file-truename now uses realpath for local files

This uses fewer syscalls on GNU/Linux and other GNUish platforms.
* lisp/files.el (file-truename): Try fileio--truename
if there are no handlers.
* src/fileio.c: Include stdlib.h, for realpath.
(Ffileio__truename): New function.

1 files changed, 8 insertions, 3 deletions

diff --git a/lisp/files.el b/lisp/files.el
index ce4dd99bd53..d32c6acb82c 100644
--- a/lisp/files.el
+++ b/lisp/files.el
@@ -1307,9 +1307,14 @@ containing it, until no links are left at any level.
       (let ((handler (find-file-name-handler filename 'file-truename)))
         ;; For file name that has a special handler, call handler.
         ;; This is so that ange-ftp can save time by doing a no-op.
-        (if handler
-            (setq filename (funcall handler 'file-truename filename)
-                  done t)
+        (or
+         (if handler
+             (setq filename (funcall handler 'file-truename filename)
+                   done t)
+           (condition-case nil
+               (setq filename (fileio--truename filename)
+                     done t)
+             (file-missing nil)))
           (let ((dir (or (file-name-directory filename) default-directory))
                 target dirfile)
             ;; Get the truename of the directory.