diff options
Diffstat (limited to 'src/google/protobuf/io/zero_copy_stream_impl.cc')
| -rw-r--r-- | src/google/protobuf/io/zero_copy_stream_impl.cc | 474 |
1 files changed, 474 insertions, 0 deletions
diff --git a/src/google/protobuf/io/zero_copy_stream_impl.cc b/src/google/protobuf/io/zero_copy_stream_impl.cc new file mode 100644 index 00000000..7ec2b5da --- /dev/null +++ b/src/google/protobuf/io/zero_copy_stream_impl.cc @@ -0,0 +1,474 @@ +// 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. + +#ifdef _MSC_VER +#include <io.h> +#else +#include <unistd.h> +#include <sys/types.h> +#include <sys/stat.h> +#include <fcntl.h> +#endif +#include <errno.h> +#include <iostream> +#include <algorithm> + +#include <google/protobuf/io/zero_copy_stream_impl.h> +#include <google/protobuf/stubs/common.h> +#include <google/protobuf/stubs/logging.h> +#include <google/protobuf/stubs/stl_util.h> + + +namespace google { +namespace protobuf { +namespace io { + +#ifdef _WIN32 +// Win32 lseek is broken: If invoked on a non-seekable file descriptor, its +// return value is undefined. We re-define it to always produce an error. +#define lseek(fd, offset, origin) ((off_t)-1) +#endif + +namespace { + +// EINTR sucks. +int close_no_eintr(int fd) { + int result; + do { + result = close(fd); + } while (result < 0 && errno == EINTR); + return result; +} + +} // namespace + + +// =================================================================== + +FileInputStream::FileInputStream(int file_descriptor, int block_size) + : copying_input_(file_descriptor), + impl_(©ing_input_, block_size) { +} + +FileInputStream::~FileInputStream() {} + +bool FileInputStream::Close() { + return copying_input_.Close(); +} + +bool FileInputStream::Next(const void** data, int* size) { + return impl_.Next(data, size); +} + +void FileInputStream::BackUp(int count) { + impl_.BackUp(count); +} + +bool FileInputStream::Skip(int count) { + return impl_.Skip(count); +} + +int64 FileInputStream::ByteCount() const { + return impl_.ByteCount(); +} + +FileInputStream::CopyingFileInputStream::CopyingFileInputStream( + int file_descriptor) + : file_(file_descriptor), + close_on_delete_(false), + is_closed_(false), + errno_(0), + previous_seek_failed_(false) { +} + +FileInputStream::CopyingFileInputStream::~CopyingFileInputStream() { + if (close_on_delete_) { + if (!Close()) { + GOOGLE_LOG(ERROR) << "close() failed: " << strerror(errno_); + } + } +} + +bool FileInputStream::CopyingFileInputStream::Close() { + GOOGLE_CHECK(!is_closed_); + + is_closed_ = true; + if (close_no_eintr(file_) != 0) { + // The docs on close() do not specify whether a file descriptor is still + // open after close() fails with EIO. However, the glibc source code + // seems to indicate that it is not. + errno_ = errno; + return false; + } + + return true; +} + +int FileInputStream::CopyingFileInputStream::Read(void* buffer, int size) { + GOOGLE_CHECK(!is_closed_); + + int result; + do { + result = read(file_, buffer, size); + } while (result < 0 && errno == EINTR); + + if (result < 0) { + // Read error (not EOF). + errno_ = errno; + } + + return result; +} + +int FileInputStream::CopyingFileInputStream::Skip(int count) { + GOOGLE_CHECK(!is_closed_); + + if (!previous_seek_failed_ && + lseek(file_, count, SEEK_CUR) != (off_t)-1) { + // Seek succeeded. + return count; + } else { + // Failed to seek. + + // Note to self: Don't seek again. This file descriptor doesn't + // support it. + previous_seek_failed_ = true; + + // Use the default implementation. + return CopyingInputStream::Skip(count); + } +} + +// =================================================================== + +FileOutputStream::FileOutputStream(int file_descriptor, int