ensure_single_process

ensure_single_process.cpp

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

void ensure_single_process(const char * id){
  struct sockaddr_un sun;
  if(NULL==id || strlen(id)+1>sizeof(sun.sun_path)){
      return ;
  }
  memset(&sun,0,sizeof(sun));
  sun.sun_family=AF_UNIX;
  strcpy(sun.sun_path+1,id); //abstract namespace.
  int s = socket(AF_UNIX, SOCK_STREAM, 0);
  if(bind(s,(struct sockaddr *) &sun,sizeof(sun))){
      printf("another process is running under %s. exiting ...\n",id);
      exit(1);
  }
  printf("ok, i am the only one under %s. running ...\n",id);
}

int
main(int argc, char **argv)
{
  int s;
  struct sockaddr_un sun;

  if (argc != 2 || strlen(argv[1]) + 1 > sizeof(sun.sun_path)) {
    fprintf(stderr, "usage: %s abstract-path\n", argv[0]);
    exit(1);
  }

  ensure_single_process(argv[1]);

  pause();
}