archive: load index before pathspec checks

git archive checks whether pathspec arguments match anything to avoid
surprises due to typos and later loads the index to get attributes.

This order was OK when these features were introduced by ba053ea
(archive: do not read .gitattributes in working directory, 2009-04-18)
and d5f53d6 (archive: complain about path specs that don't match
anything, 2009-12-12).

But when attribute matching was added to pathspec in b0db704
(pathspec: allow querying for attributes, 2017-03-13), the pathspec
checker in git archive did not support it fully, because it lacks the
attributes from the index.

Load the index earlier, before the pathspec check, to support attr
pathspecs.

Reported-by: Ronan Pigott <[email protected]>
Signed-off-by: René Scharfe <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

archive.c

@@ -304,8 +304,6 @@ int write_archive_entries(struct archiver_args *args,
 		write_archive_entry_fn_t write_entry)
 {
 	struct archiver_context context;
-	struct unpack_trees_options opts;
-	struct tree_desc t;
 	int err;
 	struct strbuf path_in_archive = STRBUF_INIT;
 	struct strbuf content = STRBUF_INIT;
@@ -331,23 +329,6 @@ int write_archive_entries(struct archiver_args *args,
 	context.args = args;
 	context.write_entry = write_entry;
 
-	/*
-	 * Setup index and instruct attr to read index only
-	 */
-	if (!args->worktree_attributes) {
-		memset(&opts, 0, sizeof(opts));
-		opts.index_only = 1;
-		opts.head_idx = -1;
-		opts.src_index = args->repo->index;
-		opts.dst_index = args->repo->index;
-		opts.fn = oneway_merge;
-		init_tree_desc(&t, &args->tree->object.oid,
-			       args->tree->buffer, args->tree->size);
-		if (unpack_trees(1, &t, &opts))
-			return -1;
-		git_attr_set_direction(GIT_ATTR_INDEX);
-	}
-
 	err = read_tree(args->repo, args->tree,
 			&args->pathspec,
 			queue_or_write_archive_entry,
@@ -540,6 +521,26 @@ static void parse_treeish_arg(const char **argv,
 	if (!tree)
 		die(_("not a tree object: %s"), oid_to_hex(&oid));
 
+	/*
+	 * Setup index and instruct attr to read index only
+	 */
+	if (!ar_args->worktree_attributes) {
+		struct unpack_trees_options opts;
+		struct tree_desc t;
+
+		memset(&opts, 0, sizeof(opts));
+		opts.index_only = 1;
+		opts.head_idx = -1;
+		opts.src_index = ar_args->repo->index;
+		opts.dst_index = ar_args->repo->index;
+		opts.fn = oneway_merge;
+		init_tree_desc(&t, &tree->object.oid, tree->buffer, tree->size);
+		if (unpack_trees(1, &t, &opts))
+			die(_("unable to checkout working tree"));
+
+		git_attr_set_direction(GIT_ATTR_INDEX);
+	}
+
 	ar_args->refname = ref;
 	ar_args->tree = tree;
 	ar_args->commit_oid = commit_oid;

t/t5000-tar-tree.sh

@@ -136,6 +136,8 @@ test_expect_success 'end-of-options is correctly eaten' '
 
 test_expect_success 'populate workdir' '
 	mkdir a &&
+	echo "a files_named_a" >.gitattributes &&
+	git add .gitattributes &&
 	echo simple textfile >a/a &&
 	ten=0123456789 &&
 	hundred="$ten$ten$ten$ten$ten$ten$ten$ten$ten$ten" &&
@@ -449,6 +451,16 @@ test_expect_success 'allow pathspecs that resolve to the current directory' '
 	test_cmp expect actual
 '
 
+test_expect_success 'attr pathspec in bare repo' '
+	test_expect_code 0 git --git-dir=bare.git archive -v HEAD \
+		":(attr:files_named_a)" >/dev/null 2>actual &&
+	cat >expect <<-\EOF &&
+	a/
+	a/a
+	EOF
+	test_cmp expect actual
+'
+
 # Pull the size and date of each entry in a tarfile using the system tar.
 #
 # We'll pull out only the year from the date; that avoids any question of