Example: Create a server that uses spawn()

/**************************************************************************/
/* Application creates an child process using spawn().                    */
/**************************************************************************/

#include <stdio.h>
#include <stdlib.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <spawn.h>

#define SERVER_PORT  12345

main (int argc, char *argv[])
{
   int    i, num, pid, rc, on = 1;
   int    listen_sd, accept_sd;
   int    spawn_fdmap[1];
   char  *spawn_argv[1];
   char  *spawn_envp[1];
   struct inheritance   inherit;
   struct sockaddr_in   addr;

   /*************************************************/
   /* If an argument was specified, use it to       */
   /* control the number of incoming connections    */
   /*************************************************/
   if (argc >= 2)
      num = atoi(argv[1]);
   else
      num = 1;

   /*************************************************/
   /* Create an AF_INET stream socket to receive    */
   /* incoming connections on                       */
   /*************************************************/
   listen_sd = socket(AF_INET, SOCK_STREAM, 0);
   if (listen_sd < 0)
   {
      perror("socket() failed");
      exit(-1);
   }

   /*************************************************/
   /* Allow socket descriptor to be reuseable       */
   /*************************************************/
   rc = setsockopt(listen_sd,
                   SOL_SOCKET,  SO_REUSEADDR,
                   (char *)&on, sizeof(on));
   if (rc < 0)
   {
      perror("setsockopt() failed");
      close(listen_sd);
      exit(-1);
   }

   /*************************************************/
   /* Bind the socket                               */
   /*************************************************/
   memset(&addr, 0, sizeof(addr));
   addr.sin_family      = AF_INET;
   addr.sin_port        = htons(SERVER_PORT);
   addr.sin_addr.s_addr = htonl(INADDR_ANY);
   rc = bind(listen_sd,
             (struct sockaddr *)&addr, sizeof(addr));
   if (rc < 0)
   {
      perror("bind() failed");
      close(listen_sd);
      exit(-1);
   }

   /*************************************************/
   /* Set the listen back log                       */
   /*************************************************/
   rc = listen(listen_sd, 5);
   if (rc < 0)
   {
      perror("listen() failed");
      close(listen_sd);
      exit(-1);
   }

   /*************************************************/
   /* Inform the user that the server is ready      */
   /*************************************************/
   printf("The server is ready\n");

   /*************************************************/
   /* Go through the loop once for each connection  */
   /*************************************************/
   for (i=0; i < num; i++)
   {
      /**********************************************/
      /* Wait for an incoming connection            */
      /**********************************************/
      printf("Interation: %d\n", i+1);
      printf("  waiting on accept()\n");
      accept_sd = accept(listen_sd, NULL, NULL);
      if (accept_sd < 0)
      {
         perror("accept() failed");
         close(listen_sd);
         exit(-1);
      }
      printf("  accept completed successfully\n");

      /**********************************************/
      /* Initialize the spawn parameters            */
      /*                                            */

      /* The socket descriptor for the new          */
      /* connection is mapped over to descriptor 0  */
      /* in the child program.                      */
      /**********************************************/
      memset(&inherit, 0, sizeof(inherit));
      spawn_argv[0]  = NULL;
      spawn_envp[0]  = NULL;
      spawn_fdmap[0] = accept_sd;

      /**********************************************/
      /* Create the worker job                      */
      /**********************************************/
      printf("  creating worker job\n");
      pid = spawn("/QSYS.LIB/QGPL.LIB/WRKR1.PGM",
                  1, spawn_fdmap, &inherit,
                  spawn_argv, spawn_envp);
      if (pid < 0)
      {
         perror("spawn() failed");
         close(listen_sd);
         close(accept_sd);
         exit(-1);
      }
      printf("  spawn completed successfully\n");

      /**********************************************/
      /* Close down the incoming connection since   */
      /* it has been given to a worker to handle    */
      /**********************************************/
      close(accept_sd);
   }

   /*************************************************/
   /* Close down the listen socket                  */
   /*************************************************/
   close(listen_sd);
}