Replace base64 decoder with Apache 2.0 licensed version.

3 files changed, 92 insertions, 253 deletions

diff --git a/Makefile.am b/Makefile.am
index fe56434..4b3593d 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -102,6 +102,7 @@ SOURCES = 					\
   chickadee/cli/bundle.scm
 
 TESTS =						\
+  tests/base64.scm				\
   tests/vector.scm				\
   tests/rect.scm				\
   tests/matrix.scm				\
diff --git a/chickadee/base64.scm b/chickadee/base64.scm
index 5b6455a..74fd0c5 100644
--- a/chickadee/base64.scm
+++ b/chickadee/base64.scm
@@ -1,259 +1,65 @@
-;; -*- mode: scheme; coding: utf-8 -*-
-;;
-;; This module was renamed from (weinholt text base64 (1 0 20100612)) to
-;; (guix base64) by Nikita Karetnikov <nikita@karetnikov.org> on
-;; February 12, 2014.
-;;
-;; Some optimizations made by Ludovic Courtès <ludo@gnu.org>, 2015.
-;; Turned into a Guile module (instead of R6RS).
-;;
-;; This program is free software: you can redistribute it and/or modify
-;; it under the terms of the GNU General Public License as published by
-;; the Free Software Foundation, either version 3 of the License, 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 General Public License for more details.
-;;
-;; You should have received a copy of the GNU General Public License
-;; along with this program.  If not, see <http://www.gnu.org/licenses/>.
-;;
-;; This file incorporates work covered by the following copyright and
-;; permission notice:
-;;
-;;   Copyright © 2009, 2010 Göran Weinholt <goran@weinholt.se>
-;;
-;;   Permission is hereby granted, free of charge, to any person obtaining a
-;;   copy of this software and associated documentation files (the "Software"),
-;;   to deal in the Software without restriction, including without limitation
-;;   the rights to use, copy, modify, merge, publish, distribute, sublicense,
-;;   and/or sell copies of the Software, and to permit persons to whom the
-;;   Software is furnished to do so, subject to the following conditions:
-;;
-;;   The above copyright notice and this permission notice shall be included in
-;;   all copies or substantial portions of the Software.
-;;
-;;   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
-;;   IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
-;;   FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
-;;   THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
-;;   LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
-;;   FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
-;;   DEALINGS IN THE SOFTWARE.
-
-;; RFC 4648 Base-N Encodings
+;;; Chickadee Game Toolkit
+;;; Copyright © 2023 David Thompson <dthompson2@worcester.edu>
+;;;
+;;; Licensed under the Apache License, Version 2.0 (the "License");
+;;; you may not use this file except in compliance with the License.
+;;; You may obtain a copy of the License at
+;;;
+;;;    http://www.apache.org/licenses/LICENSE-2.0
+;;;
+;;; Unless required by applicable law or agreed to in writing, software
+;;; distributed under the License is distributed on an "AS IS" BASIS,
+;;; WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+;;; See the License for the specific language governing permissions and
+;;; limitations under the License.
 
 (define-module (chickadee base64)
-  #:export (base64-encode
-            base64-decode
-            base64-alphabet
-            base64url-alphabet
-            get-delimited-base64
-            put-delimited-base64)
-  #:use-module (srfi srfi-11)
-  #:use-module (srfi srfi-60)
   #:use-module (rnrs bytevectors)
-  #:use-module (rnrs io ports))
-
-
-(define-syntax define-alias
-  (syntax-rules ()
-    ((_ new old)
-     (define-syntax new (identifier-syntax old)))))
-
-;; Force the use of Guile's own primitives to avoid the overhead of its 'fx'
-;; procedures.
