git_packbuilder_write: Allow setting path to NULL to use the default path

If given a NULL path, write to the object path of the repository.

Add tests for the new behavior.

Author: joshtriplett

include/git2/pack.h

@@ -155,7 +155,7 @@ GIT_EXTERN(int) git_packbuilder_write_buf(git_buf *buf, git_packbuilder *pb);
  * Write the new pack and corresponding index file to path.
  *
  * @param pb The packbuilder
- * @param path to the directory where the packfile and index should be stored
+ * @param path Path to the directory where the packfile and index should be stored, or NULL for default location
  * @param mode permissions to use creating a packfile or 0 for defaults
  * @param progress_cb function to call with progress information from the indexer (optional)
  * @param progress_cb_payload payload for the progress callback (optional)

src/pack-objects.c

@@ -1385,6 +1385,7 @@ int git_packbuilder_write(
 	void *progress_cb_payload)
 {
 	int error = -1;
+	git_buf object_path = GIT_BUF_INIT;
 	git_indexer_options opts = GIT_INDEXER_OPTIONS_INIT;
 	git_indexer *indexer = NULL;
 	git_indexer_progress stats;
@@ -1393,6 +1394,14 @@ int git_packbuilder_write(
 
 	PREPARE_PACK;
 
+	if (path == NULL) {
+		if ((error = git_repository_item_path(&object_path, pb->repo, GIT_REPOSITORY_ITEM_OBJECTS)) < 0)
+			goto cleanup;
+		if ((error = git_buf_joinpath(&object_path, git_buf_cstr(&object_path), "pack")) < 0)
+			goto cleanup;
+		path = git_buf_cstr(&object_path);
+	}
+
 	opts.progress_cb = progress_cb;
 	opts.progress_cb_payload = progress_cb_payload;
 
@@ -1415,6 +1424,7 @@ int git_packbuilder_write(
 
 cleanup:
 	git_indexer_free(indexer);
+	git_buf_dispose(&object_path);
 	return error;
 }
 

tests/pack/packbuilder.c

@@ -151,6 +151,15 @@ void test_pack_packbuilder__get_hash(void)
 	cl_assert_equal_s(hex, "7f5fa362c664d68ba7221259be1cbd187434b2f0");
 }
 
+void test_pack_packbuilder__write_default_path(void)
+{
+	seed_packbuilder();
+
+	cl_git_pass(git_packbuilder_write(_packbuilder, NULL, 0, NULL, NULL));
+	cl_assert(git_path_exists("objects/pack/pack-7f5fa362c664d68ba7221259be1cbd187434b2f0.idx"));
+	cl_assert(git_path_exists("objects/pack/pack-7f5fa362c664d68ba7221259be1cbd187434b2f0.pack"));
+}
+
 static void test_write_pack_permission(mode_t given, mode_t expected)
 {
 	struct stat statbuf;