;; 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 .
;; 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.
(use-modules (ice-9 getopt-long)
(ice-9 rdelim)
(ice-9 regex)
(mcron config)
(mcron core)
(mcron job-specifier)
(mcron vixie-specification)
(srfi srfi-2)
(srfi srfi-26))
;; Turn debugging on if indicated.
(when config-debug
(debug-enable 'debug)
(debug-enable 'backtrace))
(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)))
;; Code contributed by Sergey Poznyakoff. Print an error message (made up from
;; the parts of rest), and if the error is fatal (present and non-zero) then
;; exit to the system with this code.
(define (mcron-error exit-code . rest)
(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))))
;; 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
(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.")))))
;; 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.
(define options
(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\n
Copyright (C) 2015 the ~a authors.\n
License GPLv3+: GNU GPL version 3 or later \n
This is free software: you are free to change and redistribute it.\n
There is NO WARRANTY, to the extent permitted by law.\n"
command name version short-name)
(quit)))
(when (option-ref options 'version #f)
(show-version))
(define (show-package-information)
"Display where to get help and send bug reports."
(simple-format #t "\nReport bugs to: ~a.\n
~a home page: <~a>\n
General help using GNU software: \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]\n
Run an mcron process according to the specifications in the FILES (`-' for\n
standard input), or use all the files in ~/.config/cron (or the \n
deprecated ~/.cron) with .guile or .vixie extensions.\n
\n
-v, --version Display version\n
-h, --help Display this help message\n
-sN, --schedule[=]N Display the next N jobs that will be run by mcron\n
-d, --daemon Immediately detach the program from the terminal\n
and run as a daemon process\n
-i, --stdin=(guile|vixie) Format of data passed as standard input or\n
file arguments (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
-sN, --schedule[=]N Display the next N jobs that will be run by cron\n
-n, --noetc Do not check /etc/crontab for updates (HIGHLY\n
RECOMMENDED).")
((crontab)
" [-u user] file\n
crontab [-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")
(else "\nrubbish")))
(newline)
(show-package-information)
(quit))
(when (option-ref options 'help #f)
(show-help))
;; 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
;; invocations 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).
(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)
(c-set-cron-signals))
;; 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.
(when (eq? command-type 'crontab)
(load "crontab.scm")
(quit))
;; Code contributed by Sergey Poznyakoff. Determine if the given file is a
;; regular file or not.
(define (regular-file? file)
(catch 'system-error
(lambda ()
(eq? (stat:type (stat file)) 'regular))
(lambda (key call fmt args . rest)
(mcron-error 0 (apply format (append (list #f fmt) args)))
#f)))
;; 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 . assume-guile)
(cond ((string=? file-path "-")
(if (string=? (option-ref options 'stdin "guile") "vixie")
(read-vixie-port (current-input-port))
(eval-string (stdin->string))))
((or (not (null? assume-guile))
(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 and/or
;; $XDG_CONFIG_HOME/cron or ~/.config/cron directories (only happens under the
;; mcron personality).
(define (process-files-in-user-directory)
(let ((errors 0)
(home-directory (passwd:dir (getpw (getuid)))))
(map (lambda (config-directory)
(catch #t
(lambda ()
(let ((directory (opendir config-directory)))
(do ((file-name (readdir directory) (readdir directory)))
((eof-object? file-name) (closedir directory))
(process-user-file (string-append config-directory
"/"
file-name)))))
(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."))))
;; 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.
(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) ;; / ?? !!!!
(catch-mcron-error
(read-vixie-file (string-append config-spool-dir
"/"
file-name)))))))
(lambda (key . args)
(mcron-error
4
"You do not have permission to access the system crontabs."))))
;; 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\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 (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)))))
;; 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 '())
(when (eq? command-type 'cron)
(catch #t
(lambda ()
(let ((socket (socket AF_UNIX SOCK_STREAM 0)))
(bind socket AF_UNIX config-socket-file)
(listen socket 5)
(set! fd-list (list socket))))
(lambda (key . args)
(delete-file config-pid-file)
(mcron-error 1
"Cannot bind to UNIX socket "
config-socket-file))))
;; 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))
(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)))))))
;; Added by Sergey Poznyakoff. This no-op will collect zombie child processes
;; as soon as they die. This is a big improvement as previously they stayed
;; around the system until the next time mcron wakes to fire a new job off.
;; Unfortunately it seems to interact badly with the select system call,
;; wreaking havoc...
;; (sigaction SIGCHLD (lambda (sig) noop) SA_RESTART)
;; 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 fd-list.
(catch-mcron-error
(while #t
(run-job-loop fd-list)
(unless (null? fd-list)
(process-update-request))))