AuroraMiddleware/qt5base-lts
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Reserve extra space for '\0' in QArrayData::allocate

Browse Source 
Added implicit space reservation for '\0' in allocation functions used by
containers. In current setting, this means sizeof(char16_t) bytes extra
memory is allocated each time and implicitly exists. The extra memory is
uninitialized by default

Task-number: QTBUG-84320
Change-Id: Ia3cc268183c00ea24ea9d326db3f392f71868d52
Reviewed-by: Lars Knoll <lars.knoll@qt.io>
This commit is contained in:
Andrei Golubev 2020-08-27 12:53:20 +02:00
parent 5911335756
commit 7f3c0d8a05
1 changed files with 30 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

30
src/corelib/tools/qarraydata.cpp
View File

@ -43,6 +43,9 @@
#include <QtCore/private/qtools_p.h>
#include <QtCore/qmath.h>
#include <QtCore/qbytearray.h> // QBA::value_type
#include <QtCore/qstring.h> // QString::value_type
#include <stdlib.h>
QT_BEGIN_NAMESPACE
@ -140,6 +143,22 @@ qCalculateGrowingBlockSize(qsizetype elementCount, qsizetype elementSize, qsizet
return result;
}
/*!
\internal
Returns \a allocSize plus extra reserved bytes necessary to store '\0'.
*/
static inline qsizetype reserveExtraBytes(qsizetype allocSize)
{
// We deal with QByteArray and QString only
constexpr qsizetype extra = qMax(sizeof(QByteArray::value_type), sizeof(QString::value_type));
if (Q_UNLIKELY(allocSize < 0))
return -1;
if (Q_UNLIKELY(add_overflow(allocSize, extra, &allocSize)))
return -1;
return allocSize;
}
static inline qsizetype calculateBlockSize(qsizetype &capacity, qsizetype objectSize, qsizetype headerSize, uint options)
{
// Calculate the byte size
@ -190,6 +209,12 @@ void *QArrayData::allocate(QArrayData **dptr, qsizetype objectSize, qsizetype al
Q_ASSERT(headerSize > 0);
qsizetype allocSize = calculateBlockSize(capacity, objectSize, headerSize, options);
allocSize = reserveExtraBytes(allocSize);
if (Q_UNLIKELY(allocSize < 0)) { // handle overflow. cannot allocate reliably
*dptr = nullptr;
return nullptr;
}
QArrayData *header = allocateData(allocSize, options);
void *data = nullptr;
if (header) {
@ -211,6 +236,11 @@ QArrayData::reallocateUnaligned(QArrayData *data, void *dataPointer,
qsizetype headerSize = sizeof(QArrayData);
qsizetype allocSize = calculateBlockSize(capacity, objectSize, headerSize, options);
qptrdiff offset = dataPointer ? reinterpret_cast<char *>(dataPointer) - reinterpret_cast<char *>(data) : headerSize;
allocSize = reserveExtraBytes(allocSize);
if (Q_UNLIKELY(allocSize < 0)) // handle overflow. cannot reallocate reliably
return qMakePair(data, dataPointer);
QArrayData *header = static_cast<QArrayData *>(::realloc(data, size_t(allocSize)));
if (header) {
header->flags = options;