[mjmartin] 38899: - Fix calculation of WriteQuotaAvailable and WritePtr when moving memory. - Due to the new implementation, Quota is not charged for partial message retrievals. Therefore reset Quota Available to MaxDataLength when last message is read from buffer and check that Quota is greater than 0 before waking the write thread.

Author: mjmartin
Date: Sun Jan 18 10:31:45 2009
New Revision: 38899

URL: http://svn.reactos.org/svn/reactos?rev=38899&view=rev
Log:
- Fix calculation of WriteQuotaAvailable and WritePtr when moving memory.
- Due to the new implementation, Quota is not charged for partial message retrievals. Therefore reset Quota Available to MaxDataLength when last message is read from buffer and check that Quota is greater than 0 before waking the write thread.

Modified:
    trunk/reactos/drivers/filesystems/npfs/rw.c

Modified: trunk/reactos/drivers/filesystems/npfs/rw.c
URL: http://svn.reactos.org/svn/reactos/trunk/reactos/drivers/filesystems/npfs/rw...
==============================================================================
--- trunk/reactos/drivers/filesystems/npfs/rw.c [iso-8859-1] (original)
+++ trunk/reactos/drivers/filesystems/npfs/rw.c [iso-8859-1] Sun Jan 18 10:31:45 2009
@@ -537,10 +537,10 @@
    			/* Check if buffer is full and the read pointer is not at the start of the buffer */
    			if ((Ccb->WriteQuotaAvailable == 0) && (Ccb->ReadPtr > Ccb->Data))
    			{
+					Ccb->WriteQuotaAvailable += (ULONG_PTR)Ccb->ReadPtr - (ULONG_PTR)Ccb->Data;
    				memcpy(Ccb->Data, Ccb->ReadPtr, (ULONG_PTR)Ccb->WritePtr - (ULONG_PTR)Ccb->ReadPtr);
-					Ccb->WritePtr = (PVOID)((ULONG_PTR)Ccb->WritePtr - ((ULONG_PTR)Ccb->WritePtr - (ULONG_PTR)Ccb->ReadPtr));
+					Ccb->WritePtr = (PVOID)((ULONG_PTR)Ccb->WritePtr - ((ULONG_PTR)Ccb->ReadPtr - (ULONG_PTR)Ccb->Data));
    				Ccb->ReadPtr = Ccb->Data;
-					Ccb->WriteQuotaAvailable += (ULONG_PTR)Ccb->WritePtr - (ULONG_PTR)Ccb->ReadPtr;
    			}

/* For Message mode, the Message length is stored in the buffer preceeding the Message. */
@@ -560,7 +560,8 @@

/* Use the smaller value */
    				CopyLength = min(NextMessageLength, Length);
-
+					ASSERT(CopyLength > 0);
+					ASSERT(CopyLength <= Ccb->ReadDataAvailable);
    				/* retrieve the message from the buffer */
    				memcpy(Buffer, (PVOID)((ULONG_PTR)Ccb->ReadPtr + sizeof(NextMessageLength)), CopyLength);

@@ -571,6 +572,7 @@
    					{
    						/* Calculate the remaining message new size */
    						ULONG NewMessageSize = NextMessageLength-CopyLength;
+
    						/* Update ReadPtr to point to new Message size location */
    						Ccb->ReadPtr = (PVOID)((ULONG_PTR)Ccb->ReadPtr + CopyLength);

@@ -586,16 +588,16 @@
    				}
    				else
    				{
-						/* This was the last Message, so just zero this messages for safety sake */
+						/* This was the last Message, so just zero start of buffer for safety sake */
    					memset(Ccb->Data, 0, NextMessageLength + sizeof(NextMessageLength));
+
+						/* Reset to MaxDataLength as partial message retrievals dont
+						   give the length back to Quota */
+						Ccb->WriteQuotaAvailable = Ccb->MaxDataLength;

/* reset read and write pointer to beginning of buffer */
    					Ccb->WritePtr = Ccb->Data;
    					Ccb->ReadPtr = Ccb->Data;
-
-						/* Add both the message length and the header to the WriteQuotaAvailable
-						   as they both were removed */
-						Ccb->WriteQuotaAvailable += (CopyLength + sizeof(CopyLength));
    				}
 #ifndef NDEBUG
    				DPRINT("Length %d Buffer %x\n",CopyLength,Buffer);
@@ -619,7 +621,8 @@
    				else 
    				{
    					KeResetEvent(&Ccb->ReadEvent);
-						if (Ccb->PipeState == FILE_PIPE_CONNECTED_STATE)
+
+						if ((Ccb->PipeState == FILE_PIPE_CONNECTED_STATE) && (Ccb->WriteQuotaAvailable > 0))
    					{
    						KeSetEvent(&Ccb->OtherSide->WriteEvent, IO_NO_INCREMENT, FALSE);
    					}
@@ -870,7 +873,7 @@
    			if (CopyLength > ReaderCcb->WriteQuotaAvailable)
    			{
    				DPRINT1("Writing %lu byte to pipe would overflow as only %lu bytes are available\n",
-						CopyLength, ReaderCcb->ReadDataAvailable);
+						CopyLength, ReaderCcb->WriteQuotaAvailable);
    				ASSERT(FALSE);
    			}