block_size) + : copying_output_(file_descriptor), + impl_(©ing_output_, block_size) { +} + +FileOutputStream::~FileOutputStream() { + impl_.Flush(); +} + +bool FileOutputStream::Close() { + bool flush_succeeded = impl_.Flush(); + return copying_output_.Close() && flush_succeeded; +} + +bool FileOutputStream::Flush() { + return impl_.Flush(); +} + +bool FileOutputStream::Next(void** data, int* size) { + return impl_.Next(data, size); +} + +void FileOutputStream::BackUp(int count) { + impl_.BackUp(count); +} + +int64 FileOutputStream::ByteCount() const { + return impl_.ByteCount(); +} + +FileOutputStream::CopyingFileOutputStream::CopyingFileOutputStream( + int file_descriptor) + : file_(file_descriptor), + close_on_delete_(false), + is_closed_(false), + errno_(0) { +} + +FileOutputStream::CopyingFileOutputStream::~CopyingFileOutputStream() { + if (close_on_delete_) { + if (!Close()) { + GOOGLE_LOG(ERROR) << "close() failed: " << strerror(errno_); + } + } +} + +bool FileOutputStream::CopyingFileOutputStream::Close() { + GOOGLE_CHECK(!is_closed_); + + is_closed_ = true; + if (close_no_eintr(file_) != 0) { + // The docs on close() do not specify whether a file descriptor is still + // open after close() fails with EIO. However, the glibc source code + // seems to indicate that it is not. + errno_ = errno; + return false; + } + + return true; +} + +bool FileOutputStream::CopyingFileOutputStream::Write( + const void* buffer, int size) { + GOOGLE_CHECK(!is_closed_); + int total_written = 0; + + const uint8* buffer_base = reinterpret_cast<const uint8*>(buffer); + + while (total_written < size) { + int bytes; + do { + bytes = write(file_, buffer_base + total_written, size - total_written); + } while (bytes < 0 && errno == EINTR); + + if (bytes <= 0) { + // Write error. + + // FIXME(kenton): According to the man page, if write() returns zero, + // there was no error; write() simply did not write anything. It's + // unclear under what circumstances this might happen, but presumably + // errno won't be set in this case. I am confused as to how such an + // event should be handled. For now I'm treating it as an error, since + // retrying seems like it could lead to an infinite loop. I suspect + // this never actually happens anyway. + + if (bytes < 0) { + errno_ = errno; + } + return false; + } + total_written += bytes; + } + + return true; +} + +// =================================================================== + +IstreamInputStream::IstreamInputStream(istream* input, int block_size) + : copying_input_(input), + impl_(©ing_input_, block_size) { +} + +IstreamInputStream::~IstreamInputStream() {} + +bool IstreamInputStream::Next(const void** data, int* size) { + return impl_.Next(data, size); +} + +void IstreamInputStream::BackUp(int count) { + impl_.BackUp(count); +} + +bool IstreamInputStream::Skip(int count) { + return impl_.Skip(count); +} + +int64 IstreamInputStream::ByteCount() const { + return impl_.ByteCount(); +} + +IstreamInputStream::CopyingIstreamInputStream::CopyingIstreamInputStream( + istream* input) + : input_(input) { +} + +IstreamInputStream::CopyingIstreamInputStream::~CopyingIstreamInputStream() {} + +int IstreamInputStream::CopyingIstreamInputStream::Read( + void* buffer, int size) { + input_->read(reinterpret_cast<char*>(buffer), size); + int result = input_->gcount(); + if (result == 0 && input_->fail() && !input_->eof()) { + return -1; + } + return result; +} + +// =================================================================== + +OstreamOutputStream::OstreamOutputStream(ostream* output, int block_size) + : copying_output_(output), + impl_(©ing_output_, block_size) { +} + +OstreamOutputStream::~OstreamOutputStream() { + impl_.Flush(); +} + +bool OstreamOutputStream::Next(void** data, int* size) { + return