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authorLiang Qi <liang.qi@qt.io>2016-06-13 09:01:02 +0200
committerLiang Qi <liang.qi@qt.io>2016-06-13 12:46:46 +0200
commit511790fd1af1e2886a0e2e8dd4308099705cd815 (patch)
treeb42aee537a6103cd064f9f41ae2889b09b79fd23 /src/corelib/tools/qbytearray.cpp
parent1542d8881fc5ccbc5918cd4acbe4091ebbd24508 (diff)
parentcbe332405aa22257d432f1797b325f5e57007c20 (diff)
Merge remote-tracking branch 'origin/5.7' into dev
Conflicts: config_help.txt configure mkspecs/features/uikit/sdk.prf src/corelib/global/qhooks.cpp src/corelib/io/qfilesystemwatcher.cpp src/corelib/io/qlockfile_unix.cpp src/corelib/tools/qalgorithms.h src/gui/kernel/qwindowsysteminterface.h src/gui/text/qtextdocument_p.cpp src/network/access/access.pri src/network/access/qnetworkaccessmanager.cpp src/network/access/qnetworkreplynsurlconnectionimpl.mm src/src.pro src/testlib/qtestcase.cpp src/widgets/kernel/qwidgetbackingstore_p.h src/widgets/styles/qwindowscestyle.cpp src/widgets/styles/qwindowsmobilestyle.cpp tests/auto/corelib/io/qdiriterator/qdiriterator.pro tests/auto/corelib/io/qfileinfo/qfileinfo.pro tests/auto/gui/kernel/qwindow/BLACKLIST tests/auto/widgets/dialogs/qfilesystemmodel/tst_qfilesystemmodel.cpp tools/configure/configureapp.cpp Change-Id: Ibf7fb9c8cf263a810ade82f821345d0725c57c67
Diffstat (limited to 'src/corelib/tools/qbytearray.cpp')
-rw-r--r--src/corelib/tools/qbytearray.cpp112
1 files changed, 102 insertions, 10 deletions
diff --git a/src/corelib/tools/qbytearray.cpp b/src/corelib/tools/qbytearray.cpp
index a256b44b1f..266c2e9b57 100644
--- a/src/corelib/tools/qbytearray.cpp
+++ b/src/corelib/tools/qbytearray.cpp
@@ -46,6 +46,7 @@
#include "qlocale.h"
#include "qlocale_p.h"
#include "qlocale_tools_p.h"
+#include "private/qnumeric_p.h"
#include "qstringalgorithms_p.h"
#include "qscopedpointer.h"
#include "qbytearray_p.h"
@@ -128,17 +129,104 @@ int qFindByteArray(
const char *haystack0, int haystackLen, int from,
const char *needle0, int needleLen);
+/*
+ * This pair of functions is declared in qtools_p.h and is used by the Qt
+ * containers to allocate memory and grow the memory block during append
+ * operations.
+ *
+ * They take size_t parameters and return size_t so they will change sizes
+ * according to the pointer width. However, knowing Qt containers store the
+ * container size and element indexes in ints, these functions never return a
+ * size larger than INT_MAX. This is done by casting the element count and
+ * memory block size to int in several comparisons: the check for negative is
+ * very fast on most platforms as the code only needs to check the sign bit.
+ *
+ * These functions return SIZE_MAX on overflow, which can be passed to malloc()
+ * and will surely cause a NULL return (there's no way you can allocate a
+ * memory block the size of your entire VM space).
+ */
+
+/*!
+ \internal
+ \since 5.7
-int qAllocMore(int alloc, int extra) Q_DECL_NOTHROW
+ Returns the memory block size for a container containing \a elementCount
+ elements, each of \a elementSize bytes, plus a header of \a headerSize
+ bytes. That is, this function returns \c
+ {elementCount * elementSize + headerSize}
+
+ but unlike the simple calculation, it checks for overflows during the
+ multiplication and the addition.
+
+ Both \a elementCount and \a headerSize can be zero, but \a elementSize
+ cannot.
+
+ This function returns SIZE_MAX (~0) on overflow or if the memory block size
+ would not fit an int.
