114 lines
2.8 KiB
C++
114 lines
2.8 KiB
C++
/*
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* Copyright (c) Facebook, Inc. and its affiliates.
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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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*/
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#pragma once
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#include <algorithm>
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#include <cerrno>
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#include <folly/portability/SysUio.h>
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#include <folly/portability/Unistd.h>
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/**
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* Helper functions and templates for FileUtil.cpp. Declared here so
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* they can be unittested.
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*/
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namespace folly {
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namespace fileutil_detail {
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// Wrap call to f(args) in loop to retry on EINTR
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template <class F, class... Args>
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ssize_t wrapNoInt(F f, Args... args) {
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ssize_t r;
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do {
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r = f(args...);
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} while (r == -1 && errno == EINTR);
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return r;
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}
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inline void incr(ssize_t /* n */) {}
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inline void incr(ssize_t n, off_t& offset) {
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offset += off_t(n);
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}
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// Wrap call to read/pread/write/pwrite(fd, buf, count, offset?) to retry on
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// incomplete reads / writes. The variadic argument magic is there to support
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// an additional argument (offset) for pread / pwrite; see the incr() functions
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// above which do nothing if the offset is not present and increment it if it
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// is.
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template <class F, class... Offset>
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ssize_t wrapFull(F f, int fd, void* buf, size_t count, Offset... offset) {
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char* b = static_cast<char*>(buf);
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ssize_t totalBytes = 0;
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ssize_t r;
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do {
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r = f(fd, b, count, offset...);
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if (r == -1) {
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if (errno == EINTR) {
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continue;
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}
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return r;
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}
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totalBytes += r;
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b += r;
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count -= r;
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incr(r, offset...);
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} while (r != 0 && count); // 0 means EOF
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return totalBytes;
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}
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// Wrap call to readv/preadv/writev/pwritev(fd, iov, count, offset?) to
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// retry on incomplete reads / writes.
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template <class F, class... Offset>
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ssize_t wrapvFull(F f, int fd, iovec* iov, int count, Offset... offset) {
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ssize_t totalBytes = 0;
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ssize_t r;
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do {
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r = f(fd, iov, std::min<int>(count, kIovMax), offset...);
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if (r == -1) {
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if (errno == EINTR) {
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continue;
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}
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return r;
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}
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if (r == 0) {
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break; // EOF
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}
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totalBytes += r;
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incr(r, offset...);
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while (r != 0 && count != 0) {
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if (r >= ssize_t(iov->iov_len)) {
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r -= ssize_t(iov->iov_len);
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++iov;
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--count;
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} else {
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iov->iov_base = static_cast<char*>(iov->iov_base) + r;
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iov->iov_len -= r;
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r = 0;
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}
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}
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} while (count);
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return totalBytes;
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}
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} // namespace fileutil_detail
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} // namespace folly
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