libfstools: fix foreachdir() to pass dir with a trailing slash

Commit cc63723d886fd ("overlay: use lstat rather than stat and make sure
there are no trailing spaces") changed behavior of foreachdir() breaking
some callbacks. Before that modification all callbacks were getting
directory with a trailing slash. Above commit started removing them.

This broke handle_whiteout() which doesn't work at all since then. It
constructs file paths incorrectly: slash is missing between directory
and a file name. It seems noone noticed it for years because this issue
got hidden by switch2jffs() which also handles whiteouts with its system
command "cp -a" call.

Fix that regression by setting trailing slash back - right after calling
lstat(). Also to keep code simple just skip all entries that aren't
directories. This keeps conditions for removing/setting trailing slash
trivial. A side effect is not calling callbacks for files which is a
free bonus optimization.

Fixes: cc63723d886fd ("overlay: use lstat rather than stat and make sure there are no trailing spaces")
Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
Acked-by: John Crispin <john@phrozen.org>
(cherry picked from commit 79721f0376974859f39699a2237dbfa691233523)

diff --git a/libfstools/overlay.c b/libfstools/overlay.c
index 602458693ea32320e231a8ae3fa612866f2501c6..d7dd74b1c06aaa134f970b9a0f6862e0a11ce14a 100644 (file)
--- a/libfstools/overlay.c
+++ b/libfstools/overlay.c
@@ -91,15 +91,25 @@ foreachdir(const char *dir, int (*cb)(const char*))
        else
                sprintf(globdir, "%s/*", dir);
 
+       /* Include GLOB_MARK as callbacks expect a trailing slash */
        if (!glob(globdir, GLOB_NOESCAPE | GLOB_MARK | GLOB_ONLYDIR, NULL, &gl))
                for (j = 0; j < gl.gl_pathc; j++) {
                        char *dir = gl.gl_pathv[j];
                        int len = strlen(gl.gl_pathv[j]);
+                       int err;
 
-                       if (len > 1 && dir[len - 1] == '/')
+                       /* Quick way of skipping files */
+                       if (dir[len - 1] != '/')
+                               continue;
+
+                       /* lstat needs path without a trailing slash */
+                       if (len > 1)
                                dir[len - 1] = '\0';
+                       err = lstat(gl.gl_pathv[j], &s);
+                       if (len > 1)
+                               dir[len - 1] = '/';
 
-                       if (!lstat(gl.gl_pathv[j], &s) && !S_ISLNK(s.st_mode))
+                       if (!err && !S_ISLNK(s.st_mode))
                                foreachdir(gl.gl_pathv[j], cb);
        }
        cb(dir);