+*/
+size_t qCalculateBlockSize(size_t elementCount, size_t elementSize, size_t headerSize) Q_DECL_NOTHROW
{
- Q_ASSERT(alloc >= 0 && extra >= 0 && extra <= MaxAllocSize);
- Q_ASSERT_X(alloc <= MaxAllocSize - extra, "qAllocMore", "Requested size is too large!");
+ unsigned count = unsigned(elementCount);
+ unsigned size = unsigned(elementSize);
+ unsigned header = unsigned(headerSize);
+ Q_ASSERT(elementSize);
+ Q_ASSERT(size == elementSize);
+ Q_ASSERT(header == headerSize);
+
+ if (Q_UNLIKELY(count != elementCount))
+ return std::numeric_limits<size_t>::max();
+
+ unsigned bytes;
+ if (Q_UNLIKELY(mul_overflow(size, count, &bytes)) ||
+ Q_UNLIKELY(add_overflow(bytes, header, &bytes)))
+ return std::numeric_limits<size_t>::max();
+ if (Q_UNLIKELY(int(bytes) < 0)) // catches bytes >= 2GB
+ return std::numeric_limits<size_t>::max();
+
+ return bytes;
+}
+
+/*!
+ \internal
+ \since 5.7
- unsigned nalloc = qNextPowerOfTwo(alloc + extra);
+ Returns the memory block size and the number of elements that will fit in
+ that block for a container containing \a elementCount elements, each of \a
+ elementSize bytes, plus a header of \a headerSize bytes. This function
+ assumes the container will grow and pre-allocates a growth factor.
- Q_ASSERT(nalloc > unsigned(alloc + extra));
+ Both \a elementCount and \a headerSize can be zero, but \a elementSize
+ cannot.
+
+ This function returns SIZE_MAX (~0) on overflow or if the memory block size
+ would not fit an int.
+
+ \note The memory block may contain up to \a elementSize - 1 bytes more than
+ needed.
+*/
+CalculateGrowingBlockSizeResult
+qCalculateGrowingBlockSize(size_t elementCount, size_t elementSize, size_t headerSize) Q_DECL_NOTHROW
+{
+ CalculateGrowingBlockSizeResult result = {
+ std::numeric_limits<size_t>::max(),std::numeric_limits<size_t>::max()
+ };
+
+ unsigned bytes = unsigned(qCalculateBlockSize(elementCount, elementSize, headerSize));
+ if (int(bytes) < 0) // catches std::numeric_limits<size_t>::max()
+ return result;
+
+ unsigned morebytes = qNextPowerOfTwo(bytes);
+ if (Q_UNLIKELY(int(morebytes) < 0)) {
+ // catches morebytes == 2GB
+ // grow by half the difference between bytes and morebytes
+ bytes += (morebytes - bytes) / 2;
+ } else {
+ bytes = morebytes;
+ }
- return nalloc - extra;
+ result.elementCount = (bytes - unsigned(headerSize)) / unsigned(elementSize);
+ result.size = bytes;
+ return result;
}
/*****************************************************************************
@@ -1618,12 +1706,16 @@ void QByteArray::reallocData(uint alloc, Data::AllocationOptions options)
Data::deallocate(d);
d = x;
} else {
+ size_t blockSize;
if (options & Data::Grow) {
- if (alloc > MaxByteArraySize)
- qBadAlloc();
- alloc = qAllocMore(alloc, sizeof(Data));
+ auto r = qCalculateGrowingBlockSize(alloc, sizeof(QChar), sizeof(Data));
+ blockSize = r.size;
+ alloc = uint(r.elementCount);
+ } else {
+ blockSize = qCalculateBlockSize(alloc, sizeof(QChar), sizeof(Data));
}
- Data *x = static_cast<Data *>(::realloc(d, sizeof(Data) + alloc));
+
+ Data *x = static_cast<Data *>(::realloc(d, blockSize));
Q_CHECK_PTR(x);
x->alloc = alloc;
x->capacityReserved = (options & Data::CapacityReserved) ? 1 : 0;