(wipename): When repeatedly renaming a file, making the name shorter

and shorter, skip to the next shorter length length if a rename fails (e.g. due to
permission denied).  Otherwise, this loop would iterate for so long that shred would
appear to be stuck in an infinite loop for any but the shortest file names.

diff --git a/src/shred.c b/src/shred.c
index e8b7c8d..d192a1a 100644 (file)
--- a/src/shred.c
+++ b/src/shred.c
@@ -1589,22 +1589,34 @@ wipename (char *oldname, char const *qoldname, struct Options const *flags)
       do
        {
          struct stat st;
-         if (lstat (newname, &st) < 0 && rename (oldname, newname) == 0)
+         if (lstat (newname, &st) < 0)
            {
-             if (dir_fd < 0
-                 || (fdatasync (dir_fd) < 0 && fsync (dir_fd) < 0))
-               sync ();        /* Force directory out */
-             if (flags->verbose)
+             if (rename (oldname, newname) == 0)
                {
-                 /*
-                  * People seem to understand this better than talking
-                  * about renaming oldname.  newname doesn't need
-                  * quoting because we picked it.
-                  */
-                 error (0, 0, _("%s: renamed to `%s'"), qoldname, newname);
+                 if (dir_fd < 0
+                     || (fdatasync (dir_fd) < 0 && fsync (dir_fd) < 0))
+                   sync ();    /* Force directory out */
+                 if (flags->verbose)
+                   {
+                     /*
+                      * People seem to understand this better than talking
+                      * about renaming oldname.  newname doesn't need
+                      * quoting because we picked it.
+                      */
+                     error (0, 0, _("%s: renamed to `%s'"), qoldname, newname);
+                   }
+                 memcpy (oldname + (base - newname), base, len + 1);
+                 break;
                }
-             memcpy (oldname + (base - newname), base, len + 1);
-             break;
+             else
+               {
+                 /* The rename failed: give up on this length.  */
+                 break;
+               }
+           }
+         else
+           {
+             /* newname exists, so increment BASE so we use another */
            }
        }
       while (!incname (base, len));