Fix bug #13298 with failed backups by falling back on set-file-modes.

 src/fileio.c (Fset_file_selinux_context, Fset_file_acl): Return t if
 file's SELinux context or ACLs successfully set, nil otherwise.

 lisp/files.el (backup-buffer-copy, basic-save-buffer-2): If
 set-file-extended-attributes fails, fall back on set-file-modes
 instead of signaling an error.

 doc/lispref/files.texi (Changing Files): Document the return values of
 set-file-selinux-context and set-file-acl.

6 files changed, 45 insertions, 12 deletions

diff --git a/doc/lispref/ChangeLog b/doc/lispref/ChangeLog
index 7893424a942..b2f89024726 100644
--- a/doc/lispref/ChangeLog
+++ b/doc/lispref/ChangeLog
@@ -1,3 +1,8 @@
+2012-12-29  Eli Zaretskii  <eliz@gnu.org>
+
+        * files.texi (Changing Files): Document the return values of
+        set-file-selinux-context and set-file-acl.
+
 2012-12-27  Glenn Morris  <rgm@gnu.org>
 
         * files.texi (File Names): Mention Cygwin conversion functions.
diff --git a/doc/lispref/files.texi b/doc/lispref/files.texi
index 3faa5f5e257..4317fe42523 100644
--- a/doc/lispref/files.texi
+++ b/doc/lispref/files.texi
@@ -1703,9 +1703,11 @@ This function sets the SELinux security context of the file
 @var{filename} to @var{context}.  @xref{File Attributes}, for a brief
 description of SELinux contexts.  The @var{context} argument should be
 a list @code{(@var{user} @var{role} @var{type} @var{range})}, like the
-return value of @code{file-selinux-context}.  The function does
-nothing if SELinux is disabled, or if Emacs was compiled without
-SELinux support.
+return value of @code{file-selinux-context}.  The function returns
+@code{t} if it succeeds to set the SELinux security context of
+@var{filename}, @code{nil} otherwise.  The function does nothing and
+returns @code{nil} if SELinux is disabled, or if Emacs was compiled
+without SELinux support.
 @end defun
 
 @defun set-file-acl filename acl-string
@@ -1713,7 +1715,9 @@ This function sets the ACL entries of the file @var{filename} to
 @var{acl-string}.  @xref{File Attributes}, for a brief description of
 ACLs.  The @var{acl-string} argument should be a string containing the
 textual representation of the desired ACL entries as returned by
-@code{file-acl} (@pxref{File Attributes, file-acl}).
+@code{file-acl} (@pxref{File Attributes, file-acl}).  The function
+returns @code{t} if it succeeds to set the ACL entries of
+@var{filename}, @code{nil} otherwise.
 @end defun
 
 @node File Names
diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index b79d174d35e..0beb4a73185 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,9 @@
+2012-12-29  Eli Zaretskii  <eliz@gnu.org>
+
+        * files.el (backup-buffer-copy, basic-save-buffer-2): If
+        set-file-extended-attributes fails, fall back on set-file-modes
+        instead of signaling an error.  (Bug#13298)
+
 2012-12-29  Fabián Ezequiel Gallina  <fgallina@cuca>
 
         * progmodes/python.el: Support other commands triggering
diff --git a/lisp/files.el b/lisp/files.el
index f076530fbc8..fb82d0dbe1f 100644
--- a/lisp/files.el
+++ b/lisp/files.el
@@ -4019,10 +4019,12 @@ BACKUPNAME is the backup file name, which is the old file renamed."
               nil)))
       ;; Reset the umask.
       (set-default-file-modes umask)))
-  (and modes
-       (set-file-modes to-name (logand modes #o1777)))
-  (and extended-attributes
-       (set-file-extended-attributes to-name extended-attributes)))
+  ;; If set-file-extended-attributes fails, fall back on set-file-modes.
+  (unless (and extended-attributes
+               (with-demoted-errors
+                 (set-file-extended-attributes to-name extended-attributes)))
+    (and modes
+         (set-file-modes to-name (logand modes #o1777)))))
 
 (defvar file-name-version-regexp
   "\\(?:~\\|\\.~[-[:alnum:]:#@^._]+\\(?:~[[:digit:]]+\\)?~\\)"
@@ -4737,8 +4739,14 @@ Before and after saving the buffer, this function runs
                (setq setmodes (list (file-modes buffer-file-name)
                                     (file-extended-attributes buffer-file-name)
                                     buffer-file-name))
-               (set-file-modes buffer-file-name (logior (car setmodes) 128))
-               (set-file-extended-attributes buffer-file-name (nth 1 setmodes)))))
+               ;; If set-file-extended-attributes fails, fall back on
+               ;; set-file-modes.
+               (unless
+                   (with-demoted-errors
+                     (set-file-extended-attributes buffer-file-name
+                                                   (nth 1 setmodes)))
+                 (set-file-modes buffer-file-name
+                                 (logior (car setmodes) 128))))))
         (let (success)
           (unwind-protect
               (progn
diff --git a/src/ChangeLog b/src/ChangeLog
index 76f6865972c..f40f936d13a 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,5 +1,9 @@
 2012-12-29  Eli Zaretskii  <eliz@gnu.org>
 
+        * fileio.c (Fset_file_selinux_context, Fset_file_acl): Return t if
+        file's SELinux context or ACLs successfully set, nil otherwise.
+        (Bug#13298)
+
         * w32proc.c (reader_thread): Avoid passing NULL handles to
         SetEvent and WaitForSingleObject.
 
diff --git a/src/fileio.c b/src/fileio.c
index 9f70c790592..e824a7abcc5 100644
--- a/src/fileio.c
+++ b/src/fileio.c
@@ -2996,8 +2996,10 @@ DEFUN ("set-file-selinux-context", Fset_file_selinux_context,
 CONTEXT should be a list (USER ROLE TYPE RANGE), where the list
 elements are strings naming the components of a SELinux context.
 
-This function does nothing if SELinux is disabled, or if Emacs was not
-compiled with SELinux support.  */)
+Value is t if setting of SELinux context was successful, nil otherwise.
+
+This function does nothing and returns nil if SELinux is disabled,
+or if Emacs was not compiled with SELinux support.  */)
   (Lisp_Object filename, Lisp_Object context)
 {
   Lisp_Object absname;
@@ -3063,6 +3065,7 @@ compiled with SELinux support.  */)
 
           context_free (parsed_con);
           freecon (con);
+          return Qt;
         }
       else
         report_file_error ("Doing lgetfilecon", Fcons (absname, Qnil));
@@ -3127,6 +3130,8 @@ DEFUN ("set-file-acl", Fset_file_acl, Sset_file_acl,
 ACL-STRING should contain the textual representation of the ACL
 entries in a format suitable for the platform.
 
+Value is t if setting of ACL was successful, nil otherwise.
+
 Setting ACL for local files requires Emacs to be built with ACL
 support.  */)
   (Lisp_Object filename, Lisp_Object acl_string)
@@ -3166,6 +3171,7 @@ support.  */)
         report_file_error ("Setting ACL", Fcons (absname, Qnil));
 
       acl_free (acl);
+      return Qt;
     }
 #endif