;;; streams.lisp --- En/De-coding Streams
;;; Copyright (C) 2012 by Walter C. Pelissero
;;; Copyright (C) 2021-2023 by the TVL Authors
;;; Author: Walter C. Pelissero <walter@pelissero.de>
;;; Project: mime4cl
;;; This library 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 2.1
;;; of the License, or (at your option) any later version.
;;; This library 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 library; if not, write to the Free
;;; Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
;;; 02111-1307 USA
(in-package :mime4cl)
(defun flexi-stream-root-stream (stream)
"Return the non FLEXI-STREAM stream a given chain of FLEXI-STREAMs is based on."
(if (typep stream 'flexi-stream)
(flexi-stream-root-stream (flexi-stream-stream stream))
stream))
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
(defclass coder-stream-mixin ()
((real-stream :type stream
:initarg :underlying-stream
:reader real-stream)
(dont-close :initform nil
:initarg :dont-close)))
(defmethod stream-file-position ((stream coder-stream-mixin))
(file-position (slot-value stream 'real-stream)))
(defmethod (setf stream-file-position) (newval (stream coder-stream-mixin))
(file-position (slot-value stream 'real-stream) newval))
(defclass coder-input-stream-mixin (fundamental-binary-input-stream coder-stream-mixin)
())
(defclass coder-output-stream-mixin (fundamental-binary-output-stream coder-stream-mixin)
())
;; TODO(sterni): temporary, ugly measure to make flexi-streams happy
(defmethod stream-element-type ((stream coder-input-stream-mixin))
(declare (ignore stream))
'(unsigned-byte 8))
(defclass quoted-printable-decoder-stream (coder-input-stream-mixin quoted-printable-decoder) ())
(defclass 8bit-decoder-stream (coder-input-stream-mixin 8bit-decoder) ())
(defclass quoted-printable-encoder-stream (coder-output-stream-mixin quoted-printable-encoder) ())
(defclass base64-encoder-stream (coder-output-stream-mixin base64-encoder) ())
(defclass 8bit-encoder-stream (coder-output-stream-mixin 8bit-encoder) ())
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
(defmethod initialize-instance :after ((stream coder-stream-mixin) &key &allow-other-keys)
(unless (slot-boundp stream 'real-stream)
(error "REAL-STREAM is unbound. Must provide a :UNDERLYING-STREAM argument.")))
(defmethod initialize-instance ((stream coder-output-stream-mixin) &key &allow-other-keys)
(call-next-method)
(unless (slot-boundp stream 'output-function)
(setf (slot-value stream 'output-function)
#'(lambda (char)
(write-char char (slot-value stream 'real-stream))))))
(defmethod initialize-instance ((stream coder-input-stream-mixin) &key &allow-other-keys)
(call-next-method)
(unless (slot-boundp stream 'input-function)
(setf (slot-value stream 'input-function)
#'(lambda ()
(read-char (slot-value stream 'real-stream) nil)))))
(defmethod stream-read-byte ((stream coder-input-stream-mixin))
(or (decoder-read-byte stream)
:eof))
(defmethod stream-write-byte ((stream coder-output-stream-mixin) byte)
(encoder-write-byte stream byte))
(defmethod close ((stream coder-stream-mixin) &key abort)
(with-slots (real-stream dont-close) stream
(unless dont-close
(close real-stream :abort abort))))
(defmethod close ((stream coder-output-stream-mixin) &key abort)
(unless abort
(encoder-finish-output stream))
(call-next-method))
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
(defclass encoder-input-stream (fundamental-character-input-stream coder-stream-mixin)
((encoder)
(buffer-queue :initform (make-queue)))
(:documentation
"This is the base class for encoders with the direction swapped. It
reads from REAL-STREAM a stream of bytes, encodes it and returnes it
in a stream of character."))
(defclass quoted-printable-encoder-input-stream (encoder-input-stream) ())
(defclass base64-encoder-input-stream (encoder-input-stream) ())
(defclass 8bit-encoder-input-stream (fundamental-character-input-stream coder-stream-mixin) ())
(defmethod initialize-instance ((stream quoted-printable-encoder-input-stream) &key &allow-other-keys)
(call-next-method)
(with-slots (encoder buffer-queue) stream
(setf encoder
(make-instance 'quoted-printable-encoder
:output-function #'(lambda (char)
(queue-append buffer-queue char))))))
(defmethod initialize-instance ((stream base64-encoder-input-stream) &key &allow-other-keys)
(call-next-method)
(with-slots (encoder buffer-queue) stream
(setf encoder
(make-instance 'base64-encoder
:output-function #'(lambda (char)
(queue-append buffer-queue char))))))
(defmethod stream-read-char ((stream encoder-input-stream))
(with-slots (encoder buffer-queue real-stream) stream
(loop
while (queue-empty-p buffer-queue)
do (let ((byte (read-byte real-stream nil)))
(if byte
(encoder-write-byte encoder byte)
(progn
(encoder-finish-output encoder)
(queue-append buffer-queue :eof)))))
(queue-pop buffer-queue)))
(defmethod stream-read-char ((stream 8bit-encoder-input-stream))
(with-slots (real-stream) stream
(aif (read-byte real-stream nil)
(code-char it)
:eof)))
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
(defun make-custom-flexi-stream (class stream other-args)
(apply #'make-instance
class
:stream stream
(mapcar (lambda (x)
;; make-flexi-stream has a discrepancy between :initarg of
;; make-instance and its &key which we mirror here.
