291 lines
7.4 KiB
C
291 lines
7.4 KiB
C
/* base64.c -- Encode/decode integers in base64 format
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* Created: Mon Sep 23 16:55:12 1996 by faith@dict.org
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* Revised: Sat Mar 30 12:02:36 2002 by faith@dict.org
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* Copyright 1996, 2002 Rickard E. Faith (faith@dict.org)
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*
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* This library is free software; you can redistribute it and/or modify it
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* under the terms of the GNU Library General Public License as published
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* by the Free Software Foundation; either version 2 of the License, or (at
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* your option) any later version.
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*
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* This library is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Library General Public License for more details.
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*
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* You should have received a copy of the GNU Library General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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* 02110-1301 USA
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*
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* \section{Base-64 Routines}
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*
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* \intro These routines use the 64-character subset of International
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* Alphabet IA5 discussed in RFC 1421 (printeable encoding) and RFC 1522
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* (base64 MIME).
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*
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Value Encoding Value Encoding Value Encoding Value Encoding
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0 A 17 R 34 i 51 z
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1 B 18 S 35 j 52 0
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2 C 19 T 36 k 53 1
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3 D 20 U 37 l 54 2
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4 E 21 V 38 m 55 3
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5 F 22 W 39 n 56 4
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6 G 23 X 40 o 57 5
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7 H 24 Y 41 p 58 6
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8 I 25 Z 42 q 59 7
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9 J 26 a 43 r 60 8
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10 K 27 b 44 s 61 9
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11 L 28 c 45 t 62 +
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12 M 29 d 46 u 63 /
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13 N 30 e 47 v
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14 O 31 f 48 w (pad) =
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15 P 32 g 49 x
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16 Q 33 h 50 y
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*
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*/
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/*
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Hacked for VIPS ... does any length object (not just ints), formats
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base64 into 70 character lines, output to a malloc'd buffer.
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VIPS uses this to write BLOBs (like ICC profiles, for example) to the
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XML that follows an image.
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Modified on:
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23/7/07 JC
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- oop, needed a slightly larger worst-case buffer in im__b64_encode()
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12/5/09
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- fix signed/unsigned warning
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25/3/11
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- move to vips_ namespace
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31/5/15
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- oops siged/unsignned mess-up meant we were not padding correctly
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*/
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/*
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#define DEBUG
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*/
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#ifdef HAVE_CONFIG_H
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#include <config.h>
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#endif /*HAVE_CONFIG_H*/
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#include <vips/intl.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <assert.h>
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#include <vips/vips.h>
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#include "base64.h"
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static unsigned char b64_list[] =
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"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
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#define XX 100
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static unsigned char b64_index[256] = {
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XX,XX,XX,XX, XX,XX,XX,XX, XX,XX,XX,XX, XX,XX,XX,XX,
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XX,XX,XX,XX, XX,XX,XX,XX, XX,XX,XX,XX, XX,XX,XX,XX,
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XX,XX,XX,XX, XX,XX,XX,XX, XX,XX,XX,62, XX,XX,XX,63,
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52,53,54,55, 56,57,58,59, 60,61,XX,XX, XX,XX,XX,XX,
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XX, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9,10, 11,12,13,14,
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15,16,17,18, 19,20,21,22, 23,24,25,XX, XX,XX,XX,XX,
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XX,26,27,28, 29,30,31,32, 33,34,35,36, 37,38,39,40,
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41,42,43,44, 45,46,47,48, 49,50,51,XX, XX,XX,XX,XX,
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XX,XX,XX,XX, XX,XX,XX,XX, XX,XX,XX,XX, XX,XX,XX,XX,
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XX,XX,XX,XX, XX,XX,XX,XX, XX,XX,XX,XX, XX,XX,XX,XX,
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XX,XX,XX,XX, XX,XX,XX,XX, XX,XX,XX,XX, XX,XX,XX,XX,
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XX,XX,XX,XX, XX,XX,XX,XX, XX,XX,XX,XX, XX,XX,XX,XX,
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XX,XX,XX,XX, XX,XX,XX,XX, XX,XX,XX,XX, XX,XX,XX,XX,
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XX,XX,XX,XX, XX,XX,XX,XX, XX,XX,XX,XX, XX,XX,XX,XX,
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XX,XX,XX,XX, XX,XX,XX,XX, XX,XX,XX,XX, XX,XX,XX,XX,
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XX,XX,XX,XX, XX,XX,XX,XX, XX,XX,XX,XX, XX,XX,XX,XX,
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};
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/* Read (up to) 3 bytes from in. Be careful about byte ordering :-/ we need to
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* end up with in[2] in the bottom few bits.
