[Emacs-diffs] /srv/bzr/emacs/trunk r111919: * filelock.c (lock_file): Don't access freed storage.

[Paul Eggert]

------------------------------------------------------------
revno: 111919
committer: Paul Eggert <address@hidden>
branch nick: trunk
timestamp: Sat 2013-03-02 13:05:52 -0800
message:
  * filelock.c (lock_file): Don't access freed storage.
modified:
  src/ChangeLog
  src/filelock.c

=== modified file 'src/ChangeLog'
--- a/src/ChangeLog     2013-03-02 20:41:53 +0000
+++ b/src/ChangeLog     2013-03-02 21:05:52 +0000
@@ -27,6 +27,7 @@
        that's not portable.
        (lock_file): Document that this function can return if lock
        creation fails.
+       (lock_file): Don't access freed storage.
 
 2013-03-02  Andreas Schwab  <address@hidden>
 

=== modified file 'src/filelock.c'
--- a/src/filelock.c    2013-03-02 20:41:53 +0000
+++ b/src/filelock.c    2013-03-02 21:05:52 +0000
@@ -597,11 +597,9 @@
 void
 lock_file (Lisp_Object fn)
 {
-  register Lisp_Object attack, orig_fn, encoded_fn;
-  register char *lfname, *locker;
-  ptrdiff_t locker_size;
+  Lisp_Object orig_fn, encoded_fn;
+  char *lfname;
   lock_info_type lock_info;
-  printmax_t pid;
   struct gcpro gcpro1;
   USE_SAFE_ALLOCA;
 
@@ -642,32 +640,29 @@
       call1 (intern ("ask-user-about-supersession-threat"), fn);
 
   }
+
+  /* Try to lock the lock.  */
+  if (0 < lock_if_free (&lock_info, lfname))
+    {
+      /* Someone else has the lock.  Consider breaking it.  */
+      ptrdiff_t locker_size = (strlen (lock_info.user) + strlen 
(lock_info.host)
+                              + INT_STRLEN_BOUND (printmax_t)
+                              + sizeof "@ (pid )");
+      char *locker = SAFE_ALLOCA (locker_size);
+      printmax_t pid = lock_info.pid;
+      Lisp_Object attack;
+      esprintf (locker, "address@hidden (pid %"pMd")",
+               lock_info.user, lock_info.host, pid);
+      FREE_LOCK_INFO (lock_info);
+
+      attack = call2 (intern ("ask-user-about-lock"), fn, build_string 
(locker));
+      /* Take the lock if the user said so.  */
+      if (!NILP (attack))
+       lock_file_1 (lfname, 1);
+    }
+
   UNGCPRO;
-
-  /* Try to lock the lock. */
-  if (lock_if_free (&lock_info, lfname) <= 0)
-    /* Return now if we have locked it, or if lock creation failed */
-    return;
-
-  /* Else consider breaking the lock */
-  locker_size = (strlen (lock_info.user) + strlen (lock_info.host)
-                + INT_STRLEN_BOUND (printmax_t)
-                + sizeof "@ (pid )");
-  locker = SAFE_ALLOCA (locker_size);
-  pid = lock_info.pid;
-  esprintf (locker, "address@hidden (pid %"pMd")",
-           lock_info.user, lock_info.host, pid);
-  FREE_LOCK_INFO (lock_info);
-
-  attack = call2 (intern ("ask-user-about-lock"), fn, build_string (locker));
   SAFE_FREE ();
-  if (!NILP (attack))
-    /* User says take the lock */
-    {
-      lock_file_1 (lfname, 1);
-      return;
-    }
-  /* User says ignore the lock */
 }
 
 void