AdapterIO: Increase consistency

* Moved data locking in the internal buffer class, includes handling
of backend writes.
* Takes advantage of inheritance for getting the size. The choice is
made depending on the flags. This allow the implementer to easily
return a custom size by reimplementing GetSize. At the same time
a plain BAdapterIO can still have it's total size set, but the behavior
will change depending it's mutable or not.
* Some decisions are now made by considering everything in absolute
values.
* Other minor fixes.

headers/private/media/AdapterIO.h

@@ -72,10 +72,8 @@ private:
 			int32					fFlags;
 			bigtime_t				fTimeout;
 
-			off_t					fBackPosition;
-	mutable RWLocker				fLock;
-
 			RelativePositionIO*		fBuffer;
+			off_t					fTotalSize;
 
 			BInputAdapter*			fInputAdapter;
 

src/kits/media/AdapterIO.cpp

@@ -14,36 +14,31 @@
 class RelativePositionIO : public BPositionIO
 {
 public:
-	RelativePositionIO(BPositionIO* buffer)
+	RelativePositionIO(BAdapterIO* owner, BPositionIO* buffer)
 		:
 		BPositionIO(),
+		fOwner(owner),
+		fBackPosition(0),
 		fStartOffset(0),
-		fTotalSize(0),
 		fBuffer(buffer)
-		{}
+	{
+		fOwner->GetFlags(&fFlags);
+	}
 
 	virtual	~RelativePositionIO()
 	{
 		delete fBuffer;
 	}
 
-	void SetTotalSize(size_t size)
-	{
-		fTotalSize = size;
-	}
-
-	size_t TotalSize() const
-	{
-		return fTotalSize;
-	}
-
 	status_t ResetStartOffset(off_t offset)
 	{
 		status_t ret = fBuffer->SetSize(0);
-		if (ret == B_OK)
+		if (ret != B_OK)
-			fStartOffset = offset;
-
 			return ret;
+
+		fBackPosition = offset;
+		fStartOffset = offset;
+		return B_OK;
 	}
 
 	status_t EvaluatePosition(off_t position)
@@ -54,18 +49,25 @@ public:
 		if (position < fStartOffset)
 			return B_RESOURCE_UNAVAILABLE;
 
+		off_t size = 0;
+		if (fOwner->GetSize(&size) != B_OK)
+			return B_ERROR;
+
+		if (position > size) {
 			// This is an endless stream, we don't know
 			// how much data will come and when, we could
 			// block on that.
-		if (fTotalSize == 0)
+			if (IsMutable())
 				return B_WOULD_BLOCK;
+			else
+				return B_ERROR;
+		}
 
-		if (position >= fTotalSize)
+		off_t bufSize = 0;
+		if (GetSize(&bufSize) != B_OK)
 			return B_ERROR;
 
-		off_t size = 0;
+		if (position > bufSize)
-		fBuffer->GetSize(&size);
-		if (position >= size)
 			return B_RESOURCE_UNAVAILABLE;
 
 		return B_OK;
@@ -74,15 +76,13 @@ public:
 	status_t WaitForData(off_t position)
 	{
 		off_t bufferSize = 0;
-		position = _PositionToRelative(position);
+		status_t ret = GetSize(&bufferSize);
-
-		status_t ret = fBuffer->GetSize(&bufferSize);
 		if (ret != B_OK)
 			return B_ERROR;
 
 		while(bufferSize < position) {
 			snooze(100000);
-			fBuffer->GetSize(&bufferSize);
+			GetSize(&bufferSize);
 		}
 		return B_OK;
 	}
@@ -90,6 +90,8 @@ public:
 	virtual	ssize_t	ReadAt(off_t position, void* buffer,
 		size_t size)
 	{
+		AutoReadLocker _(fLock);
+
 		return fBuffer->ReadAt(
 			_PositionToRelative(position), buffer, size);
 
@@ -98,31 +100,36 @@ public:
 	virtual	ssize_t	WriteAt(off_t position,
 		const void* buffer, size_t size)
 	{
+		AutoWriteLocker _(fLock);
+
 		return fBuffer->WriteAt(
 			_PositionToRelative(position), buffer, size);
 	}
 
 	virtual	off_t Seek(off_t position, uint32 seekMode)
 	{
+		AutoWriteLocker _(fLock);
+
 		return fBuffer->Seek(_PositionToRelative(position), seekMode);
 	}
 
 	virtual off_t Position() const
 	{
+		AutoReadLocker _(fLock);
+
 		return _RelativeToPosition(fBuffer->Position());
 	}
 
 	virtual	status_t SetSize(off_t size)
 	{
+		AutoWriteLocker _(fLock);
+
 		return fBuffer->SetSize(_PositionToRelative(size));
 	}
 
 	virtual	status_t GetSize(off_t* size) const
 	{
-		if (fTotalSize > 0) {
+		AutoReadLocker _(fLock);
-			*size = fTotalSize;
-			return B_OK;
-		}
 
 		off_t bufferSize;
 		status_t ret = fBuffer->GetSize(&bufferSize);
@@ -132,6 +139,31 @@ public:
 		return ret;
 	}
 
