From 995bc9ca6ebf6880d7e7e6f3d1baa2941758fc47 Mon Sep 17 00:00:00 2001 From: Mathieu Lirzin Date: Sat, 7 May 2016 11:09:44 +0200 Subject: all: Rename 'scm' directory to 'src'. * scm/mcron/config.scm.in: Rename to ... * src/mcron/config.scm.in: ... this. * scm/mcron/crontab.scm: Rename to ... * src/mcron/crontab.scm: ... this. * scm/mcron/environment.scm: Rename to ... * src/mcron/environment.scm: ... this. * scm/mcron/job-specifier.scm: Rename to ... * src/mcron/job-specifier.scm: ... this. * scm/mcron/main.scm: Rename to ... * src/mcron/main.scm: ... this. * scm/mcron/mcron-core.scm: Rename to ... * src/mcron/mcron-core.scm: ... this. * scm/mcron/redirect.scm: Rename to ... * src/mcron/redirect.scm: ... this. * scm/mcron/vixie-specification.scm: Rename to ... * src/mcron/vixie-specification.scm: ... this. * scm/mcron/vixie-time.scm: Rename to ... * src/mcron/vixie-time.scm: ... this. * mcron.c: Rename to ... * src/mcron.c: ... this. * Makefile.am: Adapt to them. * build-aux/pre-inst-env.in: Likewise. * configure.ac (AC_CONFIG_FILES): Likewise. (AC_CONFIG_HEADER): Set to 'src/config.h'. * .gitignore: Update. --- src/mcron/job-specifier.scm | 253 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 253 insertions(+) create mode 100644 src/mcron/job-specifier.scm (limited to 'src/mcron/job-specifier.scm') diff --git a/src/mcron/job-specifier.scm b/src/mcron/job-specifier.scm new file mode 100644 index 0000000..1c2f9d9 --- /dev/null +++ b/src/mcron/job-specifier.scm @@ -0,0 +1,253 @@ +;; Copyright (C) 2003 Dale Mellor +;; Copyright (C) 2016 Mathieu Lirzin +;; +;; 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 module defines all the functions that can be used by scheme mcron +;; configuration files, namely the procedures for working out next times, the +;; job procedure for registering new jobs (actually a wrapper around the core +;; add-job function), and the procedure for declaring environment modifications. + +(define-module (mcron job-specifier) + #:use-module (ice-9 match) + #:use-module (mcron core) + #:use-module (mcron environment) + #:use-module (mcron vixie-time) + #:use-module (srfi srfi-1) + #:use-module (srfi srfi-26) + #:re-export (append-environment-mods) + #:export (range + next-year-from next-year + next-month-from next-month + next-day-from next-day + next-hour-from next-hour + next-minute-from next-minute + next-second-from next-second + set-configuration-user + set-configuration-time + job)) + +(define* (range start end #:optional (step 1)) + "Produces a list of values from START up to (but not including) END. An +optional STEP may be supplied, and (if positive) only every step'th value will +go into the list. For example, (range 1 6 2) returns '(1 3 5)." + (unfold (cut >= <> end) identity (cute + <> (max step 1)) start)) + +(define (%find-best-next current next-list) + ;; Takes a value and a list of possible next values (all assumed less than + ;; 9999). It returns a pair consisting of the smallest element of the + ;; NEXT-LIST, and the smallest element larger than the CURRENT value. If an + ;; example of the latter cannot be found, 9999 will be returned. + (let loop ((smallest 9999) (closest+ 9999) (lst next-list)) + (match lst + (() (cons smallest closest+)) + ((time . rest) + (loop (min time smallest) + (if (> time current) (min time closest+) closest+) + rest))))) + +;; Internal function to return the time corresponding to some near future +;; hour. If hour-list is not supplied, the time returned corresponds to the +;; start of the next hour of the day. +;; +;; If the hour-list is supplied the time returned corresponds to the first hour +;; of the day in the future which is contained in the list. If all the values in +;; the list are less than the current hour, then the time returned will +;; correspond to the first hour in the list *on the following day*. +;; +;; ... except that the function is actually generalized to deal with seconds, +;; minutes, etc., in an obvious way :-) +;; +;; Note that value-list always comes from an optional argument to a procedure, +;; so is wrapped up as the first element of a list (i.e. it is a list inside a +;; list). + +(define (bump-time time value-list component higher-component + set-component! set-higher-component!) + (if (null? value-list) + (set-component! time (+ (component time) 1)) + (let ((best-next (%find-best-next (component time) (car value-list)))) + (if (eqv? 9999 (cdr best-next)) + (begin + (set-higher-component! time (+ (higher-component time) 1)) + (set-component! time (car best-next))) + (set-component! time (cdr best-next))))) + (car (mktime time))) + + + + +;; Set of configuration methods which use the above general function to bump +;; specific components of time to the next legitimate value. In each case, all +;; the components smaller than that of interest are taken to zero, so that for +;; example the time of the next year will be the time at which the next year +;; actually starts. + +(define (next-year-from current-time . year-list) + (let ((time (localtime current-time))) + (set-tm:mon time 0) + (set-tm:mday time 1) + (set-tm:hour time 0) + (set-tm:min time 0) + (set-tm:sec time 0) + (bump-time time year-list tm:year tm:year set-tm:year set-tm:year))) + +(define (next-month-from current-time . month-list) + (let ((time (localtime current-time))) + (set-tm:mday time 1) + (set-tm:hour time 0) + (set-tm:min time 