ladybird/Userland/chroot.cpp

#include <AK/String.h>
#include <AK/StringView.h>
#include <stdio.h>
#include <unistd.h>

struct Options {
    const char* path;
    const char* program { "/bin/Shell" };
    int flags { -1 };
};

void print_usage(const char* argv0)
{
    fprintf(
        stderr,
        "Usage:\n"
        "\t%s <path> [program] [-o options]\n",
        argv0
    );
}

Options parse_options(int argc, char** argv)
{
    Options options;

    if (argc < 2) {
        print_usage(argv[0]);
        exit(1);
    }

    options.path = argv[1];
    int i = 2;
    if (i < argc && argv[i][0] != '-')
        options.program = argv[i++];

    if (i >= argc)
        return options;

    if (strcmp(argv[i], "-o") != 0) {
        print_usage(argv[0]);
        exit(1);
    }
    i++;
    if (i >= argc) {
        print_usage(argv[0]);
        exit(1);
    }

    options.flags = 0;

    StringView arg = argv[i];
    Vector<StringView> parts = arg.split_view(',');
    for (auto& part : parts) {
        if (part == "defaults")
            continue;
        else if (part == "nodev")
            options.flags |= MS_NODEV;
        else if (part == "noexec")
            options.flags |= MS_NOEXEC;
        else if (part == "nosuid")
            options.flags |= MS_NOSUID;
        else if (part == "bind")
            fprintf(stderr, "Ignoring -o bind, as it doesn't make sense for chroot");
        else
            fprintf(stderr, "Ignoring invalid option: %s\n", String(part).characters());
    }

    return options;
}

int main(int argc, char** argv)
{

    Options options = parse_options(argc, argv);

    if (chroot_with_mount_flags(options.path, options.flags) < 0) {
        perror("chroot");
        return 1;
    }

    if (chdir("/") < 0) {
        perror("chdir(/)");
        return 1;
    }

    execl(options.program, options.program, nullptr);
    perror("execl");
    return 1;
}