Add IPCMessageGetBufferLength() for retrieving buffer length from IPC message

The length of the IPC message buffer is stored as part of a larger
value. The new helper function extracts the length.

Author: tdz

src/IPCQueue.c

@@ -19,6 +19,12 @@ IPCMessageInit(IPCMessage* aMsg)
   return 0;
 }
 
+uint32_t
+IPCMessageGetBufferLength(const IPCMessage* aMsg)
+{
+  return aMsg->mStatus & 0x00ffffff;
+}
+
 int
 IPCMessageProduce(IPCMessage* aMsg)
 {

src/IPCQueue.h

@@ -27,6 +27,9 @@ typedef struct
 int
 IPCMessageInit(IPCMessage* aMsg);
 
+uint32_t
+IPCMessageGetBufferLength(const IPCMessage* aMsg);
+
 int
 IPCMessageProduce(IPCMessage* aMsg);