/* Copyright 1988,1990,1993,1994 by Paul Vixie
 * All rights reserved
 */

/*
 * Copyright (c) 1997 by Internet Software Consortium
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS
 * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
 * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
 * SOFTWARE.
 */

#if !defined(lint) && !defined(LINT)
static const char rcsid[] =
    "$Id: crontab.c,v 1.3 1998/08/14 00:32:38 vixie Exp $";
#endif

/* crontab - install and manage per-user crontab files
 * vix 02may87 [RCS has the rest of the log]
 * vix 26jan87 [original]
 */

#define MAIN_PROGRAM

#include "cron.h"
#include <md5.h>

#define MD5_SIZE 33
#define NHEADER_LINES 3

enum opt_t      { opt_unknown, opt_list, opt_delete, opt_edit, opt_replace };

#if DEBUGGING
static char     *Options[] = { "???", "list", "delete", "edit", "replace" };
#endif

static  PID_T           Pid;
static  char            User[MAXLOGNAME], RealUser[MAXLOGNAME];
static  char            Filename[MAX_FNAME];
static  FILE            *NewCrontab;
static  int             CheckErrorCount;
static  enum opt_t      Option;
static  int             fflag;
static  struct passwd   *pw;
static  void            list_cmd(void),
                        delete_cmd(void),
                        edit_cmd(void),
                        poke_daemon(void),
                        check_error(const char *),
                        parse_args(int c, char *v[]);
static  int             replace_cmd(void);

static void
usage(const char *msg)
{
        fprintf(stderr, "crontab: usage error: %s\n", msg);
        fprintf(stderr, "%s\n%s\n",
                "usage: crontab [-u user] file",
                "       crontab [-u user] { -l | -r [-f] | -e }");
        exit(ERROR_EXIT);
}

int
main(int argc, char *argv[])
{
        int     exitstatus;

        Pid = getpid();
        ProgramName = argv[0];

        setlocale(LC_ALL, "");

#if defined(BSD)
        setlinebuf(stderr);
#endif
        parse_args(argc, argv);         /* sets many globals, opens a file */
        set_cron_uid();
        set_cron_cwd();
        if (!allowed(User)) {
                warnx("you (%s) are not allowed to use this program", User);
                log_it(RealUser, Pid, "AUTH", "crontab command not allowed");
                exit(ERROR_EXIT);
        }
        exitstatus = OK_EXIT;
        switch (Option) {
        case opt_list:
                list_cmd();
                break;
        case opt_delete:
                delete_cmd();
                break;
        case opt_edit:
                edit_cmd();
                break;
        case opt_replace:
                if (replace_cmd() < 0)
                        exitstatus = ERROR_EXIT;
                break;
        case opt_unknown:
        default:
                abort();
        }
        exit(exitstatus);
        /*NOTREACHED*/
}

static void
parse_args(int argc, char *argv[])
{
        int argch;
        char resolved_path[PATH_MAX];

        if (!(pw = getpwuid(getuid())))
                errx(ERROR_EXIT, "your UID isn't in the passwd file, bailing out");
        bzero(pw->pw_passwd, strlen(pw->pw_passwd));
        (void) strncpy(User, pw->pw_name, (sizeof User)-1);
        User[(sizeof User)-1] = '\0';
        strcpy(RealUser, User);
        Filename[0] = '\0';
        Option = opt_unknown;
        while ((argch = getopt(argc, argv, "u:lerx:f")) != -1) {
                switch (argch) {
                case 'x':
                        if (!set_debug_flags(optarg))
                                usage("bad debug option");
                        break;
                case 'u':
                        if (getuid() != ROOT_UID)
                                errx(ERROR_EXIT, "must be privileged to use -u");
                        if (!(pw = getpwnam(optarg)))
                                errx(ERROR_EXIT, "user `%s' unknown", optarg);
                        bzero(pw->pw_passwd, strlen(pw->pw_passwd));
                        (void) strncpy(User, pw->pw_name, (sizeof User)-1);
                        User[(sizeof User)-1] = '\0';
                        break;
                case 'l':
                        if (Option != opt_unknown)
                                usage("only one operation permitted");
                        Option = opt_list;
                        break;
                case 'r':
                        if (Option != opt_unknown)
                                usage("only one operation permitted");
                        Option = opt_delete;
                        break;
                case 'e':
                        if (Option != opt_unknown)
                                usage("only one operation permitted");
                        Option = opt_edit;
                        break;
                case 'f':
                        fflag = 1;
                        break;
                default:
                        usage("unrecognized option");
                }
        }

        endpwent();

        if (Option != opt_unknown) {
                if (argv[optind] != NULL) {
                        usage("no arguments permitted after this option");
                }
        } else {
                if (argv[optind] != NULL) {
                        Option = opt_replace;
                        (void) strncpy (Filename, argv[optind], (sizeof Filename)-1);
                        Filename[(sizeof Filename)-1] = '\0';

