T readFromLittleEndian(zim::ifstream& in, const char* errorMsg)
{
char buffer[sizeof(T)];
in.read(buffer, sizeof(T));
if (!in)
throw ZimFileFormatError(errorMsg);
return fromLittleEndian<T>(reinterpret_cast<const T*>(buffer + 0));
}
/* This return the number of char read */
offset_type ClusterImpl::read_header(std::istream& in)
{
log_debug1("read_header");
// read first offset, which specifies, how many offsets we need to read
size_type offset;
in.read(reinterpret_cast<char*>(&offset), sizeof(offset));
if (in.fail())
{
std::cerr << "fail at read offset" << std::endl;
throw ZimFileFormatError("fail at read first offset");
}
offset = fromLittleEndian(&offset);
size_type n = offset / 4;
size_type a = offset;
log_debug1("first offset is " << offset << " n=" << n << " a=" << a);
// read offsets
offsets.clear();
offsets.reserve(n);
offsets.push_back(0);
while (--n)
{
in.read(reinterpret_cast<char*>(&offset), sizeof(offset));
if (in.fail())
{
log_debug("fail at " << n);
throw ZimFileFormatError("fail at read offset");
}
offset = fromLittleEndian(&offset);
log_debug1("offset=" << offset << '(' << offset-a << ')');
offsets.push_back(offset - a);
}
return a;
}
