/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 1988, 1993, 1994
 *      The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. 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.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``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 REGENTS OR CONTRIBUTORS 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.
 */

#include <sys/types.h>

#include <err.h>
#include <errno.h>
#include <login_cap.h>
#include <pwd.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include "envopts.h"

extern char **environ;

int      env_verbosity;

static void usage(void) __dead2;

/*
 * Exit codes.
 */
#define EXIT_CANCELED      125 /* Internal error prior to exec attempt. */
#define EXIT_CANNOT_INVOKE 126 /* Program located, but not usable. */
#define EXIT_ENOENT        127 /* Could not find program to exec. */

int
main(int argc, char **argv)
{
        char *altpath, *altwd, **ep, *p, **parg, term;
        char *cleanenv[1];
        char *login_class, *login_name;
        struct passwd *pw;
        login_cap_t *lc;
        bool login_as_user;
        uid_t uid;
        int ch, want_clear;
        int rtrn;

        altpath = NULL;
        altwd = NULL;
        login_class = NULL;
        login_name = NULL;
        pw = NULL;
        lc = NULL;
        login_as_user = false;
        want_clear = 0;
        term = '\n';
        while ((ch = getopt(argc, argv, "-0C:iL:P:S:U:u:v")) != -1)
                switch(ch) {
                case '-':
                case 'i':
                        want_clear = 1;
                        break;
                case '0':
                        term = '\0';
                        break;
                case 'C':
                        altwd = optarg;
                        break;
                case 'U':
                        login_as_user = true;
                        /* FALLTHROUGH */
                case 'L':
                        login_name = optarg;
                        break;
                case 'P':
                        altpath = optarg;
                        break;
                case 'S':
                        /*
                         * The -S option, for "split string on spaces, with
                         * support for some simple substitutions"...
                         */
                        split_spaces(optarg, &optind, &argc, &argv);
                        break;
                case 'u':
                        if (env_verbosity)
                                fprintf(stderr, "#env unset:\t%s\n", optarg);
                        rtrn = unsetenv(optarg);
                        if (rtrn == -1)
                                err(EXIT_FAILURE, "unsetenv %s", optarg);
                        break;
                case 'v':
                        env_verbosity++;
                        if (env_verbosity > 1)
                                fprintf(stderr, "#env verbosity now at %d\n",
                                    env_verbosity);
                        break;
                case '?':
                default:
                        usage();
                }
        if (want_clear) {
                environ = cleanenv;
                cleanenv[0] = NULL;
                if (env_verbosity)
                        fprintf(stderr, "#env clearing environ\n");
        }
        if (login_name != NULL) {
                login_class = strchr(login_name, '/');
                if (login_class)
                        *login_class++ = '\0';
                if (*login_name != '\0' && strcmp(login_name, "-") != 0) {
                        pw = getpwnam(login_name);
                        if (pw == NULL) {
                                char *endp = NULL;
                                errno = 0;
                                uid = strtoul(login_name, &endp, 10);
                                if (errno == 0 && *endp == '\0')
                                        pw = getpwuid(uid);
                        }
                        if (pw == NULL)
                                errx(EXIT_FAILURE, "no such user: %s", login_name);
                }
                /*
                 * Note that it is safe for pw to be null here; the libutil
                 * code handles that, bypassing substitution of $ and using
                 * the class "default" if no class name is given either.
                 */
                if (login_class != NULL) {
                        lc = login_getclass(login_class);
                        if (lc == NULL)
                                errx(EXIT_FAILURE, "no such login class: %s",
                                    login_class);
                } else {
                        lc = login_getpwclass(pw);
                        if (lc == NULL)
                                errx(EXIT_FAILURE, "login_getpwclass failed");
                }

                /*
                 * This is not done with setusercontext() because that will
                 * try and use ~/.login_conf even when we don't want it to.
                 */
                setclassenvironment(lc, pw, 1);
                setclassenvironment(lc, pw, 0);
                if (login_as_user) {
                        login_close(lc);
                        if ((lc = login_getuserclass(pw)) != NULL) {
                                setclassenvironment(lc, pw, 1);
                                setclassenvironment(lc, pw, 0);
                        }
                }
                endpwent();
                if (lc != NULL)
                        login_close(lc);
        }
        for (argv += optind; *argv && (p = strchr(*argv, '=')); ++argv) {
                if (env_verbosity)
                        fprintf(stderr, "#env setenv:\t%s\n", *argv);
                *p = '\0';
                rtrn = setenv(*argv, p + 1, 1);
                *p = '=';
                if (rtrn == -1)
                        err(EXIT_FAILURE, "setenv %s", *argv);
        }
        if (*argv) {
                if (term == '\0')
                        errx(EXIT_CANCELED, "cannot specify command with -0");
                if (altwd && chdir(altwd) != 0)
                        err(EXIT_CANCELED, "cannot change directory to '%s'",
                            altwd);
                if (altpath)
                        search_paths(altpath, argv);
                if (env_verbosity) {
                        fprintf(stderr, "#env executing:\t%s\n", *argv);
                        for (parg = argv, argc = 0; *parg; parg++, argc++)
                                fprintf(stderr, "#env    arg[%d]=\t'%s'\n",
                                    argc, *parg);
                        if (env_verbosity > 1)
                                sleep(1);
                }
                execvp(*argv, argv);
                err(errno == ENOENT ? EXIT_ENOENT : EXIT_CANNOT_INVOKE,
                    "%s", *argv);
        } else {
                if (altwd)
                        errx(EXIT_CANCELED, "must specify command with -C");
                if (altpath)
                        errx(EXIT_CANCELED, "must specify command with -P");
        }
        for (ep = environ; *ep; ep++)
                (void)printf("%s%c", *ep, term);
        if (fflush(stdout) != 0)
                err(1, "stdout");
        exit(0);
}

static void
usage(void)
{
        (void)fprintf(stderr,
            "usage: env [-0iv] [-C workdir] [-L|-U user[/class]] [-P utilpath] [-S string]\n"
            "           [-u name] [name=value ...] [utility [argument ...]]\n");
        exit(1);
}