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/* This file is part of Strigi Desktop Search
*
* Copyright (C) 2006 Jos van den Oever <jos@vandenoever.info>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 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
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public License
* along with this library; see the file COPYING.LIB. If not, write to
* the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
* Boston, MA 02110-1301, USA.
*/
#include "base64inputstream.h"
#include <cstring>
using namespace std;
using namespace Strigi;
/* code is based on public domain code at
http://www.tug.org/ftp/vm/base64-decode.c
*/
class Base64InputStream::Private {
public:
Base64InputStream* const p;
InputStream* input;
const char* pos, * pend;
int32_t bits;
int32_t nleft;
char bytestodo;
char char_count;
Private(Base64InputStream* p, InputStream* i);
bool moreData();
int32_t fillBuffer(char* start, int32_t space);
};
const unsigned char alphabet[]
= "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
bool inalphabet[256];
unsigned char decoder[133];
bool initializedAlphabet = false;
void initialize();
string decode(const char* in, string::size_type length);
void
initialize() {
if (!initializedAlphabet) {
initializedAlphabet = true;
// initialize the translation arrays
for (int i=64; i<256; ++i) {
inalphabet[i] = 0;
}
for (unsigned char i=0; i<64; ++i) {
inalphabet[alphabet[i]] = true;
decoder[alphabet[i]] = i;
}
}
}
Base64InputStream::Base64InputStream(InputStream* i)
:p(new Private(this, i))
{
}
Base64InputStream::~Base64InputStream() {
delete p;
}
Base64InputStream::Private::Private(Base64InputStream* bi, InputStream* i)
:p(bi), input(i) {
initialize();
nleft = 0;
char_count = 0;
bits = 0;
bytestodo = 0;
pos = pend = 0;
}
bool
Base64InputStream::Private::moreData() {
if (pos == pend) {
int32_t nread = input->read(pos, 1, 0);
if (nread < -1) {
p->m_status = Error;
p->m_error = input->error();
input = 0;
return false;
}
if (nread <= 0) {
input = 0;
return false;
}
pend = pos + nread;
}
return true;
}
int32_t
Base64InputStream::fillBuffer(char* start, int32_t space) {
return p->fillBuffer(start, space);
}
int32_t
Base64InputStream::Private::fillBuffer(char* start, int32_t space) {
if (input == 0 && bytestodo == 0) return -1;
// handle the bytes that were left over from the last call
if (bytestodo) {
switch (bytestodo) {
case 3:
*start = (char)(bits >> 16);
break;
case 2:
*start = (char)((bits >> 8) & 0xff);
break;
case 1:
*start = (char)(bits & 0xff);
bits = 0;
char_count = 0;
break;
}
bytestodo--;
return 1;
}
const char* end = start + space;
char* p = start;
int32_t nwritten = 0;
while (moreData()) {
unsigned char c = *pos++;
// = signals the end of the encoded block
if (c == '=') {
if (char_count == 2) {
bytestodo = 1;
bits >>= 10;
} else if (char_count == 3) {
bytestodo = 2;
bits >>= 8;
}
input = 0;
break;
}
// we ignore characters that do not fit
if (!inalphabet[c]) {
continue;
}
bits += decoder[c];
char_count++;
if (char_count == 4) {
if (p >= end) {
bytestodo = 3;
break;
}
*p++ = (char)(bits >> 16);
if (p >= end) {
bytestodo = 2;
nwritten++;
break;
}
*p++ = (char)((bits >> 8) & 0xff);
if (p >= end) {
bytestodo = 1;
nwritten += 2;
break;
}
*p++ = (char)(bits & 0xff);
bits = 0;
char_count = 0;
nwritten += 3;
} else {
bits <<= 6;
}
}
if (nwritten == 0 && input == 0 && bytestodo == 0) {
// printf("EOF\n");
nwritten = -1;
}
return nwritten;
}
string
Base64InputStream::decode(const char* in, string::size_type length) {
initialize();
string d;
if (length%4) return d;
initialize();
string::size_type words = length/4;
d.reserve(words*3);
const unsigned char* c = (const unsigned char*)in;
const unsigned char* e = c + length;
if (in[length-1] == '=') {
e -= 4;
}
char k, l, b[3];
for (; c < e; c += 4) {
if (inalphabet[c[0]] && inalphabet[c[1]] && inalphabet[c[2]]
&& inalphabet[c[3]]) {
k = decoder[c[1]];
l = decoder[c[2]];
b[0] = (char)((decoder[c[0]] << 2) + (k >> 4));
b[1] = (char)((k << 4) + (l >> 2));
b[2] = (char)((l << 6) + (decoder[c[3]]));
d.append(b, 3);
} else {
return string();
}
}
if (in[length-2] == '=') {
if (inalphabet[c[0]] && inalphabet[c[1]]) {
b[0] = (char)((decoder[c[0]] << 2)+((decoder[c[1]] >> 4)));
d.append(b, 1);
} else {
return string();
}
} else if (in[length-1] == '=') {
if (inalphabet[c[0]] && inalphabet[c[1]] && inalphabet[c[2]]) {
k = decoder[c[1]];
b[0] = (char)((decoder[c[0]] << 2) + (k >> 4));
b[1] = (char)((k << 4) + (decoder[c[2]] >> 2));
d.append(b, 2);
} else {
return string();
}
}
return d;
}
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