#define _GNU_SOURCE 1
#include <sys/socket.h>
#include <assert.h>
#include <arpa/inet.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include <signal.h>

static volatile int piped;
static void handler(int signo) {
  piped=1;
}

int main (void) {
  setbuf(stdout,NULL);
  signal(SIGPIPE,handler);
  int fd=socket(PF_INET,SOCK_STREAM,0);
  assert(fd!=-1);
  struct sockaddr_in addr;
  memset(&addr,0,sizeof addr);
  addr.sin_family=AF_INET;
  addr.sin_addr.s_addr=htonl(INADDR_LOOPBACK);
  addr.sin_port=htons(5000);
  int i=connect(fd,(struct sockaddr *)&addr,sizeof(addr));
  assert(i==0);
  char charbuf='a';
  ssize_t ssize=send(fd,&charbuf,1,0);
  assert(ssize==1);
  fputs("sleeping ...",stdout);
  sleep(5);
  charbuf='b';
  puts(" done");
  errno=0;
//  ssize=send(fd,&charbuf,1,0);
  ssize=write(fd,&charbuf,1);
  assert_perror(errno);
  assert(ssize==1);
//  puts("send ok");
  puts("write ok");
  errno=0;
//  ssize=recv(fd,&charbuf,1,0);
  ssize=read(fd,&charbuf,1);
  assert_perror(errno);
  printf("ssize=%zd\n",ssize);
  assert(ssize==0);
//  puts("recv ok");
  puts("read ok");
  errno=0;
  ssize=send(fd,&charbuf,1,0);
//  ssize=write(fd,&charbuf,1);
  assert_perror(errno);
  assert(ssize==1);
  puts("send ok");
//  puts("write ok");
  if (piped)
    puts("SIGPIPE");
  return 0;
}