source: trunk/minix/test/test4.c@ 21

/* test 4 */

#include <sys/types.h>
#include <sys/wait.h>
#include <fcntl.h>
#include <signal.h>
#include <stdlib.h>
#include <unistd.h>
#include <stdio.h>
#include <string.h>

pid_t pid0, pid1, pid2, pid3;
int s, i, fd, nextb, errct = 0;
char *tempfile = "test4.temp";
char buf[1024];
extern int errno;

_PROTOTYPE(int main, (void));
_PROTOTYPE(void subr, (void));
_PROTOTYPE(void nofork, (void));
_PROTOTYPE(void quit, (void));

int main()
{
  int k;

  printf("Test  4 ");
  fflush(stdout);               /* have to flush for child's benefit */

  system("rm -rf DIR_04; mkdir DIR_04");
  chdir("DIR_04");

  creat(tempfile, 0777);
  for (k = 0; k < 20; k++) {
        subr();
  }
  unlink(tempfile);
  quit();
  return(-1);                   /* impossible */
}

void subr()
{
  if ( (pid0 = fork()) != 0) {
        /* Parent 0 */
        if (pid0 < 0) nofork();
        if ( (pid1 = fork()) != 0) {
                /* Parent 1 */
                if (pid1 < 0) nofork();
                if ( (pid2 = fork()) != 0) {
                        /* Parent 2 */
                        if (pid2 < 0) nofork();
                        if ( (pid3 = fork()) != 0) {
                                /* Parent 3 */
                                if (pid3 < 0) nofork();
                                for (i = 0; i < 10000; i++);
                                kill(pid2, 9);
                                kill(pid1, 9);
                                kill(pid0, 9);
                                wait(&s);
                                wait(&s);
                                wait(&s);
                                wait(&s);
                        } else {
                                fd = open(tempfile, O_RDONLY);
                                lseek(fd, 20480L * nextb, 0);
                                for (i = 0; i < 10; i++) read(fd, buf, 1024);
                                nextb++;
                                close(fd);
                                exit(0);
                        }
                } else {
                        while (1) getpid();
                }
        } else {
                while (1) getpid();
        }
  } else {
        while (1) getpid();
  }
}

void nofork()
{
  int e = errno;
  printf("Fork failed: %s (%d)\n",strerror(e),e);
  exit(1);
}

void quit()
{

  chdir("..");
  system("rm -rf DIR*");

  if (errct == 0) {
        printf("ok\n");
        exit(0);
  } else {
        printf("%d errors\n", errct);
        exit(1);
  }
}