Extend QSharedMemory to work with qsizetype for sizes

This allows larger than 2G memory segments to be allocated.

Fixes: QTBUG-76995
Change-Id: I95309eeea511fadb28724c7592298c2fcc6f1d1a
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>

src/corelib/kernel/qsharedmemory.cpp

@@ -340,7 +340,7 @@ QString QSharedMemory::nativeKey() const
 
   \sa error()
  */
-bool QSharedMemory::create(int size, AccessMode mode)
+bool QSharedMemory::create(qsizetype size, AccessMode mode)
 {
     Q_D(QSharedMemory);
 
@@ -384,7 +384,7 @@ bool QSharedMemory::create(int size, AccessMode mode)
 
   \sa create(), attach()
  */
-int QSharedMemory::size() const
+qsizetype QSharedMemory::size() const
 {
     Q_D(const QSharedMemory);
     return d->size;

src/corelib/kernel/qsharedmemory.h

@@ -103,8 +103,8 @@ public:
     void setNativeKey(const QString &key);
     QString nativeKey() const;
 
-    bool create(int size, AccessMode mode = ReadWrite);
+    bool create(qsizetype size, AccessMode mode = ReadWrite);
-    int size() const;
+    qsizetype size() const;
 
     bool attach(AccessMode mode = ReadWrite);
     bool isAttached() const;

src/corelib/kernel/qsharedmemory_android.cpp

@@ -84,7 +84,7 @@ bool QSharedMemoryPrivate::cleanHandle()
     return true;
 }
 
-bool QSharedMemoryPrivate::create(int size)
+bool QSharedMemoryPrivate::create(qsizetype size)
 {
     Q_UNUSED(size);
     Q_UNIMPLEMENTED();

src/corelib/kernel/qsharedmemory_p.h

@@ -123,7 +123,7 @@ public:
     QSharedMemoryPrivate();
 
     void *memory;
-    int size;
+    qsizetype size;
     QString key;
     QString nativeKey;
     QSharedMemory::SharedMemoryError error;
@@ -145,7 +145,7 @@ public:
 #endif
     bool initKey();
     bool cleanHandle();
-    bool create(int size);
+    bool create(qsizetype size);
     bool attach(QSharedMemory::AccessMode mode);
     bool detach();
 

src/corelib/kernel/qsharedmemory_posix.cpp

@@ -82,7 +82,7 @@ bool QSharedMemoryPrivate::cleanHandle()
     return true;
 }
 
-bool QSharedMemoryPrivate::create(int size)
+bool QSharedMemoryPrivate::create(qsizetype size)
 {
     if (!handle())
         return false;
@@ -165,11 +165,11 @@ bool QSharedMemoryPrivate::attach(QSharedMemory::AccessMode mode)
         cleanHandle();
         return false;
     }
-    size = st.st_size;
+    size = qsizetype(st.st_size);
 
     // grab the memory
     const int mprot = (mode == QSharedMemory::ReadOnly ? PROT_READ : PROT_READ | PROT_WRITE);
-    memory = QT_MMAP(0, size, mprot, MAP_SHARED, hand, 0);
+    memory = QT_MMAP(0, size_t(size), mprot, MAP_SHARED, hand, 0);
     if (memory == MAP_FAILED || !memory) {
         setErrorString(QLatin1String("QSharedMemory::attach (mmap)"));
         cleanHandle();
@@ -191,7 +191,7 @@ bool QSharedMemoryPrivate::attach(QSharedMemory::AccessMode mode)
 bool QSharedMemoryPrivate::detach()
 {
     // detach from the memory segment
-    if (::munmap(memory, size) == -1) {
+    if (::munmap(memory, size_t(size)) == -1) {
         setErrorString(QLatin1String("QSharedMemory::detach (munmap)"));
         return false;
     }

src/corelib/kernel/qsharedmemory_systemv.cpp

@@ -132,7 +132,7 @@ bool QSharedMemoryPrivate::cleanHandle()
     return true;
 }
 
-bool QSharedMemoryPrivate::create(int size)
+bool QSharedMemoryPrivate::create(qsizetype size)
 {
     // build file if needed
     bool createdFile = false;
@@ -154,7 +154,7 @@ bool QSharedMemoryPrivate::create(int size)
     }
 
     // create
-    if (-1 == shmget(unix_key, size, 0600 | IPC_CREAT | IPC_EXCL)) {
+    if (-1 == shmget(unix_key, size_t(size), 0600 | IPC_CREAT | IPC_EXCL)) {
         const QLatin1String function("QSharedMemory::create");
         switch (errno) {
         case EINVAL:
@@ -192,7 +192,7 @@ bool QSharedMemoryPrivate::attach(QSharedMemory::AccessMode mode)
     // grab the size
     shmid_ds shmid_ds;
     if (!shmctl(id, IPC_STAT, &shmid_ds)) {
-        size = (int)shmid_ds.shm_segsz;
+        size = (qsizetype)shmid_ds.shm_segsz;
     } else {
         setErrorString(QLatin1String("QSharedMemory::attach (shmctl)"));
         return false;

src/corelib/kernel/qsharedmemory_win.cpp

@@ -122,7 +122,7 @@ bool QSharedMemoryPrivate::cleanHandle()
     return true;
 }
 
-bool QSharedMemoryPrivate::create(int size)
+bool QSharedMemoryPrivate::create(qsizetype size)
 {
     const QLatin1String function("QSharedMemory::create");
     if (nativeKey.isEmpty()) {
@@ -132,8 +132,14 @@ bool QSharedMemoryPrivate::create(int size)
     }
 
     // Create the file mapping.
-    hand = CreateFileMapping(INVALID_HANDLE_VALUE, 0, PAGE_READWRITE, 0, size,
+    DWORD high, low;
-                             reinterpret_cast<const wchar_t*>(nativeKey.utf16()));
+    if constexpr (sizeof(qsizetype) == 8)
+        high = DWORD(quint64(size) >> 32);
+    else
+        high = 0;
+    low = DWORD(size_t(size) & 0xffffffff);
+    hand = CreateFileMapping(INVALID_HANDLE_VALUE, 0, PAGE_READWRITE, high, low,
+                             reinterpret_cast<const wchar_t *>(nativeKey.utf16()));
     setErrorString(function);
 
     // hand is valid when it already exists unlike unix so explicitly check
@@ -160,7 +166,7 @@ bool QSharedMemoryPrivate::attach(QSharedMemory::AccessMode mode)
         errorString = QSharedMemory::tr("%1: size query failed").arg(QLatin1String("QSharedMemory::attach: "));
         return false;
     }
-    size = info.RegionSize;
+    size = qsizetype(info.RegionSize);
 
     return true;
 }