barrier/synergy/CInputPacketStream.cpp

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#include "CInputPacketStream.h"
#include "CLock.h"
#include <assert.h>
//
// CInputPacketStream
//
CInputPacketStream::CInputPacketStream(IInputStream* stream, bool adopt) :
CInputStreamFilter(stream, adopt),
m_mutex(),
m_size(0),
m_buffer(&m_mutex, NULL)
{
// do nothing
}
CInputPacketStream::~CInputPacketStream()
{
// do nothing
}
void CInputPacketStream::close()
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{
getStream()->close();
}
UInt32 CInputPacketStream::read(
void* buffer, UInt32 n)
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{
CLock lock(&m_mutex);
// wait for entire message to be read. return immediately if
// stream hungup.
if (getSizeNoLock() == 0) {
return 0;
}
// limit number of bytes to read to the number of bytes left in the
// current message.
if (n > m_size) {
n = m_size;
}
// now read from our buffer
n = m_buffer.readNoLock(buffer, n);
assert(n <= m_size);
m_size -= n;
return n;
}
UInt32 CInputPacketStream::getSize() const
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{
CLock lock(&m_mutex);
return getSizeNoLock();
}
UInt32 CInputPacketStream::getSizeNoLock() const
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{
while (!hasFullMessage()) {
// read more data
char buffer[4096];
UInt32 n = getStream()->read(buffer, sizeof(buffer));
// return if stream hungup
if (n == 0) {
m_buffer.hangup();
return 0;
}
// append to our buffer
m_buffer.write(buffer, n);
}
return m_size;
}
bool CInputPacketStream::hasFullMessage() const
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{
// get payload length if we don't have it yet
if (m_size == 0) {
// check if length field has been read yet
if (m_buffer.getSizeNoLock() < 4) {
// not enough data for payload length
return false;
}
// save payload length
UInt8 buffer[4];
UInt32 n = m_buffer.readNoLock(buffer, sizeof(buffer));
assert(n == 4);
m_size = ((UInt32)buffer[0] << 24) |
((UInt32)buffer[1] << 16) |
((UInt32)buffer[2] << 8) |
(UInt32)buffer[3];
// if payload length is zero then discard null message
if (m_size == 0) {
return false;
}
}
assert(m_size > 0);
// we have the full message when we have at least m_size bytes in
// the buffer
return (m_buffer.getSizeNoLock() >= m_size);
}