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Diffstat (limited to 'src/mcron/main.scm')
| -rw-r--r-- | src/mcron/main.scm | 401 |
1 files changed, 401 insertions, 0 deletions
diff --git a/src/mcron/main.scm b/src/mcron/main.scm new file mode 100644 index 0000000..1f2b068 --- /dev/null +++ b/src/mcron/main.scm @@ -0,0 +1,401 @@ +;; Copyright (C) 2015, 2016 Mathieu Lirzin +;; Copyright (C) 2003, 2012 Dale Mellor +;; +;; This file is part of GNU mcron. +;; +;; GNU mcron 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 3 of the License, or (at your option) +;; any later version. +;; +;; GNU mcron 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 GNU mcron. If not, see <http://www.gnu.org/licenses/>. + +;;; This is the 'main' routine for the whole system; this module is the global +;;; entry point (after the minimal C wrapper); to all intents and purposes the +;;; program is pure Guile and starts here. + +(define-module (mcron main) + #:use-module (ice-9 getopt-long) + #:use-module (ice-9 rdelim) + #:use-module (ice-9 regex) + #:use-module (mcron config) + #:use-module (mcron core) + #:use-module (mcron job-specifier) + #:use-module (mcron vixie-specification) + #:use-module (srfi srfi-2) + #:use-module (srfi srfi-26) + #:export (delete-run-file + main)) + +(define* (command-name #:optional (command (car (command-line)))) + "Extract the actual command name from COMMAND. This returns the last part +of COMMAND without any non-alphabetic characters. For example \"in.cron\" and +\"./mcron\" will return respectively \"cron\" and \"mcron\". + +When COMMAND is not specified this uses the first element of (command-line)." + (match:substring (regexp-exec (make-regexp "[[:alpha:]]*$") command))) + +(define (mcron-error exit-code . rest) + "Print an error message (made up from the parts of REST), and if the +EXIT-CODE error is fatal (present and non-zero) then exit to the system with +EXIT-CODE." + (with-output-to-port (current-error-port) + (lambda () + (for-each display (append (list (command-name) ": ") rest)) + (newline))) + (when (and exit-code (not (eq? exit-code 0))) + (primitive-exit exit-code))) + +(define-syntax-rule (catch-mcron-error exp ...) + "Evaluate EXP .... if an 'mcron-error exception occurs, print its diagnostics +and exit with its error code." + (catch 'mcron-error + (lambda () exp ...) + (lambda (key exit-code . msg) + (apply mcron-error exit-code msg)))) + +(define command-type + ;; 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. + (let* ((command (command-name)) + (command=? (cut string=? command <>))) + (cond ((command=? "mcron") 'mcron) + ((or (command=? "cron") (command=? "crond")) 'cron) + ((command=? "crontab") 'crontab) + (else (mcron-error 12 "The command name is invalid."))))) + +(define options + ;; 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. + (catch + 'misc-error + (lambda () + (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 #t) + (predicate + ,(lambda (value) + (string->number value)))) + (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)))))) + (lambda (key func fmt args . rest) + (mcron-error 1 (apply format (append (list #f fmt) args)))))) + +(define* (show-version #:optional (command (command-name))) + "Display version information for COMMAND and quit." + (let* ((name config-package-name) + (short-name (cadr (string-split name #\space))) + (version config-package-version)) + (simple-format #t "~a (~a) ~a +Copyright (C) 2015 the ~a authors. +License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html> +This is free software: you are free to change and redistribute it. +There is NO WARRANTY, to the extent permitted by law.