84 lines
2.1 KiB
C++
84 lines
2.1 KiB
C++
// Copyright (c) Facebook, Inc. and its affiliates.
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// This source code is licensed under the MIT license found in the
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// LICENSE file in the root directory of this source tree.
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#include "JSBigString.h"
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#include <fcntl.h>
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#include <sys/stat.h>
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#include <folly/Memory.h>
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#include <folly/portability/SysMman.h>
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#include <folly/ScopeGuard.h>
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namespace facebook {
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namespace react {
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JSBigFileString::JSBigFileString(int fd, size_t size, off_t offset /*= 0*/)
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: m_fd { -1 }
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, m_data { nullptr } {
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folly::checkUnixError(m_fd = dup(fd),
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"Could not duplicate file descriptor");
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// Offsets given to mmap must be page aligend. We abstract away that
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// restriction by sending a page aligned offset to mmap, and keeping track
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// of the offset within the page that we must alter the mmap pointer by to
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// get the final desired offset.
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if (offset != 0) {
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const static auto ps = getpagesize();
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auto d = lldiv(offset, ps);
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m_mapOff = d.quot;
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m_pageOff = d.rem;
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m_size = size + m_pageOff;
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} else {
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m_mapOff = 0;
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m_pageOff = 0;
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m_size = size;
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}
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}
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JSBigFileString::~JSBigFileString() {
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if (m_data) {
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munmap((void *)m_data, m_size);
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}
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close(m_fd);
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}
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const char *JSBigFileString::c_str() const {
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if (!m_data) {
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m_data =
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(const char *) mmap(0, m_size, PROT_READ, MAP_SHARED, m_fd, m_mapOff);
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CHECK(m_data != MAP_FAILED)
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<< " fd: " << m_fd
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<< " size: " << m_size
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<< " offset: " << m_mapOff
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<< " error: " << std::strerror(errno);
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}
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return m_data + m_pageOff;
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}
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size_t JSBigFileString::size() const {
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return m_size - m_pageOff;
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}
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int JSBigFileString::fd() const {
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return m_fd;
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}
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std::unique_ptr<const JSBigFileString> JSBigFileString::fromPath(const std::string& sourceURL) {
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int fd = ::open(sourceURL.c_str(), O_RDONLY);
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folly::checkUnixError(fd, "Could not open file", sourceURL);
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SCOPE_EXIT { CHECK(::close(fd) == 0); };
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struct stat fileInfo;
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folly::checkUnixError(::fstat(fd, &fileInfo), "fstat on bundle failed.");
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return folly::make_unique<const JSBigFileString>(fd, fileInfo.st_size);
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}
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} // namespace react
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} // namespace facebook
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