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Diffstat (limited to 'scm/mcron/vixie-time.scm')
| -rw-r--r-- | scm/mcron/vixie-time.scm | 385 |
1 files changed, 0 insertions, 385 deletions
diff --git a/scm/mcron/vixie-time.scm b/scm/mcron/vixie-time.scm deleted file mode 100644 index 2f26a6d..0000000 --- a/scm/mcron/vixie-time.scm +++ /dev/null @@ -1,385 +0,0 @@ -;; Copyright (C) 2003 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/>. - - -(define-module (mcron vixie-time) - #:export (parse-vixie-time) - #:use-module (mcron job-specifier)) - - -(use-modules (srfi srfi-1) (srfi srfi-13) (srfi srfi-14) - (ice-9 regex)) - - -;; In Vixie-style time specifications three-letter symbols are allowed to stand -;; for the numbers corresponding to months and days of the week. We deal with -;; this by making a textual substitution early on in the processing of the -;; strings. -;; -;; We start by defining, once and for all, a list of cons cells consisting of -;; regexps which will match the symbols - which allow an arbitrary number of -;; other letters to appear after them (so that the user can optionally complete -;; the month and day names; this is an extension of Vixie) - and the value which -;; is to replace the symbol. -;; -;; The procedure then takes a string, and then for each symbol in the -;; parse-symbols list attempts to locate an instance and replace it with an -;; ASCII representation of the value it stands for. The procedure returns the -;; modified string. (Note that each symbol can appear only once, which meets the -;; Vixie specifications technically but still allows silly users to mess things -;; up). - -(define parse-symbols - (map (lambda (symbol-cell) - (cons (make-regexp (string-append (car symbol-cell) "[[:alpha:]]*") - regexp/icase) - (cdr symbol-cell))) - '(("jan" . "0") ("feb" . "1") ("mar" . "2") ("apr" . "3") - ("may" . "4") ("jun" . "5") ("jul" . "6") ("aug" . "7") - ("sep" . "8") ("oct" . "9") ("nov" . "10") ("dec" . "11") - - ("sun" . "0") ("mon" . "1") ("tue" . "2") ("wed" . "3") - ("thu" . "4") ("fri" . "5") ("sat" . "6") ))) - -(define (vixie-substitute-parse-symbols string) - (for-each (lambda (symbol-cell) - (let ((match (regexp-exec (car symbol-cell) string))) - (if match - (set! string (string-append (match:prefix match) - (cdr symbol-cell) - (match:suffix match)))))) - parse-symbols) - string) - - - -;; A Vixie time specification is made up of a space-separated list of elements, -;; and the elements consist of a comma-separated list of subelements. The -;; procedure below takes a string holding a subelement, which should have no -;; spaces or symbols (see above) in it, and returns a list of all values which -;; that subelement indicates. There are five distinct cases which must be dealt -;; with: [1] a single '*' which returns a list of all values; [2] a '*' followed -;; by a step specifier; [3] a range and step specifier; [4] a range; and [5] a -;; single number. -;; -;; To perform the computation required for the '*' cases, we need to pass the -;; limit of the allowable range for this subelement as the third argument. As -;; days of the month start at 1 while all the other time components start at 0, -;; we must pass the base of the range to deal with this case also. - -(define parse-vixie-subelement-regexp - (make-regexp "^([[:digit:]]+)(-([[:digit:]]+)(/([[:digit:]]+))?)?$")) - -(define (parse-vixie-subelement string base limit) - (if (char=? (string-ref string 0) #\*) - (range base limit (if (> (string-length string) 1) - (string->number (substring string 2)) ;; [2] - 1)) ;; [1] - (let ((match (regexp-exec parse-vixie-subelement-regexp string))) - (cond ((not match) - (throw 'mcron-error 9 - "Bad Vixie-style time specification.")) - ((match:substring match 5) - (range (string->number (match:substring match 1)) - (+ 1 (string->number (match:substring match 3))) - (string->number (match:substring match 5)))) ;; [3] - ((match:substring match 3) - (range (string->number (match:substring match 1)) - (+ 1 (string->number (match:substring match 3))))) ;; [4] - (else - (list (string->number (match:substring match 1)))))))) ;; [5] - - - -;; A Vixie element contains the entire specification, without spaces or symbols, -;; of the acceptable values for one of the time components (minutes, hours, -;; days, months, week days). Here we break the comma-separated list into -;; subelements, and process each with the procedure above. The return value is a -;; list of all the valid values of all the subcomponents. -;; -;; The second and third arguments are the base and upper limit on the values -;; that can be accepted for this time element. -;; -;; The effect of the 'apply append' is to merge a list of lists into a single -;; list. - -(define (parse-vixie-element string base limit) - (apply