                } else {
                        usage("file name must be specified for replace");
                }
        }

        if (Option == opt_replace) {
                /* relinquish the setuid status of the binary during
                 * the open, lest nonroot users read files they should
                 * not be able to read.  we can't use access() here
                 * since there's a race condition.  thanks go out to
                 * Arnt Gulbrandsen <agulbra@pvv.unit.no> for spotting
                 * the race.
                 */

                if (swap_uids() < OK)
                        err(ERROR_EXIT, "swapping uids");

                /* we have to open the file here because we're going to
                 * chdir(2) into /var/cron before we get around to
                 * reading the file.
                 */
                if (!strcmp(Filename, "-")) {
                        NewCrontab = stdin;
                } else if (realpath(Filename, resolved_path) != NULL &&
                    !strcmp(resolved_path, SYSCRONTAB)) {
                        err(ERROR_EXIT, SYSCRONTAB " must be edited manually");
                } else {
                        if (!(NewCrontab = fopen(Filename, "r")))
                                err(ERROR_EXIT, "%s", Filename);
                }
                if (swap_uids_back() < OK)
                        err(ERROR_EXIT, "swapping uids back");
        }

        Debug(DMISC, ("user=%s, file=%s, option=%s\n",
                      User, Filename, Options[(int)Option]))
}

static void
copy_file(FILE *in, FILE *out)
{
        int x, ch;

        Set_LineNum(1)
        /* ignore the top few comments since we probably put them there.
         */
        for (x = 0; x < NHEADER_LINES; x++) {
                ch = get_char(in);
                if (EOF == ch)
                        break;
                if ('#' != ch) {
                        putc(ch, out);
                        break;
                }
                while (EOF != (ch = get_char(in)))
                        if (ch == '\n')
                                break;
                if (EOF == ch)
                        break;
        }

        /* copy the rest of the crontab (if any) to the output file.
         */
        if (EOF != ch)
                while (EOF != (ch = get_char(in)))
                        putc(ch, out);
}

static void
list_cmd(void)
{
        char n[MAX_FNAME];
        FILE *f;

        log_it(RealUser, Pid, "LIST", User);
        (void) snprintf(n, sizeof(n), CRON_TAB(User));
        if (!(f = fopen(n, "r"))) {
                if (errno == ENOENT)
                        errx(ERROR_EXIT, "no crontab for %s", User);
                else
                        err(ERROR_EXIT, "%s", n);
        }

        /* file is open. copy to stdout, close.
         */
        copy_file(f, stdout);
        fclose(f);
}

static void
delete_cmd(void)
{
        char n[MAX_FNAME];
        int ch, first;

        if (!fflag && isatty(STDIN_FILENO)) {
                (void)fprintf(stderr, "remove crontab for %s? ", User);
                first = ch = getchar();
                while (ch != '\n' && ch != EOF)
                        ch = getchar();
                if (first != 'y' && first != 'Y')
                        return;
        }

        log_it(RealUser, Pid, "DELETE", User);
        if (snprintf(n, sizeof(n), CRON_TAB(User)) >= (int)sizeof(n))
                errx(ERROR_EXIT, "path too long");
        if (unlink(n) != 0) {
                if (errno == ENOENT)
                        errx(ERROR_EXIT, "no crontab for %s", User);
                else
                        err(ERROR_EXIT, "%s", n);
        }
        poke_daemon();
}

static void
check_error(const char *msg)
{
        CheckErrorCount++;
        fprintf(stderr, "\"%s\":%d: %s\n", Filename, LineNumber-1, msg);
}

static void
edit_cmd(void)
{
        char n[MAX_FNAME], q[MAX_TEMPSTR], *editor;
        FILE *f;
        int t;
        struct stat statbuf, fsbuf;
        WAIT_T waiter;
        PID_T pid, xpid;
        mode_t um;
        int syntax_error = 0;
        char orig_md5[MD5_SIZE];
        char new_md5[MD5_SIZE];

        log_it(RealUser, Pid, "BEGIN EDIT", User);
        if (snprintf(n, sizeof(n), CRON_TAB(User)) >= (int)sizeof(n))
                errx(ERROR_EXIT, "path too long");
        if (!(f = fopen(n, "r"))) {
                if (errno != ENOENT)
                        err(ERROR_EXIT, "%s", n);
                warnx("no crontab for %s - using an empty one", User);
                if (!(f = fopen(_PATH_DEVNULL, "r")))
                        err(ERROR_EXIT, _PATH_DEVNULL);
        }

