#include <sys/types.h>
#include <sys/shm.h>
#include <strings.h>
#include <errno.h>
#include <stdio.h>

int
main (void)
{
  key_t mykey;
  int shmid;
  char *testch = NULL;

  mykey = IPC_PRIVATE;

  printf ("creating private key \n");
  shmid = shmget (mykey, 65536, 0777);
  if (shmid != -1)
    {
      printf ("shm id %x\n", shmid);
      printf ("attaching to private key\n");
      testch = (char *) shmat (shmid, NULL, 0);
      printf ("returned %x\n", testch);
      printf ("writing \'hello\'\n");
      snprintf (testch, 7, "hello\n");
      printf ("reading\n");
      printf ("value: %s\n", testch);
    }
  else
    printf ("error %d, %s\n", errno, strerror (errno));


  printf ("creating shmget.c:1\n");
  mykey = ftok ("shmget.c", 1);

  shmid = shmget (mykey, 65536, 0777 | IPC_CREAT);
  if (shmid != -1)
    {
      printf ("shm id %x\n", shmid);
      printf ("attaching to private key\n");
      testch = (char *) shmat (shmid, NULL, 0);
      printf ("returned %x\n", testch);
      printf ("current value %s\n", testch);
      printf ("waiting for enter\n");
      getc (stdin);
      printf ("writing \'hello\'\n");
      snprintf (testch, 7, "hello\n");
      printf ("reading\n");
      printf ("value: %s\n", testch);
      printf ("waiting for enter\n");
      getc (stdin);
    }
  else
    printf ("error %d, %s\n", errno, strerror (errno));

  printf ("creating shmget.c:1 (should be same keyid)\n");
  mykey = ftok ("shmget.c", 1);

  shmid = shmget (mykey, 65536, 0777 | IPC_CREAT);
  if (shmid != -1)
    printf ("shm id %x\n", shmid);
  else
    printf ("error %d, %s\n", errno, strerror (errno));

  printf ("creating exclusive shmget.c:2\n");
  mykey = ftok ("shmget.c", 2);

  printf ("%x %x %x %x\n", 0777, IPC_CREAT,  IPC_EXCL, 0777 | IPC_CREAT | IPC_EXCL);

  shmid = shmget (mykey, 65536, 0777 | IPC_CREAT | IPC_EXCL);
  if (shmid != -1)
    printf ("shm id %x\n", shmid);
  else
    printf ("error %d, %s\n", errno, strerror (errno));

  printf ("creating exclusive shmget.c:2 (should fail with EEXIST)\n");
  shmid = shmget (mykey, 65536, 0777 | IPC_CREAT | IPC_EXCL);
  if (shmid != -1 || errno != EEXIST)
    printf ("FAIL: shm id %x, errno %d\n", shmid, shmid == -1 ? 0 : errno);
  else
    printf ("PASS: error %d, %s\n", errno, strerror (errno));

  printf
    ("creating non-exclusive shmget.c:2 (should be the same as the prior id)\n");
  shmid = shmget (mykey, 65536, 0777 | IPC_CREAT);
  if (shmid != -1)
    printf ("shm id %x\n", shmid);
  else
    printf ("error %d, %s\n", errno, strerror (errno));

  return 0;
}