2006-05-09  Paul Eggert  <eggert@cs.ucla.edu>

	* src/cmp.c (cmp): The previous fix wasn't quite right either, as
	it mishandled 'cmp A B >/dev/null' when A is shorter than B and
	differs before A's end-of-file, by outputting a bogus EOF message.
	Also, it was inefficient if A and B were large.

2006-05-07  Jim Meyering  <jim@meyering.net>  (tiny change)

	Fix bug introduced in 2006-03-09 change:
	cmp always exits successfully, when stdout is redirected to /dev/null.
	* src/cmp.c (cmp): When there's a difference, arrange to return nonzero
	also when comparison_type is the new (from 2006-03-09) type_no_stdout.

2006-03-09  Paul Eggert  <eggert@cs.ucla.edu>

	* src/cmp.c (type_no_stdout): New constant.
	(main): Use it to avoid bug when the "EOF on foo" message is
	generated and stdout is /dev/null.
	Problem reported by Vincent Lefevre (Debian bug 356083).

Index: cmp.c
===================================================================
RCS file: /sources/diffutils/diffutils/src/cmp.c,v
retrieving revision 1.39
retrieving revision 1.40
diff -u -a -p -u -p -a -r1.39 -r1.40
--- cmp.c	5 Jan 2006 07:23:55 -0000	1.39
+++ cmp.c	9 Mar 2006 20:38:11 -0000	1.40
@@ -78,6 +78,7 @@ static enum comparison_type
   {
     type_first_diff,	/* Print the first difference.  */
     type_all_diffs,	/* Print all differences.  */
+    type_no_stdout,	/* Do not output to stdout; only stderr.  */
     type_status		/* Exit status only.  */
   } comparison_type;
 
@@ -317,7 +318,12 @@ main (int argc, char **argv)
       if (fstat (STDOUT_FILENO, &outstat) == 0
 	  && stat (NULL_DEVICE, &nullstat) == 0
 	  && 0 < same_file (&outstat, &nullstat))
-	comparison_type = type_status;
+	comparison_type =
+	  ((fstat (STDERR_FILENO, &outstat) == 0
+	    ? 0 < same_file (&outstat, &nullstat)
+	    : errno == EBADF)
+	   ? type_status
+	   : type_no_stdout);
     }
 
   /* If only a return code is needed,
@@ -356,7 +362,7 @@ main (int argc, char **argv)
   for (f = 0; f < 2; f++)
     if (close (file_desc[f]) != 0)
       error (EXIT_TROUBLE, errno, "%s", file[f]);
-  if (exit_status != 0  &&  comparison_type != type_status)
+  if (exit_status != EXIT_SUCCESS && comparison_type < type_no_stdout)
     check_stdout ();
   exit (exit_status);
   return exit_status;
@@ -536,6 +542,9 @@ cmp (void)
 	      while (first_diff < smaller);
 	      ret = EXIT_FAILURE;
 	      break;
+
+	    case type_no_stdout:
+	      break;
 	    }
 	}
 
Index: cmp.c
===================================================================
RCS file: /sources/diffutils/diffutils/src/cmp.c,v
retrieving revision 1.40
retrieving revision 1.41
diff -u -a -p -u -p -a -r1.40 -r1.41
--- cmp.c	9 Mar 2006 20:38:11 -0000	1.40
+++ cmp.c	9 Mar 2006 20:54:39 -0000	1.41
@@ -318,12 +318,7 @@ main (int argc, char **argv)
       if (fstat (STDOUT_FILENO, &outstat) == 0
 	  && stat (NULL_DEVICE, &nullstat) == 0
 	  && 0 < same_file (&outstat, &nullstat))
-	comparison_type =
-	  ((fstat (STDERR_FILENO, &outstat) == 0
-	    ? 0 < same_file (&outstat, &nullstat)
-	    : errno == EBADF)
-	   ? type_status
-	   : type_no_stdout);
+	comparison_type = type_no_stdout;
     }
 
   /* If only a return code is needed,
Index: cmp.c
===================================================================
RCS file: /sources/diffutils/diffutils/src/cmp.c,v
retrieving revision 1.43
retrieving revision 1.44
diff -u -a -p -u -p -a -r1.43 -r1.44
--- cmp.c	13 Mar 2006 19:11:17 -0000	1.43
+++ cmp.c	8 May 2006 01:41:04 -0000	1.44
@@ -536,10 +536,10 @@ cmp (void)
 		  first_diff++;
 		}
 	      while (first_diff < smaller);
-	      ret = EXIT_FAILURE;
-	      break;
 
+	      /* Fall through.  */
 	    case type_no_stdout:
+	      ret = EXIT_FAILURE;
 	      break;
 	    }
 	}
Index: cmp.c
===================================================================
RCS file: /sources/diffutils/diffutils/src/cmp.c,v
retrieving revision 1.44
retrieving revision 1.45
diff -u -a -p -u -p -a -r1.44 -r1.45
--- cmp.c	8 May 2006 01:41:04 -0000	1.44
+++ cmp.c	9 May 2006 22:57:20 -0000	1.45
@@ -382,7 +382,7 @@ cmp (void)
   word *buffer1 = buffer[1];
   char *buf0 = (char *) buffer0;
   char *buf1 = (char *) buffer1;
-  int ret = EXIT_SUCCESS;
+  int differing = 0;
   int f;
   int offset_width IF_LINT (= 0);
 
@@ -536,17 +536,18 @@ cmp (void)
 		  first_diff++;
 		}
 	      while (first_diff < smaller);
+	      differing = -1;
+	      break;
 
-	      /* Fall through.  */
 	    case type_no_stdout:
-	      ret = EXIT_FAILURE;
+	      differing = 1;
 	      break;
 	    }
 	}
 
       if (read0 != read1)
 	{
-	  if (comparison_type != type_status)
+	  if (differing <= 0 && comparison_type != type_status)
 	    {
 	      /* See POSIX 1003.1-2001 for this format.  */
 	      fprintf (stderr, _("cmp: EOF on %s\n"), file[read1 < read0]);
@@ -555,9 +556,9 @@ cmp (void)
 	  return EXIT_FAILURE;
 	}
     }
-  while (read0 == buf_size);
+  while (differing <= 0 && read0 == buf_size);
 
-  return ret;
+  return differing == 0 ? EXIT_SUCCESS : EXIT_FAILURE;
 }
 
 /* Compare two blocks of memory P0 and P1 until they differ,