dired.c fails to gc protect lisp object (patch included)

dired.c fails to gc protect lisp object (patch included)

[Rich Felker]

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i was experiencing random crashes because file_name_completion (in
dired.c) does not protect the "name" object from garbage collection.
the attached patch seems to fix it.

i'm using emacs-unicode-2 but this might apply to other versions as
well.

~rich felker


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Index: dired.c
===================================================================
RCS file: /sources/emacs/emacs/src/dired.c,v
retrieving revision 1.104.4.17
diff -u -r1.104.4.17 dired.c
--- dired.c	26 Jan 2007 06:15:08 -0000	1.104.4.17
+++ dired.c	11 Mar 2007 23:39:11 -0000
@@ -521,6 +521,7 @@
   for (passcount = !!all_flag; NILP (bestmatch) && passcount < 2; passcount++)
     {
       int inner_count = SPECPDL_INDEX ();
+      struct gcpro gcpro1;
 
       BLOCK_INPUT;
       d = opendir (SDATA (Fdirectory_file_name (encoded_dir)));
@@ -665,6 +666,7 @@
 	    }
 	  else
 	    name = make_string (dp->d_name, len);
+	  GCPRO1(name);
 
 	  /* Test the predicate, if any.  */
 
@@ -673,7 +675,10 @@
 	      Lisp_Object decoded;
 	      decoded = Fexpand_file_name (DECODE_FILE (name), dirname);
 	      if (NILP (call1 (predicate, decoded)))
-		continue;
+		{
+		  UNGCPRO;
+		  continue;
+		}
 	    }
 
 	  /* Suitably record this match.  */
@@ -736,6 +741,7 @@
 		matchsize++;
 	      bestmatchsize = matchsize;
 	    }
+	  UNGCPRO;
 	}
       /* This closes the directory.  */
       bestmatch = unbind_to (inner_count, bestmatch);

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Re: dired.c fails to gc protect lisp object (patch included)

[Richard Stallman]

Thanks for finding this bug.  Does this patch fix it?
I like it better because it is more local.

Index: dired.c
===================================================================
RCS file: /cvsroot/emacs/emacs/src/dired.c,v
retrieving revision 1.130
diff -c -c -r1.130 dired.c
*** dired.c	13 Jan 2007 21:45:34 -0000	1.130
--- dired.c	12 Mar 2007 03:24:31 -0000
***************
*** 670,677 ****
  	  if (!NILP (predicate))
  	    {
  	      Lisp_Object decoded;
  	      decoded = Fexpand_file_name (DECODE_FILE (name), dirname);
! 	      if (NILP (call1 (predicate, decoded)))
  		continue;
  	    }
  
--- 670,684 ----
  	  if (!NILP (predicate))
  	    {
  	      Lisp_Object decoded;
+ 	      Lisp_Object val;
+ 	      struct gcpro gcpro1;
+ 
+ 	      GCPRO1 (name);
  	      decoded = Fexpand_file_name (DECODE_FILE (name), dirname);
! 	      val = call1 (predicate, decoded);
! 	      UNGCPRO;
! 
! 	      if (NILP (val))
  		continue;
  	    }