popen2.c

//
// Implementation of popen2() which is a bi-directional variant of popen().
//
// Part of ccons, the interactive console for the C programming language.
//
// Copyright (c) 2009 Alexei Svitkine. This file is distributed under the
// terms of MIT Open Source License. See file LICENSE for details.
//

#include <sys/types.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

#define READ 0
#define WRITE 1

pid_t popen2(const char *command, int *infp, int *outfp)
{
	int p_stdin[2], p_stdout[2];
	pid_t pid;

	if (pipe(p_stdin) != 0 || pipe(p_stdout) != 0)
		return -1;

	pid = fork();
	if (pid < 0)
		return pid;

	if (pid == 0) {
		close(p_stdin[WRITE]);
		dup2(p_stdin[READ], READ);
		close(p_stdout[READ]);
		dup2(p_stdout[WRITE], WRITE);
		execl("/bin/sh", "sh", "-c", command, NULL);
		perror("execl");
		exit(1);
	}

	if (infp == NULL)
		close(p_stdin[WRITE]);
	else
		*infp = p_stdin[WRITE];

	if (outfp == NULL)
		close(p_stdout[READ]);
	else
		*outfp = p_stdout[READ];

	return pid;
}