stdio/errnobug.c

   1 /* Regression test for reported old bug that errno is clobbered
   2    by the first successful output to a stream on an unseekable object.
   3 Copyright (C) 1995 Free Software Foundation, Inc.
   4 This file is part of the GNU C Library.
   5
   6 The GNU C Library is free software; you can redistribute it and/or
   7 modify it under the terms of the GNU Library General Public License as
   8 published by the Free Software Foundation; either version 2 of the
   9 License, or (at your option) any later version.
  10
  11 The GNU C Library is distributed in the hope that it will be useful,
  12 but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14 Library General Public License for more details.
  15
  16 You should have received a copy of the GNU Library General Public
  17 License along with the GNU C Library; see the file COPYING.LIB.  If
  18 not, write to the Free Software Foundation, Inc., 675 Mass Ave,
  19 Cambridge, MA 02139, USA.  */
  20
  21 #include <errno.h>
  22 #include <stdio.h>
  23 #include <unistd.h>
  24
  25 int
  26 main (void)
  27 {
  28   int fd[2];
  29   FILE *f;
  30
  31   /* Get a stream that cannot seek.  */
  32
  33   if (pipe (fd))
  34     {
  35       perror ("pipe");
  36       return 1;
  37     }
  38   f = fdopen (fd[1], "w");
  39   if (f == NULL)
  40     {
  41       perror ("fdopen");
  42       return 1;
  43     }
  44
  45   errno = 0;
  46   if (fputs ("fnord", f))
  47     {
  48       perror ("fputs");
  49       return 1;
  50     }
  51
  52   if (errno)
  53     {
  54       perror ("errno gratuitously set -- TEST FAILED");
  55       return 1;
  56     }
  57
  58   puts ("Test succeeded.");
  59   return 0;
  60 }