;; Copyright (C) 2003 Dale Mellor ;; ;; This program is free software; you can redistribute it and/or modify ;; it under the terms of the GNU General Public License as published by ;; the Free Software Foundation; either version 2, or (at your option) ;; any later version. ;; ;; This program is distributed in the hope that it will be useful, ;; but WITHOUT ANY WARRANTY; without even the implied warranty of ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the ;; GNU General Public License for more details. ;; ;; You should have received a copy of the GNU General Public License ;; along with this program; if not, write to the Free Software ;; Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, ;; USA. ;; This is the 'main' routine for the whole system; the top of this file is the ;; global entry point (after the minimal C wrapper, mcron.c.template); to all ;; intents and purposes the program is pure Guile and starts here. ;; ;; This file is built into mcron.c.template by the makefile, which stringifies ;; the whole lot, and escapes quotation marks and escape characters ;; accordingly. Bear this in mind when considering literal multi-line strings. ;; ;; (l0ad "crontab.scm") (sic) is inlined by the makefile. All other ;; functionality comes through modules in .../share/guile/site/mcron/*.scm. ;; Pull in some constants set by the builder (via autoconf) at configuration ;; time. Turn debugging on if indicated. (use-modules (mcron config)) (if config-debug (begin (debug-enable 'debug) (debug-enable 'backtrace))) ;; To determine the name of the program, scan the first item of the command line ;; backwards for the first non-alphabetic character. This allows names like ;; in.cron to be accepted as an invocation of the cron command. (use-modules (ice-9 regex)) (define command-name (match:substring (regexp-exec (make-regexp "[[:alpha:]]*$") (car (command-line))))) ;; We will be doing a lot of testing of the command name, so it makes sense to ;; perform the string comparisons once and for all here. (define command-type (cond ((string=? command-name "mcron") 'mcron) ((or (string=? command-name "cron") (string=? command-name "crond")) 'cron) ((string=? command-name "crontab") 'crontab) (else (display "The command name is invalid.\n") (primitive-exit 12)))) ;; There are a different set of options for the crontab personality compared to ;; all the others, with the --help and --version options common to all the ;; personalities. (use-modules (ice-9 getopt-long)) (define options (getopt-long (command-line) (append (case command-type ('crontab '((user (single-char #\u) (value #t)) (edit (single-char #\e) (value #f)) (list (single-char #\l) (value #f)) (remove (single-char #\r) (value #f)))) (else `((schedule (single-char #\s) (value optional)) (daemon (single-char #\d) (value #f)) (noetc (single-char #\n) (value #f)) (stdin (single-char #\i) (value #t) (predicate ,(lambda (value) (or (string=? "vixie" value) (string=? "guile" value)))))))) '((version (single-char #\v) (value #f)) (help (single-char #\h) (value #f)))))) ;; If the user asked for the version of this program, give it to him and get ;; out. (if (option-ref options 'version #f) (begin (display (string-append "\n " command-name " (" config-package-string ")\n Written by Dale Mellor\n \n Copyright (C) 2003 Dale Mellor\n This is free software; see the source for copying conditions. There is NO\n warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.\n ")) (quit))) ;; Likewise if the user requested the help text. (if (option-ref options 'help #f) (begin (display (string-append " Usage: " (car (command-line)) (case command-type ('mcron " [OPTIONS] [FILES]\n Run an mcron process according to the specifications in the FILES (`-' for\n standard input), or use all the files in ~/.cron with .guile or .vixie\n extensions.\n \n -v, --version Display version\n -h, --help Display this help message\n -s, --schedule[=COUNT] Display the next COUNT jobs (default 8) that\n will be run by mcron\n -d, --daemon Immediately detach the program from the terminal and\n run as a daemon process\n -i, --stdin=(guile|vixie) Format of data passed as standard input\n (default guile)") ('cron " [OPTIONS]\n Unless an option is specified, run a cron daemon as a detached process, \n reading all the information in the users' crontabs and in /etc/crontab.