// http://www.nongnu.org/chmspec/latest/Internal.html#WINDOWS
void ChmDoc::ParseWindowsData() {
size_t windowsLen, stringsLen;
ScopedMem<unsigned char> windowsData(GetData("/#WINDOWS", &windowsLen));
ScopedMem<unsigned char> stringsData(GetData("/#STRINGS", &stringsLen));
if (!windowsData || !stringsData)
return;
if (windowsLen <= 8)
return;
ByteReader rw(windowsData, windowsLen);
DWORD entries = rw.DWordLE(0);
DWORD entrySize = rw.DWordLE(4);
if (entrySize < 188)
return;
for (DWORD i = 0; i < entries && (i + 1) * entrySize <= windowsLen; i++) {
DWORD off = 8 + i * entrySize;
if (!title) {
DWORD strOff = rw.DWordLE(off + 0x14);
title.Set(GetCharZ(stringsData, stringsLen, strOff));
}
if (!tocPath) {
DWORD strOff = rw.DWordLE(off + 0x60);
tocPath.Set(GetCharZ(stringsData, stringsLen, strOff));
}
if (!indexPath) {
DWORD strOff = rw.DWordLE(off + 0x64);
indexPath.Set(GetCharZ(stringsData, stringsLen, strOff));
}
if (!homePath) {
DWORD strOff = rw.DWordLE(off + 0x68);
homePath.Set(GetCharZ(stringsData, stringsLen, strOff));
}
}
}
// http://www.nongnu.org/chmspec/latest/Internal.html#SYSTEM
bool ChmDoc::ParseSystemData()
{
size_t dataLen;
ScopedMem<unsigned char> data(GetData("/#SYSTEM", &dataLen));
if (!data)
return false;
ByteReader r(data, dataLen);
DWORD len = 0;
// Note: skipping DWORD version at offset 0. It's supposed to be 2 or 3.
for (size_t off = 4; off + 4 < dataLen; off += len + 4) {
// Note: at some point we seem to get off-sync i.e. I'm seeing
// many entries with type == 0 and len == 0. Seems harmless.
len = r.WordLE(off + 2);
if (len == 0)
continue;
WORD type = r.WordLE(off);
switch (type) {
case 0:
if (!tocPath)
tocPath.Set(GetCharZ(data, dataLen, off + 4));
break;
case 1:
if (!indexPath)
indexPath.Set(GetCharZ(data, dataLen, off + 4));
break;
case 2:
if (!homePath)
homePath.Set(GetCharZ(data, dataLen, off + 4));
break;
case 3:
if (!title)
title.Set(GetCharZ(data, dataLen, off + 4));
break;
case 4:
if (!codepage && len >= 4)
codepage = LcidToCodepage(r.DWordLE(off + 4));
break;
case 6:
// compiled file - ignore
break;
case 9:
if (!creator)
creator.Set(GetCharZ(data, dataLen, off + 4));
break;
case 16:
// default font - ignore
break;
}
}
return true;
}
char* ChmDoc::ResolveTopicID(unsigned int id) {
size_t ivbLen = 0;
ScopedMem<unsigned char> ivbData(GetData("/#IVB", &ivbLen));
ByteReader br(ivbData, ivbLen);
if ((ivbLen % 8) != 4 || ivbLen - 4 != br.DWordLE(0))
return nullptr;
for (size_t off = 4; off < ivbLen; off += 8) {
if (br.DWordLE(off) == id) {
size_t stringsLen = 0;
ScopedMem<unsigned char> stringsData(GetData("/#STRINGS", &stringsLen));
return GetCharZ(stringsData, stringsLen, br.DWordLE(off + 4));
}
}
return nullptr;
}
