Patch from Havard Eidnes <Havard.Eidnes@runit.sintef.no>:

[unix-history] / usr.bin / crontab / crontab.c

/* 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
*/

#if !defined(lint) && !defined(LINT)
static char rcsid[] = "$Header: /a/cvs/386BSD/src/usr.bin/crontab/crontab.c,v 1.2 1994/01/22 20:41:10 guido 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 <errno.h>
#include <fcntl.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 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[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 __P((void)),
                       delete_cmd __P((void)),
                       edit_cmd __P((void)),
                       poke_daemon __P((void)),
                       check_error __P((char *)),
                       parse_args __P((int c, char *v[]));
static  int             replace_cmd __P((void));


static void
usage(msg)
       char *msg;
{
       fprintf(stderr, "%s: usage error: %s\n", ProgramName, msg);
       fprintf(stderr, "usage:\t%s [-u user] file\n", ProgramName);
       fprintf(stderr, "\t%s [-u user] { -e | -l | -r }\n", ProgramName);
       fprintf(stderr, "\t\t(default operation is replace, per 1003.2)\n");
       fprintf(stderr, "\t-e\t(edit user's crontab)\n");
       fprintf(stderr, "\t-l\t(list user's crontab)\n");
       fprintf(stderr, "\t-r\t(delete user's crontab)\n");
       exit(ERROR_EXIT);
}


int
main(argc, argv)
       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)) {
               fprintf(stderr,
                       "You (%s) are not allowed to use this program (%s)\n",
                       User, ProgramName);
               fprintf(stderr, "See crontab(1) for more information\n");
               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;
       }
       exit(0);
       /*NOTREACHED*/
}
       

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

       if (!(pw = getpwuid(getuid()))) {
               fprintf(stderr, "%s: your UID isn't in the passwd file.\n",
                       ProgramName);
               fprintf(stderr, "bailing out.\n");
               exit(ERROR_EXIT);
       }
       strcpy(User, pw->pw_name);
       strcpy(RealUser, User);
       Filename[0] = '\0';
       Option = opt_unknown;
       while (EOF != (argch = getopt(argc, argv, "u:lerx:"))) {
               switch (argch) {
               case 'x':
                       if (!set_debug_flags(optarg))
                               usage("bad debug option");
                       break;
               case 'u':
                       if (getuid() != ROOT_UID)
                       {
                               fprintf(stderr,
                                       "must be privileged to use -u\n");
                               exit(ERROR_EXIT);
                       }
                       if (!(pw = getpwnam(optarg)))
                       {
                               fprintf(stderr, "%s:  user `%s' unknown\n",
                                       ProgramName, optarg);
                               exit(ERROR_EXIT);
                       }
                       (void) strcpy(User, optarg);
                       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;
                       (void) strcpy (Filename, argv[optind]);
               } 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) {
                               perror("swapping uids");
                               exit(ERROR_EXIT);
                       }
                       if (!(NewCrontab = fopen(Filename, "r"))) {
                               perror(Filename);
                               exit(ERROR_EXIT);
                       }
                       if (swap_uids() < OK) {
                               perror("swapping uids back");
                               exit(ERROR_EXIT);
                       }
               }
       }

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


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

       log_it(RealUser, Pid, "LIST", User);
       (void) sprintf(n, CRON_TAB(User));
       if (!(f = fopen(n, "r"))) {
               if (errno == ENOENT)
                       fprintf(stderr, "no crontab for %s\n", User);
               else
                       perror(n);
               exit(ERROR_EXIT);
       }

       /* file is open. copy to stdout, close.
        */
       Set_LineNum(1)
       while (EOF != (ch = get_char(f)))
               putchar(ch);
       fclose(f);
}


static void
delete_cmd() {
       char    n[MAX_FNAME];

       log_it(RealUser, Pid, "DELETE", User);
       (void) sprintf(n, CRON_TAB(User));
       if (unlink(n)) {
               if (errno == ENOENT)
                       fprintf(stderr, "no crontab for %s\n", User);
               else
                       perror(n);
               exit(ERROR_EXIT);
       }
       poke_daemon();
}


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


static void
edit_cmd() {
       char            n[MAX_FNAME], q[MAX_TEMPSTR], *editor;
       FILE            *f;
       int             ch, t, x;
       struct stat     statbuf;
       time_t          mtime;
       WAIT_T          waiter;
       PID_T           pid, xpid;

       log_it(RealUser, Pid, "BEGIN EDIT", User);
       (void) sprintf(n, CRON_TAB(User));
       if (!(f = fopen(n, "r"))) {
               if (errno != ENOENT) {
                       perror(n);
                       exit(ERROR_EXIT);
               }
               fprintf(stderr, "no crontab for %s - using an empty one\n",
                       User);
               if (!(f = fopen("/dev/null", "r"))) {
                       perror("/dev/null");
                       exit(ERROR_EXIT);
               }
       }