append - (map (lambda (sub-element) - (parse-vixie-subelement sub-element base limit)) - (string-tokenize string (char-set-complement (char-set #\,)))))) - - - -;; Consider there are two lists, one of days in the month, the other of days in -;; the week. This procedure returns an augmented list of days in the month with -;; weekdays accounted for. - -(define (interpolate-weekdays mday-list wday-list month year) - (let ((t (localtime 0))) - (set-tm:mday t 1) - (set-tm:mon t month) - (set-tm:year t year) - (let ((first-day (tm:wday (cdr (mktime t))))) - (apply append - mday-list - (map (lambda (wday) - (let ((first (- wday first-day))) - (if (< first 0) (set! first (+ first 7))) - (range (+ 1 first) 32 7))) - wday-list))))) - - - -;; Return the number of days in a month. Fix up a tm object for the zero'th day -;; of the next month, rationalize the object and extract the day. - -(define (days-in-month month year) - (let ((t (localtime 0))) (set-tm:mday t 0) - (set-tm:mon t (+ month 1)) - (set-tm:year t year) - (tm:mday (cdr (mktime t))))) - - - -;; We will be working with a list of time-spec's, one for each element of a time -;; specification (minute, hour, ...). Each time-spec holds three pieces of -;; information: a list of acceptable values for this time component, a procedure -;; to get the component from a tm object, and a procedure to set the component -;; in a tm object. - -(define (time-spec:list time-spec) (vector-ref time-spec 0)) -(define (time-spec:getter time-spec) (vector-ref time-spec 1)) -(define (time-spec:setter time-spec) (vector-ref time-spec 2)) - - - -;; This procedure modifies the time tm object by setting the component referred -;; to by the time-spec object to its next acceptable value. If this value is not -;; greater than the original (because we have wrapped around the top of the -;; acceptable values list), then the function returns #t, otherwise it returns -;; #f. Thus, if the return value is true then it will be necessary for the -;; caller to increment the next coarser time component as well. -;; -;; The first part of the let block is a concession to humanity; the procedure is -;; simply unreadable without all of these aliases. - -(define (increment-time-component time time-spec) - (let* ((time-list (time-spec:list time-spec)) - (getter (time-spec:getter time-spec)) - (setter (time-spec:setter time-spec)) - (next-best (find-best-next (getter time) time-list)) - (wrap-around (eqv? (cdr next-best) 9999))) - (setter time ((if wrap-around car cdr) next-best)) - wrap-around)) - - - -;; There now follows a set of procedures for adjusting an element of time, -;; i.e. taking it to the next acceptable value. In each case, the head of the -;; time-spec-list is expected to correspond to the component of time in -;; question. If the adjusted value wraps around its allowed range, then the next -;; biggest element of time must be adjusted, and so on. - -;; There is no specification allowed for the year component of -;; time. Therefore, if we have to make an adjustment (presumably because a -;; monthly adjustment has wrapped around the top of its range) we can simply -;; go to the next year. - -(define (nudge-year! time) - (set-tm:year time (+ (tm:year time) 1))) - - -;; We nudge the month by finding the next allowable value, and if it wraps -;; around we also nudge the year. The time-spec-list will have time-spec -;; objects for month and weekday. - -(define (nudge-month! time time-spec-list) - (and (increment-time-component time (car time-spec-list)) - (nudge-year! time))) - - -;; Try to increment the day component of the time according to the combination -;; of the mday-list and the wday-list. If this wraps around the range, or if -;; this falls outside the current month (31st February, for example), then -;; bump the month, set the day to zero, and recurse on this procedure to find -;; the next day in the new month. -;; -;; The time-spec-list will have time-spec entries for mday, month, and -;; weekday. - -(define (nudge-day! time time-spec-list) - (if (or (increment-time-component - time - (vector - (interpolate-weekdays (time-spec:list (car time-spec-list)) - (time-spec:list (caddr time-spec-list)) - (tm:mon time) - (tm:year time)) - tm:mday - set-tm:mday)) - (> (tm:mday time) (days-in-month (tm:mon time) (tm:year time)))) - (begin - (nudge-month! time (cdr time-spec-list)) - (set-tm:mday time 0) - (nudge-day! time time-spec-list)))) - - - -;; The hour is bumped to the next accceptable value, and the day is bumped if -;; the hour wraps around. -;; -;; The time-spec-list holds specifications for hour, mday, month and weekday. - -(define (nudge-hour! time time-spec-list) - (and (increment-time-component time (car time-spec-list)) - (nudge-day! time (cdr time-spec-list)))) - - - -;; The