Juggled build infrastructure to make mcron.1 man page properly.

1 files changed, 503 insertions, 0 deletions

diff --git a/scm/mcron/main.scm b/scm/mcron/main.scm
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+;;   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; 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) (ice-9 rdelim))
+
+(define command-name (match:substring (regexp-exec (make-regexp "[[:alpha:]]*$")
+                                                   (car (command-line)))))
+
+
+
+;; 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)))
+  (if (and exit-code (not (eq? exit-code 0)))
+      (primitive-exit exit-code)))
+
+
+
+;; Code contributed by Sergey Poznyakoff.  Execute body. If an 'mcron-error
+;; exception occurs, print its diagnostics and exit with its error code.
+
+(defmacro catch-mcron-error (. body)
+  `(catch 'mcron-error
+          (lambda ()
+            ,@body)
+          (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 (cond ((string=? command-name "mcron") 'mcron)
+                           ((or (string=? command-name "cron")
+                                (string=? command-name "crond")) 'cron)
+                           ((string=? command-name "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.
+
+(use-modules (ice-9 getopt-long))
+
+(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))))))
+
+;; 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, 2006, 2014  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 ~/.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)
+           (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"))
+
+  (else "rubbish"))
+
+"\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
+;; 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).
+
+(if (eq? command-type 'cron)
+    (begin
+      (if (not (eqv? (getuid) 0))
+          (mcron-error 16
+                       "This program must be run by the root user (and should "
+                       "have been installed as such)."))
+      (if (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
+		       ".)"))
+      (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)))
+
+
+
+;; 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")))
+    (if (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.
+
+(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)         ;; / ?? !!!!
+                         (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)
+   (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 (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)
+    (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)
+        (if (not (null? fd-list))
+            (process-update-request))))