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