+  #:export (base64-decode))
 
-(define-alias fxbit-field bit-field)
-(define-alias fxarithmetic-shift ash)
-(define-alias fxarithmetic-shift-left ash)
-(define-alias fxand logand)
-(define-alias fxior logior)
-(define-alias fxxor logxor)
-(define-alias fx=? =)
-(define-alias fx+ +)
-(define-alias mod modulo)
-
-(define-syntax-rule (assert exp)
-  (unless exp
-    (throw 'assertion-failure 'exp)))
-
-(define base64-alphabet
+(define %base64-chars
   "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/")
 
-(define base64url-alphabet
-  "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_")
-
-(define base64-encode
-  (case-lambda
-    ;; Simple interface. Returns a string containing the canonical
-    ;; base64 representation of the given bytevector.
-    ((bv)
-     (base64-encode bv 0 (bytevector-length bv) #f #f base64-alphabet #f))
-    ((bv start)
-     (base64-encode bv start (bytevector-length bv) #f #f base64-alphabet #f))
-    ((bv start end)
-     (base64-encode bv start end #f #f base64-alphabet #f))
-    ((bv start end line-length)
-     (base64-encode bv start end line-length #f base64-alphabet #f))
-    ((bv start end line-length no-padding)
-     (base64-encode bv start end line-length no-padding base64-alphabet #f))
-    ((bv start end line-length no-padding alphabet)
-     (base64-encode bv start end line-length no-padding alphabet #f))
-    ;; Base64 encodes the bytes [start,end[ in the given bytevector.
-    ;; Lines are limited to line-length characters (unless #f),
-    ;; which must be a multiple of four. To omit the padding
-    ;; characters (#\=) set no-padding to a true value. If port is
-    ;; #f, returns a string.
-    ((bv start end line-length no-padding alphabet port)
-     (assert (or (not line-length) (zero? (mod line-length 4))))
-     (let-values (((p extract) (if port
-                                   (values port (lambda () (values)))
-                                   (open-string-output-port))))
-       (letrec ((put (if line-length
-                         (let ((chars 0))
-                           (lambda (p c)
-                             (when (fx=? chars line-length)
-                               (set! chars 0)
-                               (put-char p #\linefeed))
-                             (set! chars (fx+ chars 1))
-                             (put-char p c)))
-                         put-char)))
-         (let lp ((i start))
-           (cond ((= i end))
-                 ((<= (+ i 3) end)
-                  (let ((x (bytevector-uint-ref bv i (endianness big) 3)))
-                    (put p (string-ref alphabet (fxbit-field x 18 24)))
-                    (put p (string-ref alphabet (fxbit-field x 12 18)))
-                    (put p (string-ref alphabet (fxbit-field x 6 12)))
-                    (put p (string-ref alphabet (fxbit-field x 0 6)))
-                    (lp (+ i 3))))
-                 ((<= (+ i 2) end)
-                  (let ((x (fxarithmetic-shift-left (bytevector-u16-ref bv i (endianness big)) 8)))
-                    (put p (string-ref alphabet (fxbit-field x 18 24)))
-                    (put p (string-ref alphabet (fxbit-field x 12 18)))
-                    (put p (string-ref alphabet (fxbit-field x 6 12)))
-                    (unless no-padding
-                      (put p #\=))))
-                 (else
-                  (let ((x (fxarithmetic-shift-left (bytevector-u8-ref bv i) 16)))
-                    (put p (string-ref alphabet (fxbit-field x 18 24)))
-                    (put p (string-ref alphabet (fxbit-field x 12 18)))
-                    (unless no-padding
-                      (put p #\=)
-                      (put p #\=)))))))
-       (extract)))))
-
-  ;; Decodes a base64 string. The string must contain only pure
-  ;; unpadded base64 data.
