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- /*
- * Copyright 2013-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.
- */
- #include <folly/FileUtil.h>
- #include <cerrno>
- #include <string>
- #include <system_error>
- #include <vector>
- #include <folly/detail/FileUtilDetail.h>
- #include <folly/portability/Fcntl.h>
- #include <folly/portability/Sockets.h>
- #include <folly/portability/Stdlib.h>
- #include <folly/portability/SysFile.h>
- #include <folly/portability/SysStat.h>
- namespace folly {
- using namespace fileutil_detail;
- int openNoInt(const char* name, int flags, mode_t mode) {
- return int(wrapNoInt(open, name, flags, mode));
- }
- int closeNoInt(int fd) {
- int r = close(fd);
- // Ignore EINTR. On Linux, close() may only return EINTR after the file
- // descriptor has been closed, so you must not retry close() on EINTR --
- // in the best case, you'll get EBADF, and in the worst case, you'll end up
- // closing a different file (one opened from another thread).
- //
- // Interestingly enough, the Single Unix Specification says that the state
- // of the file descriptor is unspecified if close returns EINTR. In that
- // case, the safe thing to do is also not to retry close() -- leaking a file
- // descriptor is definitely better than closing the wrong file.
- if (r == -1 && errno == EINTR) {
- r = 0;
- }
- return r;
- }
- int fsyncNoInt(int fd) {
- return int(wrapNoInt(fsync, fd));
- }
- int dupNoInt(int fd) {
- return int(wrapNoInt(dup, fd));
- }
- int dup2NoInt(int oldfd, int newfd) {
- return int(wrapNoInt(dup2, oldfd, newfd));
- }
- int fdatasyncNoInt(int fd) {
- #if defined(__APPLE__)
- return int(wrapNoInt(fcntl, fd, F_FULLFSYNC));
- #elif defined(__FreeBSD__) || defined(_MSC_VER)
- return int(wrapNoInt(fsync, fd));
- #else
- return int(wrapNoInt(fdatasync, fd));
- #endif
- }
- int ftruncateNoInt(int fd, off_t len) {
- return int(wrapNoInt(ftruncate, fd, len));
- }
- int truncateNoInt(const char* path, off_t len) {
- return int(wrapNoInt(truncate, path, len));
- }
- int flockNoInt(int fd, int operation) {
- return int(wrapNoInt(flock, fd, operation));
- }
- int shutdownNoInt(int fd, int how) {
- return int(wrapNoInt(portability::sockets::shutdown, fd, how));
- }
- ssize_t readNoInt(int fd, void* buf, size_t count) {
- return wrapNoInt(read, fd, buf, count);
- }
- ssize_t preadNoInt(int fd, void* buf, size_t count, off_t offset) {
- return wrapNoInt(pread, fd, buf, count, offset);
- }
- ssize_t readvNoInt(int fd, const iovec* iov, int count) {
- return wrapNoInt(readv, fd, iov, count);
- }
- ssize_t writeNoInt(int fd, const void* buf, size_t count) {
- return wrapNoInt(write, fd, buf, count);
- }
- ssize_t pwriteNoInt(int fd, const void* buf, size_t count, off_t offset) {
- return wrapNoInt(pwrite, fd, buf, count, offset);
- }
- ssize_t writevNoInt(int fd, const iovec* iov, int count) {
- return wrapNoInt(writev, fd, iov, count);
- }
- ssize_t readFull(int fd, void* buf, size_t count) {
- return wrapFull(read, fd, buf, count);
- }
- ssize_t preadFull(int fd, void* buf, size_t count, off_t offset) {
- return wrapFull(pread, fd, buf, count, offset);
- }
- ssize_t writeFull(int fd, const void* buf, size_t count) {
- return wrapFull(write, fd, const_cast<void*>(buf), count);
- }
- ssize_t pwriteFull(int fd, const void* buf, size_t count, off_t offset) {
- return wrapFull(pwrite, fd, const_cast<void*>(buf), count, offset);
- }
- ssize_t readvFull(int fd, iovec* iov, int count) {
- return wrapvFull(readv, fd, iov, count);
- }
- ssize_t preadvFull(int fd, iovec* iov, int count, off_t offset) {
- return wrapvFull(preadv, fd, iov, count, offset);
- }
- ssize_t writevFull(int fd, iovec* iov, int count) {
- return wrapvFull(writev, fd, iov, count);
- }
- ssize_t pwritevFull(int fd, iovec* iov, int count, off_t offset) {
- return wrapvFull(pwritev, fd, iov, count, offset);
- }
- int writeFileAtomicNoThrow(
- StringPiece filename,
- iovec* iov,
- int count,
- mode_t permissions) {
- // We write the data to a temporary file name first, then atomically rename
- // it into place. This ensures that the file contents will always be valid,
- // even if we crash or are killed partway through writing out data.
- //
- // Create a buffer that will contain two things:
- // - A nul-terminated version of the filename
- // - The temporary file name
- std::vector<char> pathBuffer;
- // Note that we have to explicitly pass in the size here to make
- // sure the nul byte gets included in the data.
- constexpr folly::StringPiece suffix(".XXXXXX\0", 8);
- pathBuffer.resize((2 * filename.size()) + 1 + suffix.size());
- // Copy in the filename and then a nul terminator
- memcpy(pathBuffer.data(), filename.data(), filename.size());
- pathBuffer[filename.size()] = '\0';
- const char* const filenameCStr = pathBuffer.data();
- // Now prepare the temporary path template
- char* const tempPath = pathBuffer.data() + filename.size() + 1;
- memcpy(tempPath, filename.data(), filename.size());
- memcpy(tempPath + filename.size(), suffix.data(), suffix.size());
- auto tmpFD = mkstemp(tempPath);
- if (tmpFD == -1) {
- return errno;
- }
- bool success = false;
- SCOPE_EXIT {
- if (tmpFD != -1) {
- close(tmpFD);
- }
- if (!success) {
- unlink(tempPath);
- }
- };
- auto rc = writevFull(tmpFD, iov, count);
- if (rc == -1) {
- return errno;
- }
- rc = fchmod(tmpFD, permissions);
- if (rc == -1) {
- return errno;
- }
- // Close the file before renaming to make sure all data has
- // been successfully written.
- rc = close(tmpFD);
- tmpFD = -1;
- if (rc == -1) {
- return errno;
- }
- rc = rename(tempPath, filenameCStr);
- if (rc == -1) {
- return errno;
- }
- success = true;
- return 0;
- }
- void writeFileAtomic(
- StringPiece filename,
- iovec* iov,
- int count,
- mode_t permissions) {
- auto rc = writeFileAtomicNoThrow(filename, iov, count, permissions);
- if (rc != 0) {
- auto msg = std::string(__func__) + "() failed to update " + filename.str();
- throw std::system_error(rc, std::generic_category(), msg);
- }
- }
- void writeFileAtomic(StringPiece filename, ByteRange data, mode_t permissions) {
- iovec iov;
- iov.iov_base = const_cast<unsigned char*>(data.data());
- iov.iov_len = data.size();
- writeFileAtomic(filename, &iov, 1, permissions);
- }
- void writeFileAtomic(
- StringPiece filename,
- StringPiece data,
- mode_t permissions) {
- writeFileAtomic(filename, ByteRange(data), permissions);
- }
- } // namespace folly
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