Smarter initialization for dired-use-ls-dired (Bug#7546).

* lisp/dired.el (dired-use-ls-dired): Set default to a special
"unspecified" value.
(dired-insert-directory): When called the first time, check
whether "ls --dired" succeeds and set dired-use-ls-dired (Bug#7546).

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index 187a36a5f5dd5c8f47db9001659f842a666e2803..c17db89eb81e89097ab17bd1c5e4f9496716a950 100644 (file)
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,10 @@
+2010-12-04  Chong Yidong  <cyd@stupidchicken.com>
+
+       * dired.el (dired-use-ls-dired): Set default to a special
+       "unspecified" value.
+       (dired-insert-directory): When called the first time, check
+       whether "ls --dired" succeeds and set dired-use-ls-dired (Bug#7546).
+
 2010-12-04  Tak Ota  <Takaaki.Ota@am.sony.com>
 
        * replace.el: Add "collect" feature to occur.

diff --git a/lisp/dired.el b/lisp/dired.el
index 104cf4970adb4a47268b741f84f2c08fa33fe8ef..8012fcb472d7df217ac0845e6013112213b8e915 100644 (file)
--- a/lisp/dired.el
+++ b/lisp/dired.el
@@ -80,8 +80,11 @@ If nil, `dired-listing-switches' is used.")
       "/etc/chown")))
   "Name of chown command (usually `chown' or `/etc/chown').")
 
-(defvar dired-use-ls-dired (not (not (string-match "gnu" system-configuration)))
-  "Non-nil means Dired should use `ls --dired'.")
+(defvar dired-use-ls-dired 'unspecified
+  "Non-nil means Dired should use \"ls --dired\".
+The special value of `unspecified' means to check explicitly, and
+save the result in this variable.  This is performed the first
+time `dired-insert-directory' is called.")
 
 (defvar dired-chmod-program "chmod"
   "Name of chmod command (usually `chmod').")
@@ -1057,7 +1060,14 @@ If HDR is non-nil, insert a header line with the directory name."
   (let ((opoint (point))
        (process-environment (copy-sequence process-environment))
        end)
-    (if (or dired-use-ls-dired (file-remote-p dir))
+    (if (or (if (eq dired-use-ls-dired 'unspecified)
+               ;; Check whether "ls --dired" gives exit code 0, and
+               ;; save the answer in `dired-use-ls-dired'.
+               (setq dired-use-ls-dired
+                     (eq (call-process insert-directory-program nil nil nil "--dired")
+                         0))
+             dired-use-ls-dired)
+           (file-remote-p dir))
        (setq switches (concat "--dired " switches)))
     ;; We used to specify the C locale here, to force English month names;
     ;; but this should not be necessary any more,