\n \n -v, --version Display version\n -h, --help Display this help message\n -s, --schedule[=COUNT] Display the next COUNT jobs (default 8) that\n will be run by cron\n -n, --noetc Do not check /etc/crontab for updates (HIGHLY\n RECOMMENDED).") ('crontab (string-append " [-u user] file\n" " " (car (command-line)) " [-u user] { -e | -l | -r }\n" " (default operation is replace, per 1003.2)\n" " -e (edit user's crontab)\n" " -l (list user's crontab)\n" " -r (delete user's crontab)\n"))) "\n\n Report bugs to " config-package-bugreport ".\n ")) (quit))) ;; This is called from the C front-end whenever a terminal signal is ;; received. We remove the /var/run/cron.pid file so that crontab and other ;; invokations of cron don't get the wrong idea that a daemon is currently ;; running. (define (delete-run-file) (catch #t (lambda () (delete-file config-pid-file) (delete-file config-socket-file)) noop) (quit)) ;; Setup the cron process, if appropriate. If there is already a ;; /var/run/cron.pid file, then we must assume a cron daemon is already running ;; and refuse to start another one. ;; ;; Otherwise, clear the MAILTO environment variable so that output from cron ;; jobs is sent to the various users (this may still be overridden in the ;; configuration files), and call the function in the C wrapper to set up ;; terminal signal responses to vector to the procedure above. The PID file will ;; be filled in properly later when we have forked our daemon process (but not ;; done if we are only viewing the schedules). (if (eq? command-type 'cron) (begin (if (not (eqv? (getuid) 0)) (begin (display "This program must be run by the root user (and should ") (display "have been installed as such).\n") (primitive-exit 16))) (if (access? config-pid-file F_OK) (begin (display "A cron daemon is already running.\n") (display " (If you are sure this is not true, remove the file\n") (display " " config-pid-file ".)\n") (primitive-exit 1))) (if (not (option-ref options 'schedule #f)) (with-output-to-file config-pid-file noop)) (setenv "MAILTO" #f) (c-set-cron-signals))) ;; Define the functions available to the configuration files. While we're here, ;; we'll get the core loaded as well. (use-modules (mcron core) (mcron job-specifier) (mcron vixie-specification)) ;; Procedure to slurp the standard input into a string. (define (stdin->string) (with-output-to-string (lambda () (do ((in (read-char) (read-char))) ((eof-object? in)) (display in))))) ;; Now we have the procedures in place for dealing with the contents of ;; configuration files, the crontab personality is able to validate such ;; files. If the user requested the crontab personality, we load and run the ;; code here and then get out. (if (eq? command-type 'crontab) (begin (load "crontab.scm") (quit))) ;; Procedure which processes any configuration file according to the ;; extension. If a file is not recognized, it is silently ignored (this deals ;; properly with most editors' backup files, for instance). (define guile-file-regexp (make-regexp "\\.gui(le)?$")) (define vixie-file-regexp (make-regexp "\\.vix(ie)?$")) (define (process-user-file file-path) (cond ((string=? file-path "-") (if (string=? (option-ref options 'stdin "guile") "vixie") (read-vixie-port (current-input-port)) (eval-string (stdin->string)))) ((regexp-exec guile-file-regexp file-path) (load file-path)) ((regexp-exec vixie-file-regexp file-path) (read-vixie-file file-path)))) ;; Procedure to run through all the files in a user's ~/.cron directory (only ;; happens under the mcron personality). (define (process-files-in-user-directory) (catch #t (lambda () (let* ((dir-path (string-append (passwd:dir (getpw (getuid))) "/.cron")) (directory (opendir dir-path))) (do ((file-name (readdir directory) (readdir directory))) ((eof-object? file-name) (closedir directory)) (process-user-file (string-append dir-path "/" file-name))))) (lambda (key . args) (display "Cannot read files in your ~/.cron directory.\n") (primitive-exit 13)))) ;; Procedure to check that a user name is in the passwd database (it may happen ;; that a user is removed after creating a crontab). If the user name is valid, ;; the full passwd entry for that user is returned to the caller. (define (valid-user user-name) (setpwent) (do ((entry (getpw) (getpw))) ((or (not entry) (string=? (passwd:name entry) user-name)) (endpwent) entry))) ;; Procedure to process all the files in the crontab directory, making sure that ;; each file is for a legitimate user and setting the configuration-user to that ;; user. In this way, when the job procedure is run on behalf of the ;; configuration files, the jobs are