Change SkStream.

src/ports/SkOSFile_win.cpp

+/*
+ * Copyright 2013 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "SkOSFile.h"
+
+#include <io.h>
+#include <stdio.h>
+#include <sys/stat.h>
+
+typedef struct {
+    ULONGLONG fVolume;
+    ULONGLONG fLsbSize;
+    ULONGLONG fMsbSize;
+} SkFILEID;
+
+static bool sk_ino(SkFILE* f, SkFILEID* id) {
+    int fileno = _fileno((FILE*)f);
+    if (fileno < 0) {
+        return false;
+    }
+
+    HANDLE file = (HANDLE)_get_osfhandle(fileno);
+    if (INVALID_HANDLE_VALUE == file) {
+        return false;
+    }
+
+    //TODO: call GetFileInformationByHandleEx on Vista and later with FileIdInfo.
+    BY_HANDLE_FILE_INFORMATION info;
+    if (0 == GetFileInformationByHandle(file, &info)) {
+        return false;
+    }
+    id->fVolume = info.dwVolumeSerialNumber;
+    id->fLsbSize = info.nFileIndexLow + (((ULONGLONG)info.nFileIndexHigh) << 32);
+    id->fMsbSize = 0;
+
+    return true;
+}
+
+bool sk_fidentical(SkFILE* a, SkFILE* b) {
+    SkFILEID aID, bID;
+    return sk_ino(a, &aID) && sk_ino(b, &bID)
+           && aID.fLsbSize == bID.fLsbSize
+           && aID.fMsbSize == bID.fMsbSize
+           && aID.fVolume == bID.fVolume;
+}
+
+template <typename HandleType, HandleType InvalidValue, BOOL (WINAPI * Close)(HandleType)>
+class SkAutoTHandle : SkNoncopyable {
+public:
+    SkAutoTHandle(HandleType handle) : fHandle(handle) { }
+    ~SkAutoTHandle() { Close(fHandle); }
+    operator HandleType() { return fHandle; }
+    bool isValid() { return InvalidValue != fHandle; }
+private:
+    HandleType fHandle;
+};
+typedef SkAutoTHandle<HANDLE, INVALID_HANDLE_VALUE, CloseHandle> SkAutoWinFile;
+typedef SkAutoTHandle<HANDLE, NULL, CloseHandle> SkAutoWinMMap;
+
+void sk_fmunmap(const void* addr, size_t) {
+    UnmapViewOfFile(addr);
+}
+
+void* sk_fmmap(SkFILE* f, size_t* length) {
+    size_t fileSize = sk_fgetsize(f);
+    if (0 == fileSize) {
+        return NULL;
+    }
+
+    int fileno = _fileno((FILE*)f);
+    if (fileno < 0) {
+        return NULL;
+    }
+
+    HANDLE file = (HANDLE)_get_osfhandle(fileno);
+    if (INVALID_HANDLE_VALUE == file) {
+        return NULL;
+    }
+
+    SkAutoWinMMap mmap(CreateFileMapping(file, NULL, PAGE_READONLY, 0, 0, NULL));
+    if (!mmap.isValid()) {
+        //TODO: use SK_TRACEHR(GetLastError(), "Could not create file mapping.") to report.
+        return NULL;
+    }
+
+    // Eventually call UnmapViewOfFile
+    void* addr = MapViewOfFile(mmap, FILE_MAP_READ, 0, 0, 0);
+    if (NULL == addr) {
+        //TODO: use SK_TRACEHR(GetLastError(), "Could not map view of file.") to report.
+        return NULL;
+    }
+
+    *length = fileSize;
+    return addr;
+}