memcheck/tests/freebsd/pdfork_pdkill.c

   1 // this example taken from
   2 // https://gist.github.com/sebcat/a61b2ed859cee16c560e
   3
   4 // FreeBSD has pdfork which uses file descriptors instead of PIDs for
   5 // managing processes. This allows for race-less process supervision and
   6 // for using the traditional multiplexing calls (e.g., select). There's no
   7 // need wait()ing for SIGCHLD, &c.
   8 //
   9 // This example forks a child that sleeps for a certain time while the
  10 // parent is waiting for the child to exit, or for a timeout to be reached,
  11 // whichever comes first. The time values (in seconds) are provided from argv
  12 //
  13 // % ./pdfork
  14 // usage: pdfork <child-sleep> <parent-wait>
  15 // % ./pdfork 2 10
  16 // child: exit
  17 // parent: child exited
  18 // % ./pdfork 10 2
  19 // parent: kill
  20
  21
  22 #include <sys/types.h>
  23 #include <sys/select.h>
  24 #include <sys/procdesc.h>
  25 #include <stdlib.h>
  26 #include <unistd.h>
  27 #include <stdio.h>
  28 #include <errno.h>
  29
  30 #define DURATION_MAX 100
  31
  32 static long time_or_die(const char *str, const char *name) {
  33     char *cptr;
  34     long res;
  35
  36     res = strtol(str, &cptr, 10);
  37     if (errno == ERANGE || *cptr != '\0') {
  38          fprintf(stderr, "invalid %s parameter\n", name);
  39          exit(EXIT_FAILURE);
  40     } else if (res < 0 || res > DURATION_MAX) {
  41          fprintf(stderr, "%s out of permitted range\n", name);
  42          exit(EXIT_FAILURE);
  43     }
  44
  45     return res;
  46 }
  47
  48 int main(int argc, char *argv[]) {
  49     struct timeval to={0,0};
  50     long child_sleep, parent_wait;
  51     int fd, ret;
  52     fd_set fds;
  53
  54     if (argc != 3) {
  55        fprintf(stderr, "usage: pdfork <child-sleep> <parent-wait>\n");
  56        return EXIT_FAILURE;
  57     }
  58
  59     child_sleep = time_or_die(argv[1], "child-sleep");
  60     parent_wait = time_or_die(argv[2], "parent-wait");
  61     if ((ret = pdfork(&fd, 0)) == -1) {
  62         perror("pdfork");
  63         return EXIT_FAILURE;
  64     } else if (ret == 0) {
  65         sleep((unsigned int)child_sleep);
  66         fprintf(stderr, "child: exit\n");
  67         exit(0);
  68     } else {
  69         FD_ZERO(&fds);
  70         FD_SET(fd, &fds);
  71         to.tv_sec = parent_wait;
  72         if ((ret = select(fd+1, &fds, NULL, NULL, &to)) == -1) {
  73             perror("select");
  74             return EXIT_FAILURE;
  75         } else if (ret == 0) {
  76              fprintf(stderr, "parent: kill fd %d\n", fd);
  77              pid_t pid;
  78              pdgetpid(fd, &pid);
  79              pdkill(fd, 9);
  80         } else {
  81             fprintf(stderr, "parent: child exited\n");
  82         }
  83     }
  84
  85     // and generate a couple of errors for valgrind
  86     int *badfd = malloc(sizeof(int));
  87     free(badfd);
  88     if (pdfork(badfd, 0) > 0)
  89     {
  90        fprintf(stderr, "parent after 1st bad pdfork\n");
  91        int anotherfd;
  92        int badflag;
  93        pid_t* pbadpid = malloc(sizeof(pid_t));
  94        free(pbadpid);
  95        pdgetpid(anotherfd, pbadpid);
  96        pdfork(&anotherfd, badflag);
  97     }
  98
  99     return EXIT_SUCCESS;
 100 }
 101