#include <stdio.h>
#include <errno.h>
#include <stdlib.h>
#include <unistd.h>
#include <signal.h>
#include <strings.h>
#include <sys/wait.h>
#include <sys/time.h>
#include <sys/socket.h>

extern const char *__progname;

static pid_t kid_busy_a;
static pid_t kid_busy_b;
static pid_t kid_test_a;
static pid_t kid_test_b;
static int timing_fd;

static void busy_a(int fd)
{
 struct cmsghdr *cmh;
 struct msghdr mh;
 struct iovec iov;
 char *buf;
 char data;
 unsigned char reply[64];
 int n;
 int pending;
 int waiting;
 int reps;

 buf = malloc(CMSG_SPACE(sizeof(int)));
 waiting = 0;
 pending = 0;
 reps = 0;
 while (1)
  { if (! waiting)
     { cmh = (void *)buf;
       cmh->cmsg_len = CMSG_LEN(sizeof(int));
       cmh->cmsg_level = SOL_SOCKET;
       cmh->cmsg_type = SCM_RIGHTS;
       *(int *)CMSG_DATA(cmh) = 1;
       data = 'x';
       iov.iov_base = &data;
       iov.iov_len = 1;
       mh.msg_name = 0;
       mh.msg_namelen = 0;
       mh.msg_iov = &iov;
       mh.msg_iovlen = 1;
       mh.msg_control = buf;
       mh.msg_controllen = CMSG_SPACE(sizeof(int));
       mh.msg_flags = 0;
       if (sendmsg(fd,&mh,0) < 0)
	{ if (errno == ENOBUFS)
	   { waiting = 1;
	     continue;
	   }
	  fprintf(stderr,"%s: busy a sendmsg: %s\n",__progname,strerror(errno));
	  exit(1);
	}
#ifdef SLOWDOWN
	{ struct timespec ts;
	  ts.tv_sec = 0;
	  ts.tv_nsec = 100000000;
	  nanosleep(&ts,0);
	}
#endif
       pending ++;
       reps ++;
       if (reps >= ((1U<<20)-1))
	{ write(1,".",1);
	  reps = 0;
	}
       continue;
     }
    n = recv(fd,&reply[0],sizeof(reply),0);
    if (n < 0)
     { fprintf(stderr,"%s: busy a recv: %s\n",__progname,strerror(errno));
       exit(1);
     }
    pending -= n;
    waiting = 0;
  }
}

static void busy_b(int fd)
{
 int p;
 struct cmsghdr *cmh;
 struct msghdr mh;
 struct iovec iov;
 char *buf;
 unsigned char body[64];
 int n;

 buf = malloc(CMSG_SPACE(sizeof(int)));
 while (1)
  { iov.iov_base = &body[0];
    iov.iov_len = sizeof(body);
    mh.msg_name = 0;
    mh.msg_namelen = 0;
    mh.msg_iov = &iov;
    mh.msg_iovlen = 1;
    mh.msg_control = buf;
    mh.msg_controllen = CMSG_SPACE(sizeof(int));
    mh.msg_flags = 0;
    n = recvmsg(fd,&mh,0);
    if (n < 0)
     { fprintf(stderr,"%s: busy b recvmsg: %s\n",__progname,strerror(errno));
       exit(1);
     }
    if (n != 1)
     { fprintf(stderr,"%s: busy b recvmsg got %d not %d\n",__progname,n,1);
       exit(1);
     }
    if (body[0] != 'x')
     { fprintf(stderr,"%s: busy b recvmsg body %02x not %02x\n",__progname,body[0],'x');
       exit(1);
     }
    if (mh.msg_controllen < CMSG_LEN(sizeof(int)))
     { fprintf(stderr,"%s: busy b control len %d < %d\n",__progname,(int)mh.msg_controllen,(int)CMSG_LEN(sizeof(int)));
       exit(1);
     }
    cmh = (void *)buf;
    if (cmh->cmsg_level != SOL_SOCKET)
     { fprintf(stderr,"%s: busy b cmsg level %d not %d\n",__progname,(int)cmh->cmsg_level,(int)SOL_SOCKET);
       exit(1);
     }
    if (cmh->cmsg_type != SCM_RIGHTS)
     { fprintf(stderr,"%s: busy b cmsg type %d not %d\n",__progname,(int)cmh->cmsg_type,(int)SCM_RIGHTS);
       exit(1);
     }
    bcopy(CMSG_DATA(cmh),&p,sizeof(int));
    if (close(p) < 0)
     { fprintf(stderr,"%s: busy b cmsg type %d not %d\n",__progname,(int)cmh->cmsg_type,(int)SCM_RIGHTS);
       exit(1);
     }
    do n = write(fd,"\1",1); while ((n < 0) && (errno == ENOBUFS));
    if (n < 0)
     { fprintf(stderr,"%s: busy b ack write: %s\n",__progname,strerror(errno));
       exit(1);
     }
    if (n != 1)
     { fprintf(stderr,"%s: busy b ack write got %d not %d\n",__progname,n,1);
       exit(1);
     }
  }
}

