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+;;; read-rfc822 --- Validate RFC822 file by displaying it to stdout
+
+;; Copyright (C) 2002, 2004, 2006, 2011 Free Software Foundation, Inc.
+;;
+;; This program is free software; you can redistribute it and/or
+;; modify it under the terms of the GNU Lesser General Public License
+;; as published by the Free Software Foundation; either version 3, 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
+;; Lesser General Public License for more details.
+;;
+;; You should have received a copy of the GNU Lesser General Public
+;; License along with this software; see the file COPYING.LESSER. If
+;; not, write to the Free Software Foundation, Inc., 51 Franklin
+;; Street, Fifth Floor, Boston, MA 02110-1301 USA
+
+;;; Author: Thien-Thi Nguyen <ttn@gnu.org>
+
+;;; Commentary:
+
+;; Usage: read-rfc822 FILE
+;;
+;; Read FILE, assumed to be in RFC822 format, and display it to stdout.
+;; This is not very interesting, admittedly.
+;;
+;; For Scheme programming, this module exports two procs:
+;; (read-rfc822 . args) ; only first arg used
+;; (read-rfc822-silently port)
+;;
+;; Parse FILE (a string) or PORT, respectively, and return a query proc that
+;; takes a symbol COMP, and returns the message component COMP. Supported
+;; values for COMP (and the associated query return values) are:
+;; from -- #f (reserved for future mbox support)
+;; headers -- alist of (HEADER-SYMBOL . "VALUE-STRING") pairs, in order
+;; body -- rest of the mail message, a string
+;; body-lines -- rest of the mail message, as a list of lines
+;; Any other query results in a "bad component" error.
+;;
+;; TODO: Add "-m" option (mbox support).
+
+;;; Code:
+
+(define-module (scripts read-rfc822)
+ :use-module (ice-9 regex)
+ :use-module (ice-9 rdelim)
+ :autoload (srfi srfi-13) (string-join)
+ :export (read-rfc822 read-rfc822-silently))
+
+(define %include-in-guild-list #f)
+(define %summary "Validate an RFC822-style file.")
+
+(define from-line-rx (make-regexp "^From "))
+(define header-name-rx (make-regexp "^([^:]+):[ \t]*"))
+(define header-cont-rx (make-regexp "^[ \t]+"))
+
+(define option #f) ; for future "-m"
+
+(define (drain-message port)
+ (let loop ((line (read-line port)) (acc '()))
+ (cond ((eof-object? line)
+ (reverse acc))
+ ((and option (regexp-exec from-line-rx line))
+ (for-each (lambda (c)
+ (unread-char c port))
+ (cons #\newline
+ (reverse (string->list line))))
+ (reverse acc))
+ (else
+ (loop (read-line port) (cons line acc))))))
+
+(define (parse-message port)
+ (let* ((from (and option
+ (match:suffix (regexp-exec from-line-rx
+ (read-line port)))))
+ (body-lines #f)
+ (body #f)
+ (headers '())
+ (add-header! (lambda (reversed-hlines)
+ (let* ((hlines (reverse reversed-hlines))
+ (first (car hlines))
+ (m (regexp-exec header-name-rx first))
+ (name (string->symbol (match:substring m 1)))
+ (data (string-join
+ (cons (substring first (match:end m))
+ (cdr hlines))
+ " ")))
+ (set! headers (acons name data headers))))))
+ ;; "From " is only one line
+ (let loop ((line (read-line port)) (current-header #f))
+ (cond ((string-null? line)
+ (and current-header (add-header! current-header))
+ (set! body-lines (drain-message port)))
+ ((regexp-exec header-cont-rx line)
+ => (lambda (m)
+ (loop (read-line port)
+ (cons (match:suffix m) current-header))))
+ (else
+ (and current-header (add-header! current-header))
+ (loop (read-line port) (list line)))))
+ (set! headers (reverse headers))
+ (lambda (component)
+ (case component
+ ((from) from)
+ ((body-lines) body-lines)
+ ((headers) headers)
+ ((body) (or body
+ (begin (set! body (string-join body-lines "\n" 'suffix))
+ body)))
+ (else (error "bad component:" component))))))
+
+(define (read-rfc822-silently port)
+ (parse-message port))
+
+(define (display-rfc822 parse)
+ (cond ((parse 'from) => (lambda (from) (format #t "From ~A\n" from))))
+ (for-each (lambda (header)
+ (format #t "~A: ~A\n" (car header) (cdr header)))
+ (parse 'headers))
+ (format #t "\n~A" (parse 'body)))
+
+(define (read-rfc822 . args)
+ (let ((parse (read-rfc822-silently (open-file (car args) OPEN_READ))))
+ (display-rfc822 parse))
+ #t)
+
+(define main read-rfc822)
+
+;;; read-rfc822 ends here