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fs/io/FileOutputStream: merge all classes into one, add enum Mode

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Prepare to add more modes.
This commit is contained in:
Max Kellermann 2016-09-04 12:07:36 +02:00
parent b630afdeda
commit d775f13a03
3 changed files with 122 additions and 140 deletions
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3
src/PlaylistFile.cxx
View File

@ -199,7 +199,6 @@ SavePlaylistFile(const PlaylistFileContents &contents, const char *utf8path)
assert(!path_fs.IsNull());
FileOutputStream fos(path_fs);
BufferedOutputStream bos(fos);
for (const auto &uri_utf8 : contents)
@ -354,7 +353,7 @@ try {
const auto path_fs = spl_map_to_fs(utf8path);
assert(!path_fs.IsNull());
AppendFileOutputStream fos(path_fs);
FileOutputStream fos(path_fs, FileOutputStream::Mode::APPEND_EXISTING);
if (fos.Tell() / (MPD_PATH_MAX + 1) >= playlist_max_length)
throw PlaylistError(PlaylistResult::TOO_LARGE,

139
src/fs/io/FileOutputStream.cxx
View File

@ -21,22 +21,56 @@
#include "FileOutputStream.hxx"
#include "system/Error.hxx"
FileOutputStream::FileOutputStream(Path _path, Mode _mode)
:path(_path), mode(_mode)
{
switch (mode) {
case Mode::CREATE:
OpenCreate();
break;
case Mode::APPEND_EXISTING:
OpenAppendExisting();
break;
}
}
#ifdef WIN32
FileOutputStream::FileOutputStream(Path _path)
:BaseFileOutputStream(_path)
inline void
FileOutputStream::OpenCreate()
{
SetHandle(CreateFile(_path.c_str(), GENERIC_WRITE, 0, nullptr,
CREATE_ALWAYS,
FILE_ATTRIBUTE_NORMAL|FILE_FLAG_WRITE_THROUGH,
nullptr));
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",
GetPath().ToUTF8().c_str());
path.ToUTF8().c_str());
}
inline void
FileOutputStream::OpenAppendExisting()
{
handle = CreateFile(path.c_str(), GENERIC_WRITE, 0, nullptr,
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
BaseFileOutputStream::Tell() const
FileOutputStream::Tell() const
{
LONG high = 0;
DWORD low = SetFilePointer(handle, 0, &high, FILE_CURRENT);
@ -47,7 +81,7 @@ BaseFileOutputStream::Tell() const
}
void
BaseFileOutputStream::Write(const void *data, size_t size)
FileOutputStream::Write(const void *data, size_t size)
{
assert(IsDefined());
@ -108,18 +142,18 @@ OpenTempFile(FileDescriptor &fd, Path path)
#endif /* HAVE_LINKAT */
FileOutputStream::FileOutputStream(Path _path)
:BaseFileOutputStream(_path)
inline void
FileOutputStream::OpenCreate()
{
#ifdef HAVE_LINKAT
/* try Linux's O_TMPFILE first */
is_tmpfile = OpenTempFile(SetFD(), GetPath());
is_tmpfile = OpenTempFile(fd, GetPath());
if (!is_tmpfile) {
#endif
/* fall back to plain POSIX */
if (!SetFD().Open(GetPath().c_str(),
O_WRONLY|O_CREAT|O_TRUNC,
0666))
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
@ -127,14 +161,22 @@ FileOutputStream::FileOutputStream(Path _path)
#endif
}
inline void
FileOutputStream::OpenAppendExisting()
{
if (!fd.Open(path.c_str(), O_WRONLY|O_APPEND))
throw FormatErrno("Failed to append to %s",
path.c_str());
}
uint64_t
BaseFileOutputStream::Tell() const
FileOutputStream::Tell() const
{
return fd.Tell();
}
void
BaseFileOutputStream::Write(const void *data, size_t size)
FileOutputStream::Write(const void *data, size_t size)
{
assert(IsDefined());
@ -158,20 +200,20 @@ FileOutputStream::Commit()
/* hard-link the temporary file to the final path */
char fd_path[64];
snprintf(fd_path, sizeof(fd_path), "/proc/self/fd/%d",
GetFD().Get());
if (linkat(AT_FDCWD, fd_path, AT_FDCWD, GetPath().c_str(),
fd.Get());
if (linkat(AT_FDCWD, fd_path, AT_FDCWD, path.c_str(),
AT_SYMLINK_FOLLOW) < 0)
throw FormatErrno("Failed to commit %s",
GetPath().c_str());
path.c_str());
}
#endif
if (!Close()) {
#ifdef WIN32
throw FormatLastError("Failed to commit %s",
GetPath().ToUTF8().c_str());
path.ToUTF8().c_str());
#else
throw FormatErrno("Failed to commit %s", GetPath().c_str());
throw FormatErrno("Failed to commit %s", path.c_str());
#endif
}
}
@ -183,51 +225,18 @@ FileOutputStream::Cancel()
Close();
switch (mode) {
case Mode::CREATE:
#ifdef HAVE_LINKAT
if (!is_tmpfile)
if (!is_tmpfile)
#endif
unlink(GetPath().c_str());
}
unlink(GetPath().c_str());
break;
#endif
AppendFileOutputStream::AppendFileOutputStream(Path _path)
:BaseFileOutputStream(_path)
{
#ifdef WIN32
SetHandle(CreateFile(GetPath().c_str(), GENERIC_WRITE, 0, nullptr,
OPEN_EXISTING,
FILE_ATTRIBUTE_NORMAL|FILE_FLAG_WRITE_THROUGH,
nullptr));
if (!IsDefined())
throw FormatLastError("Failed to append to %s",
GetPath().ToUTF8().c_str());
if (!SeekEOF()) {
auto code = GetLastError();
Close();
throw FormatLastError(code, "Failed seek end-of-file of %s",
GetPath().ToUTF8().c_str());
}
#else
if (!SetFD().Open(GetPath().c_str(),
O_WRONLY|O_APPEND))
throw FormatErrno("Failed to append to %s",
GetPath().c_str());
#endif
}
void
AppendFileOutputStream::Commit()
{
assert(IsDefined());
if (!Close()) {
#ifdef WIN32
throw FormatLastError("Failed to commit %s",
GetPath().ToUTF8().c_str());
#else
throw FormatErrno("Failed to commit %s", GetPath().c_str());
#endif
case Mode::APPEND_EXISTING:
/* can't roll this back */
break;
}
}
#endif

