Broken all functionality out into separate modules.

1 files changed, 419 insertions, 0 deletions

diff --git a/main.scm b/main.scm
new file mode 100644
index 0000000..94cb004
--- /dev/null
+++ b/main.scm
@@ -0,0 +1,419 @@
+;;   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 "/var/run/cron.pid")
+                       (delete-file "/var/cron/socket"))
+            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? "/var/run/cron.pid" 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 "   /var/run/cron.pid.)\n")
+            (primitive-exit 1)))
+      (if (not (option-ref options 'schedule #f))
+          (with-output-to-file "/var/run/cron.pid" 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 "/var/cron/tabs")))
+                (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 "/var/cron/tabs/"
+                                                            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 "/var/run/cron.pid"
+            (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 "/var/cron/socket")
+      (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 "/var/cron/tabs/" 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))