serious bug in cmp from diffutils/cvs

[Jim Meyering]

Hi Paul,

I tried out the latest diffutils, then ran coreutils' `make check'
and saw new failures.  Tracked it back to this bug in `cmp'.

No test suite?  Is one in the works?
Do you prefer autotest-based tests?  Anyhow, maybe if you tell
us what framework you'd like, someone will contribute a few.

Demonstrate the bug (before the patch):

  $ ./cmp <(echo b) <(echo a) > /dev/null && echo bug
  bug

The fix works: after applying the patch:

  $ ./cmp <(echo b) <(echo a) > /dev/null && echo bug
  $

Test the other (inputs equal) case:

  $ ./cmp <(echo a) <(echo a) > /dev/null || echo bug
  $

2006-05-07  Jim Meyering  <address@hidden>

        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.

Index: src/cmp.c
===================================================================
RCS file: /sources/diffutils/diffutils/src/cmp.c,v
retrieving revision 1.43
diff -u -p -r1.43 cmp.c
--- src/cmp.c   13 Mar 2006 19:11:17 -0000      1.43
+++ src/cmp.c   7 May 2006 16:55:37 -0000
@@ -540,6 +540,7 @@ cmp (void)
              break;
 
            case type_no_stdout:
+             ret = EXIT_FAILURE;
              break;
            }
        }