test/test4.c

   1 /* test 4 */
   2
   3 #include <sys/types.h>
   4 #include <sys/wait.h>
   5 #include <fcntl.h>
   6 #include <signal.h>
   7 #include <stdlib.h>
   8 #include <unistd.h>
   9 #include <stdio.h>
  10 #include <string.h>
  11 #include <errno.h>
  12
  13 pid_t pid0, pid1, pid2, pid3;
  14 int s, i, fd, nextb;
  15 char *tempfile = "test4.temp";
  16 char buf[1024];
  17
  18 int max_error = 2;
  19 #include "common.h"
  20
  21
  22
  23 int main(void);
  24 void subr(void);
  25 void nofork(void);
  26 void quit(void);
  27
  28 int main()
  29 {
  30   int k;
  31
  32   start(4);
  33
  34   creat(tempfile, 0777);
  35   for (k = 0; k < 20; k++) {
  36         subr();
  37   }
  38   unlink(tempfile);
  39   quit();
  40   return(-1);                   /* impossible */
  41 }
  42
  43 void subr()
  44 {
  45   if ( (pid0 = fork()) != 0) {
  46         /* Parent 0 */
  47         if (pid0 < 0) nofork();
  48         if ( (pid1 = fork()) != 0) {
  49                 /* Parent 1 */
  50                 if (pid1 < 0) nofork();
  51                 if ( (pid2 = fork()) != 0) {
  52                         /* Parent 2 */
  53                         if (pid2 < 0) nofork();
  54                         if ( (pid3 = fork()) != 0) {
  55                                 /* Parent 3 */
  56                                 if (pid3 < 0) nofork();
  57                                 for (i = 0; i < 10000; i++);
  58                                 kill(pid2, SIGKILL);
  59                                 kill(pid1, SIGKILL);
  60                                 kill(pid0, SIGKILL);
  61                                 wait(&s);
  62                                 wait(&s);
  63                                 wait(&s);
  64                                 wait(&s);
  65                         } else {
  66                                 fd = open(tempfile, O_RDONLY);
  67                                 lseek(fd, 20480L * nextb, 0);
  68                                 for (i = 0; i < 10; i++) read(fd, buf, 1024);
  69                                 nextb++;
  70                                 close(fd);
  71                                 exit(0);
  72                         }
  73                 } else {
  74                         while (1) getpid();
  75                 }
  76         } else {
  77                 while (1) getpid();
  78         }
  79   } else {
  80         while (1) getpid();
  81   }
  82 }
  83
  84 void nofork()
  85 {
  86   int e = errno;
  87   printf("Fork failed: %s (%d)\n",strerror(e),e);
  88   exit(1);
  89 }
  90