 4) * n + 4);
 	} else {
 		index += 8;
-		return index + hashsz * n;
+		oidread(oid, index + hashsz * n);
 	}
-}
-
-int nth_packed_object_id(struct object_id *oid,
-			 struct packed_git *p,
-			 uint32_t n)
-{
-	const unsigned char *hash = nth_packed_object_sha1(p, n);
-	if (!hash)
-		return -1;
-	hashcpy(oid->hash, hash);
 	return 0;
 }
 

packfile.h

@@ -121,15 +121,9 @@ void check_pack_index_ptr(const struct packed_git *p, const void *ptr);
 int bsearch_pack(const struct object_id *oid, const struct packed_git *p, uint32_t *result);
 
 /*
- * Return the SHA-1 of the nth object within the specified packfile.
- * Open the index if it is not already open.  The return value points
- * at the SHA-1 within the mmapped index.  Return NULL if there is an
- * error.
- */
-const unsigned char *nth_packed_object_sha1(struct packed_git *, uint32_t n);
-/*
- * Like nth_packed_object_sha1, but write the data into the object specified by
- * the the first argument.  Returns 0 on success, negative otherwise.
+ * Write the oid of the nth object within the specified packfile into the first
+ * parameter. Open the index if it is not already open.  Returns 0 on success,
+ * negative otherwise.
  */
 int nth_packed_object_id(struct object_id *, struct packed_git *, uint32_t n);