sysdeps/pthread/tst-sem4.c

   1 /* Copyright (C) 2002-2024 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, see
  16    <https://www.gnu.org/licenses/>.  */
  17
  18 #include <errno.h>
  19 #include <fcntl.h>
  20 #include <semaphore.h>
  21 #include <stdio.h>
  22 #include <stdlib.h>
  23 #include <unistd.h>
  24
  25
  26 static void
  27 remove_sem (int status, void *arg)
  28 {
  29   sem_unlink (arg);
  30 }
  31
  32
  33 int
  34 do_test (void)
  35 {
  36   sem_t *s;
  37   sem_t *s2;
  38   pid_t pid;
  39   int val;
  40
  41   /* Start with a clean slate and register a clean-up action.  No need to
  42      act if sem_unlink fails because we will catch the same problem during the
  43      sem_open below.  */
  44   sem_unlink ("/glibc-tst-sem4");
  45   on_exit (remove_sem, (void *) "/glibc-tst-sem4");
  46
  47   s = sem_open ("/glibc-tst-sem4", O_CREAT, 0600, 1);
  48   if (s == SEM_FAILED)
  49     {
  50       if (errno == ENOSYS)
  51         {
  52           puts ("sem_open not supported.  Oh well.");
  53           return 0;
  54         }
  55
  56       /* Maybe the shm filesystem has strict permissions.  */
  57       if (errno == EACCES)
  58         {
  59           puts ("sem_open not allowed.  Oh well.");
  60           return 0;
  61         }
  62
  63       printf ("sem_open: %m\n");
  64       return 1;
  65     }
  66
  67   /* We have the semaphore object.  Now try again with O_EXCL, this
  68      should fail.  */
  69   s2 = sem_open ("/glibc-tst-sem4", O_CREAT | O_EXCL, 0600, 1);
  70   if (s2 != SEM_FAILED)
  71     {
  72       puts ("2nd sem_open didn't fail");
  73       return 1;
  74     }
  75   if (errno != EEXIST)
  76     {
  77       puts ("2nd sem_open returned wrong error");
  78       return 1;
  79     }
  80
  81   /* Check the value.  */
  82   if (sem_getvalue (s, &val) == -1)
  83     {
  84       puts ("getvalue failed");
  85       return 1;
  86     }
  87   if (val != 1)
  88     {
  89       printf ("initial value wrong: got %d, expected 1\n", val);
  90       return 1;
  91     }
  92
  93   if (TEMP_FAILURE_RETRY (sem_wait (s)) == -1)
  94     {
  95       puts ("1st sem_wait failed");
  96       return 1;
  97     }
  98
  99   pid = fork ();
 100   if (pid == -1)
 101     {
 102       printf ("fork failed: %m\n");
 103       return 1;
 104     }
 105
 106   if (pid == 0)
 107     {
 108       /* Child.  */
 109
 110       /* Check the value.  */
 111       if (sem_getvalue (s, &val) == -1)
 112         {
 113           puts ("child: getvalue failed");
 114           return 1;
 115         }
 116       if (val != 0)
 117         {
 118           printf ("child: value wrong: got %d, expect 0\n", val);
 119           return 1;
 120         }
 121
 122       if (sem_post (s) == -1)
 123         {
 124           puts ("child: post failed");
 125           return 1;
 126         }
 127     }
 128   else
 129     {
 130       if (TEMP_FAILURE_RETRY (sem_wait (s)) == -1)
 131         {
 132           puts ("2nd sem_wait failed");
 133           return 1;
 134         }
 135
 136       if (sem_getvalue (s, &val) == -1)
 137         {
 138           puts ("parent: 2nd getvalue failed");
 139           return 1;
 140         }
 141       if (val != 0)
 142         {
 143           printf ("parent: value wrong: got %d, expected 0\n", val);
 144           return 1;
 145         }
 146     }
 147
 148   return 0;
 149 }
 150
 151 #define TEST_FUNCTION do_test ()
 152 #include "../test-skeleton.c"