untracked cache: make a wrapper around {open,read,close}dir()

This allows us to feed different info to read_directory_recursive()
based on untracked cache in the next patch.

Helped-by: Ramsay Jones <ramsay@ramsay1.demon.co.uk>
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

dir.c

@@ -31,6 +31,15 @@ enum path_treatment {
 	path_untracked
 };
 
+/*
+ * Support data structure for our opendir/readdir/closedir wrappers
+ */
+struct cached_dir {
+	DIR *fdir;
+	struct untracked_cache_dir *untracked;
+	struct dirent *de;
+};
+
 static enum path_treatment read_directory_recursive(struct dir_struct *dir,
 	const char *path, int len, struct untracked_cache_dir *untracked,
 	int check_only, const struct path_simplify *simplify);
@@ -1418,12 +1427,13 @@ static enum path_treatment treat_one_path(struct dir_struct *dir,
 
 static enum path_treatment treat_path(struct dir_struct *dir,
 				      struct untracked_cache_dir *untracked,
-				      struct dirent *de,
+				      struct cached_dir *cdir,
 				      struct strbuf *path,
 				      int baselen,
 				      const struct path_simplify *simplify)
 {
 	int dtype;
+	struct dirent *de = cdir->de;
 
 	if (is_dot_or_dotdot(de->d_name) || !strcmp(de->d_name, ".git"))
 		return path_none;
@@ -1445,6 +1455,37 @@ static void add_untracked(struct untracked_cache_dir *dir, const char *name)
 	dir->untracked[dir->untracked_nr++] = xstrdup(name);
 }
 
+static int open_cached_dir(struct cached_dir *cdir,
+			   struct dir_struct *dir,
+			   struct untracked_cache_dir *untracked,
+			   struct strbuf *path,
+			   int check_only)
+{
+	memset(cdir, 0, sizeof(*cdir));
+	cdir->untracked = untracked;
+	cdir->fdir = opendir(path->len ? path->buf : ".");
+	if (!cdir->fdir)
+		return -1;
+	return 0;
+}
+
+static int read_cached_dir(struct cached_dir *cdir)
+{
+	if (cdir->fdir) {
+		cdir->de = readdir(cdir->fdir);
+		if (!cdir->de)
+			return -1;
+		return 0;
+	}
+	return -1;
+}
+
+static void close_cached_dir(struct cached_dir *cdir)
+{
+	if (cdir->fdir)
+		closedir(cdir->fdir);
+}
+
 /*
  * Read a directory tree. We currently ignore anything but
  * directories, regular files and symlinks. That's because git
@@ -1461,23 +1502,21 @@ static enum path_treatment read_directory_recursive(struct dir_struct *dir,
 				    struct untracked_cache_dir *untracked, int check_only,
 				    const struct path_simplify *simplify)
 {
-	DIR *fdir;
+	struct cached_dir cdir;
 	enum path_treatment state, subdir_state, dir_state = path_none;
-	struct dirent *de;
 	struct strbuf path = STRBUF_INIT;
 
 	strbuf_add(&path, base, baselen);
 
-	fdir = opendir(path.len ? path.buf : ".");
-	if (!fdir)
+	if (open_cached_dir(&cdir, dir, untracked, &path, check_only))
 		goto out;
 
 	if (untracked)
 		untracked->check_only = !!check_only;
 
-	while ((de = readdir(fdir)) != NULL) {
+	while (!read_cached_dir(&cdir)) {
 		/* check how the file or directory should be treated */
-		state = treat_path(dir, untracked, de, &path, baselen, simplify);
+		state = treat_path(dir, untracked, &cdir, &path, baselen, simplify);
 
 		if (state > dir_state)
 			dir_state = state;
@@ -1530,7 +1569,7 @@ static enum path_treatment read_directory_recursive(struct dir_struct *dir,
 			break;
 		}
 	}
-	closedir(fdir);
+	close_cached_dir(&cdir);
  out:
 	strbuf_release(&path);