#include <stdio.h>
#include <string.h>
#include <sys/wait.h>
#include <time.h>
#include <unistd.h>

#define RD_FD 0
#define WR_FD 1

int main(int argc, char **argv) {
   int childpid, gone, requestPipefd[2], answerPipefd[2];
   if ( pipe(requestPipefd) < 0) {
      perror("pipe");
      exit(1);
   } /* if */
   if ( pipe(answerPipefd) < 0) {
      perror("pipe");
      exit(1);
   } /* if */
   switch ( childpid = fork() ) {
      case -1: {
         perror("fork");
         exit(1);
      }
      case 0: { /* child */
	 char buf[128];
	 int nread;
	 /* close WRITE end of answer pipe */
	 close(answerPipefd[WR_FD]);
	 /* close READ end of request pipe */
	 close(requestPipefd[RD_FD]);
	 printf("child: requesting '%s'...\n",argv[1]);
	 /* request current time */
	 write( requestPipefd[WR_FD], argv[1], strlen(argv[1])+1 );
	 /* read current time from pipe */
	 nread = read( answerPipefd[RD_FD], buf, sizeof(buf) );
	 printf("child: result is '%s'\n",buf);
	 break;
      }  /* case 0 */
      default: { /* parent */
	 char buf[128];
         int nread;
	 /* close READ end of answer pipe */
	 close( answerPipefd[RD_FD] );
	 /* close WRITE end of request pipe */
	 close( requestPipefd[WR_FD]);
	 /* read from request pipe and copy to stdout */
	 nread = read( requestPipefd[RD_FD], buf, sizeof(buf) );
	 printf("parent: received '%s' request\n",buf);            
	 if (strcmp(buf,"getTime") == 0) {
	    char buf[10];
	    unsigned int currentTime;
	    currentTime = time(0);
	    sprintf(buf, "%d", currentTime);
	    write( answerPipefd[WR_FD], buf, sizeof(buf) );
	 } /* if */ else {
	    write(answerPipefd[WR_FD], "not implemented", sizeof("not implemented") );
	 } /* else */

	 printf("parent: waiting for child...\n");
	 do /* wait for child */ {
	    if ( (gone=wait( (int *) 0 )) < 0 ) {
	       /* no interest for exit_status */
	       perror("wait");
	       exit(2);
	    } /* if */
	 } /* do */
	 while (gone != childpid); 
      }  /* end default */ 
   } /* switch */
   exit(0);
} /* main */