[Scummvm-cvs-logs] SF.net SVN: scummvm:[52389] scummvm/trunk/common

[wjpalenstijn at users.sourceforge.net]

Revision: 52389
          http://scummvm.svn.sourceforge.net/scummvm/?rev=52389&view=rev
Author:   wjpalenstijn
Date:     2010-08-25 14:43:42 +0000 (Wed, 25 Aug 2010)

Log Message:
-----------
COMMON: Fix eos handling in BufferedReadStream

This makes it pass the test added in r52382.

Modified Paths:
--------------
    scummvm/trunk/common/stream.cpp
    scummvm/trunk/common/stream.h

Modified: scummvm/trunk/common/stream.cpp
===================================================================
--- scummvm/trunk/common/stream.cpp	2010-08-25 13:31:14 UTC (rev 52388)
+++ scummvm/trunk/common/stream.cpp	2010-08-25 14:43:42 UTC (rev 52389)
@@ -256,7 +256,6 @@
 	// Check whether the data left in the buffer suffices....
 	if (dataSize > bufBytesLeft) {
 		// Nope, we need to read more data
-		_eos = true;	// we tried to read past the buffer
 
 		// First, flush the buffer, if it is non-empty
 		if (0 < bufBytesLeft) {
@@ -269,8 +268,12 @@
 
 		// At this point the buffer is empty. Now if the read request
 		// exceeds the buffer size, just satisfy it directly.
-		if (dataSize > _realBufSize)
-			return alreadyRead + _parentStream->read(dataPtr, dataSize);
+		if (dataSize > _realBufSize) {
+			uint32 n = _parentStream->read(dataPtr, dataSize);
+			if (_parentStream->eos())
+				_eos = true;
+			return alreadyRead + n;
+		}
 
 		// Refill the buffer.
 		// If we didn't read as many bytes as requested, the reason
@@ -279,10 +282,12 @@
 		// return to the caller.
 		_bufSize = _parentStream->read(_buf, _realBufSize);
 		_pos = 0;
-		if (_bufSize)
-			_eos = false;	// we've managed to replenish our buffer
-		if (dataSize > _bufSize)
+		if (_bufSize < dataSize) {
+			// we didn't get enough data from parent
+			if (_parentStream->eos())
+				_eos = true;
 			dataSize = _bufSize;
+		}
 	}
 
 	if (dataSize) {
@@ -307,10 +312,12 @@
 	
 	if (whence == SEEK_CUR && (int)_pos + offset >= 0 && _pos + offset <= _bufSize) {
 		_pos += offset;
-		
+
+		// Note: we do not need to reset parent's eos flag here. It is
+		// sufficient that it is reset when actually seeking in the parent.
 	} else {
 		// Seek was not local enough, so we reset the buffer and
-		// just seeks normally in the parent stream.
+		// just seek normally in the parent stream.
 		if (whence == SEEK_CUR)
 			offset -= (_bufSize - _pos);
 		_pos = _bufSize;

Modified: scummvm/trunk/common/stream.h
===================================================================
--- scummvm/trunk/common/stream.h	2010-08-25 13:31:14 UTC (rev 52388)
+++ scummvm/trunk/common/stream.h	2010-08-25 14:43:42 UTC (rev 52389)
@@ -494,7 +494,7 @@
 	DisposeAfterUse::Flag _disposeParentStream;
 	byte *_buf;
 	uint32 _pos;
-	bool _eos;	// in this context it means: have we tried to read beyond the end of the buffer
+	bool _eos; // end of stream
 	uint32 _bufSize;
 	uint32 _realBufSize;
 	virtual void allocBuf(uint32 bufSize);	// virtual functions to allocate/deallocate the buffer
@@ -504,9 +504,9 @@
 	BufferedReadStream(ReadStream *parentStream, uint32 bufSize, DisposeAfterUse::Flag disposeParentStream = DisposeAfterUse::NO);
 	virtual ~BufferedReadStream();
 
-	virtual bool eos() const { return _eos && _parentStream->eos(); }
+	virtual bool eos() const { return _eos; }
 	virtual bool err() const { return _parentStream->err(); }
-	virtual void clearErr() { _parentStream->clearErr(); }
+	virtual void clearErr() { _eos = false; _parentStream->clearErr(); }
 
 	virtual uint32 read(void *dataPtr, uint32 dataSize);
 };


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