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/*
* Copyright 2003-2017 The Music Player Daemon Project
* http://www.musicpd.org
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include "config.h"
#include "FileOutputStream.hxx"
#include "system/Error.hxx"
FileOutputStream::FileOutputStream(Path _path, Mode _mode)
:path(_path), mode(_mode)
{
switch (mode) {
case Mode::CREATE:
OpenCreate(false);
break;
case Mode::CREATE_VISIBLE:
OpenCreate(true);
break;
case Mode::APPEND_EXISTING:
OpenAppend(false);
break;
case Mode::APPEND_OR_CREATE:
OpenAppend(true);
break;
}
}
#ifdef _WIN32
inline void
FileOutputStream::OpenCreate(gcc_unused bool visible)
{
handle = CreateFile(path.c_str(), GENERIC_WRITE, 0, nullptr,
CREATE_ALWAYS,
FILE_ATTRIBUTE_NORMAL|FILE_FLAG_WRITE_THROUGH,
nullptr);
if (!IsDefined())
throw FormatLastError("Failed to create %s",
path.ToUTF8().c_str());
}
inline void
FileOutputStream::OpenAppend(bool create)
{
handle = CreateFile(path.c_str(), GENERIC_WRITE, 0, nullptr,
create ? OPEN_ALWAYS : OPEN_EXISTING,
FILE_ATTRIBUTE_NORMAL|FILE_FLAG_WRITE_THROUGH,
nullptr);
if (!IsDefined())
throw FormatLastError("Failed to append to %s",
path.ToUTF8().c_str());
if (!SeekEOF()) {
auto code = GetLastError();
Close();
throw FormatLastError(code, "Failed seek end-of-file of %s",
path.ToUTF8().c_str());
}
}
uint64_t
FileOutputStream::Tell() const noexcept
{
LONG high = 0;
DWORD low = SetFilePointer(handle, 0, &high, FILE_CURRENT);
if (low == 0xffffffff)
return 0;
return uint64_t(high) << 32 | uint64_t(low);
}
void
FileOutputStream::Write(const void *data, size_t size)
{
assert(IsDefined());
DWORD nbytes;
if (!WriteFile(handle, data, size, &nbytes, nullptr))
throw FormatLastError("Failed to write to %s",
GetPath().c_str());
if (size_t(nbytes) != size)
throw FormatLastError(ERROR_DISK_FULL, "Failed to write to %s",
GetPath().c_str());
}
void
FileOutputStream::Commit()
{
assert(IsDefined());
Close();
}
void
FileOutputStream::Cancel()
{
assert(IsDefined());
Close();
DeleteFile(GetPath().c_str());
}
#else
#include <fcntl.h>
#include <unistd.h>
#include <errno.h>
#ifdef HAVE_LINKAT
#ifndef O_TMPFILE
/* supported since Linux 3.11 */
#define __O_TMPFILE 020000000
#define O_TMPFILE (__O_TMPFILE | O_DIRECTORY)
#include <stdio.h>
#endif
/**
* Open a file using Linux's O_TMPFILE for writing the given file.
*/
static bool
OpenTempFile(FileDescriptor &fd, Path path)
{
const auto directory = path.GetDirectoryName();
if (directory.IsNull())
return false;
return fd.Open(directory.c_str(), O_TMPFILE|O_WRONLY, 0666);
}
#endif /* HAVE_LINKAT */
inline void
FileOutputStream::OpenCreate(bool visible)
{
#ifdef HAVE_LINKAT
/* try Linux's O_TMPFILE first */
is_tmpfile = !visible && OpenTempFile(fd, GetPath());
if (!is_tmpfile) {
#endif
/* fall back to plain POSIX */
if (!fd.Open(GetPath().c_str(),
O_WRONLY|O_CREAT|O_TRUNC,
0666))
throw FormatErrno("Failed to create %s",
GetPath().c_str());
#ifdef HAVE_LINKAT
}
#else
(void)visible;
#endif
}
inline void
FileOutputStream::OpenAppend(bool create)
{
int flags = O_WRONLY|O_APPEND;
if (create)
flags |= O_CREAT;
if (!fd.Open(path.c_str(), flags))
throw FormatErrno("Failed to append to %s",
path.c_str());
}
uint64_t
FileOutputStream::Tell() const noexcept
{
return fd.Tell();
}
void
FileOutputStream::Write(const void *data, size_t size)
{
assert(IsDefined());
ssize_t nbytes = fd.Write(data, size);
if (nbytes < 0)
throw FormatErrno("Failed to write to %s", GetPath().c_str());
else if ((size_t)nbytes < size)
throw FormatErrno(ENOSPC, "Failed to write to %s",
GetPath().c_str());
}
void
FileOutputStream::Commit()
{
assert(IsDefined());
#ifdef HAVE_LINKAT
if (is_tmpfile) {
unlink(GetPath().c_str());
/* hard-link the temporary file to the final path */
char fd_path[64];
snprintf(fd_path, sizeof(fd_path), "/proc/self/fd/%d",
fd.Get());
if (linkat(AT_FDCWD, fd_path, AT_FDCWD, path.c_str(),
AT_SYMLINK_FOLLOW) < 0)
throw FormatErrno("Failed to commit %s",
path.c_str());
}
#endif
if (!Close()) {
#ifdef _WIN32
throw FormatLastError("Failed to commit %s",
path.ToUTF8().c_str());
#else
throw FormatErrno("Failed to commit %s", path.c_str());
#endif
}
}
void
FileOutputStream::Cancel()
{
assert(IsDefined());
Close();
switch (mode) {
case Mode::CREATE:
#ifdef HAVE_LINKAT
if (!is_tmpfile)
#endif
unlink(GetPath().c_str());
break;
case Mode::CREATE_VISIBLE:
case Mode::APPEND_EXISTING:
case Mode::APPEND_OR_CREATE:
/* can't roll this back */
break;
}
}
#endif
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