Properly handle relative symlinks when publishing

* org-publish.el (org-publish-cache-ctime-of-src): Properly handle
relative symlinks.

At Thu, 07 Apr 2011 01:11:00 -0400,
Nick Dokos wrote:
>
> org-publish-cache-ctime-of-src tries (but does not always succeed) to
> deal with symlinks: file-symlink-p returns the target as a string, but
> if the target is relative to the symlink, that's not going to fly.
> e.g. if c is a symlink like this
>
>     /a/b/c->../d/f
>
> then (file-symlink-p "/a/b/c") -> "../d/f"
> but if the current directory is any place other than /a/b, the target
> will not be found, the file attributes are going to be nil and
> the function will blow up.

lisp/org-publish.el

@@ -1157,9 +1157,12 @@ Returns value on success, else nil."
 
 (defun org-publish-cache-ctime-of-src (filename)
   "Get the FILENAME ctime as an integer."
-  (let ((src-attr (file-attributes (if (stringp (file-symlink-p filename))
-				       (file-symlink-p filename)
-				     filename))))
+  (let* ((symlink-maybe (or (file-symlink-p filename) filename))
+	 (src-attr (file-attributes (if (file-name-absolute-p symlink-maybe)
+					symlink-maybe
+				      (expand-file-name 
+				       symlink-maybe
+				       (file-name-directory filename))))))
     (+
      (lsh (car (nth 5 src-attr)) 16)
      (cadr (nth 5 src-attr)))))