static void handle_alrm(int sig)
{
 (void)sig;
 write(timing_fd,"",1);
}

static int testwrite(const char *proc, int x, int fd, const char *data, int len)
{
 int n;

 n = write(fd,data,len);
 if (n < 0)
  { fprintf(stderr,"%s: test write %s [%d]: %s\n",__progname,proc,x,strerror(errno));
    return(1);
  }
 if (n != len)
  { fprintf(stderr,"%s: test write %s [%d] got %d not %d\n",__progname,proc,x,n,len);
    return(1);
  }
 return(0);
}

static int testget(const char *proc, int x, int fd, const char *data, int len)
{
 int n;
 unsigned char reply[257];
 int i;

 n = recv(fd,&reply[0],sizeof(reply),MSG_WAITALL);
 if (n < 0)
  { fprintf(stderr,"%s: test recv %s [%d]: %s\n",__progname,proc,x,strerror(errno));
    return(1);
  }
 if (n != len)
  { fprintf(stderr,"%s: test recv %s [%d] got %d not %d\n",__progname,proc,x,n,len);
    return(1);
  }
 if (bcmp(&reply[0],data,len))
  { fprintf(stderr,"%s: test data wrong:",__progname);
    for (i=0;i<len;i++) fprintf(stderr," %02x",reply[i]);
    fprintf(stderr,"\n");
    return(1);
  }
 return(0);
}

static void test_a(int fd)
{
 int tp[2];
 struct sigaction sa;
 struct itimerval itv;
 char x;
 int n;
 int p[3][2];
 struct cmsghdr *cmh;
 struct msghdr mh;
 struct iovec iov;
 char *buf;
 char data;