       (void) sprintf(Filename, "/tmp/crontab.%d", Pid);
       if (-1 == (t = open(Filename, O_CREAT|O_EXCL|O_RDWR, 0600))) {
               perror(Filename);
               goto fatal;
       }
#ifdef HAS_FCHOWN
       if (fchown(t, getuid(), getgid()) < 0) {
#else
       if (chown(Filename, getuid(), getgid()) < 0) {
#endif
               perror("fchown");
               goto fatal;
       }
       if (!(NewCrontab = fdopen(t, "r+"))) {
               perror("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) < OK) {
               perror(Filename);
               exit(ERROR_EXIT);
       }
again:
       rewind(NewCrontab);
       if (ferror(NewCrontab)) {
               fprintf(stderr, "%s: error while writing new crontab to %s\n",
                       ProgramName, Filename);
fatal:         unlink(Filename);
               exit(ERROR_EXIT);
       }
       if (fstat(t, &statbuf) < 0) {
               perror("fstat");
               goto fatal;
       }
       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:
               perror("fork");
               goto fatal;
       case 0:
               /* child */
               if (setuid(getuid()) < 0) {
                       perror("setuid(getuid())");
                       exit(ERROR_EXIT);
               }
               if (chdir("/tmp") < 0) {
                       perror("chdir(/tmp)");
                       exit(ERROR_EXIT);
               }
               if (strlen(editor) + strlen(Filename) + 2 >= MAX_TEMPSTR) {
                       fprintf(stderr, "%s: editor or filename too long\n",
                               ProgramName);
                       exit(ERROR_EXIT);
               }
               sprintf(q, "%s %s", editor, Filename);
               execlp(_PATH_BSHELL, _PATH_BSHELL, "-c", q, NULL);
               perror(editor);
               exit(ERROR_EXIT);
               /*NOTREACHED*/
       default:
               /* parent */
               break;
       }

       /* parent */
       xpid = wait(&waiter);
       if (xpid != pid) {
               fprintf(stderr, "%s: wrong PID (%d != %d) from \"%s\"\n",
                       ProgramName, xpid, pid, editor);
               goto fatal;
       }
       if (WIFEXITED(waiter) && WEXITSTATUS(waiter)) {
               fprintf(stderr, "%s: \"%s\" exited with status %d\n",
                       ProgramName, editor, WEXITSTATUS(waiter));
               goto fatal;
       }
       if (WIFSIGNALED(waiter)) {
               fprintf(stderr,
                       "%s: \"%s\" killed; signal %d (%score dumped)\n",
                       ProgramName, editor, WTERMSIG(waiter),
                       WCOREDUMP(waiter) ?"" :"no ");
               goto fatal;
       }
       if (fstat(t, &statbuf) < 0) {
               perror("fstat");
               goto fatal;
       }
       if (mtime == statbuf.st_mtime) {
               fprintf(stderr, "%s: no changes made to crontab\n",
                       ProgramName);
               goto remove;
       }
       fprintf(stderr, "%s: installing new crontab\n", ProgramName);
       switch (replace_cmd()) {
       case 0:
               break;
       case -1:
               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':
                               goto again;
                       case 'n':
                               goto abandon;
                       default:
                               fprintf(stderr, "Enter Y or N\n");
                       }
               }
               /*NOTREACHED*/
       case -2:
       abandon:
               fprintf(stderr, "%s: edits left in %s\n",
                       ProgramName, Filename);
               goto done;
       default:
               fprintf(stderr, "%s: panic: bad switch() in replace_cmd()\n");
               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() {
       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();

       (void) sprintf(n, "tmp.%d", Pid);
       (void) sprintf(tn, CRON_TAB(n));
       if (!(tmp = fopen(tn, "w+"))) {
               perror(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), ftell(tmp));
       fflush(tmp);  rewind(tmp);

       if (ferror(tmp)) {
               fprintf(stderr, "%s: error while writing new crontab to %s\n",
                       ProgramName, 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) {
               fprintf(stderr, "errors in crontab file, can't install.\n");
               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
       {
               perror("chown");
               fclose(tmp);  unlink(tn);
               return (-2);
       }

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

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

       (void) sprintf(n, CRON_TAB(User));
       if (rename(tn, n)) {
               fprintf(stderr, "%s: error renaming %s to %s\n",
                       ProgramName, tn, n);
               perror("rename");
               unlink(tn);
               return (-2);
       }
       log_it(RealUser, Pid, "REPLACE", User);

       poke_daemon();

       return (0);
}


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

       (void) gettimeofday(&tvs[0], &tz);
       tvs[1] = tvs[0];
       if (utimes(SPOOL_DIR, tvs) < OK) {
               fprintf(stderr, "crontab: can't update mtime on spooldir\n");
               perror(SPOOL_DIR);
               return;
       }
#else
       if (utime(SPOOL_DIR, NULL) < OK) {
               fprintf(stderr, "crontab: can't update mtime on spooldir\n");
               perror(SPOOL_DIR);
               return;
       }
#endif /*USE_UTIMES*/
}