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decode.lisp
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decode.lisp
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;;;; -*- Mode: Lisp; Syntax: ANSI-Common-Lisp; Base: 10 -*-
;;;; *************************************************************************
;;;; FILE IDENTIFICATION
;;;;
;;;; Name: encode.lisp
;;;; Purpose: cl-base64 encoding routines
;;;; Programmer: Kevin M. Rosenberg
;;;; Date Started: Dec 2002
;;;;
;;;; $Id$
;;;;
;;;; This file implements the Base64 transfer encoding algorithm as
;;;; defined in RFC 1521 by Borensten & Freed, September 1993.
;;;; See: http://www.ietf.org/rfc/rfc1521.txt
;;;;
;;;; Based on initial public domain code by Juri Pakaste <[email protected]>
;;;;
;;;; Copyright 2002-2003 Kevin M. Rosenberg
;;;; Permission to use with BSD-style license included in the COPYING file
;;;; *************************************************************************
(in-package #:cl-base64)
(define-condition base64-error (error)
((input
:initarg :input
:reader base64-error-input)
(position
:initarg :position
:reader base64-error-position
:type unsigned-byte)))
(define-condition bad-base64-character (base64-error)
((code :initarg :code :reader bad-base64-character-code))
(:report (lambda (condition stream)
(format stream "Bad character ~S at index ~D of ~S"
(code-char (bad-base64-character-code condition))
(base64-error-position condition)
(base64-error-input condition)))))
(define-condition incomplete-base64-data (base64-error)
()
(:report (lambda (condition stream)
(format stream "Unexpected end of Base64 data at index ~D of ~S"
(base64-error-position condition)
(base64-error-input condition)))))
(deftype array-index (&optional (length array-dimension-limit))
`(integer 0 (,length)))
(deftype array-length (&optional (length array-dimension-limit))
`(integer 0 ,length))
(deftype character-code ()
`(integer 0 (,char-code-limit)))
(defmacro etypecase/unroll ((var &rest types) &body body)
#+sbcl `(etypecase ,var
,@(loop for type in types
collect `(,type ,@body)))
#-sbcl `(locally
(declare (type (or ,@types) ,var))
,@body))
(defmacro let/typed ((&rest vars) &body body)
`(let ,(loop for (var value) in vars
collect (list var value))
(declare ,@(loop for (var nil type) in vars
when type
collect (list 'type type var)))
,@body))
(defmacro define-base64-decoder (hose sink)
`(defun ,(intern (format nil "~A-~A-~A-~A" '#:base64 hose '#:to sink))
(input &key (table +decode-table+)
(uri nil)
,@(when (eq sink :stream) `(stream))
(whitespace :ignore))
,(format nil "~
Decode Base64 ~(~A~) to ~(~A~).
TABLE is the decode table to use. Two decode tables are provided:
+DECODE-TABLE+ (used by default) and +URI-DECODE-TABLE+. See
MAKE-DECODE-TABLE.
For backwards-compatibility the URI parameter is supported. If it is
true, then +URI-DECODE-TABLE+ is used, and the value for TABLE
parameter is ignored.
WHITESPACE can be one of:
:ignore - Whitespace characters are ignored (default).
:signal - Signal a BAD-BASE64-CHARACTER condition using SIGNAL.
:error - Signal a BAD-BASE64-CHARACTER condition using ERROR."
hose sink)
(declare (optimize (speed 3) (safety 1))
(type decode-table table)
(type ,(ecase hose
(:stream 'stream)
(:string 'string))
input))
(let/typed ((decode-table (if uri +uri-decode-table+ table)
decode-table)
,@(ecase sink
(:stream)
(:usb8-array
(ecase hose
(:stream
`((result (make-array 1024
:element-type '(unsigned-byte 8)
:adjustable t
:fill-pointer 0)
(array (unsigned-byte 8) (*)))))
(:string
`((result (make-array (* 3 (ceiling (length input) 4))
:element-type '(unsigned-byte 8))
(simple-array (unsigned-byte 8) (*)))
(rpos 0 array-index)))))
(:string
(case hose
(:stream
`((result (make-array 1024
:element-type 'character
:adjustable t
:fill-pointer 0)
(array character (*)))))
(:string
`((result (make-array (* 3 (ceiling (length input) 4))
:element-type 'character)
(simple-array character (*)))
(rpos 0 array-index)))))
(:integer
`((result 0 unsigned-byte)))))
(flet ((bad-char (pos code &optional (action :error))
(let ((args (list 'bad-base64-character
:input input
:position pos
:code code)))
(ecase action
(:error
(apply #'error args))
(:cerror
(apply #'cerror "Ignore the error and continue." args))
(:signal
(apply #'signal args)))))
(incomplete-input (pos)
(error 'incomplete-base64-data :input input :position pos)))
,(let ((body
`(let/typed ((ipos 0 array-index)
(bitstore 0 (unsigned-byte 24))
(bitcount 0 (integer 0 14))
(svalue -1 (signed-byte 8))
(padchar 0 (integer 0 3))
(code 0 fixnum))
(loop
,@(ecase hose
(:string
`((if (< ipos length)
(setq code (char-code (aref input ipos)))
(return))))
(:stream
`((let ((char (read-char input nil nil)))
(if char
(setq code (char-code char))
(return))))))
(cond
((or (< 127 code)
(= -1 (setq svalue (aref decode-table code))))
(bad-char ipos code))
((= -2 svalue)
(cond ((<= (incf padchar) 2)
(unless (<= 2 bitcount)
(bad-char ipos code))
(decf bitcount 2))
(t
(bad-char ipos code))))
((= -3 svalue)
(ecase whitespace
(:ignore
;; Do nothing.
)
(:error
(bad-char ipos code :error))
(:signal
(bad-char ipos code :signal))))
((not (zerop padchar))
(bad-char ipos code))
(t
(setf bitstore (logior (the (unsigned-byte 24)
(ash bitstore 6))
svalue))
(incf bitcount 6)
(when (>= bitcount 8)
(decf bitcount 8)
(let ((byte (logand (the (unsigned-byte 24)
(ash bitstore (- bitcount)))
#xFF)))
(declare (type (unsigned-byte 8) byte))
,@(ecase sink
(:usb8-array
(ecase hose
(:string
`((setf (aref result rpos) byte)
(incf rpos)))
(:stream
`((vector-push-extend byte result)))))
(:string
(ecase hose
(:string
`((setf (schar result rpos)
(code-char byte))
(incf rpos)))
(:stream
`((vector-push-extend (code-char byte)
result)))))
(:integer
`((setq result
(logior (ash result 8) byte))))
(:stream
'((write-char (code-char byte) stream)))))
(setf bitstore (logand bitstore #xFF)))))
(incf ipos))
(unless (zerop bitcount)
(incomplete-input ipos))
,(ecase sink
((:string :usb8-array)
(ecase hose
(:string
`(if (= rpos (length result))
result
(subseq result 0 rpos)))
(:stream
`(copy-seq result))))
(:integer
'result)
(:stream
'stream)))))
(ecase hose
(:string
`(let ((length (length input)))
(declare (type array-length length))
(etypecase/unroll (input simple-base-string
simple-string
string)
,body)))
(:stream
body)))))))
(define-base64-decoder :string :usb8-array)
(define-base64-decoder :string :string)
(define-base64-decoder :string :integer)
(define-base64-decoder :string :stream)
(define-base64-decoder :stream :usb8-array)
(define-base64-decoder :stream :string)
(define-base64-decoder :stream :integer)
(define-base64-decoder :stream :stream)
;; input-mode can be :string or :stream
;; input-format can be :character or :usb8