* net/tramp.el (tramp-remote-selinux-p): New defun.

(tramp-handle-file-selinux-context)
(tramp-handle-set-file-selinux-context): Use it.

2 files changed, 25 insertions, 7 deletions

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index 3eba70f40af..649fa409ff4 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,9 @@
+2010-04-28  Michael Albinus  <michael.albinus@gmx.de>
+
+        * net/tramp.el (tramp-remote-selinux-p): New defun.
+        (tramp-handle-file-selinux-context)
+        (tramp-handle-set-file-selinux-context): Use it.
+
 2010-04-28  Sam Steingold  <sds@gnu.org>
 
         * progmodes/bug-reference.el (bug-reference-url-format): Mark as
diff --git a/lisp/net/tramp.el b/lisp/net/tramp.el
index a4442e9b54b..f82ecddc3c4 100644
--- a/lisp/net/tramp.el
+++ b/lisp/net/tramp.el
@@ -3030,6 +3030,17 @@ and gid of the corresponding user is taken.  Both parameters must be integers."
          "chown" nil nil nil
          (format "%d:%d" uid gid) (tramp-shell-quote-argument filename))))))
 
+(defun tramp-remote-selinux-p (vec)
+  "Check, whether SELINUX is enabled on the remote host."
+  (with-connection-property (tramp-get-connection-process vec) "selinux-p"
+    (let ((result (tramp-find-executable
+                   vec "getenforce" (tramp-get-remote-path vec) t t)))
+      (and result
+           (string-equal
+            (tramp-send-command-and-read
+             vec (format "echo \\\"`%S`\\\"" result))
+            "Enforcing")))))
+
 (defun tramp-handle-file-selinux-context (filename)
   "Like `file-selinux-context' for Tramp files."
   (with-parsed-tramp-file-name filename nil
@@ -3037,11 +3048,12 @@ and gid of the corresponding user is taken.  Both parameters must be integers."
       (let ((context '(nil nil nil nil))
             (regexp (concat "\\([a-z0-9_]+\\):" "\\([a-z0-9_]+\\):"
                             "\\([a-z0-9_]+\\):" "\\([a-z0-9_]+\\)")))
-        (when (zerop (tramp-send-command-and-check
-                      v (format
-                         "%s -d -Z %s"
-                         (tramp-get-ls-command v)
-                         (tramp-shell-quote-argument localname))))
+        (when (and (tramp-remote-selinux-p v)
+                   (zerop (tramp-send-command-and-check
+                           v (format
+                              "%s -d -Z %s"
+                              (tramp-get-ls-command v)
+                              (tramp-shell-quote-argument localname)))))
           (with-current-buffer (tramp-get-connection-buffer v)
             (goto-char (point-min))
             (when (re-search-forward regexp (tramp-compat-line-end-position) t)
@@ -3054,6 +3066,7 @@ and gid of the corresponding user is taken.  Both parameters must be integers."
   "Like `set-file-selinux-context' for Tramp files."
   (with-parsed-tramp-file-name filename nil
     (if (and (consp context)
+             (tramp-remote-selinux-p v)
              (zerop (tramp-send-command-and-check
                      v (format "chcon %s %s %s %s %s"
                                (if (stringp (nth 0 context))
@@ -6924,7 +6937,7 @@ process to set up.  VEC specifies the connection."
           (tramp-send-command-and-read vec "echo \\\"`uname -sr`\\\""))))
     (when (and (stringp old-uname) (not (string-equal old-uname new-uname)))
       (with-current-buffer (tramp-get-debug-buffer vec)
-        ;; Keep the debug buffer
+        ;; Keep the debug buffer.
         (rename-buffer
          (generate-new-buffer-name tramp-temp-buffer-name) 'unique)
         (funcall (symbol-function 'tramp-cleanup-connection) vec)
@@ -8752,7 +8765,6 @@ Only works for Bourne-like shells."
 ;;   on remote hosts.
 ;; * Use secrets.el for password handling.
 ;; * Load ~/.emacs_SHELLNAME on the remote host for `shell'.
-;; * Implement selinux-context.
 
 ;; Functions for file-name-handler-alist:
 ;; diff-latest-backup-file -- in diff.el