Re: pipe-filter self-tests

[Bruno Haible]

Eric Blake wrote:
> > These tests fails the same way on a Debian x86 system (the gcc compile
> > farm host "gcc60") as well, see:
> >
> > http://autobuild.josefsson.org/gnulib/log-200908232214355360000.txt
> 
> That log also shows that test-dup2.c and test-popen.sh are failing; it
> appears all of the failures are of the case: close(n),dup2(n,n) not
> returning -1 EBADF.

Indeed. This is a Linux bug that affects only 64-bit kernels. It was
introduced in July 2008
  
http://git.kernel.org/?p=linux/kernel/git/stable/linux-2.6.30.y.git;a=commitdiff;h=6c5d0512a091480c9f981162227fdb1c9d70e555
and only fixed in May 2009
  
http://git.kernel.org/?p=linux/kernel/git/stable/linux-2.6.30.y.git;a=commitdiff;h=2b79bc4f7ebbd5af3c8b867968f9f15602d5f802

I'm applying this supposed workaround, but cannot test it because
I don't have access to a machine with that version range of Linux kernel
and a 64-bit kernel.


2009-08-25  Bruno Haible  <address@hidden>

        dup2: work around a Linux bug.
        * m4/dup2.m4 (gl_FUNC_DUP2): Test for the Linux bug.
        * lib/dup2.c (rpl_dup2): Correct the return value if it is -EBADF.
        * doc/posix-functions/dup2.texi: Mention the Linux bug.
        Reported by Simon Josefsson.

*** doc/posix-functions/dup2.texi.orig  2009-08-25 10:51:19.000000000 +0200
--- doc/posix-functions/dup2.texi       2009-08-25 10:51:16.000000000 +0200
***************
*** 17,26 ****
  mingw.
  
  @item
! This function returns 0 for dup2 (1, 1) on some platforms:
  Cygwin 1.5.x.
  
  @item
  This function is missing on some older platforms.
  @end itemize
  
--- 17,30 ----
  mingw.
  
  @item
! This function returns 0 for @code(dup2 (1, 1)} on some platforms:
  Cygwin 1.5.x.
  
  @item
+ This function may return @code{-EBADF} instead of @code{-1} on some platforms:
+ Linux releases between July 2008 and May 2009.
+ 
+ @item
  This function is missing on some older platforms.
  @end itemize
  
*** lib/dup2.c.orig     2009-08-25 10:51:19.000000000 +0200
--- lib/dup2.c  2009-08-25 10:40:31.000000000 +0200
***************
*** 55,60 ****
--- 55,70 ----
      }
  # endif
    result = dup2 (fd, desired_fd);
+ # ifdef __linux__
+   /* Correct a Linux return value.
+      
<http://git.kernel.org/?p=linux/kernel/git/stable/linux-2.6.30.y.git;a=commitdiff;h=2b79bc4f7ebbd5af3c8b867968f9f15602d5f802>
+    */
+   if (fd == desired_fd && result == (unsigned int) -EBADF)
+     {
+       errno = EBADF;
+       result = -1;
+     }
+ # endif
    if (result == 0)
      result = desired_fd;
    /* Correct a cygwin 1.5.x errno value.  */
*** m4/dup2.m4.orig     2009-08-25 10:51:19.000000000 +0200
--- m4/dup2.m4  2009-08-25 10:45:48.000000000 +0200
***************
*** 1,4 ****
! #serial 6
  dnl Copyright (C) 2002, 2005, 2007, 2009 Free Software Foundation, Inc.
  dnl This file is free software; the Free Software Foundation
  dnl gives unlimited permission to copy and/or distribute it,
--- 1,4 ----
! #serial 7
  dnl Copyright (C) 2002, 2005, 2007, 2009 Free Software Foundation, Inc.
  dnl This file is free software; the Free Software Foundation
  dnl gives unlimited permission to copy and/or distribute it,
***************
*** 14,30 ****
      AC_LIBOBJ([dup2])
    else
      AC_CACHE_CHECK([whether dup2 works], [gl_cv_func_dup2_works],
!       [AC_RUN_IFELSE([AC_LANG_PROGRAM([[
! #include <unistd.h>
! ]], [return 1 - dup2 (1, 1);])],
        [gl_cv_func_dup2_works=yes], [gl_cv_func_dup2_works=no],
        [case "$host_os" in
           mingw*) # on this platform, dup2 always returns 0 for success
             gl_cv_func_dup2_works=no;;
           cygwin*) # on cygwin 1.5.x, dup2(1,1) returns 0
             gl_cv_func_dup2_works=no;;
           *) gl_cv_func_dup2_works=yes;;
!        esac])])
      if test "$gl_cv_func_dup2_works" = no; then
        REPLACE_DUP2=1
        AC_LIBOBJ([dup2])
--- 14,41 ----
      AC_LIBOBJ([dup2])
    else
      AC_CACHE_CHECK([whether dup2 works], [gl_cv_func_dup2_works],
!       [AC_RUN_IFELSE([
!          AC_LANG_PROGRAM([[#include <unistd.h>]],
!            [if (dup2 (1, 1) == 0)
!               return 1;
!             close (0);
!             if (dup2 (0, 0) != -1)
!               return 1;
!             return 0;
!            ])
!         ],
        [gl_cv_func_dup2_works=yes], [gl_cv_func_dup2_works=no],
        [case "$host_os" in
           mingw*) # on this platform, dup2 always returns 0 for success
             gl_cv_func_dup2_works=no;;
           cygwin*) # on cygwin 1.5.x, dup2(1,1) returns 0
             gl_cv_func_dup2_works=no;;
+          linux*) # On linux between 2008-07-27 and 2009-05-11, dup2 of a
+                  # closed fd may yield -EBADF instead of -1 / errno=EBADF.
+            gl_cv_func_dup2_works=no;;
           *) gl_cv_func_dup2_works=yes;;
!        esac])
!       ])
      if test "$gl_cv_func_dup2_works" = no; then
        REPLACE_DUP2=1
        AC_LIBOBJ([dup2])