Reland of Initial version of file wrapper

webrtc/base/file_win.cc

+/*
+ *  Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include "webrtc/base/file.h"
+
+#include <io.h>
+#include "webrtc/base/win32.h"
+
+#include <limits>  // NOLINT: win32.h should be considered a system header
+
+#include "webrtc/base/checks.h"
+
+namespace rtc {
+
+File File::Open(const std::string& path) {
+  HANDLE handle =
+      ::CreateFile(ToUtf16(path).c_str(), GENERIC_READ | GENERIC_WRITE, 0,
+                   nullptr, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, nullptr);
+  return File(handle);
+}
+
+size_t File::Write(const uint8_t* data, size_t length) {
+  RTC_DCHECK_LT(length, std::numeric_limits<DWORD>::max());
+  size_t total_written = 0;
+  do {
+    DWORD written;
+    if (!::WriteFile(file_, data + total_written,
+                     static_cast<DWORD>(length - total_written), &written,
+                     nullptr)) {
+      break;
+    }
+    total_written += written;
+  } while (total_written < length);
+  return total_written;
+}
+
+size_t File::Read(uint8_t* buffer, size_t length) {
+  RTC_DCHECK_LT(length, std::numeric_limits<DWORD>::max());
+  size_t total_read = 0;
+  do {
+    DWORD read;
+    if (!::ReadFile(file_, buffer + total_read,
+                    static_cast<DWORD>(length - total_read), &read, nullptr)) {
+      break;
+    }
+    total_read += read;
+  } while (total_read < length);
+  return total_read;
+}
+
+size_t File::WriteAt(const uint8_t* data, size_t length, size_t offset) {
+  RTC_DCHECK_LT(length, std::numeric_limits<DWORD>::max());
+  size_t total_written = 0;
+  do {
+    DWORD written;
+
+    LARGE_INTEGER offset_li;
+    offset_li.QuadPart = offset + total_written;
+
+    OVERLAPPED overlapped = {0};
+    overlapped.Offset = offset_li.LowPart;
+    overlapped.OffsetHigh = offset_li.HighPart;
+
+    if (!::WriteFile(file_, data + total_written,
+                     static_cast<DWORD>(length - total_written), &written,
+                     &overlapped)) {
+      break;
+    }
+
+    total_written += written;
+  } while (total_written < length);
+  return total_written;
+}
+
+size_t File::ReadAt(uint8_t* buffer, size_t length, size_t offset) {
+  RTC_DCHECK_LT(length, std::numeric_limits<DWORD>::max());
+  size_t total_read = 0;
+  do {
+    DWORD read;
+
+    LARGE_INTEGER offset_li;
+    offset_li.QuadPart = offset + total_read;
+
+    OVERLAPPED overlapped = {0};
+    overlapped.Offset = offset_li.LowPart;
+    overlapped.OffsetHigh = offset_li.HighPart;
+
+    if (!::ReadFile(file_, buffer + total_read,
+                    static_cast<DWORD>(length - total_read), &read,
+                    &overlapped)) {
+      break;
+    }
+
+    total_read += read;
+  } while (total_read < length);
+  return total_read;
+}
+
+bool File::Seek(size_t offset) {
+  LARGE_INTEGER distance;
+  distance.QuadPart = offset;
+  return SetFilePointerEx(file_, distance, nullptr, FILE_BEGIN) != 0;
+}
+
+bool File::Close() {
+  if (file_ == kInvalidPlatformFileValue)
+    return false;
+  bool ret = CloseHandle(file_) != 0;
+  file_ = kInvalidPlatformFileValue;
+  return ret;
+}
+
+}  // namespace rtc