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*/
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static int
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read24( const unsigned char *in, int remaining )
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{
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int bits;
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int i;
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bits = 0;
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for( i = 0; i < 3; i++ ) {
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bits <<= 8;
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if( remaining > 0 ) {
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bits |= in[i];
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remaining -= 1;
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}
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}
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return( bits );
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}
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/* Output (up to) 24 bits as four base64 chars. Pad with '=' characters.
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*/
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static void
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encode24( char *p, int bits, int remaining )
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{
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int i;
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for( i = 0; i < 4; i++ ) {
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if( remaining <= 0 )
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p[i] = '=';
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else {
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/* Take the top 6 bits of 24.
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*/
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p[i] = b64_list[(bits >> 18) & 63];
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bits <<= 6;
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remaining -= 6;
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}
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}
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}
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/* Output to a malloc'd buffer, NULL on error. Try to be simple and reliable,
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* rather than quick.
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*/
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char *
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vips__b64_encode( const unsigned char *data, size_t data_length )
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{
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/* Worst case: 1.333 chars per byte, plus 10% for extra carriage
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* returns and stuff. And the \n\0 at the end.
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*/
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const size_t output_data_length = data_length * 44 / 30 + 2;
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char *buffer;
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char *p;
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int i;
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int cursor;
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if( output_data_length > 10 * 1024 * 1024 ) {
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/* We shouldn't really be used for large amounts of data, plus
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* we are using int offsets.
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*
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* A large ICC profile can be 1MB, so allow 10MB of b64.
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*/
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vips_error( "vips__b64_encode", "%s", _( "too much data" ) );
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return( NULL );
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}
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if( !(buffer = vips_malloc( NULL, output_data_length )) )
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return( NULL );
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p = buffer;
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*p++ = '\n';
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cursor = 0;
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for( i = 0; i < data_length; i += 3 ) {
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int remaining = data_length - i;
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int bits;
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bits = read24( data + i, remaining );
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encode24( p, bits, remaining * 8 );
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p += 4;
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cursor += 4;
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if( cursor >= 76 ) {
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*p++ = '\n';
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cursor = 0;
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}
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}
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if( cursor > 0 )
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*p++ = '\n';
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*p++ = '\0';
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#ifdef DEBUG
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{
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unsigned int total;
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/* Calculate a very simple checksum for debugging.
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*/
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for( total = 0, i = 0; i < data_length; i++ )
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total += data[i];
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printf( "vips__b64_encode: length = %zu, checksum 0x%x\n",
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data_length, total & 0xffff );
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}
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#endif /*DEBUG*/
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return( buffer );
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}
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/* Decode base64 back to binary in a malloc'd buffer. NULL on error.
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*/
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unsigned char *
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vips__b64_decode( const char *buffer, size_t *data_length )
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{
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const size_t buffer_length = strlen( buffer );
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/* Worst case. Add one, since we don't want to return NULL for an empty
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* input string, it would look like an error return.
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*/
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const size_t output_data_length = 1 + buffer_length * 3 / 4;
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unsigned char *data;
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unsigned char *p;
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unsigned int bits;
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int nbits;
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int i;
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if( output_data_length > 1024 * 1024 ) {
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/* We shouldn't really be used for large amounts of data, plus
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* we are using an int for offset.
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*/
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vips_error( "vips__b64_decode", "%s", _( "too much data" ) );
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return( NULL );
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}
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if( !(data = vips_malloc( NULL, output_data_length )) )
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return( NULL );
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p = data;
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bits = 0;
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nbits = 0;
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for( i = 0; i < buffer_length; i++ ) {
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unsigned int val;
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if( (val = b64_index[(int) buffer[i]]) != XX ) {
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bits <<= 6;
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bits |= val;
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nbits += 6;
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if( nbits >= 8 ) {
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*p++ = (bits >> (nbits - 8)) & 0xff;
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nbits -= 8;
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}
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}
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}
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g_assert( (size_t) (p - data) < output_data_length );
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if( data_length )
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*data_length = p - data;
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#ifdef DEBUG
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{
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unsigned int total;
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/* Calculate a very simple checksum for debugging.
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*/
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for( total = 0, i = 0; i < p - data; i++ )
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total += data[i];
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printf( "vips__b64_decode: length = %d, checksum 0x%x\n",
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p - data, total & 0xffff );
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}
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#endif /*DEBUG*/
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return( data );
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}
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