/*
 * Copyright 2017-2025, Haiku, Inc. All rights reserved.
 * Distributed under the terms of the MIT License.
 *
 * Authors:
 *              Axel Dörfler, axeld@pinc-software.de
 *              Augustin Cavalier <waddlesplash>
 */


#include <SupportDefs.h>

#include <errno.h>
#include <pwd.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <syslog.h>
#include <termios.h>
#include <unistd.h>

#include "multiuser_utils.h"


extern const char* __progname;
const char* kProgramName = __progname;

const uint32 kRetries = 3;


static void
usage()
{
        fprintf(stderr, "usage: %s [-pl] [-c command] [username]\n", kProgramName);
        exit(1);
}


int
main(int argc, char *argv[])
{
        bool loginShell = false;
        const char* command = NULL;

        char c;
        while ((c = getopt(argc, argv, "c:l")) != -1) {
                switch (c) {
                        case 'l':
                                loginShell = true;
                                break;

                        case 'c':
                                command = optarg;
                                break;

                        default:
                                usage();
                                break;
                }
        }

        argc -= optind;
        argv += optind;

        const char* user = NULL;
        if (argc > 0)
                user = argv[0];

        if (user == NULL)
                user = "user";
                // aka 'root' on Haiku

        // login

        openlog(kProgramName, 0, LOG_AUTH);

        struct passwd* passwd = getpwnam(user);
        if (passwd == NULL) {
                syslog(LOG_NOTICE, "su attempt for non-existent user \"%s\"", user);
                fprintf(stderr, "su: user \"%s\" does not exist\n", user);
                exit(1);
        }

        // if not root, the user needs to authenticate
        status_t status = B_ERROR;
        if (getuid() != 0) {
                status = authenticate_user("password: ", passwd, NULL, kRetries, false);

                if (status < B_OK) {
                        syslog(LOG_NOTICE, "su failed for \"%s\"", passwd->pw_name);
                        exit(1);
                }
        }

        // setup environment for the user

        status = setup_environment(passwd, true, false);
        if (status < B_OK) {
                // refused login
                fprintf(stderr, "%s: Refused login. Setting up environment failed: %s\n",
                        kProgramName, strerror(status));
                syslog(LOG_NOTICE, "su refused for \"%s\"", passwd->pw_name);
                exit(1);
        }

        syslog(LOG_INFO, "su as \"%s\"", passwd->pw_name);

        // start shell
        const char* args[] = {getenv("SHELL"), NULL, NULL, NULL, NULL};
        int nextarg = 1;
        if (loginShell) {
                args[nextarg++] = "-login";
        }
        if (command != NULL) {
                args[nextarg++] = "-c";
                args[nextarg++] = command;
        }

        execv(args[0], (char **)args);

        // try default shell
        args[0] = "/bin/sh";
        execv(args[0], (char **)args);

        fprintf(stderr, "%s: starting the shell failed: %s", kProgramName,
                strerror(errno));

        return 1;
}