utils

chroot.c (1259B)

// Collection of Unix tools, comparable to coreutils
// SPDX-FileCopyrightText: 2017-2023 Haelwenn (lanodan) Monnier <contact+utils@hacktivis.me>
// SPDX-License-Identifier: MPL-2.0
#define _POSIX_C_SOURCE 200809L
#define _DEFAULT_SOURCE // chroot
#include <assert.h>     // assert
#include <errno.h>      // errno
#include <stdbool.h>    // false
#include <stdio.h>      // fprintf, perror
#include <stdlib.h>     // getenv
#include <unistd.h>     // chroot, execl, execv
int
main(int argc, char *argv[])
{
	if(argc < 2)
	{
		fprintf(stderr, "chroot: Needs arguments\n");
		fprintf(stderr, "Usage: chroot <newroot> [command [args ...]]\n");
		return 125;
	}
	if(chroot(argv[1]) < 0)
	{
		perror("chroot");
		return 125;
	}
	if(chdir("/") < 0)
	{
		perror("chdir");
		return 125;
	}
	int ret = 0;
	errno   = 0;
	if(argc == 2)
	{
		char *shell = getenv("SHELL");
		if(shell == NULL) shell = "/bin/sh";
		/* flawfinder: ignore. No restrictions on commands is intended */
		ret = execlp(shell, shell, "-i", NULL);
	}
	else
	{
		argv += 2;
		/* flawfinder: ignore. No restrictions on commands is intended */
		ret = execvp(argv[0], argv);
	}
	if(ret != 0)
	{
		perror("chroot: exec");
		if(errno == ENOENT) return 127;
		return 126;
	}
	assert(false);
}