dir: introduce readdir_skip_dot_and_dotdot() helper

Many places in the code were doing
    while ((d = readdir(dir)) != NULL) {
        if (is_dot_or_dotdot(d->d_name))
            continue;
        ...process d...
    }
Introduce a readdir_skip_dot_and_dotdot() helper to make that a one-liner:
    while ((d = readdir_skip_dot_and_dotdot(dir)) != NULL) {
        ...process d...
    }

This helper particularly simplifies checks for empty directories.

Also use this helper in read_cached_dir() so that our statistics are
consistent across platforms.  (In other words, read_cached_dir() should
have been using is_dot_or_dotdot() and skipping such entries, but did
not and left it to treat_path() to detect and mark such entries as
path_none.)

Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/clean.c

@@ -189,10 +189,8 @@ static int remove_dirs(struct strbuf *path, const char *prefix, int force_flag,
 	strbuf_complete(path, '/');
 
 	len = path->len;
-	while ((e = readdir(dir)) != NULL) {
+	while ((e = readdir_skip_dot_and_dotdot(dir)) != NULL) {
 		struct stat st;
-		if (is_dot_or_dotdot(e->d_name))
-			continue;
 
 		strbuf_setlen(path, len);
 		strbuf_addstr(path, e->d_name);

builtin/worktree.c

@@ -118,10 +118,8 @@ static void prune_worktrees(void)
 	struct dirent *d;
 	if (!dir)
 		return;
-	while ((d = readdir(dir)) != NULL) {
+	while ((d = readdir_skip_dot_and_dotdot(dir)) != NULL) {
 		char *path;
-		if (is_dot_or_dotdot(d->d_name))
-			continue;
 		strbuf_reset(&reason);
 		if (should_prune_worktree(d->d_name, &reason, &path, expire))
 			prune_worktree(d->d_name, reason.buf);

diff-no-index.c

@@ -26,9 +26,8 @@ static int read_directory_contents(const char *path, struct string_list *list)
 	if (!(dir = opendir(path)))
 		return error("Could not open directory %s", path);
 
-	while ((e = readdir(dir)))
+	while ((e = readdir_skip_dot_and_dotdot(dir)))
-		if (!is_dot_or_dotdot(e->d_name))
+		string_list_insert(list, e->d_name);
-			string_list_insert(list, e->d_name);
 
 	closedir(dir);
 	return 0;

dir.c

@@ -59,6 +59,17 @@ void dir_init(struct dir_struct *dir)
 	memset(dir, 0, sizeof(*dir));
 }
 
+struct dirent *readdir_skip_dot_and_dotdot(DIR *dirp)
+{
+	struct dirent *e;
+
+	while ((e = readdir(dirp)) != NULL) {
+		if (!is_dot_or_dotdot(e->d_name))
+			break;
+	}
+	return e;
+}
+
 int count_slashes(const char *s)
 {
 	int cnt = 0;
@@ -2332,7 +2343,7 @@ static int read_cached_dir(struct cached_dir *cdir)
 	struct dirent *de;
 
 	if (cdir->fdir) {
-		de = readdir(cdir->fdir);
+		de = readdir_skip_dot_and_dotdot(cdir->fdir);
 		if (!de) {
 			cdir->d_name = NULL;
 			cdir->d_type = DT_UNKNOWN;
@@ -2931,11 +2942,9 @@ int is_empty_dir(const char *path)
 	if (!dir)
 		return 0;
 
-	while ((e = readdir(dir)) != NULL)
+	e = readdir_skip_dot_and_dotdot(dir);
-		if (!is_dot_or_dotdot(e->d_name)) {
+	if (e)
-			ret = 0;
+		ret = 0;
-			break;
-		}
 
 	closedir(dir);
 	return ret;
@@ -2975,10 +2984,8 @@ static int remove_dir_recurse(struct strbuf *path, int flag, int *kept_up)
 	strbuf_complete(path, '/');
 
 	len = path->len;
-	while ((e = readdir(dir)) != NULL) {
+	while ((e = readdir_skip_dot_and_dotdot(dir)) != NULL) {
 		struct stat st;
-		if (is_dot_or_dotdot(e->d_name))
-			continue;
 
 		strbuf_setlen(path, len);
 		strbuf_addstr(path, e->d_name);

dir.h

@@ -342,6 +342,8 @@ struct dir_struct {
 	unsigned visited_directories;
 };
 