120
src/fs/io/FileOutputStream.hxx
View File

@ -38,7 +38,7 @@
class Path;
class BaseFileOutputStream : public OutputStream {
class FileOutputStream final : public OutputStream {
const AllocatedPath path;
#ifdef WIN32
@ -47,40 +47,58 @@ class BaseFileOutputStream : public OutputStream {
FileDescriptor fd = FileDescriptor::Undefined();
#endif
protected:
#ifdef WIN32
template<typename P>
BaseFileOutputStream(P &&_path)
:path(std::forward<P>(_path)) {}
#else
template<typename P>
BaseFileOutputStream(P &&_path)
:path(std::forward<P>(_path)) {}
#ifdef HAVE_LINKAT
/**
* Was O_TMPFILE used? If yes, then linkat() must be used to
* create a link to this file.
*/
bool is_tmpfile = false;
#endif
~BaseFileOutputStream() {
assert(!IsDefined());
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,
/**
* Append to a file that already exists. If it does
* not, an exception is thrown.
*/
APPEND_EXISTING,
};
private:
Mode mode;
public:
FileOutputStream(Path _path, Mode _mode=Mode::CREATE);
~FileOutputStream() {
if (IsDefined())
Cancel();
}
#ifdef WIN32
void SetHandle(HANDLE _handle) {
assert(!IsDefined());
handle = _handle;
assert(IsDefined());
}
#else
FileDescriptor &SetFD() {
assert(!IsDefined());
return fd;
public:
Path GetPath() const {
return path;
}
const FileDescriptor &GetFD() const {
return fd;
}
#endif
gcc_pure
uint64_t Tell() const;
/* virtual methods from class OutputStream */
void Write(const void *data, size_t size) override;
void Commit();
void Cancel();
private:
void OpenCreate();
void OpenAppendExisting();
bool Close() {
assert(IsDefined());
@ -108,50 +126,6 @@ protected:
return fd.IsDefined();
#endif
}
public:
Path GetPath() const {
return path;
}
gcc_pure
uint64_t Tell() const;
/* virtual methods from class OutputStream */
void Write(const void *data, size_t size) override;
};
class FileOutputStream final : public BaseFileOutputStream {
#ifdef HAVE_LINKAT
/**
* Was O_TMPFILE used? If yes, then linkat() must be used to
* create a link to this file.
*/
bool is_tmpfile;
#endif
public:
FileOutputStream(Path _path);
~FileOutputStream() {
if (IsDefined())
Cancel();
}
void Commit();
void Cancel();
};
class AppendFileOutputStream final : public BaseFileOutputStream {
public:
AppendFileOutputStream(Path _path);
~AppendFileOutputStream() {
if (IsDefined())
Close();
}
void Commit();
};
#endif