void ClusterImpl::read(std::istream& in)
{
log_debug1("read");
// 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())
return;
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();
data.clear();
offsets.reserve(n);
offsets.push_back(0);
while (--n)
{
in.read(reinterpret_cast<char*>(&offset), sizeof(offset));
if (in.fail())
{
log_debug1("fail at " << n);
return;
}
offset = fromLittleEndian(&offset);
log_debug1("offset=" << offset << '(' << offset-a << ')');
offsets.push_back(offset - a);
}
// last offset points past the end of the cluster, so we know now, how may bytes to read
if (offsets.size() > 1)
{
n = offsets.back() - offsets.front();
if (n > 0)
{
data.resize(n);
log_debug1("read " << n << " bytes of data");
in.read(&(data[0]), n);
}
else
log_warn("read empty cluster");
}
}
void ClusterImpl::write(std::ostream& out) const
{
size_type a = offsets.size() * sizeof(size_type);
for (Offsets::const_iterator it = offsets.begin(); it != offsets.end(); ++it)
{
size_type o = *it;
o += a;
o = fromLittleEndian(&o);
out.write(reinterpret_cast<const char*>(&o), sizeof(size_type));
}
out.write(&(data[0]), data.size());
}
/* 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;
}
