Merge branch 'devel'

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diff --git a/src/mcron/scripts/crontab.scm b/src/mcron/scripts/crontab.scm
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+;;;; crontab -- edit user's cron tabs
+;;; Copyright © 2003, 2004 Dale Mellor <dale_mellor@users.sourceforge.net>
+;;; Copyright © 2016 Mathieu Lirzin <mthl@gnu.org>
+;;;
+;;; 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/>.
+
+(define-module (mcron scripts crontab)
+  #:use-module (ice-9 rdelim)
+  #:use-module (mcron config)
+  #:use-module (mcron utils)
+  #:use-module (mcron vixie-specification)
+  #:export (main))
+
+(define* (show-help)
+  (display "Usage: 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")
+  (newline)
+  (show-package-information))
+
+(define %options
+  '((user     (single-char #\u) (value #t))
+    (edit     (single-char #\e) (value #f))
+    (list     (single-char #\l) (value #f))
+    (remove   (single-char #\r) (value #f))
+    (version  (single-char #\v) (value #f))
+    (help     (single-char #\h) (value #f))))
+
+
+;;;
+;;; Entry point.
+;;;
+
+(define* (main #:optional (args (command-line)))
+  (let ((opts (parse-args args %options)))
+    (when config-debug
+      (debug-enable 'backtrace))
+    (cond ((option-ref opts 'help #f)
+           (show-help)
+           (exit 0))
+          ((option-ref opts 'version #f)
+           (show-version "crontab")
+           (exit 0)))
+    (let ((hit-server
+           (λ (user-name)
+             ;; Procedure to communicate with running cron daemon that a user
+             ;; has modified his crontab. The user name is written to the
+             ;; /var/cron/socket UNIX socket.
+             (catch #t
+               (λ ()
+                 (let ((socket (socket AF_UNIX SOCK_STREAM 0)))
+                   (connect socket AF_UNIX config-socket-file)
+                   (display user-name socket)
+                   (close socket)))
+               (λ (key . args)
+                 (display "Warning: a cron daemon is not running.\n")))))
+
+          ;; Procedure to scan a file containing one user name per line (such
+          ;; as /var/cron/allow and /var/cron/deny), and determine if the
+          ;; given name is in there. The procedure returns #t, #f, or '() if
+          ;; the file does not exist.
+          (in-access-file?
+           (λ (file name)
+             (catch #t
+               (λ ()
+                 (with-input-from-file file
+                   (λ ()
+                     (let loop ((input (read-line)))
+                       (if (eof-object? input)
+                           #f
+                           (if (string=? input name)
+                               #t
+                               (loop (read-line))))))))
+               (λ (key . args) '()))))
+
+          ;; This program should have been installed SUID root. Here we get
+          ;; the passwd entry for the real user who is running this program.
+          (crontab-real-user (passwd:name (getpw (getuid)))))
+
+      ;; If the real user is not allowed to use crontab due to the
+      ;; /var/cron/allow and/or /var/cron/deny files, bomb out now.
+      (if (or (eq? (in-access-file? config-allow-file crontab-real-user) #f)
+              (eq? (in-access-file? config-deny-file crontab-real-user) #t))
+          (mcron-error 6 "Access denied by system operator."))
+
+      ;; Check that no more than one of the mutually exclusive options are
+      ;; being used.
+      (when (> (+ (if (option-ref opts 'edit #f) 1 0)
+                  (if (option-ref opts 'list #f) 1 0)
+                  (if (option-ref opts 'remove #f) 1 0))
+               1)
+        (mcron-error 7 "Only one of options -e, -l or -r can be used."))
+
+      ;; Check that a non-root user is trying to read someone else's files.
+      (when (and (not (zero? (getuid)))
+                 (option-ref opts 'user #f))
+        (mcron-error 8 "Only root can use the -u option."))
+
+      (letrec* (;; Iff the --user option is given, the crontab-user may be
+                ;; different from the real user.
+                (crontab-user (option-ref opts 'user crontab-real-user))
+                ;; So now we know which crontab file we will be manipulating.
+                (crontab-file (string-append config-spool-dir "/" crontab-user))
+                ;; Display the prompt and wait for user to type his
+                ;; choice. Return #t if the answer begins with 'y' or 'Y',
+                ;; return #f if it begins with 'n' or 'N', otherwise ask
+                ;; again.
