bool
InflaterIOChannel::seek(std::streampos pos)
{
if (m_error)
{
log_debug("Inflater is in error condition");
return false;
}
// If we're seeking backwards, then restart from the beginning.
if (pos < m_logical_stream_pos)
{
log_debug("inflater reset due to seek back from %d to %d",
m_logical_stream_pos, pos );
reset();
}
unsigned char temp[ZBUF_SIZE];
// Now seek forwards, by just reading data in blocks.
while (m_logical_stream_pos < pos)
{
std::streamsize to_read = pos - m_logical_stream_pos;
assert(to_read > 0);
std::streamsize readNow = std::min<std::streamsize>(to_read, ZBUF_SIZE);
assert(readNow > 0);
std::streamsize bytes_read = inflate_from_stream(temp, readNow);
assert(bytes_read <= readNow);
if (bytes_read == 0)
{
// Trouble; can't seek any further.
log_debug("Trouble: can't seek any further.. ");
return false;
break;
}
}
assert(m_logical_stream_pos == pos);
return true;
}
// See dox in IOChannel
virtual std::streamsize read(void* dst, std::streamsize bytes) {
if (m_error) return 0;
return inflate_from_stream(dst, bytes);
}
void
InflaterIOChannel::go_to_end()
{
if (m_error) {
throw IOException("InflaterIOChannel is in error condition, "
"can't seek to end");
}
// Keep reading until we can't read any more.
unsigned char temp[ZBUF_SIZE];
// Seek forwards.
for (;;) {
const std::streamsize bytes_read = inflate_from_stream(temp, ZBUF_SIZE);
if (!bytes_read) {
// We've seeked as far as we can.
break;
}
}
}
