1 files changed, 68 insertions, 0 deletions
diff --git a/runtime/base/unix_file/random_access_file.h b/runtime/base/unix_file/random_access_file.h
new file mode 100644
index 0000000..22da37f
--- /dev/null
+++ b/runtime/base/unix_file/random_access_file.h
@@ -0,0 +1,68 @@
+/*
+ * Copyright (C) 2009 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.
+ */
+
+#ifndef BASE_UNIX_FILE_RANDOM_ACCESS_FILE_H_
+#define BASE_UNIX_FILE_RANDOM_ACCESS_FILE_H_
+
+#include <stdint.h>
+
+namespace unix_file {
+
+// A file interface supporting random-access reading and writing of content,
+// along with the ability to set the length of a file (smaller or greater than
+// its current extent).
+//
+// This interface does not support a stream position (i.e. every read or write
+// must specify an offset). This interface does not imply any buffering policy.
+//
+// All operations return >= 0 on success or -errno on failure.
+//
+// Implementations never return EINTR; callers are spared the need to manually
+// retry interrupted operations.
+//
+// Any concurrent access to files should be externally synchronized.
+class RandomAccessFile {
+ public:
+  virtual ~RandomAccessFile() { }
+
+  virtual int Close() = 0;
+
+  // Reads 'byte_count' bytes into 'buf' starting at offset 'offset' in the
+  // file. Returns the number of bytes actually read.
+  virtual int64_t Read(char* buf, int64_t byte_count, int64_t offset) const = 0;
+
+  // Sets the length of the file to 'new_length'. If this is smaller than the
+  // file's current extent, data is discarded. If this is greater than the
+  // file's current extent, it is as if a write of the relevant number of zero
+  // bytes occurred. Returns 0 on success.
+  virtual int SetLength(int64_t new_length) = 0;
+
+  // Returns the current size of this file.
+  virtual int64_t GetLength() const = 0;
+
+  // Writes 'byte_count' bytes from 'buf' starting at offset 'offset' in the
+  // file. Zero-byte writes are acceptable, and writes past the end are as if
+  // a write of the relevant number of zero bytes also occurred. Returns the
+  // number of bytes actually written.
+  virtual int64_t Write(const char* buf, int64_t byte_count, int64_t offset) = 0;
+
+  // Flushes file data.
+  virtual int Flush() = 0;
+};
+
+}  // namespace unix_file
+
+#endif  // BASE_UNIX_FILE_RANDOM_ACCESS_FILE_H_