218 lines
7.5 KiB
EmacsLisp
218 lines
7.5 KiB
EmacsLisp
;;; cgi.el -- Using Emacs for CGI scripting
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;; Copyright (C) 2000, 2006, 2012 Free Software Foundation, Inc.
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;; Author: Eric Marsden <emarsden@laas.fr>
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;; Michael Olson <mwolson@gnu.org> (slight modifications)
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;; Keywords: CGI web scripting slow
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;; Version: 0.3
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;; Time-stamp: <2001-08-24 emarsden>
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;; This program is free software; you can redistribute it and/or
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;; modify it under the terms of the GNU General Public License as
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;; published by the Free Software Foundation; either version 3 of
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;; the License, or (at your option) any later version.
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;;
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;; This program is distributed in the hope that it will be useful,
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;; but WITHOUT ANY WARRANTY; without even the implied warranty of
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;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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;; GNU General Public License for more details.
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;;
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;; You should have received a copy of the GNU General Public
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;; License along with this program; if not, write to the Free
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;; Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
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;; MA 02111-1307, USA.
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;;; Commentary:
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;; People who like this sort of thing will find this the sort of
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;; thing they like. -- Abraham Lincoln
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;;
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;;
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;; Overview ==========================================================
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;;
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;; A simple library for the Common Gateway Interface for Emacs,
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;; allowing you to service requests for non static web pages in elisp.
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;; Provides routines for decoding arguments to GET- and POST-type CGI
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;; requests.
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;;
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;; Usage: place a shell script such as the following in your web
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;; server's CGI directory (typically called something like
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;; /var/www/cgi-bin/):
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;;
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;; ,-------------------------------------------------------------------
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;; | #!/bin/sh
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;; |
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;; | emacs -batch -l cgi.el -f cgi-calendar
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;; `-------------------------------------------------------------------
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;;
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;; (`cgi-calendar' is a sample elisp CGI script provided at the end of
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;; this file).
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;;
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;; Alternatively, if you're running version 2.x of the linux kernel
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;; you could make .elc files directly executable via the binfmt_misc
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;; mechanism and run them straight from the cgi-bin directory.
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;;
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;; Efficiency would be improved by having Emacs bind to the http
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;; service port and spawn a thread per connection. Extending Emacs to
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;; support server sockets and multithreading is left as an exercise
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;; for the reader.
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;;
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;; References:
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;; * rfc1738 "Uniform Resource Locators"
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;; * rfc1630 "Universal Resource Identifiers in WWW"
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;;
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;; Thanks to Christoph Conrad <christoph.conrad@gmx.de> for pointing
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;; out a bug in the URI-decoding.
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;;; Code:
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(eval-when-compile
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(require 'cl)
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(require 'calendar))
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(defconst cgi-url-unreserved-chars '(
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?a ?b ?c ?d ?e ?f ?g ?h ?i ?j ?k ?l ?m
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?n ?o ?p ?q ?r ?s ?t ?u ?v ?w ?x ?y ?z
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?A ?B ?C ?D ?E ?F ?G ?H ?I ?J ?K ?L ?M
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?N ?O ?P ?Q ?R ?S ?T ?U ?V ?W ?X ?Y ?Z
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?0 ?1 ?2 ?3 ?4 ?5 ?6 ?7 ?8 ?9
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?\$ ?\- ?\_ ?\. ?\! ?\~ ?\* ?\' ?\( ?\) ?\,))
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(defun cgi-int-char (i)
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(if (fboundp 'int-char) (int-char i) i))
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(defun cgi-hex-char-p (ch)
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(declare (character ch))
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(let ((hexchars '(?0 ?1 ?2 ?3 ?4 ?5 ?6 ?7 ?8 ?9
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?A ?B ?C ?D ?E ?F)))
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(member (upcase ch) hexchars)))
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;; decode %xx to the corresponding character and + to ' '
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(defun cgi-decode-string (str)
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(do ((i 0)
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(len (length str))
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(decoded '()))
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((>= i len) (concat (nreverse decoded)))
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(let ((ch (aref str i)))
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(cond ((eq ?+ ch)
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(push ?\ decoded)
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(incf i))
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((and (eq ?% ch)
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(< (+ i 2) len)
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(cgi-hex-char-p (aref str (+ i 1)))
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(cgi-hex-char-p (aref str (+ i 2))))
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(let ((hex (string-to-number (substring str (+ i 1) (+ i 3)) 16)))
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(push (cgi-int-char hex) decoded)
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(incf i 3)))
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(t (push ch decoded)
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(incf i))))))
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(defun cgi-position (item seq &optional start end)
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(or start (setq start 0))
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(or end (setq end (length seq)))
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(while (and (< start end)
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(not (equal item (aref seq start))))
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(setq start (1+ start)))
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(and (< start end) start))
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;; Parse "foo=x&bar=y+re" into (("foo" . "x") ("bar" . "y re"))
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;; Substrings are plus-decoded and then URI-decoded.
