switch_root: code shrink - use iterate_on_dir()

function                                             old     new   delta
rmrf                                                   -      46     +46
delete_contents                                      181      99     -82
------------------------------------------------------------------------------
(add/remove: 1/0 grow/shrink: 0/1 up/down: 46/-82)            Total: -36 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 14 insertions, 21 deletions

diff --git a/util-linux/switch_root.c b/util-linux/switch_root.c
index f2674b5ac..901c0b8db 100644
--- a/util-linux/switch_root.c
+++ b/util-linux/switch_root.c
@@ -68,11 +68,22 @@ extern int capget(cap_user_header_t header, const cap_user_data_t data);
 # define MS_MOVE     8192
 #endif
 
+static void delete_contents(const char *directory, dev_t rootdev);
+
+static int FAST_FUNC rmrf(const char *directory, struct dirent *d, void *rootdevp)
+{
+        char *newdir = concat_subpath_file(directory, d->d_name);
+        if (newdir) { // not . or ..
+                // Recurse to delete contents
+                delete_contents(newdir, *(dev_t*)rootdevp);
+                free(newdir);
+        }
+        return 0;
+}
+
 // Recursively delete contents of rootfs
 static void delete_contents(const char *directory, dev_t rootdev)
 {
-        DIR *dir;
-        struct dirent *d;
         struct stat st;
 
         // Don't descend into other filesystems
@@ -81,25 +92,7 @@ static void delete_contents(const char *directory, dev_t rootdev)
 
         // Recursively delete the contents of directories
         if (S_ISDIR(st.st_mode)) {
-                dir = opendir(directory);
-                if (dir) {
-                        while ((d = readdir(dir))) {
-                                char *newdir = d->d_name;
-
-                                // Skip . and ..
-                                if (DOT_OR_DOTDOT(newdir))
-                                        continue;
-
-                                // Recurse to delete contents
-                                newdir = concat_path_file(directory, newdir);
-                                delete_contents(newdir, rootdev);
-                                free(newdir);
-                        }
-                        closedir(dir);
-
-                        // Directory should now be empty, zap it
-                        rmdir(directory);
-                }
+                iterate_on_dir(directory, rmrf, &rootdev);
         } else {
                 // It wasn't a directory, zap it
                 unlink(directory);