impl_.Next(data, size); +} + +void OstreamOutputStream::BackUp(int count) { + impl_.BackUp(count); +} + +int64 OstreamOutputStream::ByteCount() const { + return impl_.ByteCount(); +} + +OstreamOutputStream::CopyingOstreamOutputStream::CopyingOstreamOutputStream( + ostream* output) + : output_(output) { +} + +OstreamOutputStream::CopyingOstreamOutputStream::~CopyingOstreamOutputStream() { +} + +bool OstreamOutputStream::CopyingOstreamOutputStream::Write( + const void* buffer, int size) { + output_->write(reinterpret_cast<const char*>(buffer), size); + return output_->good(); +} + +// =================================================================== + +ConcatenatingInputStream::ConcatenatingInputStream( + ZeroCopyInputStream* const streams[], int count) + : streams_(streams), stream_count_(count), bytes_retired_(0) { +} + +ConcatenatingInputStream::~ConcatenatingInputStream() { +} + +bool ConcatenatingInputStream::Next(const void** data, int* size) { + while (stream_count_ > 0) { + if (streams_[0]->Next(data, size)) return true; + + // That stream is done. Advance to the next one. + bytes_retired_ += streams_[0]->ByteCount(); + ++streams_; + --stream_count_; + } + + // No more streams. + return false; +} + +void ConcatenatingInputStream::BackUp(int count) { + if (stream_count_ > 0) { + streams_[0]->BackUp(count); + } else { + GOOGLE_LOG(DFATAL) << "Can't BackUp() after failed Next()."; + } +} + +bool ConcatenatingInputStream::Skip(int count) { + while (stream_count_ > 0) { + // Assume that ByteCount() can be used to find out how much we actually + // skipped when Skip() fails. + int64 target_byte_count = streams_[0]->ByteCount() + count; + if (streams_[0]->Skip(count)) return true; + + // Hit the end of the stream. Figure out how many more bytes we still have + // to skip. + int64 final_byte_count = streams_[0]->ByteCount(); + GOOGLE_DCHECK_LT(final_byte_count, target_byte_count); + count = target_byte_count - final_byte_count; + + // That stream is done. Advance to the next one. + bytes_retired_ += final_byte_count; + ++streams_; + --stream_count_; + } + + return false; +} + +int64 ConcatenatingInputStream::ByteCount() const { + if (stream_count_ == 0) { + return bytes_retired_; + } else { + return bytes_retired_ + streams_[0]->ByteCount(); + } +} + + +// =================================================================== + +LimitingInputStream::LimitingInputStream(ZeroCopyInputStream* input, + int64 limit) + : input_(input), limit_(limit) { + prior_bytes_read_ = input_->ByteCount(); +} + +LimitingInputStream::~LimitingInputStream() { + // If we overshot the limit, back up. + if (limit_ < 0) input_->BackUp(-limit_); +} + +bool LimitingInputStream::Next(const void** data, int* size) { + if (limit_ <= 0) return false; + if (!input_->Next(data, size)) return false; + + limit_ -= *size; + if (limit_ < 0) { + // We overshot the limit. Reduce *size to hide the rest of the buffer. + *size += limit_; + } + return true; +} + +void LimitingInputStream::BackUp(int count) { + if (limit_ < 0) { + input_->BackUp(count - limit_); + limit_ = count; + } else { + input_->BackUp(count); + limit_ += count; + } +} + +bool LimitingInputStream::Skip(int count) { + if (count > limit_) { + if (limit_ < 0) return false; + input_->Skip(limit_); + limit_ = 0; + return false; + } else { + if (!input_->Skip(count)) return false; + limit_ -= count; + return true; + } +} + +int64 LimitingInputStream::ByteCount() const { + if (limit_ < 0) { + return input_->ByteCount() + limit_ - prior_bytes_read_; + } else { + return input_->ByteCount() - prior_bytes_read_; + } +} + + +// =================================================================== + +} // namespace io +} // namespace protobuf +} // namespace google |