>Number:         30779
>Category:       bin
>Synopsis:       diff fails to recognise identical special files
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    bin-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Tue Jul 19 11:56:00 +0000 2005
>Originator:     Alan Barrett
>Release:        NetBSD 3.99.7
>Organization:
Not much
>Environment:
System: NetBSD 3.99.7
Architecture: i386
Machine: i386
>Description:
When diff(1) is asked to compare special files, it outputs
information like

	/dev/null is a character special file while /altroot/dev/null is a character special file

I would prefer it to be silent when both files are identical.

>How-To-Repeat:
# mkdir /altroot
# cp -RPp /dev /altroot/dev
# diff -r -u3 /dev /altroot/dev | grep "special file while .* special file" | wc
    2057   30855  207216

>Fix:
Apply the following patch.

Index: gnu/dist/diffutils/src/diff.c
===================================================================
RCS file: /usr/netbsd/anoncvs/main/src/gnu/dist/diffutils/src/diff.c,v
retrieving revision 1.1.1.1
diff -u -r1.1.1.1 diff.c
--- src/diff.c	26 Jan 2003 00:43:16 -0000	1.1.1.1
+++ src/diff.c	19 Jul 2005 11:45:56 -0000
@@ -1208,9 +1208,10 @@
   else if ((same_files
 	    = (cmp.file[0].desc != NONEXISTENT
 	       && cmp.file[1].desc != NONEXISTENT
-	       && 0 < same_file (&cmp.file[0].stat, &cmp.file[1].stat)
-	       && same_file_attributes (&cmp.file[0].stat,
-					&cmp.file[1].stat)))
+	       && (same_special_file (&cmp.file[0].stat, &cmp.file[1].stat)
+	           || (0 < same_file (&cmp.file[0].stat, &cmp.file[1].stat)
+		       && same_file_attributes (&cmp.file[0].stat,
+					&cmp.file[1].stat)))))
 	   && no_diff_means_no_output)
     {
       /* The two named files are actually the same physical file.
Index: gnu/dist/diffutils/src/system.h
===================================================================
RCS file: /usr/netbsd/anoncvs/main/src/gnu/dist/diffutils/src/system.h,v
retrieving revision 1.1.1.1
diff -u -r1.1.1.1 system.h
--- src/system.h	26 Jan 2003 00:43:16 -0000	1.1.1.1
+++ src/system.h	19 Jul 2005 11:45:56 -0000
@@ -349,7 +349,7 @@
 
 /* Do struct stat *S, *T describe the same special file?  */
 #ifndef same_special_file
-# if HAVE_ST_RDEV && defined S_ISBLK && defined S_ISCHR
+# if HAVE_STRUCT_STAT_ST_RDEV && defined S_ISBLK && defined S_ISCHR
 #  define same_special_file(s, t) \
      (((S_ISBLK ((s)->st_mode) && S_ISBLK ((t)->st_mode)) \
        || (S_ISCHR ((s)->st_mode) && S_ISCHR ((t)->st_mode))) \