scummvm/backends/fs/posix-drives/posix-drives-fs.cpp
Le Philousophe fdd11d0714 BACKENDS: FS: Implement atomic file write for stdio stream backend
This implementation creates a temporary file (suffixed with .tmp) and
renames it to the expected file name when the file is closed.
If the renaming fails, the destination file is removed and renaming is
tried again to handle cases where renaming over an existing file is not
supported by the underlying OS.
2024-10-15 22:45:50 +02:00

193 lines
5.2 KiB
C++

/* ScummVM - Graphic Adventure Engine
*
* ScummVM is the legal property of its developers, whose names
* are too numerous to list here. Please refer to the COPYRIGHT
* file distributed with this source distribution.
*
* 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 3 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, see <http://www.gnu.org/licenses/>.
*
*/
#if defined(POSIX) || defined(PSP2) || defined(__DS__)
#define FORBIDDEN_SYMBOL_ALLOW_ALL
#include "backends/fs/posix-drives/posix-drives-fs.h"
#include "backends/fs/posix/posix-iostream.h"
#include "common/algorithm.h"
#include "common/bufferedstream.h"
#include <dirent.h>
DrivePOSIXFilesystemNode::DrivePOSIXFilesystemNode(const Common::String &path, const Config &config) :
POSIXFilesystemNode(path),
_isPseudoRoot(false),
_config(config) {
if (isDrive(path)) {
_isDirectory = true;
_isValid = true;
// FIXME: Add a setting for deciding whether drive paths need to end with a slash
if (!_path.hasSuffix("/")) {
_path += "/";
}
return;
}
}
DrivePOSIXFilesystemNode::DrivePOSIXFilesystemNode(const Config &config) :
_isPseudoRoot(true),
_config(config) {
_isDirectory = true;
_isValid = false;
}
void DrivePOSIXFilesystemNode::configureStream(StdioStream *stream) {
if (!stream) {
return;
}
if (_config.bufferingMode != kBufferingModeStdio) {
// Disable stdio buffering
stream->setBufferSize(0);
} else if (_config.bufferSize) {
stream->setBufferSize(_config.bufferSize);
}
}
Common::SeekableReadStream *DrivePOSIXFilesystemNode::createReadStream() {
StdioStream *readStream = PosixIoStream::makeFromPath(getPath(), StdioStream::WriteMode_Read);
configureStream(readStream);
if (_config.bufferingMode == kBufferingModeScummVM) {
uint32 bufferSize = _config.bufferSize != 0 ? _config.bufferSize : 1024;
return Common::wrapBufferedSeekableReadStream(readStream, bufferSize, DisposeAfterUse::YES);
}
return readStream;
}
Common::SeekableWriteStream *DrivePOSIXFilesystemNode::createWriteStream(bool atomic) {
StdioStream *writeStream = PosixIoStream::makeFromPath(getPath(), atomic ?
StdioStream::WriteMode_WriteAtomic : StdioStream::WriteMode_Write);
configureStream(writeStream);
if (_config.bufferingMode == kBufferingModeScummVM) {
uint32 bufferSize = _config.bufferSize != 0 ? _config.bufferSize : 1024;
return Common::wrapBufferedWriteStream(writeStream, bufferSize);
}
return writeStream;
}
DrivePOSIXFilesystemNode *DrivePOSIXFilesystemNode::getChildWithKnownType(const Common::String &n, bool isDirectoryFlag) const {
assert(_isDirectory);
// Make sure the string contains no slashes
assert(!n.contains('/'));
Common::String newPath(_path);
if (_path.lastChar() != '/')
newPath += '/';
newPath += n;
DrivePOSIXFilesystemNode *child = reinterpret_cast<DrivePOSIXFilesystemNode *>(makeNode());
child->_path = newPath;
child->_isValid = true;
child->_isPseudoRoot = false;
child->_isDirectory = isDirectoryFlag;
child->_displayName = n;
return child;
}
AbstractFSNode *DrivePOSIXFilesystemNode::getChild(const Common::String &n) const {
DrivePOSIXFilesystemNode *child = getChildWithKnownType(n, false);
child->setFlags();
return child;
}
bool DrivePOSIXFilesystemNode::getChildren(AbstractFSList &list, AbstractFSNode::ListMode mode, bool hidden) const {
assert(_isDirectory);
if (_isPseudoRoot) {
return _config.getDrives(list, hidden);
} else {
DIR *dirp = opendir(_path.c_str());
struct dirent *dp;
if (!dirp)
return false;
while ((dp = readdir(dirp)) != nullptr) {
// Skip 'invisible' files if necessary
if (dp->d_name[0] == '.' && !hidden) {
continue;
}
// Skip '.' and '..' to avoid cycles
if ((dp->d_name[0] == '.' && dp->d_name[1] == 0) || (dp->d_name[0] == '.' && dp->d_name[1] == '.')) {
continue;
}
AbstractFSNode *child = nullptr;
#if !defined(SYSTEM_NOT_SUPPORTING_D_TYPE)
if (dp->d_type == DT_DIR || dp->d_type == DT_REG) {
child = getChildWithKnownType(dp->d_name, dp->d_type == DT_DIR);
} else
#endif
{
child = getChild(dp->d_name);
}
// Honor the chosen mode
if ((mode == Common::FSNode::kListFilesOnly && child->isDirectory()) ||
(mode == Common::FSNode::kListDirectoriesOnly && !child->isDirectory())) {
delete child;
continue;
}
list.push_back(child);
}
closedir(dirp);
return true;
}
}
AbstractFSNode *DrivePOSIXFilesystemNode::getParent() const {
if (_isPseudoRoot) {
return nullptr;
}
if (isDrive(_path)) {
return makeNode();
}
return POSIXFilesystemNode::getParent();
}
bool DrivePOSIXFilesystemNode::isDrive(const Common::String &path) const {
Common::String normalizedPath = Common::normalizePath(path, '/');
return _config.isDrive(normalizedPath);
}
#endif //#if defined(POSIX)