string/test-strerror-errno.c

   1 /* BZ #24024 strerror and errno test.
   2
   3    Copyright (C) 2019 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 <dlfcn.h>
  21 #include <errno.h>
  22 #include <string.h>
  23
  24 #include <support/check.h>
  25 #include <support/support.h>
  26
  27 /* malloc is allowed to change errno to a value different than 0, even when
  28    there is no actual error.  This happens for example when the memory
  29    allocation through sbrk fails.  Simulate this by interposing our own
  30    malloc implementation which sets errno to ENOMEM and calls the original
  31    malloc.  */
  32 void
  33 *malloc (size_t size)
  34 {
  35   static void *(*real_malloc) (size_t size);
  36
  37   if (!real_malloc)
  38     real_malloc = dlsym (RTLD_NEXT, "malloc");
  39
  40   errno = ENOMEM;
  41
  42   return (*real_malloc) (size);
  43 }
  44
  45 /* strerror must not change the value of errno.  Unfortunately due to GCC bug
  46    #88576, this happens when -fmath-errno is used.  This simple test checks
  47    that it doesn't happen.  */
  48 static int
  49 do_test (void)
  50 {
  51   char *msg;
  52
  53   errno = 0;
  54   msg = strerror (-3);
  55   (void) msg;
  56   TEST_COMPARE (errno, 0);
  57
  58   return 0;
  59 }
  60
  61 #include <support/test-driver.c>