\n" + command name version short-name) + (quit))) + +(define (show-package-information) + "Display where to get help and send bug reports." + (simple-format #t "\nReport bugs to: ~a. +~a home page: <~a> +General help using GNU software: <http://www.gnu.org/gethelp/>\n" + config-package-bugreport + config-package-name + config-package-url)) + +(define* (show-help #:optional (command (command-name))) + "Display informations of usage for COMMAND and quit." + (simple-format #t "Usage: ~a" command) + (display + (case command-type + ((mcron) + " [OPTIONS] [FILES] +Run an mcron process according to the specifications in the FILES (`-' for +standard input), or use all the files in ~/.config/cron (or the +deprecated ~/.cron) with .guile or .vixie extensions. + + -v, --version Display version + -h, --help Display this help message + -sN, --schedule[=]N Display the next N jobs that will be run by mcron + -d, --daemon Immediately detach the program from the terminal + and run as a daemon process + -i, --stdin=(guile|vixie) Format of data passed as standard input or + file arguments (default guile)") + ((cron) + " [OPTIONS] +Unless an option is specified, run a cron daemon as a detached process, +reading all the information in the users' crontabs and in /etc/crontab. + + -v, --version Display version + -h, --help Display this help message + -sN, --schedule[=]N Display the next N jobs that will be run by cron + -n, --noetc Do not check /etc/crontab for updates (HIGHLY + RECOMMENDED).") + ((crontab) + " [-u user] file + crontab [-u user] { -e | -l | -r } + (default operation is replace, per 1003.2) + -e (edit user's crontab) + -l (list user's crontab) + -r (delete user's crontab") + (else "\nrubbish"))) + (newline) + (show-package-information) + (quit)) + +(define (delete-run-file) + "Remove the /var/run/cron.pid file so that crontab and other invocations of +cron don't get the wrong idea that a daemon is currently running. This +procedure is called from the C front-end whenever a terminal signal is +received." + (catch #t (lambda () (delete-file config-pid-file) + (delete-file config-socket-file)) + noop) + (quit)) + +(define (stdin->string) + "Return standard input as a string." + (with-output-to-string (lambda () (do ((in (read-char) (read-char))) + ((eof-object? in)) + (display in))))) + +(define (for-each-file proc directory) + "Apply PROC to each file in DIRECTORY. DIRECTORY must be a valid directory name. +PROC must be a procedure that take one file name argument. The return value +is not specified" + (let ((dir (opendir directory))) + (do ((file-name (readdir dir) (readdir dir))) + ((eof-object? file-name) (closedir dir)) + (proc file-name)))) + +(define process-user-file + (let ((guile-regexp (make-regexp "\\.gui(le)?$")) + (vixie-regexp (make-regexp "\\.vix(ie)?$"))) + (lambda* (file-name #:optional guile-syntax?) + "Process FILE-NAME according its extension. When GUILE-SYNTAX? is TRUE, +force guile syntax usage. If FILE-NAME format is not recognized, it is +silently ignored." + (cond ((string=? "-" file-name) + (if (string=? (option-ref options 'stdin "guile") "vixie") + (read-vixie-port (current-input-port)) + (eval-string (stdin->string)))) + ((or guile-syntax? (regexp-exec guile-regexp file-name)) + (load file-name)) + ((regexp-exec vixie-regexp file-name) + (read-vixie-file file-name)))))) + +(define (process-files-in-user-directory) + "Process files in $XDG_CONFIG_HOME/cron and/or ~/.cron directories (if +$XDG_CONFIG_HOME is not defined uses ~/.config/cron instead)." + (let ((errors 0) + (home-directory (passwd:dir (getpw (getuid))))) + (map (lambda (dir) + (catch #t + (lambda () + (for-each-file + (lambda (file) + (process-user-file (string-append dir "/" file))) + dir)) + (lambda (key . args) + (set! errors (1+ errors))))) + (list (string-append home-directory "/.cron") + (string-append (or (getenv "XDG_CONFIG_HOME") + (string-append home-directory "/.config")) + "/cron"))) + (when (eq? 2 errors) + (mcron-error 13 + "Cannot read files in your ~/.config/cron (or ~/.cron) directory.")))) + +(define (process-files-in-system-directory) + "Process all the files in the crontab directory. When the job procedure is +run on behalf of the configuration files, the jobs are registered on the +system with the appropriate user. Only root should be able to perform this +operation. The permissions on the /var/cron/tabs directory enforce this." + + (define (user-entry name) + ;; Return the user database entry if NAME is valid, otherwise #f. + (false-if-exception (getpwnam name))) + + (catch #t + (lambda () + (for-each-file + (lambda (user) + (and-let* ((entry (user-entry user))) ;crontab without user? + (set-configuration-user entry) + (catch-mcron-error + (read-vixie-file (string-append config-spool-dir "/" user))))) + config-spool-dir)) + (lambda (key . args) + (mcron-error 4 + "You do not have permission to access the system crontabs.")))) + +(define (cron-file-descriptors) + "Establish a socket to listen for updates from a crontab program, and return +a list containing the file descriptors correponding to the files read by +crontab. This requires that command-type is 'cron." + (if (eq? command-type 'cron) + (catch #t + (lambda () + (let ((sock (socket AF_UNIX SOCK_STREAM 0))) + (bind sock AF_UNIX config-socket-file) + (listen sock 5) + (list sock))) + (lambda (key . args) + (delete-file config-pid-file) + (mcron-error 1 "Cannot bind to UNIX socket " config-socket-file))) + '())) + +(define (process-update-request fdes-list) + "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 drop all the system jobs and re-read +the /etc/crontab file. This function should be called whenever a message +comes in on the above socket." + (let* ((sock (car (accept (car fdes-list)))) + (user-name (read-line sock))) + (close sock) + (set-configuration-time (current-time)) + (catch-mcron-error + (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))))))) + + +;;; +;;; Entry point. +;;; + +(define (main . args) + ;; Turn debugging on if indicated. + (when config-debug + (debug-enable 'backtrace)) + (when (option-ref options 'version #f) + (show-version)) + (when (option-ref options 'help #f) + (show-help)) + + ;; 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). + (when (eq? command-type 'cron) + (unless (eqv? (getuid) 0) + (mcron-error 16 + "This program must be run by the root user (and should have been " + "installed as such).")) + (when (access? config-pid-file F_OK) + (mcron-error 1 + "A cron daemon is already running.\n (If you are sure this is not" + " true, remove the file\n " config-pid-file ".)")) + (unless (option-ref options 'schedule #f) + (with-output-to-file config-pid-file noop)) + (setenv "MAILTO" #f) + ;; XXX: At compile time, this yields a "possibly unbound variable" + ;; warning, but this is OK since it is bound in the C wrapper. + (c-set-cron-signals)) + + ;; 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. + (when (eq? command-type 'crontab) + (load "crontab.scm") + (quit)) + + ;; 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 + ;; .config/cron (or .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 #t)) + (option-ref options '() '())))) + ((cron) + (process-files-in-system-directory) + (use-system-job-list) + (catch-mcron-error (read-vixie-file "/etc/crontab" + parse-system-vixie-line)) + (use-user-job-list) + (unless (option-ref options 'noetc #f) + (display "\ +WARNING: cron will check for updates to /etc/crontab EVERY MINUTE. If you do +not use this file, or you are prepared to manually restart cron whenever you +make a change, then it is HIGHLY RECOMMENDED that you use the --noetc +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 (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. + (when (option-ref options 'daemon (eq? command-type 'cron)) + (unless (eqv? (primitive-fork) 0) + (quit)) + (setsid) + (when (eq? command-type 'cron) + (with-output-to-file config-pid-file + (lambda () (display (getpid)) (newline))))) + + ;; 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. Sergey Poznyakoff: we can also drop out of run-job-loop + ;; because of a SIGCHLD, so must test FDES-LIST. + (catch-mcron-error + (let ((fdes-list (cron-file-descriptors))) + (while #t + (run-job-loop fdes-list) + (unless (null? fdes-list) + (process-update-request fdes-list)))))) |