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diff --git a/icing/portable/gzip_stream.h b/icing/portable/gzip_stream.h
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+// Copyright (C) 2009 Google LLC
+//
+// 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.
+
+// This file contains the definition for classes GzipInputStream and
+// GzipOutputStream. It is forked from protobuf because these classes are only
+// provided in libprotobuf-full but we would like to link libicing against the
+// smaller libprotobuf-lite instead.
+//
+// GzipInputStream decompresses data from an underlying
+// ZeroCopyInputStream and provides the decompressed data as a
+// ZeroCopyInputStream.
+//
+// GzipOutputStream is an ZeroCopyOutputStream that compresses data to
+// an underlying ZeroCopyOutputStream.
+
+#ifndef GOOGLE3_ICING_PORTABLE_GZIP_STREAM_H_
+#define GOOGLE3_ICING_PORTABLE_GZIP_STREAM_H_
+
+#include "icing/portable/zlib.h"
+#include <google/protobuf/io/zero_copy_stream_impl_lite.h>
+
+namespace icing {
+namespace lib {
+namespace protobuf_ports {
+
+// A ZeroCopyInputStream that reads compressed data through zlib
+class GzipInputStream : public google::protobuf::io::ZeroCopyInputStream {
+ public:
+  // Format key for constructor
+  enum Format {
+    // zlib will autodetect gzip header or deflate stream
+    AUTO = 0,
+
+    // GZIP streams have some extra header data for file attributes.
+    GZIP = 1,
+
+    // Simpler zlib stream format.
+    ZLIB = 2,
+  };
+
+  // buffer_size and format may be -1 for default of 64kB and GZIP format
+  explicit GzipInputStream(google::protobuf::io::ZeroCopyInputStream* sub_stream,
+                           Format format = AUTO, int buffer_size = -1);
+  virtual ~GzipInputStream();
+
+  // Return last error message or NULL if no error.
+  inline const char* ZlibErrorMessage() const { return zcontext_.msg; }
+  inline int ZlibErrorCode() const { return zerror_; }
+
+  // implements ZeroCopyInputStream ----------------------------------
+  bool Next(const void** data, int* size) override;
+  void BackUp(int count) override;
+  bool Skip(int count) override;
+  int64_t ByteCount() const override;
+
+ private:
+  Format format_;
+
+  google::protobuf::io::ZeroCopyInputStream* sub_stream_;
+
+  z_stream zcontext_;
+  int zerror_;
+
+  void* output_buffer_;
+  void* output_position_;
+  size_t output_buffer_length_;
+  int64_t byte_count_;
+
+  int Inflate(int flush);
+  void DoNextOutput(const void** data, int* size);
+};
+
+class GzipOutputStream : public google::protobuf::io::ZeroCopyOutputStream {
+ public:
+  // Format key for constructor
+  enum Format {
+    // GZIP streams have some extra header data for file attributes.
+    GZIP = 1,
+
+    // Simpler zlib stream format.
+    ZLIB = 2,
+  };
+
+  struct Options {
+    // Defaults to GZIP.
+    Format format;
+
+    // What size buffer to use internally.  Defaults to 64kB.
+    int buffer_size;
+
+    // A number between 0 and 9, where 0 is no compression and 9 is best
+    // compression.  Defaults to Z_DEFAULT_COMPRESSION (see zlib.h).
+    int compression_level;
+
+    // Defaults to Z_DEFAULT_STRATEGY.  Can also be set to Z_FILTERED,
+    // Z_HUFFMAN_ONLY, or Z_RLE.  See the documentation for deflateInit2 in
+    // zlib.h for definitions of these constants.
+    int compression_strategy;
+
+    Options();  // Initializes with default values.
+  };
+
+  // Create a GzipOutputStream with default options.
+  explicit GzipOutputStream(google::protobuf::io::ZeroCopyOutputStream* sub_stream);
+
+  // Create a GzipOutputStream with the given options.
+  GzipOutputStream(google::protobuf::io::ZeroCopyOutputStream* sub_stream,
+                   const Options& options);
+
+  virtual ~GzipOutputStream();
+
+  // Return last error message or NULL if no error.
+  inline const char* ZlibErrorMessage() const { return zcontext_.msg; }
+  inline int ZlibErrorCode() const { return zerror_; }
+
+  // Flushes data written so far to zipped data in the underlying stream.
+  // It is the caller's responsibility to flush the underlying stream if
+  // necessary.
+  // Compression may be less efficient stopping and starting around flushes.
+  // Returns true if no error.
+  //
+  // Please ensure that block size is > 6. Here is an excerpt from the zlib
+  // doc that explains why:
+  //
+  // In the case of a Z_FULL_FLUSH or Z_SYNC_FLUSH, make sure that avail_out
+  // is greater than six to avoid repeated flush markers due to
+  // avail_out == 0 on return.
+  bool Flush();
+
+  // Writes out all data and closes the gzip stream.
+  // It is the caller's responsibility to close the underlying stream if
+  // necessary.
+  // Returns true if no error.
+  bool Close();
+
+  // implements ZeroCopyOutputStream ---------------------------------
+  bool Next(void** data, int* size) override;
+  void BackUp(int count) override;
+  int64_t ByteCount() const override;
+
+ private:
+  google::protobuf::io::ZeroCopyOutputStream* sub_stream_;
+  // Result from calling Next() on sub_stream_
+  void* sub_data_;
+  int sub_data_size_;
+
+  z_stream zcontext_;
+  int zerror_;
+  void* input_buffer_;
+  size_t input_buffer_length_;
+
+  // Shared constructor code.
+  void Init(google::protobuf::io::ZeroCopyOutputStream* sub_stream,
+            const Options& options);
+
+  // Do some compression.
+  // Takes zlib flush mode.
+  // Returns zlib error code.
+  int Deflate(int flush);
+};
+
+}  // namespace protobuf_ports
+}  // namespace lib
+}  // namespace icing
+
+#endif  // GOOGLE3_ICING_PORTABLE_GZIP_STREAM_H_