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glibc  2.9
Defines | Functions
tst-shm.c File Reference
#include <errno.h>
#include <error.h>
#include <fcntl.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <unistd.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include "../test-skeleton.c"

Go to the source code of this file.

Defines

#define STDOUT_UNBUFFERED
#define TEST_FUNCTION   do_test ()
#define CLEANUP_HANDLER   shm_unlink ("/shm-test");

Functions

static int do_open (void)
static void worker (int write_now)
static int do_test (void)

Define Documentation

#define CLEANUP_HANDLER   shm_unlink ("/shm-test");

Definition at line 211 of file tst-shm.c.

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

#define TEST_FUNCTION   do_test ()

Definition at line 209 of file tst-shm.c.


Function Documentation

static int do_open ( void  ) [static]

Definition at line 40 of file tst-shm.c.

{
  int fd;

  /* Create the shared memory object.  */
  fd = shm_open ("/shm-test", O_RDWR, 0600);
  if (fd == -1)
    {
      /* We don't regard this as a bug.  Simply don't run the test.  It could
        means there is no such implementation or the object is already in
        use in which case we don't want to disturb.  */
      perror ("failed to open shared memory object: shm_open");
      return -1;
    }

  return fd;
}

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static int do_test ( void  ) [static]

Definition at line 129 of file tst-shm.c.

{
  int fd;
  pid_t pid1;
  pid_t pid2;
  int status1;
  int status2;
  struct stat64 st;

  /* Create the shared memory object.  */
  fd = shm_open ("/shm-test", O_RDWR | O_CREAT | O_TRUNC | O_EXCL, 0600);
  if (fd == -1)
    {
      /* We don't regard this as a bug.  Simply don't run the test.  It could
        means there is no such implementation or the object is already in
        use in which case we don't want to disturb.  */
      perror ("failed to create a shared memory object: shm_open");
      return 0;
    }

  /* Size the object.  We make it 4000 bytes long.  */
  if (ftruncate (fd, 4000) == -1)
    {
      /* This failed.  Must be a bug in the implementation of the
         shared memory itself.  */
      perror ("failed to size of shared memory object: ftruncate");
      close (fd);
      shm_unlink ("/shm-test");
      return 0;
    }

  if (fstat64 (fd, &st) == -1)
    {
      shm_unlink ("/shm-test");
      error (EXIT_FAILURE, 0, "initial stat failed");
    }
  if (st.st_size != 4000)
    {
      shm_unlink ("/shm-test");
      error (EXIT_FAILURE, 0, "initial size not correct");
    }

  /* Spawn to processes which will do the work.  */
  pid1 = fork ();
  if (pid1 == 0)
    worker (0);
  else if (pid1 == -1)
    {
      /* Couldn't create a second process.  */
      perror ("fork");
      close (fd);
      shm_unlink ("/shm-test");
      return 0;
    }

  pid2 = fork ();
  if (pid2 == 0)
    worker (1);
  else if (pid2 == -1)
    {
      /* Couldn't create a second process.  */
      int ignore;
      perror ("fork");
      kill (pid1, SIGTERM);
      waitpid (pid1, &ignore, 0);
      close (fd);
      shm_unlink ("/shm-test");
      return 0;
    }

  /* Wait until the two processes are finished.  */
  waitpid (pid1, &status1, 0);
  waitpid (pid2, &status2, 0);

  /* Now we can unlink the shared object.  */
  shm_unlink ("/shm-test");

  return (!WIFEXITED (status1) || WEXITSTATUS (status1) != 0
         || !WIFEXITED (status2) || WEXITSTATUS (status2) != 0);
}

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static void worker ( int  write_now) [static]

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

{
  struct timespec ts;
  struct stat64 st;
  int i;
  int fd = do_open ();
  char *mem;

  if (fd == -1)
    exit (fd);

  if (fstat64 (fd, &st) == -1)
    error (EXIT_FAILURE, 0, "stat failed");
  if (st.st_size != 4000)
    error (EXIT_FAILURE, 0, "size incorrect");

  mem = mmap (NULL, 4000, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
  if (mem == NULL)
    error (EXIT_FAILURE, 0, "mmap failed");

  ts.tv_sec = 0;
  ts.tv_nsec = 500000000;

  if (write_now)
    for (i = 0; i <= 4; ++i)
      mem[i] = i;
  else
    /* Wait until the first bytes of the memory region are 0, 1, 2, 3, 4.  */
    while (1)
      {
       for (i = 0; i <= 4; ++i)
         if (mem[i] != i)
           break;

       if (i > 4)
         /* OK, that's done.  */
         break;

       nanosleep (&ts, NULL);
      }

  if (!write_now)
    for (i = 0; i <= 4; ++i)
      mem[i] = 4 + i;
  else
    /* Wait until the first bytes of the memory region are 4, 5, 6, 7, 8.  */
    while (1)
      {
       for (i = 0; i <= 4; ++i)
         if (mem[i] != 4 + i)
           break;

       if (i > 4)
         /* OK, that's done.  */
         break;

       nanosleep (&ts, NULL);
      }

  if (munmap (mem, 4000) == -1)
    error (EXIT_FAILURE, errno, "munmap");

  close (fd);

  exit (0);
}

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