registered with the system with the ;; appropriate user. Note that only the root user should be able to perform this ;; operation, but we leave it to the permissions on the /var/cron/tabs directory ;; to enforce this. (use-modules (srfi srfi-2)) ;; For and-let*. (define (process-files-in-system-directory) (catch #t (lambda () (let ((directory (opendir config-spool-dir))) (do ((file-name (readdir directory) (readdir directory))) ((eof-object? file-name)) (and-let* ((user (valid-user file-name))) (set-configuration-user user) (read-vixie-file (string-append config-spool-dir file-name)))))) (lambda (key . args) (display "You do not have permission to access the system crontabs.\n") (primitive-exit 4)))) ;; Having defined all the necessary procedures for scanning various sets of ;; files, we perform the actual configuration of the program depending on the ;; personality we are running as. If it is mcron, we either scan the files ;; passed on the command line, or else all the ones in the user's .cron ;; directory. If we are running under the cron personality, we read the ;; /var/cron/tabs directory and also the /etc/crontab file. (case command-type ('mcron (if (null? (option-ref options '() '())) (process-files-in-user-directory) (for-each (lambda (file-path) (process-user-file file-path)) (option-ref options '() '())))) ('cron (process-files-in-system-directory) (use-system-job-list) (read-vixie-file "/etc/crontab" parse-system-vixie-line) (use-user-job-list) (if (not (option-ref options 'noetc #f)) (begin (display "WARNING: cron will check for updates to /etc/crontab EVERY MINUTE. If you do\n not use this file, or you are prepared to manually restart cron whenever you\n make a change, then it is HIGHLY RECOMMENDED that you use the --noetc\n option.\n") (set-configuration-user "root") (job '(- (next-minute-from (next-minute)) 6) check-system-crontab "/etc/crontab update checker."))))) ;; If the user has requested a schedule of jobs that will run, we provide the ;; information here and then get out. ;; ;; Start by determining the number of time points in the future that output is ;; required for. This may be provided on the command line as a parameter to the ;; --schedule option, or else we assume a default of 8. Finally, ensure that the ;; count is some positive integer. (and-let* ((count (option-ref options 'schedule #f))) (set! count (if (eq? count #t) 8 (string->number count))) (display (get-schedule (if (<= count 0) 1 count))) (quit)) ;; If we are supposed to run as a daemon process (either a --daemon option has ;; been explicitly used, or we are running as cron or crond), detach from the ;; terminal now. If we are running as cron, we can now write the PID file. (if (option-ref options 'daemon (eq? command-type 'cron)) (begin (if (not (eqv? (primitive-fork) 0)) (quit)) (setsid) (if (eq? command-type 'cron) (with-output-to-file config-pid-file (lambda () (display (getpid)) (newline)))))) ;; If we are running as cron or crond, we establish a socket to listen for ;; updates from a crontab program. This is put into fd-list so that we can ;; inform the main wait-run-wait execution loop to listen for incoming messages ;; on this socket. (define fd-list '()) (if (eq? command-type 'cron) (let ((socket (socket AF_UNIX SOCK_STREAM 0))) (bind socket AF_UNIX config-socket-file) (listen socket 5) (set! fd-list (list socket)))) ;; This function is called whenever a message comes in on the above socket. We ;; read a user name from the socket, dealing with the "/etc/crontab" special ;; case, remove all the user's jobs from the job list, and then re-read the ;; user's updated file. In the special case we drop all the system jobs and ;; re-read the /etc/crontab file. (define (process-update-request) (let* ((socket (car (accept (car fd-list)))) (user-name (read-line socket))) (close socket) (set-configuration-time (current-time)) (if (string=? user-name "/etc/crontab") (begin (clear-system-jobs) (use-system-job-list) (read-vixie-file "/etc/crontab" parse-system-vixie-line) (use-user-job-list)) (let ((user (getpw user-name))) (remove-user-jobs user) (set-configuration-user user) (read-vixie-file (string-append config-spool-dir "/" user-name)))))) ;; Now the main loop. Forever execute the run-job-loop procedure in the mcron ;; core, and when it drops out (can only be because a message has come in on the ;; socket) we process the socket request before restarting the loop again. (while #t (run-job-loop fd-list) (process-update-request))