        um = umask(077);
        (void) snprintf(Filename, sizeof(Filename), "/tmp/crontab.XXXXXXXXXX");
        if ((t = mkstemp(Filename)) == -1) {
                warn("%s", Filename);
                (void) umask(um);
                goto fatal;
        }
        (void) umask(um);
#ifdef HAS_FCHOWN
        if (fchown(t, getuid(), getgid()) < 0) {
#else
        if (chown(Filename, getuid(), getgid()) < 0) {
#endif
                warn("fchown");
                goto fatal;
        }
        if (!(NewCrontab = fdopen(t, "r+"))) {
                warn("fdopen");
                goto fatal;
        }

        copy_file(f, NewCrontab);
        fclose(f);
        if (fflush(NewCrontab))
                err(ERROR_EXIT, "%s", Filename);
        if (fstat(t, &fsbuf) < 0) {
                warn("unable to fstat temp file");
                goto fatal;
        }
 again:
        if (swap_uids() < OK)
                err(ERROR_EXIT, "swapping uids");
        if (stat(Filename, &statbuf) < 0) {
                warn("stat");
 fatal:
                unlink(Filename);
                exit(ERROR_EXIT);
        }
        if (swap_uids_back() < OK)
                err(ERROR_EXIT, "swapping uids back");
        if (statbuf.st_dev != fsbuf.st_dev || statbuf.st_ino != fsbuf.st_ino)
                errx(ERROR_EXIT, "temp file must be edited in place");
        if (MD5File(Filename, orig_md5) == NULL) {
                warn("MD5");
                goto fatal;
        }

        if ((editor = getenv("VISUAL")) == NULL &&
            (editor = getenv("EDITOR")) == NULL) {
                editor = EDITOR;
        }

        /* we still have the file open.  editors will generally rewrite the
         * original file rather than renaming/unlinking it and starting a
         * new one; even backup files are supposed to be made by copying
         * rather than by renaming.  if some editor does not support this,
         * then don't use it.  the security problems are more severe if we
         * close and reopen the file around the edit.
         */

        switch (pid = fork()) {
        case -1:
                warn("fork");
                goto fatal;
        case 0:
                /* child */
                if (setuid(getuid()) < 0)
                        err(ERROR_EXIT, "setuid(getuid())");
                if (chdir("/tmp") < 0)
                        err(ERROR_EXIT, "chdir(/tmp)");
                if (strlen(editor) + strlen(Filename) + 2 >= MAX_TEMPSTR)
                        errx(ERROR_EXIT, "editor or filename too long");
                execlp(editor, editor, Filename, (char *)NULL);
                err(ERROR_EXIT, "%s", editor);
                /*NOTREACHED*/
        default:
                /* parent */
                break;
        }

        /* parent */
        {
        void (*sig[3])(int signal);
        sig[0] = signal(SIGHUP, SIG_IGN);
        sig[1] = signal(SIGINT, SIG_IGN);
        sig[2] = signal(SIGTERM, SIG_IGN);
        xpid = wait(&waiter);
        signal(SIGHUP, sig[0]);
        signal(SIGINT, sig[1]);
        signal(SIGTERM, sig[2]);
        }
        if (xpid != pid) {
                warnx("wrong PID (%d != %d) from \"%s\"", xpid, pid, editor);
                goto fatal;
        }
        if (WIFEXITED(waiter) && WEXITSTATUS(waiter)) {
                warnx("\"%s\" exited with status %d", editor, WEXITSTATUS(waiter));
                goto fatal;
        }
        if (WIFSIGNALED(waiter)) {
                warnx("\"%s\" killed; signal %d (%score dumped)",
                        editor, WTERMSIG(waiter), WCOREDUMP(waiter) ?"" :"no ");
                goto fatal;
        }
        if (swap_uids() < OK)
                err(ERROR_EXIT, "swapping uids");
        if (stat(Filename, &statbuf) < 0) {
                warn("stat");
                goto fatal;
        }
        if (statbuf.st_dev != fsbuf.st_dev || statbuf.st_ino != fsbuf.st_ino)
                errx(ERROR_EXIT, "temp file must be edited in place");
        if (MD5File(Filename, new_md5) == NULL) {
                warn("MD5");
                goto fatal;
        }
        if (swap_uids_back() < OK)
                err(ERROR_EXIT, "swapping uids back");
        if (strcmp(orig_md5, new_md5) == 0 && !syntax_error) {
                warnx("no changes made to crontab");
                goto remove;
        }
        warnx("installing new crontab");
        switch (replace_cmd()) {
        case 0:                 /* Success */
                break;
        case -1:                /* Syntax error */
                for (;;) {
                        printf("Do you want to retry the same edit? ");
                        fflush(stdout);
                        q[0] = '\0';
                        (void) fgets(q, sizeof q, stdin);
                        switch (islower(q[0]) ? q[0] : tolower(q[0])) {
                        case 'y':
                                syntax_error = 1;
                                goto again;
                        case 'n':
                                goto abandon;
                        default:
                                fprintf(stderr, "Enter Y or N\n");
                        }
                }
                /*NOTREACHED*/
        case -2:                /* Install error */
        abandon:
                warnx("edits left in %s", Filename);
                goto done;
        default:
                warnx("panic: bad switch() in replace_cmd()");
                goto fatal;
        }
 remove:
        unlink(Filename);
 done:
        log_it(RealUser, Pid, "END EDIT", User);
}


