unix-socket-reader.c

#include <sys/socket.h>
#include <sys/un.h>
#include <stdio.h>
#include <unistd.h>
#include <libgen.h>
#include <string.h>
#include <errno.h>

const struct sockaddr_un sockaddr={
  AF_UNIX,
  "/tmp/unix_socket"
};

const char * basename_argv0;

int main(int argc, char * const argv[]) {
  int sockfd,readfd;
  int status;
  basename_argv0=basename(argv[0]);
  sockfd=socket(AF_UNIX,SOCK_STREAM,0);
  if (sockfd==-1) {
    fprintf(stderr,"%s: cannot open socket: %s\n",basename_argv0,strerror(errno));
    return (2);
  }
  status=bind(sockfd,(const struct sockaddr *)&sockaddr,sizeof(sockaddr));
  if (status!=0) {
    fprintf(stderr,"%s: cannot bind to socket: %s\n",basename_argv0,strerror(errno));
    return (2);
  }
  status=listen(sockfd,1);
  if (status!=0) {
    fprintf(stderr,"%s: cannot listen on socket: %s\n",basename_argv0,strerror(errno));
    return (2);
  }
  readfd=accept(sockfd,NULL,NULL);
  if (readfd==-1) {
    fprintf(stderr,"%s: cannot accept incoming connection: %s\n",basename_argv0,strerror(errno));
    return (2);
  }
  do {
    char buffer[1];
    ssize_t readsize;
    readsize=read(readfd,buffer,sizeof(buffer));
    if (readsize==0)
      break;
    else if (readsize==-1) {
      fprintf(stderr,"%s: cannot read: %s\n",basename_argv0,strerror(errno));
      return (2);
    }
    write(STDOUT_FILENO,buffer,readsize);
    sleep(1);
  } while (1);
  status=close(sockfd);
  if (status!=0) {
    fprintf(stderr,"%s: cannot close sockfd: %s\n",basename_argv0,strerror(errno));
    return (2);
  }
  status=unlink(sockaddr.sun_path);
  if (status!=0) {
    fprintf(stderr,"%s: %s: %s\n",basename_argv0,sockaddr.sun_path,strerror(errno));
    return (2);
  }
  return (0);
}