 if (socketpair(AF_LOCAL,SOCK_STREAM,0,&tp[0]) < 0)
  { fprintf(stderr,"%s: test a socketpair: %s\n",__progname,strerror(errno));
    exit(1);
  }
 timing_fd = tp[1];
 sa.sa_handler = &handle_alrm;
 sigemptyset(&sa.sa_mask);
 sa.sa_flags = SA_RESTART;
 sigaction(SIGALRM,&sa,0);
 itv.it_value.tv_sec = 1;
 itv.it_value.tv_usec = 0;
 itv.it_interval = itv.it_value;
 setitimer(ITIMER_REAL,&itv,0);
 buf = malloc(CMSG_SPACE(3*sizeof(int)));
 if (! buf)
  { fprintf(stderr,"%s: malloc failed: %s\n",__progname,strerror(errno));
    exit(1);
  }
 while (1)
  { n = read(tp[0],&x,1);
    if (n < 0)
     { if (errno == EINTR) continue;
       fprintf(stderr,"%s: test a read: %s\n",__progname,strerror(errno));
       exit(1);
     }
    if (n == 0)
     { fprintf(stderr,"%s: test a read EOF\n",__progname);
       exit(1);
     }
    for (n=3-1;n>=0;n--)
     { if (socketpair(AF_LOCAL,SOCK_STREAM,0,&p[n][0]) < 0)
	{ fprintf(stderr,"%s: AF_LOCAL SOCK_STREAM socketpair: %s\n",__progname,strerror(errno));
	  exit(1);
	}
     }
    do
     { cmh = (void *)buf;
       cmh->cmsg_len = CMSG_LEN(3*sizeof(int));
       cmh->cmsg_level = SOL_SOCKET;
       cmh->cmsg_type = SCM_RIGHTS;
       ((int *)CMSG_DATA(cmh))[0] = p[0][0];
       ((int *)CMSG_DATA(cmh))[1] = p[1][0];
       ((int *)CMSG_DATA(cmh))[2] = p[2][0];
       data = 'x';
       iov.iov_base = &data;
       iov.iov_len = 1;
       mh.msg_name = 0;
       mh.msg_namelen = 0;
       mh.msg_iov = &iov;
       mh.msg_iovlen = 1;
       mh.msg_control = buf;
       mh.msg_controllen = CMSG_SPACE(3*sizeof(int));
       mh.msg_flags = 0;
       if (sendmsg(fd,&mh,0) < 0)
	{ fprintf(stderr,"%s: test 3 sendmsg: %s\n",__progname,strerror(errno));
	  break;
	}
       close(p[0][0]);
       p[0][0] = -1;
       close(p[1][0]);
       p[1][0] = -1;
       close(p[2][0]);
       p[2][0] = -1;
       if ( testwrite("a",0,p[0][1],"hello on 1",10) ||
	    testwrite("a",1,p[1][1],"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz",52) ) break;
       for (n=0;n<256;n++)
	{ data = n;
	  if (testwrite("a",2,p[2][1],&data,1)) break; // XXX oh for LCS....
	}
       if (n < 256) break;
       shutdown(p[0][1],SHUT_WR);
       shutdown(p[1][1],SHUT_WR);
       shutdown(p[2][1],SHUT_WR);
       if ( testget("a",0,p[0][1],"zero",4) ||
	    testget("a",1,p[1][1],"one",3) ||
	    testget("a",2,p[2][1],"two",3) ) break;
       close(p[0][1]);
       p[0][1] = -1;
       close(p[1][1]);
       p[1][1] = -1;
       close(p[2][1]);
       p[2][1] = -1;
     } while (0);
    if (p[0][0] >= 0) close(p[0][0]);
    if (p[0][1] >= 0) close(p[0][1]);
    if (p[1][0] >= 0) close(p[1][0]);
    if (p[1][1] >= 0) close(p[1][1]);
    if (p[2][0] >= 0) close(p[2][0]);
    if (p[2][1] >= 0) close(p[2][1]);
    write(1,"*",1);
  }
}

static void test_b(int fd)
{
 int p[3];
 struct cmsghdr *cmh;
 struct msghdr mh;
 struct iovec iov;
 char *buf;
 unsigned char body[256];
 int n;

