rm: give a sensible diagnostic when failing to remove a symlink

On some systems (those with openat et al), when rm would fail to
remove a symlink, it would fail with the misleading diagnostic,
"Too many levels of symbolic links".
* NEWS: Mention the bug fix.
* src/remove.c (is_nondir_lstat): New function.
(remove_entry): Use it to catch failed-to-remove symlink (and any
other non-dir) here so that we don't fall through and try to treat
it as directory, which -- with a symlink -- would provoke the bogus
ELOOP failure.
* tests/rm/fail-eacces: Add a test for the above.
* src/c99-to-c89.diff: Adjust offsets.

1 files changed, 18 insertions, 1 deletions

diff --git a/src/remove.c b/src/remove.c
index aae7a8888..ac1010953 100644
--- a/src/remove.c
+++ b/src/remove.c
@@ -937,6 +937,21 @@ is_dir_lstat (int fd_cwd, char const *filename, struct stat *st)
   return is_dir;
 }
 
+/* Return true if FILENAME is a non-directory.
+   Otherwise, including the case in which lstat fails, return false.
+   *ST is FILENAME's tstatus.
+   Do not modify errno.  */
+static inline bool
+is_nondir_lstat (int fd_cwd, char const *filename, struct stat *st)
+{
+  int saved_errno = errno;
+  bool is_non_dir =
+    (cache_fstatat (fd_cwd, filename, st, AT_SYMLINK_NOFOLLOW) == 0
+     && !S_ISDIR (st->st_mode));
+  errno = saved_errno;
+  return is_non_dir;
+}
+
 #define DO_UNLINK(Fd_cwd, Filename, X)					\
   do									\
     {									\
@@ -1066,7 +1081,9 @@ remove_entry (int fd_cwd, Dirstack_state const *ds, char const *filename,
 	errno = EISDIR;
 
       if (! x->recursive
-	  || (cache_stat_ok (st) && !S_ISDIR (st->st_mode)))
+	  || (cache_stat_ok (st) && !S_ISDIR (st->st_mode))
+	  || (errno == EACCES && is_nondir_lstat (fd_cwd, filename, st))
+	  )
 	{
 	  if (ignorable_missing (x, errno))
 	    return RM_OK;