+struct dirent *readdir_skip_dot_and_dotdot(DIR *dirp);
+
 /*Count the number of slashes for string s*/
 int count_slashes(const char *s);
 

entry.c

@@ -56,12 +56,9 @@ static void remove_subtree(struct strbuf *path)
 
 	if (!dir)
 		die_errno("cannot opendir '%s'", path->buf);
-	while ((de = readdir(dir)) != NULL) {
+	while ((de = readdir_skip_dot_and_dotdot(dir)) != NULL) {
 		struct stat st;
 
-		if (is_dot_or_dotdot(de->d_name))
-			continue;
-
 		strbuf_addch(path, '/');
 		strbuf_addstr(path, de->d_name);
 		if (lstat(path->buf, &st))

notes-merge.c

@@ -695,13 +695,10 @@ int notes_merge_commit(struct notes_merge_options *o,
 
 	strbuf_addch(&path, '/');
 	baselen = path.len;
-	while ((e = readdir(dir)) != NULL) {
+	while ((e = readdir_skip_dot_and_dotdot(dir)) != NULL) {
 		struct stat st;
 		struct object_id obj_oid, blob_oid;
 
-		if (is_dot_or_dotdot(e->d_name))
-			continue;
-
 		if (get_oid_hex(e->d_name, &obj_oid)) {
 			if (o->verbosity >= 3)
 				printf("Skipping non-SHA1 entry '%s%s'\n",

object-file.c

@@ -2304,10 +2304,8 @@ int for_each_file_in_obj_subdir(unsigned int subdir_nr,
 	strbuf_addch(path, '/');
 	baselen = path->len;
 
-	while ((de = readdir(dir))) {
+	while ((de = readdir_skip_dot_and_dotdot(dir))) {
 		size_t namelen;
-		if (is_dot_or_dotdot(de->d_name))
-			continue;
 
 		namelen = strlen(de->d_name);
 		strbuf_setlen(path, baselen);

packfile.c

@@ -813,10 +813,7 @@ void for_each_file_in_pack_dir(const char *objdir,
 	}
 	strbuf_addch(&path, '/');
 	dirnamelen = path.len;
-	while ((de = readdir(dir)) != NULL) {
+	while ((de = readdir_skip_dot_and_dotdot(dir)) != NULL) {
-		if (is_dot_or_dotdot(de->d_name))
-			continue;
-
 		strbuf_setlen(&path, dirnamelen);
 		strbuf_addstr(&path, de->d_name);
 

rerere.c

@@ -1190,13 +1190,11 @@ void rerere_gc(struct repository *r, struct string_list *rr)
 	if (!dir)
 		die_errno(_("unable to open rr-cache directory"));
 	/* Collect stale conflict IDs ... */
-	while ((e = readdir(dir))) {
+	while ((e = readdir_skip_dot_and_dotdot(dir))) {
 		struct rerere_dir *rr_dir;
 		struct rerere_id id;
 		int now_empty;
 
-		if (is_dot_or_dotdot(e->d_name))
-			continue;
 		if (!is_rr_cache_dirname(e->d_name))
 			continue; /* or should we remove e->d_name? */
 

worktree.c

@@ -128,10 +128,8 @@ struct worktree **get_worktrees(void)
 	dir = opendir(path.buf);
 	strbuf_release(&path);
 	if (dir) {
-		while ((d = readdir(dir)) != NULL) {
+		while ((d = readdir_skip_dot_and_dotdot(dir)) != NULL) {
 			struct worktree *linked = NULL;
-			if (is_dot_or_dotdot(d->d_name))
-				continue;
 
 			if ((linked = get_linked_worktree(d->d_name))) {
 				ALLOC_GROW(list, counter + 1, alloc);
@@ -486,13 +484,9 @@ int submodule_uses_worktrees(const char *path)
 	if (!dir)
 		return 0;
 
-	while ((d = readdir(dir)) != NULL) {
+	d = readdir_skip_dot_and_dotdot(dir);
-		if (is_dot_or_dotdot(d->d_name))
+	if (d != NULL)
-			continue;
-
 		ret = 1;
-		break;
-	}
 	closedir(dir);
 	return ret;
 }