stdio-common/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) 1995-2017 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 Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the 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    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, see
  18    <http://www.gnu.org/licenses/>.  */
  19
  20 #include <errno.h>
  21 #include <stdio.h>
  22 #include <unistd.h>
  23
  24 int
  25 main (void)
  26 {
  27   int fd[2];
  28   FILE *f;
  29
  30   /* Get a stream that cannot seek.  */
  31
  32   if (pipe (fd))
  33     {
  34       perror ("pipe");
  35       return 1;
  36     }
  37   f = fdopen (fd[1], "w");
  38   if (f == NULL)
  39     {
  40       perror ("fdopen");
  41       return 1;
  42     }
  43
  44   errno = 0;
  45   if (fputs ("fnord", f) == EOF)
  46     {
  47       perror ("fputs");
  48       return 1;
  49     }
  50
  51   if (errno)
  52     {
  53       perror ("errno gratuitously set -- TEST FAILED");
  54       return 1;
  55     }
  56
  57   puts ("Test succeeded.");
  58   return 0;
  59 }