0) + (set-tm:sec time 0) + (bump-time time month-list tm:mon tm:year set-tm:mon set-tm:year))) + +(define (next-day-from current-time . day-list) + (let ((time (localtime current-time))) + (set-tm:hour time 0) + (set-tm:min time 0) + (set-tm:sec time 0) + (bump-time time day-list tm:mday tm:mon set-tm:mday set-tm:mon))) + +(define (next-hour-from current-time . hour-list) + (let ((time (localtime current-time))) + (set-tm:min time 0) + (set-tm:sec time 0) + (bump-time time hour-list tm:hour tm:mday set-tm:hour set-tm:mday))) + +(define (next-minute-from current-time . minute-list) + (let ((time (localtime current-time))) + (set-tm:sec time 0) + (bump-time time minute-list tm:min tm:hour set-tm:min set-tm:hour))) + +(define (next-second-from current-time . second-list) + (let ((time (localtime current-time))) + (bump-time time second-list tm:sec tm:min set-tm:sec set-tm:min))) + + + +;; The current-action-time is the time a job was last run, the time from which +;; the next time to run a job must be computed. (When the program is first run, +;; this time is set to the configuration time so that jobs run from that moment +;; forwards.) Once we have this, we supply versions of the time computation +;; commands above which implicitly assume this value. + +(define current-action-time 0) + + + +;; We want to provide functions which take a single optional argument (as well +;; as implicitly the current action time), but unlike usual scheme behaviour if +;; the argument is missing we want to act like it is really missing, and if it +;; is there we want to act like it is a genuine argument, not a list of +;; optionals. + +(define (maybe-args function args) + (if (null? args) + (function current-action-time) + (function current-action-time (car args)))) + + + +;; These are the convenience functions we were striving to define for the +;; configuration files. They are wrappers for the next-X-from functions above, +;; but implicitly use the current-action-time for the time argument. + +(define (next-year . args) (maybe-args next-year-from args)) +(define (next-month . args) (maybe-args next-month-from args)) +(define (next-day . args) (maybe-args next-day-from args)) +(define (next-hour . args) (maybe-args next-hour-from args)) +(define (next-minute . args) (maybe-args next-minute-from args)) +(define (next-second . args) (maybe-args next-second-from args)) + + + +;; The default user for running jobs is the current one (who invoked this +;; program). There are exceptions: when cron parses /etc/crontab the user is +;; specified on each individual line; when cron parses /var/cron/tabs/* the user +;; is derived from the filename of the crontab. These cases are dealt with by +;; mutating this variable. Note that the variable is only used at configuration +;; time; a UID is stored with each job and it is that which takes effect when +;; the job actually runs. + +(define configuration-user (getpw (getuid))) +(define configuration-time (current-time)) + +(define (set-configuration-user user) + (set! configuration-user (if (or (string? user) + (integer? user)) + (getpw user) + user))) +(define (set-configuration-time time) (set! configuration-time time)) + + + +;; The job function, available to configuration files for adding a job rule to +;; the system. +;; +;; Here we must 'normalize' the next-time-function so that it is always a lambda +;; function which takes one argument (the last time the job ran) and returns a +;; single value (the next time the job should run). If the input value is a +;; string this is parsed as a Vixie-style time specification, and if it is a +;; list then we arrange to eval it (but note that such lists are expected to +;; ignore the function parameter - the last run time is always read from the +;; current-action-time global variable). A similar normalization is applied to +;; the action. +;; +;; Here we also compute the first time that the job is supposed to run, by +;; finding the next legitimate time from the current configuration time (set +;; right at the top of this program). + +(define (job time-proc action . displayable) + (let ((action (cond ((procedure? action) action) + ((list? action) (lambda () (primitive-eval action))) + ((string? action) (lambda () (system action))) + (else + (throw 'mcron-error 2 + "job: invalid second argument (action; should be lambda " + "function, string or list)")))) + + (time-proc + (cond ((procedure? time-proc) time-proc) + ((string? time-proc) (parse-vixie-time time-proc)) + ((list? time-proc) (lambda (current-time) + (primitive-eval time-proc))) + (else + (throw 'mcron-error 3 + "job: invalid first argument (next-time-function; " + "should be function, string or list)")))) + (displayable + (cond ((not (null? displayable)) (car displayable)) + ((procedure? action) "Lambda function") + ((string? action) action) + ((list? action) (with-output-to-string + (lambda () (display action))))))) + (add-job (lambda (current-time) + (set! current-action-time current-time) ;; ?? !!!! Code + + ;; Contributed by Sergey Poznyakoff to allow for daylight savings + ;; time changes. + (let* ((next (time-proc current-time)) + (gmtoff (tm:gmtoff (localtime next))) + (d (+ next (- gmtoff + (tm:gmtoff (localtime current-time)))))) + (if (eqv? (tm:gmtoff (localtime d)) gmtoff) + d + next))) + action + displayable + configuration-time + configuration-user))) -- cgit v1.2.3