(if (eq x :external-format) :flexi-stream-external-format x))
other-args)))
(defclass adapter-flexi-input-stream (flexi-input-stream)
((ignore-close
:initform nil
:initarg :ignore-close
:documentation
"If T, calling CLOSE on the stream does nothing.
If NIL, the underlying stream is closed."))
(:documentation "FLEXI-STREAM that does not close the underlying stream on
CLOSE if :IGNORE-CLOSE is T."))
(defmethod close ((stream adapter-flexi-input-stream) &key abort)
(declare (ignore abort))
(with-slots (ignore-close) stream
(unless ignore-close
(call-next-method))))
(defun make-input-adapter (source)
(etypecase source
;; If it's already a stream, we need to make sure it's not closed by the adapter
(stream
(assert (input-stream-p source))
(if (and (typep source 'adapter-flexi-input-stream)
(slot-value source 'ignore-close))
source ; already ignores CLOSE
(make-adapter-flexi-input-stream source :ignore-close t)))
;; TODO(sterni): is this necessary? (maybe with (not *lazy-mime-decode*)?)
(string
(make-input-adapter (string-to-octets source)))
((vector (unsigned-byte 8))
(make-in-memory-input-stream source))
(pathname
(make-flexi-stream (open source :element-type '(unsigned-byte 8))))
(file-portion
(open-decoded-file-portion source))))
(defun make-adapter-flexi-input-stream (stream &rest args)
"Create a ADAPTER-FLEXI-INPUT-STREAM. Accepts the same keyword arguments as
MAKE-FLEXI-STREAM as well as :IGNORE-CLOSE. If T, the underlying stream is not
closed."
(make-custom-flexi-stream 'adapter-flexi-input-stream stream args))
(defclass positioned-flexi-input-stream (adapter-flexi-input-stream)
()
(:documentation
"FLEXI-INPUT-STREAM that automatically advances the underlying :STREAM to
the location given by :POSITION. This uses FILE-POSITION internally, so it'll
only works if the underlying stream position is tracked in bytes. Note that
the underlying stream is still advanced, so having multiple instances of
POSITIONED-FLEXI-INPUT-STREAM based with the same underlying stream won't work
reliably.
Also supports :IGNORE-CLOSE of ADAPTER-FLEXI-INPUT-STREAM."))
(defmethod initialize-instance ((stream positioned-flexi-input-stream)
&key &allow-other-keys)
(call-next-method)
;; The :POSITION initarg is only informational for flexi-streams: It assumes
;; it is were the stream it got is already at and continuously updates it
;; for querying (via FLEXI-STREAM-POSITION) and bound checking.
;; Since we have streams that are not positioned correctly, we need to do this
;; here using FILE-POSITION. Note that assumes the underlying implementation
;; uses bytes for FILE-POSITION which is not guaranteed (probably some streams
;; even in SBCL don't).
(file-position (flexi-stream-stream stream) (flexi-stream-position stream)))
(defun make-positioned-flexi-input-stream (stream &rest args)
"Create a POSITIONED-FLEXI-INPUT-STREAM. Accepts the same keyword arguments as
MAKE-FLEXI-STREAM as well as :IGNORE-CLOSE. Causes the FILE-POSITION of STREAM to
be modified to match the :POSITION argument."
(make-custom-flexi-stream 'positioned-flexi-input-stream stream args))
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; TODO(sterni): test correct behavior with END NIL
(defstruct file-portion
data ; string or a pathname
encoding
start
end)
(defun open-decoded-file-portion (file-portion)
(with-slots (data encoding start end)
file-portion
(let* ((binary-stream
(etypecase data
(pathname
(open data :element-type '(unsigned-byte 8)))
((vector (unsigned-byte 8))
(flexi-streams:make-in-memory-input-stream data))
(stream
;; TODO(sterni): assert that bytes/flexi-stream
data)))
(params (ccase encoding
((:quoted-printable :base64) '(:external-format :us-ascii))
(:8bit '(:element-type (unsigned-byte 8)))
(:7bit '(:external-format :us-ascii))))
(portion-stream (apply #'make-positioned-flexi-input-stream
binary-stream
:position start
:bound end
;; if data is a stream we can't have a
;; FILE-PORTION without modifying it when
;; reading etc. The least we can do, though,
;; is forgo destroying it.
:ignore-close (typep data 'stream)
params))
(needs-decoder-stream (member encoding '(:quoted-printable
:base64))))
(if needs-decoder-stream
(make-instance
(ccase encoding
(:quoted-printable 'quoted-printable-decoder-stream)
(:base64 'qbase64:decode-stream))
:underlying-stream portion-stream)
portion-stream))))