-
-(define base64-decode
-  (case-lambda
-    ((str)
-     (base64-decode str base64-alphabet #f))
-    ((str alphabet)
-     (base64-decode str alphabet #f))
-    ((str alphabet port)
-     (unless (zero? (mod (string-length str) 4))
-       (error 'base64-decode
-              "input string must be a multiple of four characters"))
-     (let-values (((p extract) (if port
-                                   (values port (lambda () (values)))
-                                   (open-bytevector-output-port))))
-       (do ((i 0 (+ i 4)))
-           ((= i (string-length str))
-            (extract))
-         (let ((c1 (string-ref str i))
-               (c2 (string-ref str (+ i 1)))
-               (c3 (string-ref str (+ i 2)))
-               (c4 (string-ref str (+ i 3))))
-           ;; TODO: be more clever than string-index
-           (let ((i1 (string-index alphabet c1))
-                 (i2 (string-index alphabet c2))
-                 (i3 (string-index alphabet c3))
-                 (i4 (string-index alphabet c4)))
-             (cond ((and i1 i2 i3 i4)
-                    (let ((x (fxior (fxarithmetic-shift-left i1 18)
-                                    (fxarithmetic-shift-left i2 12)
-                                    (fxarithmetic-shift-left i3 6)
-                                    i4)))
-                      (put-u8 p (fxbit-field x 16 24))
-                      (put-u8 p (fxbit-field x 8 16))
-                      (put-u8 p (fxbit-field x 0 8))))
-                   ((and i1 i2 i3 (char=? c4 #\=)
-                         (= i (- (string-length str) 4)))
-                    (let ((x (fxior (fxarithmetic-shift-left i1 18)
-                                    (fxarithmetic-shift-left i2 12)
-                                    (fxarithmetic-shift-left i3 6))))
-                      (put-u8 p (fxbit-field x 16 24))
-                      (put-u8 p (fxbit-field x 8 16))))
-                   ((and i1 i2 (char=? c3 #\=) (char=? c4 #\=)
-                         (= i (- (string-length str) 4)))
-                    (let ((x (fxior (fxarithmetic-shift-left i1 18)
-                                    (fxarithmetic-shift-left i2 12))))
-                      (put-u8 p (fxbit-field x 16 24))))
-                   (else
-                    (error 'base64-decode "invalid input"
-                           (list c1 c2 c3 c4)))))))))))
-
-(define (get-line-comp f port)
-  (if (port-eof? port)
-      (eof-object)
-      (f (get-line port))))
-
-  ;; Reads the common -----BEGIN/END type----- delimited format from
-  ;; the given port. Returns two values: a string with the type and a
-  ;; bytevector containing the base64 decoded data. The second value
-  ;; is the eof object if there is an eof before the BEGIN delimiter.
-
-(define (get-delimited-base64 port)
-  (define (get-first-data-line port)
-    ;; Some MIME data has header fields in the same format as mail
-    ;; or http. These are ignored.
-    (let ((line (get-line-comp string-trim-both port)))
-      (cond ((eof-object? line) line)
-            ((string-index line #\:)
-             (let lp ()                           ;read until empty line
-               (let ((line (get-line-comp string-trim-both port)))
-                 (if (string=? line "")
-                     (get-line-comp string-trim-both port)
-                     (lp)))))
-            (else line))))
-  (let ((line (get-line-comp string-trim-both port)))
-    (cond ((eof-object? line)
-           (values "" (eof-object)))
-          ((string=? line "")
-           (get-delimited-base64 port))
-          ((and (string-prefix? "-----BEGIN " line)
-                (string-suffix? "-----" line))
-           (let* ((type (substring line 11 (- (string-length line) 5)))
-                  (endline (string-append "-----END " type "-----")))
-             (let-values (((outp extract) (open-bytevector-output-port)))
-               (let lp ((line (get-first-data-line port)))
-                 (cond ((eof-object? line)
-                        (error 'get-delimited-base64
-                               "unexpected end of file"))
-                       ((string-prefix? "-" line)
-                        (unless (string=? line endline)
-                          (error 'get-delimited-base64
-                                 "bad end delimiter" type line))
-                        (values type (extract)))
-                       (else
-                        (unless (and (= (string-length line) 5)
-                                     (string-prefix? "=" line)) ;Skip Radix-64 checksum
-                          (base64-decode line base64-alphabet outp))
-                        (lp (get-line-comp string-trim-both port))))))))
-          (else     ;skip garbage (like in openssl x509 -in foo -text output).
