| // 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. |
| |
| #include "google/protobuf/json/internal/zero_copy_buffered_stream.h" |
| |
| #include <algorithm> |
| #include <iterator> |
| #include <string> |
| #include <utility> |
| |
| #include "absl/algorithm/container.h" |
| #include "absl/strings/str_format.h" |
| #include "absl/strings/string_view.h" |
| #include "google/protobuf/stubs/status_macros.h" |
| |
| // Must be included last. |
| #include "google/protobuf/port_def.inc" |
| |
| namespace google { |
| namespace protobuf { |
| namespace json_internal { |
| absl::Status ZeroCopyBufferedStream::Advance(size_t bytes) { |
| while (bytes != 0) { |
| if (Unread().empty() && !ReadChunk()) { |
| return absl::InvalidArgumentError("unexpected EOF"); |
| } |
| size_t to_skip = std::min(bytes, Unread().size()); |
| cursor_ += to_skip; |
| bytes -= to_skip; |
| } |
| |
| if (using_buf_) { |
| GOOGLE_DCHECK_LE(cursor_, buffer_start_ + buf_.size()); |
| } else { |
| GOOGLE_DCHECK_LE(cursor_, last_chunk_.size()); |
| } |
| |
| return absl::OkStatus(); |
| } |
| |
| absl::StatusOr<BufferingGuard> ZeroCopyBufferedStream::BufferAtLeast( |
| size_t bytes) { |
| // This MUST be an empty guard before the first call to ReadChunk(); |
| // otherwise we risk unconditional buffering. |
| BufferingGuard guard; |
| while (Unread().size() < bytes) { |
| if (!Unread().empty()) { |
| // We must buffer before reading if Unread() is nonempty; otherwise we |
| // risk discarding part of the unread buffer. However, we must NOT |
| // buffer before calling ReadChunk if it *is* empty, because then we |
| // would buffer unconditionally. |
| // |
| // There are tests to verify both of these cases. |
| guard = BufferingGuard(this); |
| } |
| if (!ReadChunk()) { |
| return absl::InvalidArgumentError("unexpected EOF"); |
| } |
| guard = BufferingGuard(this); |
| } |
| GOOGLE_DCHECK_GE(Unread().size(), bytes); |
| return BufferingGuard(this); |
| } |
| |
| void ZeroCopyBufferedStream::DownRefBuffer() { |
| GOOGLE_DCHECK_GT(outstanding_buffer_borrows_, 0); |
| |
| --outstanding_buffer_borrows_; |
| if (outstanding_buffer_borrows_ > 0 || !using_buf_) { |
| return; |
| } |
| |
| // The "virtual length" is the size of the buffer cursor_ indexes into, which |
| // is bigger than buf_. |
| size_t virtual_buf_len = buf_.size() + buffer_start_; |
| size_t last_chunk_in_buf = virtual_buf_len - last_chunk_.size(); |
| // If we are inside of `last_chunk_`, set the cursor there; otherwise, we have |
| // a dangling reference somewhere. |
| GOOGLE_DCHECK_LE(last_chunk_in_buf, virtual_buf_len) << absl::StrFormat( |
| "%d, %d, %d", buf_.size(), last_chunk_.size(), buffer_start_); |
| if (cursor_ <= last_chunk_in_buf) { |
| cursor_ = 0; |
| } else { |
| cursor_ -= last_chunk_in_buf; |
| } |
| buf_.clear(); |
| using_buf_ = false; |
| } |
| |
| bool ZeroCopyBufferedStream::ReadChunk() { |
| if (eof_) { |
| return false; |
| } |
| // We are buffering a second chunk, so we need to put the current chunk |
| // into the buffer. |
| if (outstanding_buffer_borrows_ > 0 && !using_buf_) { |
| absl::c_copy(RawBuffer(buffer_start_), std::back_inserter(buf_)); |
| using_buf_ = true; |
| } |
| |
| const void* data; |
| int len; |
| if (!stream_->Next(&data, &len)) { |
| eof_ = true; |
| return false; |
| } |
| |
| last_chunk_ = absl::string_view(static_cast<const char*>(data), |
| static_cast<size_t>(len)); |
| if (using_buf_) { |
| absl::c_copy(last_chunk_, std::back_inserter(buf_)); |
| // Cursor does not need to move, because it is still inside of `buf_`. |
| } else { |
| cursor_ = 0; |
| buffer_start_ = 0; |
| } |
| return true; |
| } |
| } // namespace json_internal |
| } // namespace protobuf |
| } // namespace google |