/* returns      0       on success
 *              -1      on syntax error
 *              -2      on install error
 */
static int
replace_cmd(void)
{
        char n[MAX_FNAME], envstr[MAX_ENVSTR], tn[MAX_FNAME];
        FILE *tmp;
        int ch, eof;
        entry *e;
        time_t now = time(NULL);
        char **envp = env_init();

        if (envp == NULL) {
                warnx("cannot allocate memory");
                return (-2);
        }

        (void) snprintf(n, sizeof(n), "tmp.%d", Pid);
        if (snprintf(tn, sizeof(tn), CRON_TAB(n)) >= (int)sizeof(tn)) {
                warnx("path too long");
                return (-2);
        }

        if (!(tmp = fopen(tn, "w+"))) {
                warn("%s", tn);
                return (-2);
        }

        /* write a signature at the top of the file.
         *
         * VERY IMPORTANT: make sure NHEADER_LINES agrees with this code.
         */
        fprintf(tmp, "# DO NOT EDIT THIS FILE - edit the master and reinstall.\n");
        fprintf(tmp, "# (%s installed on %-24.24s)\n", Filename, ctime(&now));
        fprintf(tmp, "# (Cron version -- %s)\n", rcsid);

        /* copy the crontab to the tmp
         */
        rewind(NewCrontab);
        Set_LineNum(1)
        while (EOF != (ch = get_char(NewCrontab)))
                putc(ch, tmp);
        ftruncate(fileno(tmp), ftello(tmp));
        fflush(tmp);  rewind(tmp);

        if (ferror(tmp)) {
                warnx("error while writing new crontab to %s", tn);
                fclose(tmp);  unlink(tn);
                return (-2);
        }

        /* check the syntax of the file being installed.
         */

        /* BUG: was reporting errors after the EOF if there were any errors
         * in the file proper -- kludged it by stopping after first error.
         *              vix 31mar87
         */
        Set_LineNum(1 - NHEADER_LINES)
        CheckErrorCount = 0;  eof = FALSE;
        while (!CheckErrorCount && !eof) {
                switch (load_env(envstr, tmp)) {
                case ERR:
                        eof = TRUE;
                        break;
                case FALSE:
                        e = load_entry(tmp, check_error, pw, envp);
                        if (e)
                                free_entry(e);
                        break;
                case TRUE:
                        break;
                }
        }

        if (CheckErrorCount != 0) {
                warnx("errors in crontab file, can't install");
                fclose(tmp);  unlink(tn);
                return (-1);
        }

#ifdef HAS_FCHOWN
        if (fchown(fileno(tmp), ROOT_UID, -1) < OK)
#else
        if (chown(tn, ROOT_UID, -1) < OK)
#endif
        {
                warn("chown");
                fclose(tmp);  unlink(tn);
                return (-2);
        }

#ifdef HAS_FCHMOD
        if (fchmod(fileno(tmp), 0600) < OK)
#else
        if (chmod(tn, 0600) < OK)
#endif
        {
                warn("chown");
                fclose(tmp);  unlink(tn);
                return (-2);
        }

        if (fclose(tmp) == EOF) {
                warn("fclose");
                unlink(tn);
                return (-2);
        }

        if (snprintf(n, sizeof(n), CRON_TAB(User)) >= (int)sizeof(n)) {
                warnx("path too long");
                unlink(tn);
                return (-2);
        }

        if (rename(tn, n)) {
                warn("error renaming %s to %s", tn, n);
                unlink(tn);
                return (-2);
        }

        log_it(RealUser, Pid, "REPLACE", User);

        /*
         * Creating the 'tn' temp file has already updated the
         * modification time of the spool directory.  Sleep for a
         * second to ensure that poke_daemon() sets a later
         * modification time.  Otherwise, this can race with the cron
         * daemon scanning for updated crontabs.
         */
        sleep(1);

        poke_daemon();

        return (0);
}

static void
poke_daemon(void)
{
        if (utime(SPOOL_DIR, NULL) < OK) {
                warn("can't update mtime on spooldir %s", SPOOL_DIR);
                return;
        }
}