From ef0f7f424872a27c8397f854eecff753428bcddc Mon Sep 17 00:00:00 2001
From: Ulf Hermann <ulf.hermann@theqtcompany.com>
Date: Wed, 3 Jun 2015 15:57:42 +0200
Subject: Unify QByteArray::MaxSize and MaxAllocSize

We have established the maximum size qAllocMore can deal with in
commit 880986be2357a1f80827d038d770dc2f80300201 and we should use
it.

The maximum size for byte arrays is reduced by one byte as with
the previous code we could make qAllocMore produce ((1 << 31) - extra)
by passing (1 << 30). That is not a problem for qAllocMore itself
(as long as extra > 0) but it's hard to verify that no related
code casts the total sum back to signed int, which would overflow
to -1.

To make the compiler inline access to the maximum size, a private
enum MaxByteArraySize is provided, which can be used in internal
code.

This fixes the merge of commits
880986be2357a1f80827d038d770dc2f80300201 and
c70658d301e274c3aaa1fb6cebe2a5e56db12779

Change-Id: Idb04856f7c2e53ef383063e7555d3083020ff2b7
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
---
 src/corelib/tools/qringbuffer.cpp | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

(limited to 'src/corelib/tools/qringbuffer.cpp')

diff --git a/src/corelib/tools/qringbuffer.cpp b/src/corelib/tools/qringbuffer.cpp
index bcf6d2646ea..658267a521c 100644
--- a/src/corelib/tools/qringbuffer.cpp
+++ b/src/corelib/tools/qringbuffer.cpp
@@ -33,6 +33,7 @@
 ****************************************************************************/
 
 #include "private/qringbuffer_p.h"
+#include "private/qbytearray_p.h"
 #include <string.h>
 
 QT_BEGIN_NAMESPACE
@@ -79,7 +80,7 @@ void QRingBuffer::free(qint64 bytes)
                     clear(); // try to minify/squeeze us
                 }
             } else {
-                Q_ASSERT(quint64(bytes) < QByteArray::MaxSize);
+                Q_ASSERT(bytes < MaxByteArraySize);
                 head += int(bytes);
                 bufferSize -= bytes;
             }
@@ -96,14 +97,14 @@ void QRingBuffer::free(qint64 bytes)
 
 char *QRingBuffer::reserve(qint64 bytes)
 {
-    if (bytes <= 0 || quint64(bytes) >= QByteArray::MaxSize)
+    if (bytes <= 0 || bytes >= MaxByteArraySize)
         return 0;
 
     const qint64 newSize = bytes + tail;
     // if need buffer reallocation
     if (newSize > buffers.last().size()) {
         if (newSize > buffers.last().capacity() && (tail >= basicBlockSize
-                || quint64(newSize) >= QByteArray::MaxSize)) {
+                || newSize >= MaxByteArraySize)) {
             // shrink this buffer to its current size
             buffers.last().resize(tail);
 
@@ -117,7 +118,7 @@ char *QRingBuffer::reserve(qint64 bytes)
 
     char *writePtr = buffers.last().data() + tail;
     bufferSize += bytes;
-    Q_ASSERT(quint64(bytes) < QByteArray::MaxSize);
+    Q_ASSERT(bytes < MaxByteArraySize);
     tail += int(bytes);
     return writePtr;
 }
@@ -129,7 +130,7 @@ char *QRingBuffer::reserve(qint64 bytes)
 */
 char *QRingBuffer::reserveFront(qint64 bytes)
 {
-    if (bytes <= 0 || quint64(bytes) >= QByteArray::MaxSize)
+    if (bytes <= 0 || bytes >= MaxByteArraySize)
         return 0;
 
     if (head < bytes) {
@@ -163,7 +164,7 @@ void QRingBuffer::chop(qint64 bytes)
                     clear(); // try to minify/squeeze us
                 }
             } else {
-                Q_ASSERT(quint64(bytes) < QByteArray::MaxSize);
+                Q_ASSERT(bytes < MaxByteArraySize);
                 tail -= int(bytes);
                 bufferSize -= bytes;
             }
-- 
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