bugfix: With slashes near a multiples of PATH_MAX - 1 into the path,...

bugfix: With slashes near a multiples of PATH_MAX - 1 into the path, liblongpath could return results for a wrong path

skip all trailing slashes before starting the search, this is
required because otherwise the 'rest' path could start with a
slash (would work on wrong path) or be the empty string
(yield undefined error)

src/longpath.c

@@ -374,8 +374,18 @@ oatl_im(int filedes, const char *path, const char **remaining) {
 		assert(l == strlen(p));
 
 		/* find last slash for strlen(component) < PATH_MAX */
+
 		sl = p + PATH_MAX - 1;
 
+		/*
+		 * skip all trailing slashes before starting the search, this is
+		 * required because otherwise the 'rest' path could start with a
+		 * slash (would work on wrong path) or be the empty string
+		 * (yield undefined error)
+		 */
+		while ((sl > p) && (*sl == '/'))
+			sl--;
+
 		while (sl > p) {
 			if (*sl == '/')
 				goto found;