/*
 * Copyright (c) 2009 Martin Decky
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/** @addtogroup redir Redirector
 * @brief Redirect stdin/stdout/stderr.
 * @{
 */
/**
 * @file
 */

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

static void usage(void)
{
	printf("Usage: redir [-i <stdin>] [-o <stdout>] [-e <stderr>] -- <cmd> [args ...]\n");
}

static void reopen(FILE **stream, int fd, const char *path, int flags, const char *mode)
{
	if (fclose(*stream))
		return;
	
	*stream = NULL;
	
	int oldfd = open(path, flags);
	if (oldfd < 0)
		return;
	
	if (oldfd != fd) {
		if (dup2(oldfd, fd) != fd)
			return;
		
		if (close(oldfd))
			return;
	}
	
	*stream = fdopen(fd, mode);
}

static task_id_t spawn(int argc, char *argv[])
{
	char **args = (char **) calloc(argc + 1, sizeof(char *));
	if (!args) {
		printf("No memory available\n");
		return 0;
	}
	
	int i;
	for (i = 0; i < argc; i++)
		args[i] = argv[i];
	
	args[argc] = NULL;
	
	task_id_t id = task_spawn(argv[0], args);
	
	free(args);
	
	if (id == 0)
		printf("Error spawning %s\n", argv[0]);
	
	return id;
}

int main(int argc, char *argv[])
{
	if (argc < 3) {
		usage();
		return -1;
	}
	
	int i;
	for (i = 1; i < argc; i++) {
		if (str_cmp(argv[i], "-i") == 0) {
			i++;
			if (i >= argc) {
				usage();
				return -2;
			}
			reopen(&stdin, 0, argv[i], O_RDONLY, "r");
		} else if (str_cmp(argv[i], "-o") == 0) {
			i++;
			if (i >= argc) {
				usage();
				return -3;
			}
			reopen(&stdout, 1, argv[i], O_WRONLY | O_CREAT, "w");
		} else if (str_cmp(argv[i], "-e") == 0) {
			i++;
			if (i >= argc) {
				usage();
				return -4;
			}
			reopen(&stderr, 2, argv[i], O_WRONLY | O_CREAT, "w");
		} else if (str_cmp(argv[i], "--") == 0) {
			i++;
			break;
		}
	}
	
	if (i >= argc) {
		usage();
		return -5;
	}
	
	/*
	 * FIXME: fdopen() should actually detect that we are opening a console
	 * and it should set line-buffering mode automatically.
	 */
	setvbuf(stdout, NULL, _IOLBF, BUFSIZ);
	
	task_id_t id = spawn(argc - i, argv + i);
	
	if (id != 0) {
		task_exit_t texit;
		int retval;
		task_wait(id, &texit, &retval);
		
		return retval;
	}
	
	return -6;
}

/** @}
 */
