fs/io: move to io/
This commit is contained in:
Max Kellermann
304
src/io/FileOutputStream.cxx
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304
src/io/FileOutputStream.cxx
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/*
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* Copyright (C) 2014-2018 Max Kellermann <max.kellermann@gmail.com>
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* - Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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*
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* - Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the
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* distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* FOUNDATION OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
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* OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include "FileOutputStream.hxx"
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#include "system/Error.hxx"
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#include "util/StringFormat.hxx"
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#ifdef __linux__
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#include <fcntl.h>
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#endif
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#ifdef __linux__
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FileOutputStream::FileOutputStream(FileDescriptor _directory_fd,
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Path _path, Mode _mode)
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:path(_path),
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directory_fd(_directory_fd),
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mode(_mode)
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{
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Open();
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}
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#endif
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FileOutputStream::FileOutputStream(Path _path, Mode _mode)
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:path(_path),
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#ifdef __linux__
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directory_fd(AT_FDCWD),
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#endif
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mode(_mode)
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{
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Open();
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}
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inline void
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FileOutputStream::Open()
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{
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switch (mode) {
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case Mode::CREATE:
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OpenCreate(false);
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break;
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case Mode::CREATE_VISIBLE:
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OpenCreate(true);
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break;
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case Mode::APPEND_EXISTING:
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OpenAppend(false);
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break;
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case Mode::APPEND_OR_CREATE:
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OpenAppend(true);
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break;
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}
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}
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#ifdef _WIN32
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inline void
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FileOutputStream::OpenCreate([[maybe_unused]] bool visible)
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{
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handle = CreateFile(path.c_str(), GENERIC_WRITE, 0, nullptr,
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CREATE_ALWAYS,
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FILE_ATTRIBUTE_NORMAL|FILE_FLAG_WRITE_THROUGH,
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nullptr);
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if (!IsDefined())
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throw FormatLastError("Failed to create %s",
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path.ToUTF8().c_str());
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}
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inline void
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FileOutputStream::OpenAppend(bool create)
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{
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handle = CreateFile(path.c_str(), GENERIC_WRITE, 0, nullptr,
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create ? OPEN_ALWAYS : OPEN_EXISTING,
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FILE_ATTRIBUTE_NORMAL|FILE_FLAG_WRITE_THROUGH,
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nullptr);
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if (!IsDefined())
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throw FormatLastError("Failed to append to %s",
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path.ToUTF8().c_str());
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if (!SeekEOF()) {
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auto code = GetLastError();
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Close();
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throw FormatLastError(code, "Failed seek end-of-file of %s",
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path.ToUTF8().c_str());
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}
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}
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uint64_t
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FileOutputStream::Tell() const noexcept
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{
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LONG high = 0;
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DWORD low = SetFilePointer(handle, 0, &high, FILE_CURRENT);
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if (low == 0xffffffff)
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return 0;
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return uint64_t(high) << 32 | uint64_t(low);
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}
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void
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FileOutputStream::Write(const void *data, size_t size)
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{
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assert(IsDefined());
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DWORD nbytes;
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if (!WriteFile(handle, data, size, &nbytes, nullptr))
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throw FormatLastError("Failed to write to %s",
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GetPath().c_str());
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if (size_t(nbytes) != size)
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throw FormatLastError(ERROR_DISK_FULL, "Failed to write to %s",
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GetPath().c_str());
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}
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void
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FileOutputStream::Commit()
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{
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assert(IsDefined());
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Close();
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}
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void
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FileOutputStream::Cancel() noexcept
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{
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assert(IsDefined());
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Close();
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DeleteFile(GetPath().c_str());
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}
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#else
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#include <cerrno>
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#include <fcntl.h>
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#include <unistd.h>
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#ifdef HAVE_O_TMPFILE
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#ifndef O_TMPFILE
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/* supported since Linux 3.11 */
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#define __O_TMPFILE 020000000
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#define O_TMPFILE (__O_TMPFILE | O_DIRECTORY)
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#include <stdio.h>
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#endif
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/**
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* Open a file using Linux's O_TMPFILE for writing the given file.
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*/
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static bool
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OpenTempFile(FileDescriptor directory_fd,
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FileDescriptor &fd, Path path) noexcept
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{
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if (directory_fd != FileDescriptor(AT_FDCWD))
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return fd.Open(directory_fd, ".", O_TMPFILE|O_WRONLY, 0666);
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const auto directory = path.GetDirectoryName();
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if (directory.IsNull())
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return false;
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return fd.Open(directory.c_str(), O_TMPFILE|O_WRONLY, 0666);
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}
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#endif /* HAVE_O_TMPFILE */
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inline void
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FileOutputStream::OpenCreate(bool visible)
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{
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#ifdef HAVE_O_TMPFILE
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/* try Linux's O_TMPFILE first */
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is_tmpfile = !visible && OpenTempFile(directory_fd, fd, GetPath());
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if (!is_tmpfile) {
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#endif
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/* fall back to plain POSIX */
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if (!fd.Open(
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#ifdef __linux__
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directory_fd,
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#endif
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GetPath().c_str(),
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O_WRONLY|O_CREAT|O_TRUNC,
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0666))
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throw FormatErrno("Failed to create %s",
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GetPath().c_str());
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#ifdef HAVE_O_TMPFILE
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}
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#else
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(void)visible;
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#endif
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}
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inline void
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FileOutputStream::OpenAppend(bool create)
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{
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int flags = O_WRONLY|O_APPEND;
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if (create)
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flags |= O_CREAT;
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if (!fd.Open(
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#ifdef __linux__
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directory_fd,
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#endif
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path.c_str(), flags))
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throw FormatErrno("Failed to append to %s",
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path.c_str());
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}
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uint64_t
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FileOutputStream::Tell() const noexcept
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{
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return fd.Tell();
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}
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void
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FileOutputStream::Write(const void *data, size_t size)
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{
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assert(IsDefined());
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ssize_t nbytes = fd.Write(data, size);
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if (nbytes < 0)
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throw FormatErrno("Failed to write to %s", GetPath().c_str());
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else if ((size_t)nbytes < size)
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throw FormatErrno(ENOSPC, "Failed to write to %s",
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GetPath().c_str());
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}
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void
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FileOutputStream::Commit()
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{
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assert(IsDefined());
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#ifdef HAVE_O_TMPFILE
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if (is_tmpfile) {
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unlinkat(directory_fd.Get(), GetPath().c_str(), 0);
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/* hard-link the temporary file to the final path */
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if (linkat(AT_FDCWD,
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StringFormat<64>("/proc/self/fd/%d", fd.Get()),
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directory_fd.Get(), path.c_str(),
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AT_SYMLINK_FOLLOW) < 0)
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throw FormatErrno("Failed to commit %s",
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path.c_str());
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}
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#endif
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if (!Close()) {
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throw FormatErrno("Failed to commit %s", path.c_str());
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}
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}
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void
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FileOutputStream::Cancel() noexcept
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{
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assert(IsDefined());
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Close();
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switch (mode) {
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case Mode::CREATE:
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#ifdef HAVE_O_TMPFILE
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if (!is_tmpfile)
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#endif
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#ifdef __linux__
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unlinkat(directory_fd.Get(), GetPath().c_str(), 0);
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#else
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unlink(GetPath().c_str());
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#endif
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break;
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case Mode::CREATE_VISIBLE:
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case Mode::APPEND_EXISTING:
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case Mode::APPEND_OR_CREATE:
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/* can't roll this back */
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break;
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}
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}
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#endif
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