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Saveload: Save to temporary file name and rename to target on success

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This commit is contained in:
Jonathan G Rennison
2024-03-21 17:27:27 +00:00
parent 5e87d95013
commit 16577279a1
1 changed files with 58 additions and 8 deletions
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64
src/sl/saveload.cpp
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@@ -49,6 +49,8 @@
#include "../timer/timer_game_tick.h"
#include <atomic>
#include <string>
#include <sys/stat.h>
#include <sys/types.h>
#ifdef __EMSCRIPTEN__
# include <emscripten.h>
#endif
@@ -2809,19 +2811,24 @@ struct FileReader : LoadFilter {
/** Yes, simply writing to a file. */
struct FileWriter : SaveFilter {
FILE *file; ///< The file to write to.
std::string temp_name;
std::string target_name;
/**
* Create the file writer, so it writes to a specific file.
* @param file The file to write to.
* @param temp_name The temporary name of the file being written to.
* @param target_name The target name of the file to rename to, on success.
*/
FileWriter(FILE *file) : SaveFilter(nullptr), file(file)
FileWriter(FILE *file, std::string temp_name, std::string target_name) : SaveFilter(nullptr), file(file), temp_name(std::move(temp_name)), target_name(std::move(target_name))
{
}
/** Make sure everything is cleaned up. */
~FileWriter()
{
this->Finish();
this->CloseFile();
if (!this->temp_name.empty()) unlink(this->temp_name.c_str());
}
void Write(byte *buf, size_t size) override
@@ -2833,6 +2840,39 @@ struct FileWriter : SaveFilter {
}
void Finish() override
{
this->CloseFile();
size_t save_size = 0;
if (_game_session_stats.savegame_size.has_value()) save_size = _game_session_stats.savegame_size.value();
if (save_size <= 8) SlError(STR_GAME_SAVELOAD_ERROR_FILE_NOT_WRITEABLE, "Insufficient bytes written");
#if defined(_WIN32)
struct _stat st;
int stat_result = _wstat(OTTD2FS(this->temp_name).c_str(), &st);
#else
struct stat st;
int stat_result = stat(this->temp_name.c_str(), &st);
#endif
if (stat_result != 0) {
SlError(STR_GAME_SAVELOAD_ERROR_FILE_NOT_WRITEABLE, "Failed to stat temporary save file");
}
if ((size_t)st.st_size != save_size) {
SlError(STR_GAME_SAVELOAD_ERROR_FILE_NOT_WRITEABLE, stdstr_fmt("Temporary save file does not have expected file size: " PRINTF_SIZE " != " PRINTF_SIZE, (size_t)st.st_size, save_size));
}
#if defined(_WIN32)
/* Renaming over an existing file is not supported on Windows, manually unlink the target filename first */
unlink(this->target_name.c_str());
#endif
if (!FioRenameFile(this->temp_name, this->target_name)) SlError(STR_GAME_SAVELOAD_ERROR_FILE_NOT_WRITEABLE, "Failed to rename temporary save file to target name");
this->temp_name.clear(); // Now no need to unlink temporary name
}
private:
void CloseFile()
{
if (this->file != nullptr) {
_game_session_stats.savegame_size = ftell(this->file);
@@ -4063,22 +4103,32 @@ SaveOrLoadResult SaveOrLoad(const std::string &filename, SaveLoadOperation fop,
}
_sl.save_flags = save_flags;
FILE *fh = (fop == SLO_SAVE) ? FioFOpenFile(filename, "wb", sb) : FioFOpenFile(filename, "rb", sb);
FILE *fh = nullptr;
std::string temp_save_filename;
std::string temp_save_filename_suffix;
if (fop == SLO_SAVE) {
temp_save_filename_suffix = stdstr_fmt(".tmp-%08x", InteractiveRandom());
fh = FioFOpenFile(filename + temp_save_filename_suffix, "wb", sb, nullptr, &temp_save_filename);
} else {
fh = FioFOpenFile(filename, "rb", sb);
/* Make it a little easier to load savegames from the console */
if (fh == nullptr && fop != SLO_SAVE) fh = FioFOpenFile(filename, "rb", SAVE_DIR);
if (fh == nullptr && fop != SLO_SAVE) fh = FioFOpenFile(filename, "rb", BASE_DIR);
if (fh == nullptr && fop != SLO_SAVE) fh = FioFOpenFile(filename, "rb", SCENARIO_DIR);
if (fh == nullptr) fh = FioFOpenFile(filename, "rb", SAVE_DIR);
if (fh == nullptr) fh = FioFOpenFile(filename, "rb", BASE_DIR);
if (fh == nullptr) fh = FioFOpenFile(filename, "rb", SCENARIO_DIR);
}
if (fh == nullptr) {
SlError(fop == SLO_SAVE ? STR_GAME_SAVELOAD_ERROR_FILE_NOT_WRITEABLE : STR_GAME_SAVELOAD_ERROR_FILE_NOT_READABLE);
}
if (fop == SLO_SAVE) { // SAVE game
if (temp_save_filename.size() <= temp_save_filename_suffix.size()) SlError(STR_GAME_SAVELOAD_ERROR_FILE_NOT_WRITEABLE, "Failed to get temporary file name");
DEBUG(desync, 1, "save: %s; %s", debug_date_dumper().HexDate(), filename.c_str());
if (!_settings_client.gui.threaded_saves) threaded = false;
return DoSave(std::make_shared<FileWriter>(fh), threaded);
return DoSave(std::make_shared<FileWriter>(fh, temp_save_filename, temp_save_filename.substr(0, temp_save_filename.size() - temp_save_filename_suffix.size())), threaded);
}
/* LOAD game */