pcas: support larger than max array bytes

clientBufMemoryManager already supports allocations
larger than max array bytes, adjust callers inBuf/outBuf
to actually request larger allocations.

src/ca/legacy/pcas/generic/casStrmClient.cc

@@ -205,7 +205,7 @@ caStatus casStrmClient :: processMsg ()
                 if ( bytesLeft < msgSize ) {
                     status = S_cas_success;
                     if ( msgSize > this->in.bufferSize() ) {
-                        this->in.expandBuffer ();
+                        this->in.expandBuffer (msgSize);
                         // msg to large - set up message drain
                         if ( msgSize > this->in.bufferSize() ) {
                             caServerI::dumpMsg ( this->pHostName, this->pUserName, & msgTmp, 0, 

src/ca/legacy/pcas/generic/clientBufMemoryManager.cpp

@@ -16,11 +16,6 @@
 #define epicsExportSharedSymbols
 #include "clientBufMemoryManager.h"
 
-bufSizeT clientBufMemoryManager::maxSize () const
-{
-    return bufferFactory.largeBufferSize ();
-}
-
 casBufferParm clientBufMemoryManager::allocate ( bufSizeT newMinSize )
 {
     casBufferParm parm;

src/ca/legacy/pcas/generic/clientBufMemoryManager.h

@@ -39,9 +39,9 @@ struct casBufferParm {
 
 class clientBufMemoryManager {
 public:
+    //! @throws std::bad_alloc on failure
     casBufferParm allocate ( bufSizeT newMinSize );
     void release ( char * pBuf, bufSizeT bufSize );
-    bufSizeT maxSize () const;
 private:
     casBufferFactory bufferFactory;
 };

src/ca/legacy/pcas/generic/inBuf.cc

@@ -13,6 +13,8 @@
  *              505 665 1831
  */
 
+#include <stdexcept>
+
 #include <stdio.h>
 #include <string.h>
 
@@ -155,11 +157,17 @@ bufSizeT inBuf::popCtx ( const inBufCtx &ctx )
     }
 }
 
-void inBuf::expandBuffer ()
+void inBuf::expandBuffer (bufSizeT needed)
 {
-    bufSizeT max = this->memMgr.maxSize();
-    if ( this->bufSize <  max ) {
-        casBufferParm bufParm = this->memMgr.allocate ( max );
+    if (needed > bufSize) {
+        casBufferParm bufParm;
+        try {
+            bufParm = this->memMgr.allocate ( needed );
+        } catch (std::bad_alloc& e) {
+            // caller must check that buffer size has expended
+            return;
+        }
+
         bufSizeT unprocessedBytes = this->bytesPresent ();
         memcpy ( bufParm.pBuf, &this->pBuf[this->nextReadIndex], unprocessedBytes );
         this->bytesInBuffer = unprocessedBytes;
@@ -170,7 +178,7 @@ void inBuf::expandBuffer ()
     }
 }
 
-unsigned inBuf::bufferSize () const
+bufSizeT inBuf::bufferSize() const
 {
     return this->bufSize;
 }

src/ca/legacy/pcas/generic/inBuf.h

@@ -82,8 +82,8 @@ public:
     //
     const inBufCtx pushCtx ( bufSizeT headerSize, bufSizeT bodySize );
 	bufSizeT popCtx ( const inBufCtx & ); // returns actual size
-    unsigned bufferSize () const;
-    void expandBuffer ();
+    bufSizeT bufferSize () const;
+    void expandBuffer (bufSizeT needed);
 private:
     class inBufClient & client;
     class clientBufMemoryManager & memMgr;

src/ca/legacy/pcas/generic/outBuf.cc

@@ -59,7 +59,7 @@ caStatus outBuf::allocRawMsg ( bufSizeT msgsize, void **ppMsg )
     msgsize = CA_MESSAGE_ALIGN ( msgsize );
 
     if ( msgsize > this->bufSize ) {
-        this->expandBuffer ();
+        this->expandBuffer (msgsize);
         if ( msgsize > this->bufSize ) {
             return S_cas_hugeRequest;
         }
@@ -316,11 +316,17 @@ void outBuf::show (unsigned level) const
     }
 }
 
-void outBuf::expandBuffer ()
+void outBuf::expandBuffer (bufSizeT needed)
 {
-    bufSizeT max = this->memMgr.maxSize();
-    if ( this->bufSize < max  ) {
-        casBufferParm bufParm = this->memMgr.allocate ( max );
+    if (needed > bufSize) {
+        casBufferParm bufParm;
+        try {
+            bufParm = this->memMgr.allocate ( needed );
+        } catch (std::bad_alloc& e) {
+            // caller must check that buffer size has expended
+            return;
+        }
+
         memcpy ( bufParm.pBuf, this->pBuf, this->stack );
         this->memMgr.release ( this->pBuf, this->bufSize );
         this->pBuf = bufParm.pBuf;

src/ca/legacy/pcas/generic/outBuf.h

@@ -122,7 +122,7 @@ private:
 	bufSizeT stack;
     unsigned ctxRecursCount;
 
-    void expandBuffer ();
+    void expandBuffer (bufSizeT needed);
 
 	outBuf ( const outBuf & );
 	outBuf & operator = ( const outBuf & );