+	ssize_t BackWrite(const void* buffer, size_t size)
+	{
+		AutoWriteLocker _(fLock);
+
+		off_t currentPos = Position();
+		off_t ret = fBuffer->WriteAt(fBackPosition, buffer, size);
+		fBackPosition += ret;
+		return fBuffer->Seek(currentPos, SEEK_SET);
+	}
+
+	bool IsStreaming() const
+	{
+		return (fFlags & B_MEDIA_STREAMING) == true;
+	}
+
+	bool IsMutable() const
+	{
+		return (fFlags & B_MEDIA_MUTABLE_SIZE) == true;
+	}
+
+	bool IsSeekable() const
+	{
+		return (fFlags & B_MEDIA_SEEKABLE) == true;
+	}
+
 private:
 
 	off_t _PositionToRelative(off_t position) const
@@ -144,10 +176,14 @@ private:
 		return position + fStartOffset;
 	}
 
+	BAdapterIO*			fOwner;
+	off_t				fBackPosition;
 	off_t				fStartOffset;
-	off_t			fTotalSize;
 
 	BPositionIO*		fBuffer;
+	int32				fFlags;
+
+	mutable	RWLocker	fLock;
 };
 
 
@@ -155,11 +191,10 @@ BAdapterIO::BAdapterIO(int32 flags, bigtime_t timeout)
 	:
 	fFlags(flags),
 	fTimeout(timeout),
-	fBackPosition(0),
 	fBuffer(NULL),
 	fInputAdapter(NULL)
 {
-	fBuffer = new RelativePositionIO(new BMallocIO());
+	fBuffer = new RelativePositionIO(this, new BMallocIO());
 }
 
 
@@ -191,8 +226,6 @@ BAdapterIO::ReadAt(off_t position, void* buffer, size_t size)
 	if (ret != B_OK)
 		return ret;
 
-	AutoReadLocker _(fLock);
-
 	return fBuffer->ReadAt(position, buffer, size);
 }
 
@@ -204,8 +237,6 @@ BAdapterIO::WriteAt(off_t position, const void* buffer, size_t size)
 	if (ret != B_OK)
 		return ret;
 
-	AutoWriteLocker _(fLock);
-
 	return fBuffer->WriteAt(position, buffer, size);
 }
 
@@ -217,8 +248,6 @@ BAdapterIO::Seek(off_t position, uint32 seekMode)
 	if (ret != B_OK)
 		return ret;
 
-	AutoWriteLocker _(fLock);
-
 	return fBuffer->Seek(position, seekMode);
 }
 
@@ -226,8 +255,6 @@ BAdapterIO::Seek(off_t position, uint32 seekMode)
 off_t
 BAdapterIO::Position() const
 {
-	AutoReadLocker _(fLock);
-
 	return fBuffer->Position();
 }
 
@@ -235,7 +262,10 @@ BAdapterIO::Position() const
 status_t
 BAdapterIO::SetSize(off_t size)
 {
-	AutoWriteLocker _(fLock);
+	if (!fBuffer->IsMutable()) {
+		fTotalSize = size;
+		return B_OK;
+	}
 
 	return fBuffer->SetSize(size);
 }
@@ -244,19 +274,32 @@ BAdapterIO::SetSize(off_t size)
 status_t
 BAdapterIO::GetSize(off_t* size) const
 {
-	AutoReadLocker _(fLock);
+	if (!fBuffer->IsMutable()) {
+		*size = fTotalSize;
+		return B_OK;
+	}
 
 	return fBuffer->GetSize(size);
 }
 
 
+ssize_t
+BAdapterIO::BackWrite(const void* buffer, size_t size)
+{
+	return fBuffer->BackWrite(buffer, size);
+}
+
+
 status_t
 BAdapterIO::_EvaluateWait(off_t pos)
 {
 	status_t err = fBuffer->EvaluatePosition(pos);
-	if (err == B_ERROR && err != B_WOULD_BLOCK)
+
-		return B_ERROR;
+	if (err != B_RESOURCE_UNAVAILABLE && err != B_OK)
-	else if (err == B_RESOURCE_UNAVAILABLE) {
+		return B_UNSUPPORTED;
+
+	if (err == B_RESOURCE_UNAVAILABLE && fBuffer->IsStreaming()
+			&& fBuffer->IsSeekable()) {
 		if (SeekRequested(pos) != B_OK)
 			return B_UNSUPPORTED;
 	}
@@ -276,18 +319,6 @@ BAdapterIO::BuildInputAdapter()
 }
 
 
-ssize_t
-BAdapterIO::BackWrite(const void* buffer, size_t size)
-{
-	AutoWriteLocker _(fLock);
-
-	off_t currentPos = Position();
-	off_t ret = fBuffer->WriteAt(fBackPosition, buffer, size);
-	fBackPosition += ret;
-	return fBuffer->Seek(currentPos, SEEK_SET);
-}
-
-
 status_t
 BAdapterIO::SeekRequested(off_t position)
 {