Add a way to copy a file in archive into filesystem.

atom/common/asar/scoped_temporary_file.cc

@@ -0,0 +1,52 @@
+// Copyright (c) 2014 GitHub, Inc. All rights reserved.
+// Use of this source code is governed by the MIT license that can be
+// found in the LICENSE file.
+
+#include "atom/common/asar/scoped_temporary_file.h"
+
+#include "base/file_util.h"
+#include "base/threading/thread_restrictions.h"
+
+namespace asar {
+
+ScopedTemporaryFile::ScopedTemporaryFile() {
+}
+
+ScopedTemporaryFile::~ScopedTemporaryFile() {
+  if (!path_.empty()) {
+    base::ThreadRestrictions::ScopedAllowIO allow_io;
+    base::DeleteFile(path_, false);
+  }
+}
+
+bool ScopedTemporaryFile::Init() {
+  if (!path_.empty())
+    return true;
+
+  base::ThreadRestrictions::ScopedAllowIO allow_io;
+  return base::CreateTemporaryFile(&path_);
+}
+
+bool ScopedTemporaryFile::InitFromFile(const base::FilePath& path,
+                                       uint64 offset, uint64 size) {
+  if (!Init())
+    return false;
+
+  base::File src(path, base::File::FLAG_OPEN | base::File::FLAG_READ);
+  if (!src.IsValid())
+    return false;
+
+  std::vector<char> buf(size);
+  int len = src.Read(offset, buf.data(), buf.size());
+  if (len != static_cast<int>(size))
+    return false;
+
+  base::File dest(path_, base::File::FLAG_OPEN | base::File::FLAG_WRITE);
+  if (!dest.IsValid())
+    return false;
+
+  return dest.WriteAtCurrentPos(buf.data(), buf.size()) ==
+      static_cast<int>(size);
+}
+
+}  // namespace asar