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- /*
- * Copyright 2014-present Facebook, Inc.
- *
- * 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.
- */
- #ifndef FOLLY_GEN_FILE_H_
- #error This file may only be included from folly/gen/File.h
- #endif
- #include <system_error>
- #include <folly/gen/String.h>
- namespace folly {
- namespace gen {
- namespace detail {
- class FileReader : public GenImpl<ByteRange, FileReader> {
- public:
- FileReader(File file, std::unique_ptr<IOBuf> buffer)
- : file_(std::move(file)), buffer_(std::move(buffer)) {
- buffer_->clear();
- }
- template <class Body>
- bool apply(Body&& body) const {
- for (;;) {
- ssize_t n;
- do {
- n = ::read(file_.fd(), buffer_->writableTail(), buffer_->capacity());
- } while (n == -1 && errno == EINTR);
- if (n == -1) {
- throw std::system_error(errno, std::system_category(), "read failed");
- }
- if (n == 0) {
- return true;
- }
- if (!body(ByteRange(buffer_->tail(), size_t(n)))) {
- return false;
- }
- }
- }
- // Technically, there could be infinite files (e.g. /dev/random), but people
- // who open those can do so at their own risk.
- static constexpr bool infinite = false;
- private:
- File file_;
- std::unique_ptr<IOBuf> buffer_;
- };
- class FileWriter : public Operator<FileWriter> {
- public:
- FileWriter(File file, std::unique_ptr<IOBuf> buffer)
- : file_(std::move(file)), buffer_(std::move(buffer)) {
- if (buffer_) {
- buffer_->clear();
- }
- }
- template <class Source, class Value>
- void compose(const GenImpl<Value, Source>& source) const {
- auto fn = [&](ByteRange v) {
- if (!this->buffer_ || v.size() >= this->buffer_->capacity()) {
- this->flushBuffer();
- this->write(v);
- } else {
- if (v.size() > this->buffer_->tailroom()) {
- this->flushBuffer();
- }
- memcpy(this->buffer_->writableTail(), v.data(), v.size());
- this->buffer_->append(v.size());
- }
- };
- // Iterate
- source.foreach(std::move(fn));
- flushBuffer();
- file_.close();
- }
- private:
- void write(ByteRange v) const {
- ssize_t n;
- while (!v.empty()) {
- do {
- n = ::write(file_.fd(), v.data(), v.size());
- } while (n == -1 && errno == EINTR);
- if (n == -1) {
- throw std::system_error(
- errno, std::system_category(), "write() failed");
- }
- v.advance(size_t(n));
- }
- }
- void flushBuffer() const {
- if (buffer_ && buffer_->length() != 0) {
- write(ByteRange(buffer_->data(), buffer_->length()));
- buffer_->clear();
- }
- }
- mutable File file_;
- std::unique_ptr<IOBuf> buffer_;
- };
- inline auto byLineImpl(File file, char delim, bool keepDelimiter) {
- // clang-format off
- return fromFile(std::move(file))
- | eachAs<StringPiece>()
- | resplit(delim, keepDelimiter);
- // clang-format on
- }
- } // namespace detail
- /**
- * Generator which reads lines from a file.
- * Note: This produces StringPieces which reference temporary strings which are
- * only valid during iteration.
- */
- inline auto byLineFull(File file, char delim = '\n') {
- return detail::byLineImpl(std::move(file), delim, true);
- }
- inline auto byLineFull(int fd, char delim = '\n') {
- return byLineFull(File(fd), delim);
- }
- inline auto byLineFull(const char* f, char delim = '\n') {
- return byLineFull(File(f), delim);
- }
- inline auto byLine(File file, char delim = '\n') {
- return detail::byLineImpl(std::move(file), delim, false);
- }
- inline auto byLine(int fd, char delim = '\n') {
- return byLine(File(fd), delim);
- }
- inline auto byLine(const char* f, char delim = '\n') {
- return byLine(File(f), delim);
- }
- } // namespace gen
- } // namespace folly
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