-           (get-delimited-base64 port)))))
-
-(define put-delimited-base64
-  (case-lambda
-    ((port type bv line-length)
-     (display (string-append "-----BEGIN " type "-----\n") port)
-     (base64-encode bv 0 (bytevector-length bv)
-                    line-length #f base64-alphabet port)
-     (display (string-append "\n-----END " type "-----\n") port))
-    ((port type bv)
-     (put-delimited-base64 port type bv 76))))
+(define %decode-table
+  (let ((table (make-hash-table)))
+    (let loop ((i 0))
+      (when (< i 64)
+        (hashv-set! table (string-ref %base64-chars i) i)
+        (loop (+ i 1))))
+    (hashv-set! table #\= 0)
+    table))
+
+(define (base64-decode str)
+  "Decode the base64 encoded string STR and return a bytevector
+containing the decoded data."
+  (let* ((n (string-length str))
+         (groups (/ n 4)))
+    (define (padding? i)
+      (eqv? (string-ref str i) #\=))
+    (define (decode i)
+      (let ((c (string-ref str i)))
+        (or (hashv-ref %decode-table c)
+            (error 'base64-error "invalid base64 character" c))))
+    (define (decode4 group)
+      (let ((start (* group 4)))
+        (logior (ash (decode start) 18)
+                (ash (decode (+ start 1)) 12)
+                (ash (decode (+ start 2)) 6)
+                (decode (+ start 3)))))
+    (unless (exact-integer? groups)
+      (error 'base64-error "invalid character count"))
+    (let* ((padding (cond
+                     ((and (padding? (- n 2)) (padding? (- n 1))) 2)
+                     ((padding? (- n 1)) 1)
+                     (else 0)))
+           (bv (make-bytevector (- (* groups 3) padding))))
+      (let loop ((i 0))
+        (cond
+         ((= i (- groups 1))
+          (let ((x (ash (decode4 i) (* padding -8))))
+            (bytevector-sint-set! bv (* i 3) x (endianness big) (- 3 padding))
+            bv))
+         ((< i groups)
+          (bytevector-sint-set! bv (* i 3) (decode4 i) (endianness big) 3)
+          (loop (+ i 1)))))
+      bv)))
diff --git a/tests/base64.scm b/tests/base64.scm
new file mode 100644
index 0000000..dba4f3b
--- /dev/null
+++ b/tests/base64.scm
@@ -0,0 +1,32 @@
+;;; Chickadee Game Toolkit
+;;; Copyright © 2023 David Thompson <dthompson2@worcester.edu>
+;;;
+;;; Licensed under the Apache License, Version 2.0 (the "License");
+;;; you may not use this file except in compliance with the License.
+;;; You may obtain a copy of the License at
+;;;
+;;;    http://www.apache.org/licenses/LICENSE-2.0
+;;;
+;;; Unless required by applicable law or agreed to in writing, software
+;;; distributed under the License is distributed on an "AS IS" BASIS,
+;;; WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+;;; See the License for the specific language governing permissions and
+;;; limitations under the License.
+
+(define-module (tests base64)
+  #:use-module (chickadee base64)
+  #:use-module (rnrs bytevectors)
+  #:use-module (srfi srfi-64)
+  #:use-module (tests utils))
+
+(with-tests "base64"
+  (test-group "base64-decode"
+    (test-equal "encoded text no padding"
+      "hello!"
+      (utf8->string (base64-decode "aGVsbG8h")))
+    (test-equal "encoded text with one byte of padding"
+      "hello"
+      (utf8->string (base64-decode "aGVsbG8=")))
+    (test-equal "encoded text with two bytes of padding"
+      "what's up?"
+      (utf8->string (base64-decode "d2hhdCdzIHVwPw==")))))