upload android base code part3

android/art/runtime/os_linux.cc

@@ -0,0 +1,83 @@
+/*
+ * Copyright (C) 2010 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "os.h"
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <cstddef>
+#include <memory>
+
+#include "base/logging.h"
+#include "base/unix_file/fd_file.h"
+
+namespace art {
+
+File* OS::OpenFileForReading(const char* name) {
+  return OpenFileWithFlags(name, O_RDONLY);
+}
+
+File* OS::OpenFileReadWrite(const char* name) {
+  return OpenFileWithFlags(name, O_RDWR);
+}
+
+static File* CreateEmptyFile(const char* name, int extra_flags) {
+  // In case the file exists, unlink it so we get a new file. This is necessary as the previous
+  // file may be in use and must not be changed.
+  unlink(name);
+
+  return OS::OpenFileWithFlags(name, O_CREAT | extra_flags);
+}
+
+File* OS::CreateEmptyFile(const char* name) {
+  return art::CreateEmptyFile(name, O_RDWR | O_TRUNC);
+}
+
+File* OS::CreateEmptyFileWriteOnly(const char* name) {
+  return art::CreateEmptyFile(name, O_WRONLY | O_TRUNC | O_NOFOLLOW | O_CLOEXEC);
+}
+
+File* OS::OpenFileWithFlags(const char* name, int flags, bool auto_flush) {
+  CHECK(name != nullptr);
+  bool read_only = ((flags & O_ACCMODE) == O_RDONLY);
+  bool check_usage = !read_only && auto_flush;
+  std::unique_ptr<File> file(new File(name, flags, 0666, check_usage));
+  if (!file->IsOpened()) {
+    return nullptr;
+  }
+  return file.release();
+}
+
+bool OS::FileExists(const char* name) {
+  struct stat st;
+  if (stat(name, &st) == 0) {
+    return S_ISREG(st.st_mode);  // TODO: Deal with symlinks?
+  } else {
+    return false;
+  }
+}
+
+bool OS::DirectoryExists(const char* name) {
+  struct stat st;
+  if (stat(name, &st) == 0) {
+    return S_ISDIR(st.st_mode);  // TODO: Deal with symlinks?
+  } else {
+    return false;
+  }
+}
+
+}  // namespace art