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glibc  2.9
Functions
tst-sem4.c File Reference
#include <errno.h>
#include <fcntl.h>
#include <semaphore.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

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Functions

static void remove_sem (int status, void *arg)
int main (void)

Function Documentation

int main ( void  )

Definition at line 36 of file tst-sem4.c.

{
  sem_t *s;
  sem_t *s2;
  pid_t pid;
  int val;

  s = sem_open ("/glibc-tst-sem4", O_CREAT, 0600, 1);
  if (s == SEM_FAILED)
    {
      if (errno == ENOSYS)
       {
         puts ("sem_open not supported.  Oh well.");
         return 0;
       }

      /* Maybe the shm filesystem has strict permissions.  */
      if (errno == EACCES)
       {
         puts ("sem_open not allowed.  Oh well.");
         return 0;
       }

      printf ("sem_open: %m\n");
      return 1;
    }

  on_exit (remove_sem, (void *) "/glibc-tst-sem4");

  /* We have the semaphore object.  Now try again with O_EXCL, this
     should fail.  */
  s2 = sem_open ("/glibc-tst-sem4", O_CREAT | O_EXCL, 0600, 1);
  if (s2 != SEM_FAILED)
    {
      puts ("2nd sem_open didn't fail");
      return 1;
    }
  if (errno != EEXIST)
    {
      puts ("2nd sem_open returned wrong error");
      return 1;
    }

  /* Check the value.  */
  if (sem_getvalue (s, &val) == -1)
    {
      puts ("getvalue failed");
      return 1;
    }
  if (val != 1)
    {
      printf ("initial value wrong: got %d, expected 1\n", val);
      return 1;
    }

  if (TEMP_FAILURE_RETRY (sem_wait (s)) == -1)
    {
      puts ("1st sem_wait failed");
      return 1;
    }

  pid = fork ();
  if (pid == -1)
    {
      printf ("fork failed: %m\n");
      return 1;
    }

  if (pid == 0)
    {
      /* Child.  */

      /* Check the value.  */
      if (sem_getvalue (s, &val) == -1)
       {
         puts ("child: getvalue failed");
         return 1;
       }
      if (val != 0)
       {
         printf ("child: value wrong: got %d, expect 0\n", val);
         return 1;
       }

      if (sem_post (s) == -1)
       {
         puts ("child: post failed");
         return 1;
       }
    }
  else
    {
      if (TEMP_FAILURE_RETRY (sem_wait (s)) == -1)
       {
         puts ("2nd sem_wait failed");
         return 1;
       }

      if (sem_getvalue (s, &val) == -1)
       {
         puts ("parent: 2nd getvalue failed");
         return 1;
       }
      if (val != 0)
       {
         printf ("parent: value wrong: got %d, expected 0\n", val);
         return 1;
       }
    }

  return 0;
}

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static void remove_sem ( int  status,
void *  arg 
) [static]

Definition at line 29 of file tst-sem4.c.

{
  sem_unlink (arg);
}

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