Create OutputStream abstraction

Allows data to be sent to file or memory transparently.
Standard C++ streams don't allow to create a stream from a file descriptor.

Change-Id: I820a864172e756949c61f29ef1517d1ebb253a0b
diff --git a/src/output_stream_test.cc b/src/output_stream_test.cc
new file mode 100644
index 0000000..8415d9f
--- /dev/null
+++ b/src/output_stream_test.cc
@@ -0,0 +1,81 @@
+/*
+ * Copyright (C) 2013 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 "base/logging.h"
+#include "common_test.h"
+#include "file_output_stream.h"
+#include "vector_output_stream.h"
+
+namespace art {
+
+class OutputStreamTest : public CommonTest {
+ protected:
+  void CheckOffset(off_t expected) {
+    off_t actual = output_stream_->lseek(0, SEEK_CUR);
+    CHECK_EQ(expected, actual);
+  }
+
+  void SetOutputStream(OutputStream& output_stream) {
+    output_stream_ = &output_stream;
+  }
+
+  void GenerateTestOutput() {
+    CHECK_EQ(3, output_stream_->lseek(3, SEEK_CUR));
+    CheckOffset(3);
+    CHECK_EQ(2, output_stream_->lseek(2, SEEK_SET));
+    CheckOffset(2);
+    uint8_t buf[] = { 1, 2, 3, 4, 5, 6, 7, 8, 9 };
+    CHECK(output_stream_->WriteFully(buf, 2));
+    CheckOffset(4);
+    CHECK_EQ(6, output_stream_->lseek(2, SEEK_END));
+    CheckOffset(6);
+    CHECK(output_stream_->WriteFully(buf, 4));
+    CheckOffset(10);
+  }
+
+  void CheckTestOutput(const std::vector<uint8_t>& actual) {
+    uint8_t expected[] = {
+        0, 0, 1, 2, 0, 0, 1, 2, 3, 4
+    };
+    CHECK_EQ(sizeof(expected), actual.size());
+    CHECK_EQ(0, memcmp(expected, &actual[0], actual.size()));
+  }
+
+  OutputStream* output_stream_;
+};
+
+TEST_F(OutputStreamTest, File) {
+  ScratchFile tmp;
+  FileOutputStream output_stream(tmp.GetFile());
+  SetOutputStream(output_stream);
+  GenerateTestOutput();
+  UniquePtr<File> in(OS::OpenFile(tmp.GetFilename().c_str(), false));
+  CHECK(in.get() != NULL);
+  std::vector<uint8_t> actual(in->GetLength());
+  bool readSuccess = in->ReadFully(&actual[0], actual.size());
+  CHECK(readSuccess);
+  CheckTestOutput(actual);
+}
+
+TEST_F(OutputStreamTest, Vector) {
+  std::vector<uint8_t> output;
+  VectorOutputStream output_stream("test vector output", output);
+  SetOutputStream(output_stream);
+  GenerateTestOutput();
+  CheckTestOutput(output);
+}
+
+}  // namespace std