 buf = malloc(CMSG_SPACE(3*sizeof(int)));
 while (1)
  { iov.iov_base = &body[0];
    iov.iov_len = sizeof(body);
    mh.msg_name = 0;
    mh.msg_namelen = 0;
    mh.msg_iov = &iov;
    mh.msg_iovlen = 1;
    mh.msg_control = buf;
    mh.msg_controllen = CMSG_SPACE(3*sizeof(int));
    mh.msg_flags = 0;
    n = recvmsg(fd,&mh,0);
    if (n < 0)
     { fprintf(stderr,"%s: test 3 recvmsg: %s\n",__progname,strerror(errno));
       exit(1);
     }
    if (n != 1)
     { fprintf(stderr,"%s: test 3 recvmsg got %d not %d\n",__progname,n,1);
       exit(1);
     }
    if (body[0] != 'x')
     { fprintf(stderr,"%s: test 3 recvmsg body %02x not %02x\n",__progname,body[0],'x');
       exit(1);
     }
    if (mh.msg_controllen < CMSG_LEN(3*sizeof(int)))
     { fprintf(stderr,"%s: test 3 control len %d < %d\n",__progname,(int)mh.msg_controllen,(int)CMSG_LEN(3*sizeof(int)));
       exit(1);
     }
    cmh = (void *)buf;
    if (cmh->cmsg_level != SOL_SOCKET)
     { fprintf(stderr,"%s: test 3 cmsg level %d not %d\n",__progname,(int)cmh->cmsg_level,(int)SOL_SOCKET);
       exit(1);
     }
    if (cmh->cmsg_type != SCM_RIGHTS)
     { fprintf(stderr,"%s: test 3 cmsg type %d not %d\n",__progname,(int)cmh->cmsg_type,(int)SCM_RIGHTS);
       exit(1);
     }
    bcopy(CMSG_DATA(cmh),&p[0],3*sizeof(int));
    if ( testget("b",0,p[0],"hello on 1",10) ||
	 testget("b",1,p[1],"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz",52) ||
	 testget("b",2,p[2],"\0\1\2\3\4\5\6\7\10\11\12\13\14\15\16\17\20\21\22\23\24\25\26\27\30\31\32\33\34\35\36\37"
			    " !\"#$%&'()*+,-./0123456789:;<=>?"
			    "@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_"
			    "`abcdefghijklmnopqrstuvwxyz{|}~\177"
			    "\200\201\202\203\204\205\206\207\210\211\212\213\214\215\216\217"
			    "\220\221\222\223\224\225\226\227\230\231\232\233\234\235\236\237"
			    "\240\241\242\243\244\245\246\247\250\251\252\253\254\255\256\257"
			    "\260\261\262\263\264\265\266\267\270\271\272\273\274\275\276\277"
			    "\300\301\302\303\304\305\306\307\310\311\312\313\314\315\316\317"
			    "\320\321\322\323\324\325\326\327\330\331\332\333\334\335\336\337"
			    "\340\341\342\343\344\345\346\347\350\351\352\353\354\355\356\357"
			    "\360\361\362\363\364\365\366\367\370\371\372\373\374\375\376\377",256) ) exit(1);
    if ( testwrite("b",0,p[0],"zero",4) ||
	 testwrite("b",1,p[1],"one",3) ||
	 testwrite("b",2,p[2],"two",3) ) exit(1);
    close(p[0]);
    close(p[1]);
    close(p[2]);
  }
}

static void fork_pair(void (*a)(int), void (*b)(int), pid_t *kap, pid_t *kbp)
{
 int p[2];
 pid_t k;

 if (socketpair(AF_LOCAL,SOCK_DGRAM,0,&p[0]) < 0)
  { fprintf(stderr,"%s: busy parent socketpair: %s\n",__progname,strerror(errno));
    exit(1);
  }
 k = fork();
 if (k < 0)
  { fprintf(stderr,"%s: busy parent fork: %s\n",__progname,strerror(errno));
    exit(1);
  }
 if (k == 0)
  { close(p[0]);
    (*a)(p[1]);
    _exit(0);
  }
 *kap = k;
 k = fork();
 if (k < 0)
  { fprintf(stderr,"%s: busy parent fork: %s\n",__progname,strerror(errno));
    exit(1);
  }
 if (k == 0)
  { close(p[1]);
    (*b)(p[0]);
    _exit(0);
  }
 *kbp = k;
 close(p[0]);
 close(p[1]);
}

static void fork_kids(void)
{
 fork_pair(&busy_a,&busy_b,&kid_busy_a,&kid_busy_b);
 fork_pair(&test_a,&test_b,&kid_test_a,&kid_test_b);
}

static void await(void)
{
 pid_t k;

 while (1)
  { k = wait4(-1,0,0,0);
    if (k < 0)
     { if (errno == EINTR) continue;
       fprintf(stderr,"%s: parent wait: %s\n",__progname,strerror(errno));
       break;
     }
    break;
  }
 if (k != kid_busy_a) kill(kid_busy_a,SIGKILL);
 if (k != kid_busy_b) kill(kid_busy_b,SIGKILL);
 if (k != kid_test_a) kill(kid_test_a,SIGKILL);
 if (k != kid_test_b) kill(kid_test_b,SIGKILL);
}

static void ignore_pipe(void)
{
 signal(SIGPIPE,SIG_IGN);
}

int main(void);
int main(void)
{
 ignore_pipe();
 fork_kids();
 await();
 return(0);
}