+                (get-yes-no (λ (prompt . re-prompt)
+                              (if (not (null? re-prompt))
+                                  (display "Please answer y or n.\n"))
+                              (display (string-append prompt " "))
+                              (let ((r (read-line)))
+                                (if (not (string-null? r))
+                                    (case (string-ref r 0)
+                                      ((#\y #\Y) #t)
+                                      ((#\n #\N) #f)
+                                      (else (get-yes-no prompt #t)))
+                                    (get-yes-no prompt #t))))))
+        ;; There are four possible sub-personalities to the crontab
+        ;; personality: list, remove, edit and replace (when the user uses no
+        ;; options but supplies file names on the command line).
+        (cond
+         ;; In the list personality, we simply open the crontab and copy it
+         ;; character-by-character to the standard output. If anything goes
+         ;; wrong, it can only mean that this user does not have a crontab
+         ;; file.
+         ((option-ref opts 'list #f)
+          (catch #t
+            (λ ()
+              (with-input-from-file crontab-file
+                (λ ()
+                  (do ((input (read-char) (read-char)))
+                      ((eof-object? input))
+                    (display input)))))
+            (λ (key . args)
+              (display (string-append "No crontab for "
+                                      crontab-user
+                                      " exists.\n")))))
+
+         ;; In the edit personality, we determine the name of a temporary file
+         ;; and an editor command, copy an existing crontab file (if it is
+         ;; there) to the temporary file, making sure the ownership is set so
+         ;; the real user can edit it; once the editor returns we try to read
+         ;; the file to check that it is parseable (but do nothing more with
+         ;; the configuration), and if it is okay (this program is still
+         ;; running!) we move the temporary file to the real crontab, wake the
+         ;; cron daemon up, and remove the temporary file. If the parse fails,
+         ;; we give user a choice of editing the file again or quitting the
+         ;; program and losing all changes made.
+         ((option-ref opts 'edit #f)
+          (let ((temp-file (string-append config-tmp-dir
+                                          "/crontab."
+                                          (number->string (getpid)))))
+            (catch #t
+              (λ () (copy-file crontab-file temp-file))
+              (λ (key . args) (with-output-to-file temp-file noop)))
+            (chown temp-file (getuid) (getgid))
+            (let retry ()
+              (system (string-append
+                       (or (getenv "VISUAL") (getenv "EDITOR") "vi")
+                       " "
+                       temp-file))
+              (catch 'mcron-error
+                (λ () (read-vixie-file temp-file))
+                (λ (key exit-code . msg)
+                  (apply mcron-error 0 msg)
+                  (if (get-yes-no "Edit again?")
+                      (retry)
+                      (begin
+                        (mcron-error 0 "Crontab not changed")
+                        (primitive-exit 0))))))
+            (copy-file temp-file crontab-file)
+            (delete-file temp-file)
+            (hit-server crontab-user)))
+
+         ;; In the remove personality we simply make an effort to delete the
+         ;; crontab and wake the daemon. No worries if this fails.
+         ((option-ref opts 'remove #f)
+          (catch #t
+            (λ ()
+              (delete-file crontab-file)
+              (hit-server crontab-user))
+            noop))
+
+         ;; XXX: This comment is wrong.
+         ;; In the case of the replace personality we loop over all the
+         ;; arguments on the command line, and for each one parse the file to
+         ;; make sure it is parseable (but subsequently ignore the
+         ;; configuration), and all being well we copy it to the crontab
+         ;; location; we deal with the standard input in the same way but
+         ;; different. :-) In either case the server is woken so that it will
+         ;; read the newly installed crontab.
+         ((not (null? (option-ref opts '() '())))
+          (let ((input-file (car (option-ref opts '() '()))))
+            (catch-mcron-error
+             (if (string=? input-file "-")
+                 (let ((input-string (read-string)))
+                   (read-vixie-port (open-input-string input-string))
+                   (with-output-to-file crontab-file
+                     (λ () (display input-string))))
+                 (begin
+                   (read-vixie-file input-file)
+                   (copy-file input-file crontab-file))))
+            (hit-server crontab-user)))
+
+         ;; The user is being silly. The message here is identical to the one
+         ;; Vixie cron used to put out, for total compatibility.
+         (else (mcron-error 15
+                 "usage error: file name must be specified for replace.")))))))