nptl/tst-sem4.c

   1 /* Copyright (C) 2002-2014 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <http://www.gnu.org/licenses/>.  */
  18
  19 #include <errno.h>
  20 #include <fcntl.h>
  21 #include <semaphore.h>
  22 #include <stdio.h>
  23 #include <stdlib.h>
  24 #include <unistd.h>
  25
  26
  27 static void
  28 remove_sem (int status, void *arg)
  29 {
  30   sem_unlink (arg);
  31 }
  32
  33
  34 int
  35 main (void)
  36 {
  37   sem_t *s;
  38   sem_t *s2;
  39   pid_t pid;
  40   int val;
  41
  42   s = sem_open ("/glibc-tst-sem4", O_CREAT, 0600, 1);
  43   if (s == SEM_FAILED)
  44     {
  45       if (errno == ENOSYS)
  46         {
  47           puts ("sem_open not supported.  Oh well.");
  48           return 0;
  49         }
  50
  51       /* Maybe the shm filesystem has strict permissions.  */
  52       if (errno == EACCES)
  53         {
  54           puts ("sem_open not allowed.  Oh well.");
  55           return 0;
  56         }
  57
  58       printf ("sem_open: %m\n");
  59       return 1;
  60     }
  61
  62   on_exit (remove_sem, (void *) "/glibc-tst-sem4");
  63
  64   /* We have the semaphore object.  Now try again with O_EXCL, this
  65      should fail.  */
  66   s2 = sem_open ("/glibc-tst-sem4", O_CREAT | O_EXCL, 0600, 1);
  67   if (s2 != SEM_FAILED)
  68     {
  69       puts ("2nd sem_open didn't fail");
  70       return 1;
  71     }
  72   if (errno != EEXIST)
  73     {
  74       puts ("2nd sem_open returned wrong error");
  75       return 1;
  76     }
  77
  78   /* Check the value.  */
  79   if (sem_getvalue (s, &val) == -1)
  80     {
  81       puts ("getvalue failed");
  82       return 1;
  83     }
  84   if (val != 1)
  85     {
  86       printf ("initial value wrong: got %d, expected 1\n", val);
  87       return 1;
  88     }
  89
  90   if (TEMP_FAILURE_RETRY (sem_wait (s)) == -1)
  91     {
  92       puts ("1st sem_wait failed");
  93       return 1;
  94     }
  95
  96   pid = fork ();
  97   if (pid == -1)
  98     {
  99       printf ("fork failed: %m\n");
 100       return 1;
 101     }
 102
 103   if (pid == 0)
 104     {
 105       /* Child.  */
 106
 107       /* Check the value.  */
 108       if (sem_getvalue (s, &val) == -1)
 109         {
 110           puts ("child: getvalue failed");
 111           return 1;
 112         }
 113       if (val != 0)
 114         {
 115           printf ("child: value wrong: got %d, expect 0\n", val);
 116           return 1;
 117         }
 118
 119       if (sem_post (s) == -1)
 120         {
 121           puts ("child: post failed");
 122           return 1;
 123         }
 124     }
 125   else
 126     {
 127       if (TEMP_FAILURE_RETRY (sem_wait (s)) == -1)
 128         {
 129           puts ("2nd sem_wait failed");
 130           return 1;
 131         }
 132
 133       if (sem_getvalue (s, &val) == -1)
 134         {
 135           puts ("parent: 2nd getvalue failed");
 136           return 1;
 137         }
 138       if (val != 0)
 139         {
 140           printf ("parent: value wrong: got %d, expected 0\n", val);
 141           return 1;
 142         }
 143     }
 144
 145   return 0;
 146 }