111 lines
3.9 KiB
C++
111 lines
3.9 KiB
C++
// Copyright 2017 The Crashpad Authors. All rights reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#include "util/file/delimited_file_reader.h"
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#include <sys/types.h>
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#include <algorithm>
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#include <iterator>
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#include <limits>
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#include "base/check_op.h"
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#include "base/numerics/safe_conversions.h"
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namespace crashpad {
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DelimitedFileReader::DelimitedFileReader(FileReaderInterface* file_reader)
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: file_reader_(file_reader), buf_pos_(0), buf_len_(0), eof_(false) {
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static_assert(sizeof(buf_) <= std::numeric_limits<decltype(buf_pos_)>::max(),
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"buf_pos_ must cover buf_");
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static_assert(sizeof(buf_) <= std::numeric_limits<decltype(buf_len_)>::max(),
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"buf_len_ must cover buf_");
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}
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DelimitedFileReader::~DelimitedFileReader() {}
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DelimitedFileReader::Result DelimitedFileReader::GetDelim(char delimiter,
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std::string* field) {
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if (eof_) {
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DCHECK_EQ(buf_pos_, buf_len_);
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// Allow subsequent calls to attempt to read more data from the file. If the
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// file is still at EOF in the future, the read will return 0 and cause
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// kEndOfFile to be returned anyway.
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eof_ = false;
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return Result::kEndOfFile;
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}
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std::string local_field;
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while (true) {
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if (buf_pos_ == buf_len_) {
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// buf_ is empty. Refill it.
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FileOperationResult read_result = file_reader_->Read(buf_, sizeof(buf_));
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if (read_result < 0) {
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return Result::kError;
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} else if (read_result == 0) {
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if (!local_field.empty()) {
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// The file ended with a field that wasn’t terminated by a delimiter
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// character.
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//
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// This is EOF, but EOF can’t be returned because there’s a field that
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// needs to be returned to the caller. Cache the detected EOF so it
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// can be returned next time. This is done to support proper semantics
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// for weird “files” like terminal input that can reach EOF and then
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// “grow”, allowing subsequent reads past EOF to block while waiting
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// for more data. Once EOF is detected by a read that returns 0, that
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// EOF signal should propagate to the caller before attempting a new
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// read. Here, it will be returned on the next call to this method
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// without attempting to read more data.
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eof_ = true;
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field->swap(local_field);
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return Result::kSuccess;
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}
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return Result::kEndOfFile;
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}
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DCHECK_LE(static_cast<size_t>(read_result), std::size(buf_));
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DCHECK(
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base::IsValueInRangeForNumericType<decltype(buf_len_)>(read_result));
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buf_len_ = static_cast<decltype(buf_len_)>(read_result);
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buf_pos_ = 0;
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}
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const char* const start = buf_ + buf_pos_;
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const char* const end = buf_ + buf_len_;
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const char* const found = std::find(start, end, delimiter);
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local_field.append(start, found);
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buf_pos_ = static_cast<decltype(buf_pos_)>(found - buf_);
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DCHECK_LE(buf_pos_, buf_len_);
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if (found != end) {
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// A real delimiter character was found. Append it to the field being
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// built and return it.
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local_field.push_back(delimiter);
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++buf_pos_;
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DCHECK_LE(buf_pos_, buf_len_);
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field->swap(local_field);
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return Result::kSuccess;
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}
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}
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}
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DelimitedFileReader::Result DelimitedFileReader::GetLine(std::string* line) {
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return GetDelim('\n', line);
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}
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} // namespace crashpad
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