minute is bumped to the next accceptable value, and the hour is bumped -;; if the minute wraps around. -;; -;; The time-spec-list holds specifications for minute, hour, day-date, month -;; and weekday. - -(define (nudge-min! time time-spec-list) - (and (increment-time-component time (car time-spec-list)) - (nudge-hour! time (cdr time-spec-list)))) - - - - -;; This is a procedure which returns a procedure which computes the next time a -;; command should run after the current time, based on the information in the -;; Vixie-style time specification. -;; -;; We start by computing a list of time-spec objects (described above) for the -;; minute, hour, date, month, year and weekday components of the overall time -;; specification [1]. Special care is taken to produce proper values for -;; fields 2 and 4: according to Vixie specification "If both fields are -;; restricted (ie, aren't *), the command will be run when _either_ field -;; matches the current time." This implies that if one of these fields is *, -;; while the other is not, its value should be '() [0], otherwise -;; interpolate-weekdays below will produce incorrect results. - -;; When we create the return procedure, it is this list to -;; which references to a time-spec-list will be bound. It will be used by the -;; returned procedure [3] to compute the next time a function should run. Any -;; 7's in the weekday component of the list (the last one) are folded into 0's -;; (both values represent sunday) [2]. Any 0's in the month-day component of the -;; list are removed (this allows a solitary zero to be used to indicate that -;; jobs should only run on certain days of the _week_) [2.1]. -;; -;; The returned procedure itself:- -;; -;; Starts by obtaining the current broken-down time [4], and fixing it to -;; ensure that it is an acceptable value, as follows. Each component from the -;; biggest down is checked for acceptability, and if it is not acceptable it -;; is bumped to the next acceptable value (this may cause higher components to -;; also be bumped if there is range wrap-around) and all the lower components -;; are set to -1 so that it can successfully be bumped up to zero if this is -;; an allowed value. The -1 value will be bumped up subsequently to an allowed -;; value [5]. -;; -;; Once it has been asserted that the current time is acceptable, or has been -;; adjusted to one minute before the next acceptable time, the minute -;; component is then bumped to the next acceptable time, which may ripple -;; through the higher components if necessary [6]. We now have the next time -;; the command needs to run. -;; -;; The new time is then converted back into a UNIX time and returned [7]. - -(define (parse-vixie-time string) - (let ((tokens (string-tokenize (vixie-substitute-parse-symbols string)))) - (cond - ((> (length tokens) 5) - (throw 'mcron-error 9 - "Too many fields in Vixie-style time specification")) - ((< (length tokens) 5) - (throw 'mcron-error 9 - "Not enough fields in Vixie-style time specification"))) - (let ((time-spec-list - (map-in-order (lambda (x) (vector - (let* ((n (vector-ref x 0)) - (tok (list-ref tokens n))) - (cond - ((and (= n 4) - (string=? tok "*") - (not (string=? - (list-ref tokens 2) "*"))) - '()) - ((and (= n 2) - (string=? tok "*") - (not (string=? - (list-ref tokens 4) "*"))) - '()) - (else - (parse-vixie-element - tok - (vector-ref x 1) - (vector-ref x 2))))) ; [0] - (vector-ref x 3) - (vector-ref x 4))) - ;; token range-top+1 getter setter - `( #( 0 0 60 ,tm:min ,set-tm:min ) - #( 1 0 24 ,tm:hour ,set-tm:hour ) - #( 2 1 32 ,tm:mday ,set-tm:mday ) - #( 3 0 12 ,tm:mon ,set-tm:mon ) - #( 4 0 7 ,tm:wday ,set-tm:wday ))))) ;; [1] - - (vector-set! (car (last-pair time-spec-list)) - 0 - (map (lambda (time-spec) - (if (eqv? time-spec 7) 0 time-spec)) - (vector-ref (car (last-pair time-spec-list)) 0))) ;; [2] - - (vector-set! (caddr time-spec-list) - 0 - (remove (lambda (day) (eqv? day 0)) - (vector-ref (caddr time-spec-list) 0))) ;; [2.1] - - - (lambda (current-time) ;; [3] - (let ((time (localtime current-time))) ;; [4] - - (if (not (member (tm:mon time) - (time-spec:list (cadddr time-spec-list)))) - (begin - (nudge-month! time (cdddr time-spec-list)) - (set-tm:mday time 0))) - (if (or (eqv? (tm:mday time) 0) - (not (member (tm:mday time) - (interpolate-weekdays - (time-spec:list (caddr time-spec-list)) - (time-spec:list (caddr (cddr time-spec-list))) - (tm:mon time) - (tm:year time))))) - (begin - (nudge-day! time (cddr time-spec-list)) - (set-tm:hour time -1))) - (if (not (member (tm:hour time) - (time-spec:list (cadr time-spec-list)))) - (begin - (nudge-hour! time (cdr time-spec-list)) - (set-tm:min time -1))) ;; [5] - - (set-tm:sec time 0) - (nudge-min! time time-spec-list) ;; [6] - (car (mktime time))))))) ;; [7] - - |