gistfile1.cpp

char* executeProcess(char** args) {
  int p[2], p2[2], pid, output_length = 100, current_size = 0, num_args = 3, i, child_stat;
  bool error = false;
  char cread;
  char* output = NULL;
  char** cmd_args;
  std::string cmd(args[1]);
  
  // take off args[0], since will be sent into stdin of process
  std::string input_data(args[0]);
  num_args--;
  
  // copy the args array (starting at index 1) into cmd_args
  cmd_args = (char**)malloc((num_args+1)*sizeof(char*));
  for (i=0; i<num_args; i++) {
    cmd_args[i] = (char*)malloc(strlen(args[i+1]))*sizeof(char));
    strcpy(cmd_args[i],args[i+1]);
  }
  cmd_args[num_args] = (char *)0;	// mark the end of the args array for execvp()
  
  if (pipe(p) == -1) {
    error = true;
  }
  if (pipe(p2) == -1) {
    error = true;
  }
  
  if (!error) {
    pid = fork();
    switch (pid) {
      case -1: // error
        error = true;

      case 0: // child process
        close(p2[0]);
        close(p[1]);
		
        close(1);	// close regular stdout
        dup(p2[1]); // redirect pipe2 write end to be stdin of this child process
        close(p2[1]); // pipe not needed anymore
		
        close(0);	// close regular stdin
        dup(p[0]); // redirect pipe1 read end to be stdin of this child process
        close(p[0]); // pipe not needed anymore

        execvp(cmd.c_str(),cmd_args);
        exit(1);	// if we get here, the execute didn't work, so bail on child process
	  
      default: // parent process
        close(p[0]);
        close(p2[1]);
        if (input_data != "") {
          write(p[1],input_data.c_str(),strlen(input_data.c_str()));
        }
        close(p[1]);
	  
        waitpid(pid,&child_stat,0);
        if (child_stat != 0) {
          error = true;
        }
        else {
          while ((read(p2[0],&cread,1)) && (cread != EOF)) {
            if (output==NULL) output = (char*)malloc(output_length*sizeof(char));
            else if (current_size == output_length-2) {
              output_length *= 2;
              output = (char*)realloc(output,output_length);
            }
            if (output!=NULL) {
              output[current_size++] = cread;
            }
            else {
              error = true;
            }
          }
        }
        if (!error && output!=NULL) {
          output[current_size] = '\0';
        }
    }
  }

  close(p2[0]);	// close rest of pipe
  
  for (i=0; i<num_args; i++) free(cmd_args[i]);
  free(cmd_args);
  
  if (!error) {
    return output;
  }
  return NULL;
}

the cmd that is sent to this program is another executable (in my testing, a simple CLI php script), which loops reading from stdin until it receives EOF, and then does its business. The above code (L44) where it write()'s the input from parent to child, even though it's followed on L46 with a close() on the pipe, the EOF is not getting sent, so the child process sits and waits for more input (it IS getting the initial written input).

How do i force EOF to be sent to the child after the write, other than closing the pipe?

updated the code with two pipes and it seems to be working correctly now.