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// Protocol Buffers - Google's data interchange format
// Copyright 2008 Google Inc. All rights reserved.
// https://developers.google.com/protocol-buffers/
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
// Author: kenton@google.com (Kenton Varda)
// Based on original Protocol Buffers design by
// Sanjay Ghemawat, Jeff Dean, and others.
//
// This file contains common implementations of the interfaces defined in
// zero_copy_stream.h which are only included in the full (non-lite)
// protobuf library. These implementations include Unix file descriptors
// and C++ iostreams. See also: zero_copy_stream_impl_lite.h
#ifndef GOOGLE_PROTOBUF_IO_ZERO_COPY_STREAM_IMPL_H__
#define GOOGLE_PROTOBUF_IO_ZERO_COPY_STREAM_IMPL_H__
#include <string>
#include <iosfwd>
#include <google/protobuf/io/zero_copy_stream.h>
#include <google/protobuf/io/zero_copy_stream_impl_lite.h>
#include <google/protobuf/stubs/common.h>
namespace google {
namespace protobuf {
namespace io {
// ===================================================================
// A ZeroCopyInputStream which reads from a file descriptor.
//
// FileInputStream is preferred over using an ifstream with IstreamInputStream.
// The latter will introduce an extra layer of buffering, harming performance.
// Also, it's conceivable that FileInputStream could someday be enhanced
// to use zero-copy file descriptors on OSs which support them.
class LIBPROTOBUF_EXPORT FileInputStream : public ZeroCopyInputStream {
public:
// Creates a stream that reads from the given Unix file descriptor.
// If a block_size is given, it specifies the number of bytes that
// should be read and returned with each call to Next(). Otherwise,
// a reasonable default is used.
explicit FileInputStream(int file_descriptor, int block_size = -1);
~FileInputStream();
// Flushes any buffers and closes the underlying file. Returns false if
// an error occurs during the process; use GetErrno() to examine the error.
// Even if an error occurs, the file descriptor is closed when this returns.
bool Close();
// By default, the file descriptor is not closed when the stream is
// destroyed. Call SetCloseOnDelete(true) to change that. WARNING:
// This leaves no way for the caller to detect if close() fails. If
// detecting close() errors is important to you, you should arrange
// to close the descriptor yourself.
void SetCloseOnDelete(bool value) { copying_input_.SetCloseOnDelete(value); }
// If an I/O error has occurred on this file descriptor, this is the
// errno from that error. Otherwise, this is zero. Once an error
// occurs, the stream is broken and all subsequent operations will
// fail.
int GetErrno() { return copying_input_.GetErrno(); }
// implements ZeroCopyInputStream ----------------------------------
bool Next(const void** data, int* size);
void BackUp(int count);
bool Skip(int count);
int64 ByteCount() const;
private:
class LIBPROTOBUF_EXPORT CopyingFileInputStream : public CopyingInputStream {
public:
CopyingFileInputStream(int file_descriptor);
~CopyingFileInputStream();
bool Close();
void SetCloseOnDelete(bool value) { close_on_delete_ = value; }
int GetErrno() { return errno_; }
// implements CopyingInputStream ---------------------------------
int Read(void* buffer, int size);
int Skip(int count);
private:
// The file descriptor.
const int file_;
bool close_on_delete_;
bool is_closed_;
// The errno of the I/O error, if one has occurred. Otherwise, zero.
int errno_;
// Did we try to seek once and fail? If so, we assume this file descriptor
// doesn't support seeking and won't try again.
bool previous_seek_failed_;
GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(CopyingFileInputStream);
};
CopyingFileInputStream copying_input_;
CopyingInputStreamAdaptor impl_;
GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(FileInputStream);
};
// ===================================================================
// A ZeroCopyOutputStream which writes to a file descriptor.
//
// FileOutputStream is preferred over using an ofstream with
// OstreamOutputStream. The latter will introduce an extra layer of buffering,
// harming performance. Also, it's conceivable that FileOutputStream could
// someday be enhanced to use zero-copy file descriptors on OSs which
// support them.
class LIBPROTOBUF_EXPORT FileOutputStream : public ZeroCopyOutputStream {
public:
// Creates a stream that writes to the given Unix file descriptor.
// If a block_size is given, it specifies the size of the buffers
// that should be returned by Next(). Otherwise, a reasonable default
// is used.
explicit FileOutputStream(int file_descriptor, int block_size = -1);
~FileOutputStream();
// Flushes any buffers and closes the underlying file. Returns false if
// an error occurs during the process; use GetErrno() to examine the error.
// Even if an error occurs, the file descriptor is closed when this returns.
bool Close();
// Flushes FileOutputStream's buffers but does not close the
// underlying file. No special measures are taken to ensure that
// underlying operating system file object is synchronized to disk.
bool Flush();
// By default, the file descriptor is not closed when the stream is
// destroyed. Call SetCloseOnDelete(true) to change that. WARNING:
// This leaves no way for the caller to detect if close() fails. If
// detecting close() errors is important to you, you should arrange
// to close the descriptor yourself.
void SetCloseOnDelete(bool value) { copying_output_.SetCloseOnDelete(value); }
// If an I/O error has occurred on this file descriptor, this is the
// errno from that error. Otherwise, this is zero. Once an error
// occurs, the stream is broken and all subsequent operations will
// fail.
