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/*
* Copyright (C) 2014-2018 Max Kellermann <max.kellermann@gmail.com>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* - Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the
* distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* FOUNDATION OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
* OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef FILE_OUTPUT_STREAM_HXX
#define FILE_OUTPUT_STREAM_HXX
#include "OutputStream.hxx"
#include "fs/AllocatedPath.hxx"
#include "util/Compiler.h"
#ifndef _WIN32
#include "system/FileDescriptor.hxx"
#endif
#include <cassert>
#include <stdint.h>
#ifdef _WIN32
#include <windows.h>
#endif
#if defined(__linux__) && !defined(ANDROID)
/* we don't use O_TMPFILE on Android because Android's braindead
SELinux policy disallows hardlinks
(https://android.googlesource.com/platform/external/sepolicy/+/85ce2c7),
even hardlinks from /proc/self/fd/N, which however is required to
use O_TMPFILE */
#define HAVE_O_TMPFILE
#endif
class Path;
class FileOutputStream final : public OutputStream {
const AllocatedPath path;
#ifdef __linux__
const FileDescriptor directory_fd;
#endif
#ifdef _WIN32
HANDLE handle = INVALID_HANDLE_VALUE;
#else
FileDescriptor fd = FileDescriptor::Undefined();
#endif
#ifdef HAVE_O_TMPFILE
/**
* Was O_TMPFILE used? If yes, then linkat() must be used to
* create a link to this file.
*/
bool is_tmpfile = false;
#endif
public:
enum class Mode : uint8_t {
/**
* Create a new file, or replace an existing file.
* File contents may not be visible until Commit() has
* been called.
*/
CREATE,
/**
* Like #CREATE, but no attempt is made to hide file
* contents during the transaction (e.g. via O_TMPFILE
* or a hidden temporary file).
*/
CREATE_VISIBLE,
/**
* Append to a file that already exists. If it does
* not, an exception is thrown.
*/
APPEND_EXISTING,
/**
* Like #APPEND_EXISTING, but create the file if it
* does not exist.
*/
APPEND_OR_CREATE,
};
private:
Mode mode;
public:
explicit FileOutputStream(Path _path, Mode _mode=Mode::CREATE);
#ifdef __linux__
FileOutputStream(FileDescriptor _directory_fd, Path _path,
Mode _mode=Mode::CREATE);
#endif
~FileOutputStream() noexcept {
if (IsDefined())
Cancel();
}
FileOutputStream(const FileOutputStream &) = delete;
FileOutputStream &operator=(const FileOutputStream &) = delete;
public:
Path GetPath() const noexcept {
return path;
}
gcc_pure
uint64_t Tell() const noexcept;
/* virtual methods from class OutputStream */
void Write(const void *data, size_t size) override;
void Commit();
void Cancel() noexcept;
private:
void OpenCreate(bool visible);
void OpenAppend(bool create);
void Open();
bool Close() noexcept {
assert(IsDefined());
#ifdef _WIN32
CloseHandle(handle);
handle = INVALID_HANDLE_VALUE;
return true;
#else
return fd.Close();
#endif
}
#ifdef _WIN32
bool SeekEOF() noexcept {
return SetFilePointer(handle, 0, nullptr,
FILE_END) != 0xffffffff;
}
#endif
bool IsDefined() const noexcept {
#ifdef _WIN32
return handle != INVALID_HANDLE_VALUE;
#else
return fd.IsDefined();
#endif
}
};
#endif
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