From: rtel <rtel@1d2547de-c912-0410-9cb9-b8ca96c0e9e2>
Date: Thu, 15 Mar 2018 15:51:22 +0000 (+0000)
Subject: Introduce sbBYTES_TO_STORE_MESSAGE_LENGTH to allow the number of bytes used to hold... 
X-Git-Tag: V10.1.0~30
X-Git-Url: https://git.sur5r.net/?a=commitdiff_plain;h=d5533b189399e8ce042f4561d7f5d0f50eb48205;p=freertos

Introduce sbBYTES_TO_STORE_MESSAGE_LENGTH to allow the number of bytes used to hold a message length in a message buffer to be reduced if 4 bytes is always too many (save a little RAM).

git-svn-id: https://svn.code.sf.net/p/freertos/code/trunk@2535 1d2547de-c912-0410-9cb9-b8ca96c0e9e2
---

diff --git a/FreeRTOS/Source/include/FreeRTOS.h b/FreeRTOS/Source/include/FreeRTOS.h
index 2b51f2b8f..c6f344513 100644
--- a/FreeRTOS/Source/include/FreeRTOS.h
+++ b/FreeRTOS/Source/include/FreeRTOS.h
@@ -826,6 +826,13 @@ extern "C" {
 	#define configSTACK_DEPTH_TYPE uint16_t
 #endif
 
+#ifndef configMESSAGE_BUFFER_LENGTH_TYPE
+	/* Defaults to size_t for backward compatibility, but can be overridden
+	in FreeRTOSConfig.h if lengths will always be less than the number of bytes
+	in a size_t. */
+	#define configMESSAGE_BUFFER_LENGTH_TYPE size_t
+#endif
+
 /* Sanity check the configuration. */
 #if( configUSE_TICKLESS_IDLE != 0 )
 	#if( INCLUDE_vTaskSuspend != 1 )
diff --git a/FreeRTOS/Source/stream_buffer.c b/FreeRTOS/Source/stream_buffer.c
index 9e518907a..ed8baef91 100644
--- a/FreeRTOS/Source/stream_buffer.c
+++ b/FreeRTOS/Source/stream_buffer.c
@@ -129,7 +129,7 @@ that uses task notifications. */
 /*lint -restore (9026) */
 
 /* The number of bytes used to hold the length of a message in the buffer. */
-#define sbBYTES_TO_STORE_MESSAGE_LENGTH ( sizeof( size_t ) )
+#define sbBYTES_TO_STORE_MESSAGE_LENGTH ( sizeof( configMESSAGE_BUFFER_LENGTH_TYPE ) )
 
 /* Bits stored in the ucFlags field of the stream buffer. */
 #define sbFLAGS_IS_MESSAGE_BUFFER		( ( uint8_t ) 1 ) /* Set if the stream buffer was created as a message buffer, in which case it holds discrete messages rather than a stream. */
@@ -504,6 +504,9 @@ TimeOut_t xTimeOut;
 	if( ( pxStreamBuffer->ucFlags & sbFLAGS_IS_MESSAGE_BUFFER ) != ( uint8_t ) 0 )
 	{
 		xRequiredSpace += sbBYTES_TO_STORE_MESSAGE_LENGTH;
+
+		/* Overflow? */
+		configASSERT( xRequiredSpace > xDataLengthBytes );
 	}
 	else
 	{
@@ -906,6 +909,9 @@ size_t xOriginalTail, xReceivedLength, xNextMessageLength;
 		returned to its prior state if the length of the message is too
 		large for the provided buffer. */
 		xOriginalTail = pxStreamBuffer->xTail;
+		/* Ensure xNextMessageLength is cleared to 0 in case
+		sizeof( configMESSAGE_BUFFER_LENGTH_TYPE ) != sizeof( size_t ). */
+		xNextMessageLength = 0;
 		( void ) prvReadBytesFromBuffer( pxStreamBuffer, ( uint8_t * ) &xNextMessageLength, xBytesToStoreMessageLength, xBytesAvailable );
 
 		/* Reduce the number of bytes available by the number of bytes just