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/* 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., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA.
*/
#include <qfile.h>
#include "chmfile.h"
#include "decompress.h"
uint Chm::getEncInt(QFile& f, uint &value) const
{
int c;
uint result = 0;
ulong count = 0;
do
{
c = f.getch();
result <<= 7;
result |= (c & 0x7F);
count++;
} while (c & 0x80);
value = result;
return count;
}
uint Chm::getName(QFile& f, QString& name) const
{
int len = f.getch();
char *buf = new char[len];
f.readBlock(buf, len);
name = QString::fromUtf8(buf, len);
if (name.startsWith("/"))
name = name.lower();
delete [] buf;
return len + 1;
}
uint Chm::getIntel32(QFile& f) const
{
uint value = f.getch() | f.getch() << 8 | f.getch() << 16 | f.getch() << 24;
return value;
}
uint Chm::getIntel64(QFile& f) const
{
uint value = getIntel32(f);
f.at(f.at() + 4);
return value;
}
bool Chm::getChunk(QFile& f, uint chunkSize, ChmDirectoryMap& directoryMap) const
{
char tag[4];
if (f.readBlock(tag, 4) != 4) return false;
if (!qstrncmp(tag, "PMGL", 4))
{
uint quickref_length = getIntel32(f);
f.at(f.at() + 12);
uint pos = 20;
while (pos < chunkSize - quickref_length)
{
uint section, offset, length;
QString name;
pos += getName(f, name);
pos += getEncInt(f, section);
pos += getEncInt(f, offset);
pos += getEncInt(f, length);
directoryMap[name] = ChmDirTableEntry(section, offset, length);
if (name.endsWith(".hhc"))
directoryMap["/@contents"] = ChmDirTableEntry(section, offset, length);
}
return (f.at(f.at() + quickref_length));
}
else if (!qstrncmp(tag, "PMGI", 4))
{
// evaluation of the index chunk is not yet implemented => skip it
return f.at(f.at() + chunkSize - 4);
}
else
{
return false;
}
}
bool Chm::read(const QString& fileSpec, ChmDirectoryMap& dirMap, QByteArray& contents) const
{
QFile f(fileSpec);
if (!f.open(IO_ReadOnly)) return false;
// read CHM file header
char tag[4];
if (f.readBlock(tag, 4) != 4 || qstrncmp(tag, "ITSF", 4)) return false;
uint chm_version = getIntel32(f);
if (!f.at(f.at() + 0x30)) return false;
// read header section table
uint section_0_offset = getIntel64(f);
uint section_0_length = getIntel64(f);
uint section_1_offset = getIntel64(f);
uint section_1_length = getIntel64(f);
uint contentStart = 0;
if (chm_version >= 3) contentStart = getIntel32(f);
// read directory header
if (!f.at(section_1_offset)) return false;
if (f.readBlock(tag, 4) != 4 || qstrncmp(tag, "ITSP", 4)) return false;
if (!f.at(f.at() + 12)) return false;
uint directory_chunk_size = getIntel32(f);
if (!f.at(f.at() + 24)) return false;
uint num_directory_chunks = getIntel32(f);
if (!f.at(f.at() + 36)) return false;
// read directory table
for (uint i = 0; i < num_directory_chunks; i++)
if (!getChunk(f, directory_chunk_size, dirMap)) return false;
// current position is start of content area
if (chm_version < 3) contentStart = f.at();
// read reset table
if (!f.at(contentStart)) return false;
uint resetTableOffset =
dirMap["::DataSpace/Storage/MSCompressed/Transform/{7FC28940-9D31-11D0-9B27-00A0C91E9C7C}/InstanceData/ResetTable"].offset;
if (!f.at(f.at() + resetTableOffset + 4)) return false;
uint numResetTableEntries = getIntel32(f);
if (!f.at(f.at() + 8)) return false;
uint uncompressedLength = getIntel64(f);
uint compressedLength = getIntel64(f);
uint blockSize = getIntel64(f);
uint *resetTable = new uint[numResetTableEntries + 1];
for (uint i = 0; i < numResetTableEntries; i++)
resetTable[i] = getIntel64(f);
resetTable[numResetTableEntries] = compressedLength;
// read compressed contents
if (!f.at(contentStart)) return false;
uint contentsOffset = dirMap["::DataSpace/Storage/MSCompressed/Content"].offset;
if (!f.at(f.at() + contentsOffset)) return false;
char *compressedContents = new char[compressedLength];
if ((uint)f.readBlock(compressedContents, compressedLength) != compressedLength) return false;
f.close();
// allocate buffer for uncompressed contents
char *uncompressedContents = new char[uncompressedLength];
// get window size
uint window = 1;
uint tmp = blockSize;
while (tmp >>= 1) window++;
// decompress
uint outlen = uncompressedLength;
int res = 1;
for (uint i = 0; i < numResetTableEntries; i++)
{
if (!(i & 1)) LZXinit(window);
uint inlen = resetTable[i+1] - resetTable[i];
res = LZXdecompress((uchar*)&compressedContents[resetTable[i]],
inlen,
(uchar*)uncompressedContents + i * blockSize,
(outlen < blockSize) ? outlen : blockSize);
if (res) break;
outlen -= blockSize;
}
delete [] resetTable;
delete [] compressedContents;
if (res == 0)
contents.duplicate(uncompressedContents, uncompressedLength);
delete [] uncompressedContents;
return (res == 0);
}
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