launchd/testing/missed-EVFILT_WRITE.c

   1 /*
   2  * <rdar://problem/4038866> Lots of hangs in GetLaunchDaemonService state
   3  */
   4
   5 #include <sys/types.h>
   6 #include <sys/time.h>
   7 #include <sys/event.h>
   8 #include <sys/socket.h>
   9 #include <stdio.h>
  10 #include <stdlib.h>
  11 #include <unistd.h>
  12 #include <fcntl.h>
  13 #include <string.h>
  14 #include <errno.h>
  15
  16 static void do_parent(int thefd);
  17 static void do_child(int thefd);
  18
  19 int main(void)
  20 {
  21         int sp[2];
  22
  23         if (-1 == socketpair(AF_UNIX, SOCK_STREAM, 0, sp)) {
  24                 fprintf(stderr, "socketpair(): %s\n", strerror(errno));
  25                 exit(EXIT_FAILURE);
  26         }
  27
  28         switch (fork()) {
  29         case -1:
  30                 fprintf(stderr, "fork(): %s\n", strerror(errno));
  31                 exit(EXIT_FAILURE);
  32         case 0:
  33                 close(sp[0]);
  34                 do_child(sp[1]);
  35                 break;
  36         default:
  37                 close(sp[1]);
  38                 do_parent(sp[0]);
  39                 break;
  40         }
  41
  42         exit(EXIT_SUCCESS);
  43 }
  44
  45 static void do_child(int thefd)
  46 {
  47         char buf[500000];
  48         fd_set rfds;
  49         int r, readhunks = 2;
  50
  51         if (-1 == fcntl(thefd, F_SETFL, O_NONBLOCK)) {
  52                 fprintf(stderr, "fcntl(): %s\n", strerror(errno));
  53                 exit(EXIT_FAILURE);
  54         }
  55
  56         for (;;) {
  57                 if (2 == readhunks) {
  58                         if (-1 == write(thefd, buf, 1)) {
  59                                 fprintf(stderr, "%d: write(): %s\n", __LINE__, strerror(errno));
  60                                 exit(EXIT_FAILURE);
  61                         }
  62                         readhunks = 0;
  63                 }
  64                 r = read(thefd, buf, sizeof(buf));
  65
  66                 if (-1 == r && errno != EAGAIN) {
  67                         fprintf(stderr, "%d: read(): %s\n", __LINE__, strerror(errno));
  68                         exit(EXIT_FAILURE);
  69                 }
  70
  71                 if (r > 0)
  72                         readhunks++;
  73
  74                 if (readhunks == 2)
  75                         continue;
  76
  77                 FD_ZERO(&rfds);
  78                 FD_SET(thefd, &rfds);
  79
  80                 select(thefd + 1, &rfds, NULL, NULL, NULL);
  81         }
  82 }
  83
  84 static void do_parent(int thefd)
  85 {
  86         struct timespec timeout = { 1, 0 };
  87         char buf[500000];
  88         struct kevent kev;
  89         int iter = 0, kq = kqueue();
  90
  91         if (-1 == (kq = kqueue())) {
  92                 fprintf(stderr, "kqueue(): %s\n", strerror(errno));
  93                 exit(EXIT_FAILURE);
  94         }
  95
  96         if (-1 == fcntl(thefd, F_SETFL, O_NONBLOCK)) {
  97                 fprintf(stderr, "fcntl(): %s\n", strerror(errno));
  98                 exit(EXIT_FAILURE);
  99         }
 100
 101         EV_SET(&kev, thefd, EVFILT_READ, EV_ADD, 0, 0, NULL);
 102
 103         if (-1 == kevent(kq, &kev, 1, NULL, 0, NULL)) {
 104                 fprintf(stderr, "%d: kevent(): %s\n", __LINE__, strerror(errno));
 105                 exit(EXIT_FAILURE);
 106         }
 107
 108         for (;;) {
 109                 switch (kevent(kq, NULL, 0, &kev, 1, &timeout)) {
 110                 case -1:
 111                         fprintf(stderr, "%d: kevent(): %s\n", __LINE__, strerror(errno));
 112                         exit(EXIT_FAILURE);
 113                 case 0:
 114                         fprintf(stderr, "After %d iterations, 4038866 still exists!\n", iter);
 115                         exit(EXIT_FAILURE);
 116                 case 1:
 117                         break;
 118                 default:
 119                         fprintf(stderr, "kevent should only return -1, 0 or 1 for this case!\n");
 120                         exit(EXIT_FAILURE);
 121                 }
 122
 123                 switch (kev.filter) {
 124                 case EVFILT_READ:
 125                         if (-1 == read(thefd, buf, sizeof(buf))) {
 126                                 fprintf(stderr, "read(): %s\n", strerror(errno));
 127                                 exit(EXIT_FAILURE);
 128                         }
 129                         if (-1 == write(thefd, buf, sizeof(buf))) {
 130                                 fprintf(stderr, "%d: write(): %s\n", __LINE__, strerror(errno));
 131                                 exit(EXIT_FAILURE);
 132                         }
 133                         EV_SET(&kev, thefd, EVFILT_WRITE, EV_ADD, 0, 0, NULL);
 134                         if (-1 == kevent(kq, &kev, 1, NULL, 0, NULL)) {
 135                                 fprintf(stderr, "%d: kevent(): %s\n", __LINE__, strerror(errno));
 136                                 exit(EXIT_FAILURE);
 137                         }
 138                         break;
 139                 case EVFILT_WRITE:
 140                         if (-1 == write(thefd, buf, 1)) {
 141                                 fprintf(stderr, "%d: write(): %s\n", __LINE__, strerror(errno));
 142                                 exit(EXIT_FAILURE);
 143                         }
 144                         EV_SET(&kev, thefd, EVFILT_WRITE, EV_DELETE, 0, 0, NULL);
 145                         if (-1 == kevent(kq, &kev, 1, NULL, 0, NULL)) {
 146                                 fprintf(stderr, "%d: kevent(): %s\n", __LINE__, strerror(errno));
 147                                 exit(EXIT_FAILURE);
 148                         }
 149                         break;
 150                 default:
 151                         fprintf(stderr, "kevent filter isn't EVFILT_READ or EVFILT_WRITE!\n");
 152                         exit(EXIT_FAILURE);
 153                 }
 154                 iter++;
 155         }
 156 }