/*
 * switchroot.c - switch to new root directory and start init.
 *
 * Copyright 2002-2008 Red Hat, Inc.  All rights reserved.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 * Authors:
 * 	Peter Jones <pjones@redhat.com>
 *	Jeremy Katz <katzj@redhat.com>
 */

#define _GNU_SOURCE 1

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

enum {
	ok,
	err_invalid_failscript,
	err_no_directory,
	err_usage,
};

static int readFD(int fd, char **buf)
{
	char *p;
	size_t size = 16384;
	int s = 0, filesize = 0;

	if (!(*buf = calloc (16384, sizeof (char))))
		return -1;

	do {
		p = *buf + filesize;
		s = read(fd, p, 16384 - s);
		if (s < 0)
			break;
		filesize += s;
		/* only exit for empty reads */
		if (s == 0)
			break;
		else if (s == 16384) {
			*buf = realloc(*buf, size + 16384);
			memset(*buf + size, '\0', 16384);
			size += s;
			s = 0;
		} else {
			size += s;
		}
	} while (1);

	*buf = realloc(*buf, filesize+1);
	(*buf)[filesize] = '\0';

	return *buf ? filesize : -1;
}

static void build_init_args(char **init, char ***initargs)
{
	const char *initprogs[] = { "/sbin/init", "/etc/init",
				    "/bin/init", "/bin/sh", NULL };
	const char *ignoreargs[] = { "console=", "BOOT_IMAGE=", NULL };
	char *cmdline = NULL;
	int fd = -1;
	int rc = -1;

	fd = open("/proc/cmdline", O_RDONLY);
	if (fd < 0) {
		fprintf(stderr, "Error: Could not open /proc/cmdline: %m\n");
	} else {
		if (readFD(fd, &cmdline) < 0) {
			fprintf(stderr, "Error: could not read /proc/cmdline: %m\n");
		} else {
			
		}
	}

}

static void switchroot(const char *newroot, const char *failscript)
{
	/*  Don't try to unmount the old "/", there's no way to do it. */
	const char *umounts[] = { "/dev", "/proc", "/sys", NULL };
	char *init, **initargs;
	char *new = NULL, *arg;
	int fd, i = 0, j = 0, rc = 0;

	build_init_args(&init, &initargs);

}

static void usage(FILE *output)
{
	fprintf(output, "usage: switchroot [ {-f|--failscript} <failscript> ] {-n|--newroot} <newrootdir>\n");
	if (output == stderr)
		exit(err_usage);
	exit(ok);
}

int main(int argc, char *argv[])
{
	int rc = ok;
	int oldroot = -1;
	char *newroot = NULL;
	char *failscript = NULL;
	char *failscriptargs[] = { NULL, NULL };

	for (i = 1; i < argc; i++) {
		if (!strcmp(argv[i], "-f")
				|| !strcmp(argv[i], "--failscript")) {
			failscript = argv[++i];
		} else if (!strncmp(argv[i], "--failscript=", 13)) {
			failscript = argv[i] + 13;
		} else if (!strcmp(argv[i], "--help")
				|| !strcmp(argv[i], "-h")
				|| !strcmp(argv[i], "--usage")) {
			usage(stdout);
		} else if (!strcmp(argv[i], "-n")
				|| !strcmp(argv[i], "--newroot")) {
			newroot = argv[++i];
		} else if (!strncmp(argv[i], "--newroot=", 10)) {
			newroot = argv[i] + 10;
		} else {
			usage(stderr);
		}
	}

	if (failscript != NULL && failscript[0] == '\0') {
		failscript == NULL;
	}
	if (newroot == NULL || newroot[0] == '\0') {
		usage(stderr);
	}

	if (failscript) {
		if (access(failscript, F_OK|X_OK)) {
			fprintf(stderr, "Error: Cannot access failure script \"%s\": %m\n", failscript);
		} else if ((oldroot = open("/", O_RDONLY)) < 0) {
			fprintf(stderr, "Error: Cannot open root directory: %m\n");
		}
	}

	rc = switchroot(newroot);

	if (oldroot >= 0) {
		fchdir(oldroot);
		close(oldroot);
		failscriptargs[0] = failscript;
		execv(failscript, failscriptargs);
	}

	fprintf(stderr, "Booting has failed.  Sorry.\n");
	while (1) {
		sleep(60);
	}

	return rc;
}

/*
 * vim:noet:ts=8:sw=8:sts=8
 */