/* Copyright 1988,1990,1993,1994 by Paul Vixie
 * All rights reserved
 *
 * Distribute freely, except: don't remove my name from the source or
 * documentation (don't take credit for my work), mark your changes (don't
 * get me blamed for your possible bugs), don't alter or remove this
 * notice.  May be sold if buildable source is provided to buyer.  No
 * warrantee of any kind, express or implied, is included with this
 * software; use at your own risk, responsibility for damages (if any) to
 * anyone resulting from the use of this software rests entirely with the
 * user.
 *
 * Send bug reports, bug fixes, enhancements, requests, flames, etc., and
 * I'll try to keep a version up to date.  I can be reached as follows:
 * Paul Vixie          <paul@vix.com>          uunet!decwrl!vixie!paul
 *
 * From Id: crontab.c,v 2.13 1994/01/17 03:20:37 vixie Exp
 * $FreeBSD: src/usr.sbin/cron/crontab/crontab.c,v 1.12.2.4 2001/06/16 03:18:37 peter Exp $
 */

/* 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 <errno.h>
#include <fcntl.h>
#include <paths.h>
#include <sys/file.h>
#include <sys/stat.h>
#ifdef USE_UTIMES
# include <sys/time.h>
#else
# include <time.h>
# include <utime.h>
#endif
#if defined(POSIX)
# include <locale.h>
#endif


#define NHEADER_LINES 2


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

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


static  PID_T           Pid;
static  char            User[MAX_UNAME], RealUser[MAX_UNAME];
static  char            Filename[MAX_FNAME];
static  FILE            *NewCrontab;
static  int             CheckErrorCount;
static  enum opt_t      Option;
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] { -e | -l | -r }");
        exit(ERROR_EXIT);
}


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

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

#if defined(POSIX)
        setlocale(LC_ALL, "");
#endif

#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:
                                break;
        }
        exit(exitstatus);
        /*NOTREACHED*/
}


static void
parse_args(int argc, char **argv)
{
        int             argch;

        if (!(pw = getpwuid(getuid())))
                errx(ERROR_EXIT, "your UID isn't in the passwd file, bailing out");
        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:")) != -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);
                        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;
                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;
                        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) {
                /* 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 {
                        /* 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");
                        if (!(NewCrontab = fopen(Filename, "r")))
                                err(ERROR_EXIT, "%s", Filename);
                        if (swap_uids() < OK)
                                err(ERROR_EXIT, "swapping uids back");
                }
        }

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


static void
list_cmd(void)
{
        char    n[MAX_FNAME];
        FILE    *f;
        int     ch, x;

        log_it(RealUser, Pid, "LIST", User);
        sprintf(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.
         */
        Set_LineNum(1)

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

        while (EOF != (ch = get_char(f)))
                putchar(ch);
        fclose(f);
}


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

        if (isatty(STDIN_FILENO)) {
                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);
        sprintf(n, CRON_TAB(User));
        if (unlink(n)) {
                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];
        const char      *editor;
        FILE            *f;
        int             ch, t, x;
        struct stat     statbuf, fsbuf;
        time_t          mtime;
        WAIT_T          waiter;
        PID_T           pid, xpid;
        mode_t          um;

        log_it(RealUser, Pid, "BEGIN EDIT", User);
        sprintf(n, CRON_TAB(User));
        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);
        sprintf(Filename, "/tmp/crontab.XXXXXXXXXX");
        if ((t = mkstemp(Filename)) == -1) {
                warn("%s", Filename);
                umask(um);
                goto fatal;
        }
        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;
        }

        Set_LineNum(1)

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

        /* copy the rest of the crontab (if any) to the temp file.
         */
        if (EOF != ch)
                while (EOF != (ch = get_char(f)))
                        putc(ch, 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 (stat(Filename, &statbuf) < 0) {
                warn("stat");
 fatal:         unlink(Filename);
                exit(ERROR_EXIT);
        }
        if (statbuf.st_dev != fsbuf.st_dev || statbuf.st_ino != fsbuf.st_ino)
                errx(ERROR_EXIT, "temp file must be edited in place");
        mtime = statbuf.st_mtime;

        if ((!(editor = getenv("VISUAL")))
         && (!(editor = getenv("EDITOR")))
            ) {
                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, NULL);
                err(ERROR_EXIT, "%s", editor);
                /*NOTREACHED*/
        default:
                /* parent */
                break;
        }

        /* parent */
        {
        void (*fn[4])(int);
        fn[0] = signal(SIGHUP, SIG_IGN);
        fn[1] = signal(SIGINT, SIG_IGN);
        fn[2] = signal(SIGTERM, SIG_IGN);
        xpid = wait(&waiter);
        signal(SIGHUP, fn[0]);
        signal(SIGINT, fn[1]);
        signal(SIGTERM, fn[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 (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 (mtime == statbuf.st_mtime) {
                warnx("no changes made to crontab");
                goto remove;
        }
        warnx("installing new crontab");
        switch (replace_cmd()) {
        case 0:
                break;
        case -1:
                for (;;) {
                        printf("Do you want to retry the same edit? ");
                        fflush(stdout);
                        q[0] = '\0';
                        fgets(q, sizeof q, stdin);
                        switch (islower(q[0]) ? q[0] : tolower(q[0])) {
                        case 'y':
                                goto again;
                        case 'n':
                                goto abandon;
                        default:
                                fprintf(stderr, "Enter Y or N\n");
                        }
                }
                /*NOTREACHED*/
        case -2:
        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 - 5], 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);
        }

        sprintf(n, "tmp.%d", Pid);
        sprintf(tn, CRON_TAB(n));
        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));

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

        sprintf(n, CRON_TAB(User));
        if (rename(tn, n)) {
                warn("error renaming %s to %s", tn, n);
                unlink(tn);
                return (-2);
        }
        log_it(RealUser, Pid, "REPLACE", User);

        poke_daemon();

        return (0);
}


static void
poke_daemon(void)
{
#ifdef USE_UTIMES
        struct timeval tvs[2];
        struct timezone tz;

        gettimeofday(&tvs[0], &tz);
        tvs[1] = tvs[0];
        if (utimes(SPOOL_DIR, tvs) < OK) {
                warn("can't update mtime on spooldir %s", SPOOL_DIR);
                return;
        }
#else
        if (utime(SPOOL_DIR, NULL) < OK) {
                warn("can't update mtime on spooldir %s", SPOOL_DIR);
                return;
        }
#endif /*USE_UTIMES*/
}