Fix FIFO on Windows not working with Windows linebreaks

[Robyt3]

Carriage return \r characters were not properly ignored in Windows' FIFO implementation (named pipes), leading to incorrect commands being executed (including a trailing \r) which was causing some commands like rcon authentication and map changes to fail due to incorrect password/filename unless the arguments were escaped with quotes.

Checklist

• Tested the change ingame
• Provided screenshots if it is a visual change
• Tested in combination with possibly related configuration options
• Written a unit test (especially base/) or added coverage to integration test
• Considered possible null pointers and out of bounds array indexing
• Changed no physics that affect existing maps
• Tested the change with ASan+UBSan or valgrind's memcheck (optional)

[Robyt3]

Necessary for #9493. (Well, probably not strictly, but it would require additional changes. From what I can tell, the fifo.write function will automatically translate \n to \r\n.)

[heinrich5991]

Perhaps we could simply treat \r and \n the same, i.e. both as line endings? As I understand it, this PR would ignore everything between \r and \n.

[def-]

Then there are lots of empty lines on Windows. We should probably check that it's actually \r\n or \n\r and only then ignore them.

[Robyt3]

I changed it to be consistent with the behavior of CLineReader so only \n and \r\n will be considered as line breaks. Stray \r are not considered line breaks.

ddnet/src/engine/shared/linereader.cpp

Lines 59 to 74 in 85a30b6

	if(m_pBuffer[m_BufferPos] == '\0' || m_pBuffer[m_BufferPos] == '\n' || (m_pBuffer[m_BufferPos] == '\r' && m_pBuffer[m_BufferPos + 1] == '\n'))
	{
	if(m_pBuffer[m_BufferPos] == '\0')
	{
	m_ReadLastLine = true;
	}
	else
	{
	if(m_pBuffer[m_BufferPos] == '\r')
	{
	m_pBuffer[m_BufferPos] = '\0';
	++m_BufferPos;
	}
	m_pBuffer[m_BufferPos] = '\0';
	++m_BufferPos;
	}

[heinrich5991]

Thanks!