int GetErrno() { return copying_output_.GetErrno(); }
// implements ZeroCopyOutputStream ---------------------------------
bool Next(void** data, int* size);
void BackUp(int count);
int64 ByteCount() const;
private:
class LIBPROTOBUF_EXPORT CopyingFileOutputStream : public CopyingOutputStream {
public:
CopyingFileOutputStream(int file_descriptor);
~CopyingFileOutputStream();
bool Close();
void SetCloseOnDelete(bool value) { close_on_delete_ = value; }
int GetErrno() { return errno_; }
// implements CopyingOutputStream --------------------------------
bool Write(const void* buffer, int size);
private:
// The file descriptor.
const int file_;
bool close_on_delete_;
bool is_closed_;
// The errno of the I/O error, if one has occurred. Otherwise, zero.
int errno_;
GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(CopyingFileOutputStream);
};
CopyingFileOutputStream copying_output_;
CopyingOutputStreamAdaptor impl_;
GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(FileOutputStream);
};
// ===================================================================
// A ZeroCopyInputStream which reads from a C++ istream.
//
// Note that for reading files (or anything represented by a file descriptor),
// FileInputStream is more efficient.
class LIBPROTOBUF_EXPORT IstreamInputStream : public ZeroCopyInputStream {
public:
// Creates a stream that reads from the given C++ istream.
// If a block_size is given, it specifies the number of bytes that
// should be read and returned with each call to Next(). Otherwise,
// a reasonable default is used.
explicit IstreamInputStream(istream* stream, int block_size = -1);
~IstreamInputStream();
// implements ZeroCopyInputStream ----------------------------------
bool Next(const void** data, int* size);
void BackUp(int count);
bool Skip(int count);
int64 ByteCount() const;
private:
class LIBPROTOBUF_EXPORT CopyingIstreamInputStream : public CopyingInputStream {
public:
CopyingIstreamInputStream(istream* input);
~CopyingIstreamInputStream();
// implements CopyingInputStream ---------------------------------
int Read(void* buffer, int size);
// (We use the default implementation of Skip().)
private:
// The stream.
istream* input_;
GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(CopyingIstreamInputStream);
};
CopyingIstreamInputStream copying_input_;
CopyingInputStreamAdaptor impl_;
GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(IstreamInputStream);
};
// ===================================================================
// A ZeroCopyOutputStream which writes to a C++ ostream.
//
// Note that for writing files (or anything represented by a file descriptor),
// FileOutputStream is more efficient.
class LIBPROTOBUF_EXPORT OstreamOutputStream : public ZeroCopyOutputStream {
public:
// Creates a stream that writes to the given C++ ostream.
// If a block_size is given, it specifies the size of the buffers
// that should be returned by Next(). Otherwise, a reasonable default
// is used.
explicit OstreamOutputStream(ostream* stream, int block_size = -1);
~OstreamOutputStream();
// implements ZeroCopyOutputStream ---------------------------------
bool Next(void** data, int* size);
void BackUp(int count);
int64 ByteCount() const;
private:
class LIBPROTOBUF_EXPORT CopyingOstreamOutputStream : public CopyingOutputStream {
public:
CopyingOstreamOutputStream(ostream* output);
~CopyingOstreamOutputStream();
// implements CopyingOutputStream --------------------------------
bool Write(const void* buffer, int size);
private:
// The stream.
ostream* output_;
GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(CopyingOstreamOutputStream);
};
CopyingOstreamOutputStream copying_output_;
CopyingOutputStreamAdaptor impl_;
GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(OstreamOutputStream);
};
// ===================================================================
// A ZeroCopyInputStream which reads from several other streams in sequence.
// ConcatenatingInputStream is unable to distinguish between end-of-stream
// and read errors in the underlying streams, so it assumes any errors mean
// end-of-stream. So, if the underlying streams fail for any other reason,
// ConcatenatingInputStream may do odd things. It is suggested that you do
// not use ConcatenatingInputStream on streams that might produce read errors
// other than end-of-stream.
class LIBPROTOBUF_EXPORT ConcatenatingInputStream : public ZeroCopyInputStream {
public:
// All streams passed in as well as the array itself must remain valid
// until the ConcatenatingInputStream is destroyed.
ConcatenatingInputStream(ZeroCopyInputStream* const streams[], int count);
~ConcatenatingInputStream();
// implements ZeroCopyInputStream ----------------------------------
bool Next(const void** data, int* size);
void BackUp(int count);
bool Skip(int count);
int64 ByteCount() const;
private:
// As streams are retired, streams_ is incremented and count_ is
// decremented.
ZeroCopyInputStream* const* streams_;
int stream_count_;
int64 bytes_retired_; // Bytes read from previous streams.
GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(ConcatenatingInputStream);
};
// ===================================================================
// A ZeroCopyInputStream which wraps some other stream and limits it to
// a particular byte count.
class LIBPROTOBUF_EXPORT LimitingInputStream : public ZeroCopyInputStream {
public:
LimitingInputStream(ZeroCopyInputStream* input, int64 limit);
~LimitingInputStream();
// implements ZeroCopyInputStream ----------------------------------
bool Next(const void** data, int* size);
void BackUp(int count);
bool Skip(int count);
int64 ByteCount() const;
private:
ZeroCopyInputStream* input_;
int64 limit_; // Decreases as we go, becomes negative if we overshoot.
int64 prior_bytes_read_; // Bytes read on underlying stream at construction
GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(LimitingInputStream);
};
// ===================================================================
} // namespace io
} // namespace protobuf
} // namespace google
#endif // GOOGLE_PROTOBUF_IO_ZERO_COPY_STREAM_IMPL_H__