Back to index

glibc  2.9
Defines | Functions | Variables
tst-flock2.c File Reference
#include <errno.h>
#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/file.h>
#include <sys/mman.h>
#include <sys/wait.h>
#include "../test-skeleton.c"

Go to the source code of this file.

Defines

#define TEST_FUNCTION   do_test ()

Functions

static void * tf (void *arg)
static int do_test (void)

Variables

static pthread_mutex_t lock = PTHREAD_MUTEX_INITIALIZER
static pthread_mutex_t lock2 = PTHREAD_MUTEX_INITIALIZER
static int fd

Define Documentation

#define TEST_FUNCTION   do_test ()

Definition at line 259 of file tst-flock2.c.


Function Documentation

static int do_test ( void  ) [static]

Definition at line 60 of file tst-flock2.c.

{
  char tmp[] = "/tmp/tst-flock2-XXXXXX";

  fd = mkstemp (tmp);
  if (fd == -1)
    {
      puts ("mkstemp failed");
      return 1;
    }

  unlink (tmp);

  int i;
  for (i = 0; i < 20; ++i)
    write (fd, "foobar xyzzy", 12);

  pthread_barrier_t *b;
  b = mmap (NULL, sizeof (pthread_barrier_t), PROT_READ | PROT_WRITE,
           MAP_SHARED, fd, 0);
  if (b == MAP_FAILED)
    {
      puts ("mmap failed");
      return 1;
    }

  pthread_barrierattr_t ba;
  if (pthread_barrierattr_init (&ba) != 0)
    {
      puts ("barrierattr_init failed");
      return 1;
    }

  if (pthread_barrierattr_setpshared (&ba, PTHREAD_PROCESS_SHARED) != 0)
    {
      puts ("barrierattr_setpshared failed");
      return 1;
    }

  if (pthread_barrier_init (b, &ba, 2) != 0)
    {
      puts ("barrier_init failed");
      return 1;
    }

  if (pthread_barrierattr_destroy (&ba) != 0)
    {
      puts ("barrierattr_destroy failed");
      return 1;
    }

  struct flock fl =
    {
      .l_type = F_WRLCK,
      .l_start = 0,
      .l_whence = SEEK_SET,
      .l_len = 10
    };
  if (TEMP_FAILURE_RETRY (fcntl (fd, F_SETLKW, &fl)) != 0)
    {
      puts ("first fcntl failed");
      return 1;
    }

  pid_t pid = fork ();
  if (pid == -1)
    {
      puts ("fork failed");
      return 1;
    }

  if (pid == 0)
    {
      /* Make sure the child does not stay around indefinitely.  */
      alarm (10);

      /* Try to get the lock.  */
      if (TEMP_FAILURE_RETRY (fcntl (fd, F_SETLK, &fl)) == 0)
       {
         puts ("child:  second flock succeeded");
         return 1;
       }
    }

  pthread_barrier_wait (b);

  if (pid != 0)
    {
      fl.l_type = F_UNLCK;
      if (TEMP_FAILURE_RETRY (fcntl (fd, F_SETLKW, &fl)) != 0)
       {
         puts ("third fcntl failed");
         return 1;
       }
    }

  pthread_barrier_wait (b);

  pthread_t th;
  if (pid == 0)
    {
      if (pthread_mutex_lock (&lock) != 0)
       {
         puts ("1st locking of lock failed");
         return 1;
       }

      if (pthread_mutex_lock (&lock2) != 0)
       {
         puts ("1st locking of lock2 failed");
         return 1;
       }

      if (pthread_create (&th, NULL, tf, NULL) != 0)
       {
         puts ("pthread_create failed");
         return 1;
       }

      if (pthread_mutex_lock (&lock) != 0)
       {
         puts ("2nd locking of lock failed");
         return 1;
       }

      puts ("child locked file");
    }

  pthread_barrier_wait (b);

  if (pid != 0)
    {
      fl.l_type = F_WRLCK;
      if (TEMP_FAILURE_RETRY (fcntl (fd, F_SETLK, &fl)) == 0)
       {
         puts ("fifth fcntl succeeded");
         return 1;
       }

      puts ("file locked by child");
    }

  pthread_barrier_wait (b);

  if (pid == 0)
    {
      if (pthread_mutex_unlock (&lock2) != 0)
       {
         puts ("unlock of lock2 failed");
         return 1;
       }

      if (pthread_join (th, NULL) != 0)
       {
         puts ("join failed");
         return 1;
       }

      puts ("child's thread terminated");
    }

  pthread_barrier_wait (b);

  if (pid != 0)
    {
      fl.l_type = F_WRLCK;
      if (TEMP_FAILURE_RETRY (fcntl (fd, F_SETLK, &fl)) == 0)
       {
         puts ("fifth fcntl succeeded");
         return 1;
       }

      puts ("file still locked");
    }

  pthread_barrier_wait (b);

  if (pid == 0)
    {
      _exit (0);
    }

  int status;
  if (TEMP_FAILURE_RETRY (waitpid (pid, &status, 0)) != pid)
    {
      puts ("waitpid failed");
      return 1;
    }
  puts ("child terminated");

  if (TEMP_FAILURE_RETRY (fcntl (fd, F_SETLKW, &fl)) != 0)
    {
      puts ("sixth fcntl failed");
      return 1;
    }

  return status;
}

Here is the call graph for this function:

static void* tf ( void *  arg) [static]

Definition at line 36 of file tst-flock2.c.

{
  struct flock fl =
    {
      .l_type = F_WRLCK,
      .l_start = 0,
      .l_whence = SEEK_SET,
      .l_len = 10
    };
  if (TEMP_FAILURE_RETRY (fcntl (fd, F_SETLKW, &fl)) != 0)
    {
      puts ("fourth fcntl failed");
      exit (1);
    }

  pthread_mutex_unlock (&lock);

  pthread_mutex_lock (&lock2);

  return NULL;
}

Here is the call graph for this function:


Variable Documentation

int fd [static]

Definition at line 32 of file tst-flock2.c.

Definition at line 30 of file tst-flock2.c.

Definition at line 31 of file tst-flock2.c.