scripts/read-rfc822

   1 #!/bin/sh
   2 # aside from this initial boilerplate, this is actually -*- scheme -*- code
   3 main='(module-ref (resolve-module '\''(scripts read-rfc822)) '\'main')'
   4 exec ${GUILE-guile} -l $0 -c "(apply $main (cdr (command-line)))" "$@"
   5 !#
   6 ;;; read-rfc822 --- Validate RFC822 file by displaying it to stdout
   7
   8 ;;      Copyright (C) 2002, 2004, 2006 Free Software Foundation, Inc.
   9 ;;
  10 ;; This program is free software; you can redistribute it and/or
  11 ;; modify it under the terms of the GNU General Public License as
  12 ;; published by the Free Software Foundation; either version 2, or
  13 ;; (at your option) any later version.
  14 ;;
  15 ;; This program is distributed in the hope that it will be useful,
  16 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  17 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  18 ;; General Public License for more details.
  19 ;;
  20 ;; You should have received a copy of the GNU General Public License
  21 ;; along with this software; see the file COPYING.  If not, write to
  22 ;; the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  23 ;; Boston, MA 02110-1301 USA
  24
  25 ;;; Author: Thien-Thi Nguyen <ttn@gnu.org>
  26
  27 ;;; Commentary:
  28
  29 ;; Usage: read-rfc822 FILE
  30 ;;
  31 ;; Read FILE, assumed to be in RFC822 format, and display it to stdout.
  32 ;; This is not very interesting, admittedly.
  33 ;;
  34 ;; For Scheme programming, this module exports two procs:
  35 ;;   (read-rfc822 . args)               ; only first arg used
  36 ;;   (read-rfc822-silently port)
  37 ;;
  38 ;; Parse FILE (a string) or PORT, respectively, and return a query proc that
  39 ;; takes a symbol COMP, and returns the message component COMP.  Supported
  40 ;; values for COMP (and the associated query return values) are:
  41 ;;   from       -- #f (reserved for future mbox support)
  42 ;;   headers    -- alist of (HEADER-SYMBOL . "VALUE-STRING") pairs, in order
  43 ;;   body       -- rest of the mail message, a string
  44 ;;   body-lines -- rest of the mail message, as a list of lines
  45 ;; Any other query results in a "bad component" error.
  46 ;;
  47 ;; TODO: Add "-m" option (mbox support).
  48
  49 ;;; Code:
  50
  51 (define-module (scripts read-rfc822)
  52   :use-module (ice-9 regex)
  53   :use-module (ice-9 rdelim)
  54   :autoload (srfi srfi-13) (string-join)
  55   :export (read-rfc822 read-rfc822-silently))
  56
  57 (define from-line-rx   (make-regexp "^From "))
  58 (define header-name-rx (make-regexp "^([^:]+):[ \t]*"))
  59 (define header-cont-rx (make-regexp "^[ \t]+"))
  60
  61 (define option #f)                      ; for future "-m"
  62
  63 (define (drain-message port)
  64   (let loop ((line (read-line port)) (acc '()))
  65     (cond ((eof-object? line)
  66            (reverse acc))
  67           ((and option (regexp-exec from-line-rx line))
  68            (for-each (lambda (c)
  69                        (unread-char c port))
  70                      (cons #\newline
  71                            (reverse (string->list line))))
  72            (reverse acc))
  73           (else
  74            (loop (read-line port) (cons line acc))))))
  75
  76 (define (parse-message port)
  77   (let* ((from (and option
  78                     (match:suffix (regexp-exec from-line-rx
  79                                                (read-line port)))))
  80          (body-lines #f)
  81          (body #f)
  82          (headers '())
  83          (add-header! (lambda (reversed-hlines)
  84                         (let* ((hlines (reverse reversed-hlines))
  85                                (first (car hlines))
  86                                (m (regexp-exec header-name-rx first))
  87                                (name (string->symbol (match:substring m 1)))
  88                                (data (string-join
  89                                       (cons (substring first (match:end m))
  90                                             (cdr hlines))
  91                                       " ")))
  92                           (set! headers (acons name data headers))))))
  93     ;; "From " is only one line
  94     (let loop ((line (read-line port)) (current-header #f))
  95       (cond ((string-null? line)
  96              (and current-header (add-header! current-header))
  97              (set! body-lines (drain-message port)))
  98             ((regexp-exec header-cont-rx line)
  99              => (lambda (m)
 100                   (loop (read-line port)
 101                         (cons (match:suffix m) current-header))))
 102             (else
 103              (and current-header (add-header! current-header))
 104              (loop (read-line port) (list line)))))
 105     (set! headers (reverse headers))
 106     (lambda (component)
 107       (case component
 108         ((from) from)
 109         ((body-lines) body-lines)
 110         ((headers) headers)
 111         ((body) (or body
 112                     (begin (set! body (string-join body-lines "\n" 'suffix))
 113                            body)))
 114         (else (error "bad component:" component))))))
 115
 116 (define (read-rfc822-silently port)
 117   (parse-message port))
 118
 119 (define (display-rfc822 parse)
 120   (cond ((parse 'from) => (lambda (from) (format #t "From ~A\n" from))))
 121   (for-each (lambda (header)
 122               (format #t "~A: ~A\n" (car header) (cdr header)))
 123             (parse 'headers))
 124   (format #t "\n~A" (parse 'body)))
 125
 126 (define (read-rfc822 . args)
 127   (let ((parse (read-rfc822-silently (open-file (car args) OPEN_READ))))
 128     (display-rfc822 parse))
 129   #t)
 130
 131 (define main read-rfc822)
 132
 133 ;;; read-rfc822 ends here