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(defun cgi-decode (q)
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(when q
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(flet ((split-= (str)
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(let ((pos (or (cgi-position ?= str) 0)))
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(cons (cgi-decode-string (substring str 0 pos))
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(cgi-decode-string (substring str (+ pos 1)))))))
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(mapcar #'split-= (split-string q "&")))))
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(defun cgi-lose (fmt &rest args)
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(let ((why (apply #'format fmt args)))
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(message "Script error: %s" why) ; to error_log
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(princ "Content-type: text/html\n\n") ; to browser
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(princ "<html><head><title>Script error</title></head>\r\n")
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(princ "<body><h1>Script error</h1>\r\n<p>\r\n")
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(princ why)
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(princ "\r\n</body></html>\r\n")
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(kill-emacs 0)))
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(defmacro cgi-evaluate (&rest forms)
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`(condition-case why
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(princ (with-output-to-string ,@forms))
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(error (cgi-lose "Emacs Lisp error: %s" why))))
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(defun cgi-arguments ()
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(let ((method (getenv "REQUEST_METHOD"))
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req buf)
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(cond ((null method)
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(cgi-lose "No request method specified"))
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((string= "GET" method)
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(unless (getenv "QUERY_STRING")
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(cgi-lose "No query string for GET request"))
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(cgi-decode (getenv "QUERY_STRING")))
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((string= "POST" method)
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(setq req (getenv "CONTENT_LENGTH"))
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(unless req
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(cgi-lose "No content-length for POST request"))
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(setq buf (get-buffer-create " *cgi*"))
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(set-buffer buf)
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(erase-buffer)
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(loop for i from 1 to (string-to-number req)
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do (insert (read-event)))
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(cgi-decode (buffer-string)))
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(t
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(cgi-lose "Can't handle request method %s" method)))))
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;; ====================================================================
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;; a sample application: calendar via the web. If invoked without
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;; arguments, presents a calendar for the three months around the
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;; current date. You can request a calendar for a specific period by
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;; specifying the year and the month in the query string:
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;;
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;; ~$ lynx -dump 'http://localhost/cgi-bin/cal?year=1975&month=6'
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;;
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;; When run in batch mode, text normally displayed in the echo area
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;; (via `princ' for example) goes to stdout, and thus to the browser.
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;; Text output using `message' goes to stderr, and thus normally to
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;; your web server's error_log.
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;; ====================================================================
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(eval-and-compile
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(if (fboundp 'calendar-extract-month)
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(defalias 'cgi-calendar-extract-month 'calendar-extract-month)
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(defalias 'cgi-calendar-extract-month 'extract-calendar-month))
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(if (fboundp 'calendar-extract-year)
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(defalias 'cgi-calendar-extract-year 'calendar-extract-year)
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(defalias 'cgi-calendar-extract-year 'extract-calendar-year))
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(if (fboundp 'calendar-generate)
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(defalias 'cgi-calendar-generate 'calendar-generate)
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(defalias 'cgi-calendar-generate 'generate-calendar)))
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(defun cgi-calendar-string ()
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(require 'calendar)
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(let* ((args (cgi-arguments))
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(now (calendar-current-date))
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(mnth (cdr (assoc "month" args)))
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(month (if mnth (string-to-number mnth)
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(cgi-calendar-extract-month now)))
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(yr (cdr (assoc "year" args)))
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(year (if yr (string-to-number yr)
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(cgi-calendar-extract-year now))))
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(with-temp-buffer
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(cgi-calendar-generate month year)
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(buffer-string))))
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(defun cgi-calendar ()
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(cgi-evaluate
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(princ "Content-type: text/html\n\n")
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(princ "<html><head><title>Emacs calendar</title></head>\r\n")
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(princ "<body> <h1>Emacs calendar</h1>\r\n")
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(princ "<pre>\r\n")
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(princ (cgi-calendar-string))
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(princ "\r\n</pre></body></html>\r\n")))
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(provide 'cgi)
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;;; cgi.el ends here
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