enhancement: Optionally keep a backup of existing file, when download…

…ing updates (#1155)

src/main.cpp

@@ -1089,7 +1089,7 @@ static void parse_cmdline_and_init_file(int argc, TCHAR **argv)
 * of start_program () and leave_program () if you need to do anything special.
 * Add #ifdefs around these as appropriate.
 */
-static void do_start_program (void)
+static void do_start_program ()
 {
 	if (quit_program == -UAE_QUIT)
 		return;
@@ -1111,12 +1111,12 @@ static void do_start_program (void)
 	}
 }
 
-static void start_program (void)
+static void start_program ()
 {
 	do_start_program ();
 }
 
-static void leave_program (void)
+static void leave_program ()
 {
 	do_leave_program ();
 }
@@ -1128,7 +1128,7 @@ long get_file_size(const std::string& filename)
 	return rc == 0 ? static_cast<long>(stat_buf.st_size) : -1;
 }
 
-bool file_exists(std::string file)
+bool file_exists(const std::string& file)
 {
 	#ifdef USE_OLDGCC
 	namespace fs = std::experimental::filesystem;
@@ -1139,7 +1139,7 @@ bool file_exists(std::string file)
 	return (fs::exists(f));
 }
 
-bool download_file(const std::string& source, const std::string& destination)
+bool download_file(const std::string& source, const std::string& destination, bool keep_backup)
 {
 	// homebrew installs in different locations on OSX Intel vs OSX Apple Silicon
 #if defined (__MACH__) && defined (__arm64__)	
@@ -1204,7 +1204,18 @@ bool download_file(const std::string& source, const std::string& destination)
 
 	if (file_exists(tmp))
 	{
-		write_log("Tmp file will now be renamed: %s\n", tmp.c_str());
+		if (file_exists(destination) && keep_backup)
+		{
+			write_log("Backup requested, renaming destination file %s to .bak\n", destination.c_str());
+			std::string new_filename = destination.substr(0, destination.find_last_of('.')).append(".bak");
+			if (std::rename(destination.c_str(), new_filename.c_str()) < 0)
+			{
+				write_log(strerror(errno));
+				write_log("\n");
+			}
+		}
+
+		write_log("Renaming downloaded temporary file %s to final destination\n", tmp.c_str());
 		if (std::rename(tmp.c_str(), destination.c_str()) < 0)
 		{
 			write_log(strerror(errno));
@@ -1216,15 +1227,15 @@ bool download_file(const std::string& source, const std::string& destination)
 	return false;
 }
 
-void download_rtb(const std::string filename)
+void download_rtb(const std::string& filename)
 {
 	std::string destination_filename = "save-data/Kickstarts/" + filename;
 	const std::string destination = prefix_with_whdboot_path(destination_filename);
 	if (!file_exists(destination))
 	{
 		write_log("Downloading %s ...\n", destination.c_str());
 		const std::string url = "https://github.com/midwan/amiberry/blob/master/whdboot/save-data/Kickstarts/" + filename + "?raw=true";
-		download_file(url,  destination);
+		download_file(url,  destination, false);
 	}
 }
 

src/osdep/gui/PanelPaths.cpp

@@ -214,12 +214,12 @@ class DownloadXMLButtonActionListener : public gcn::ActionListener
 		//  download WHDLoad executable
 		destination = prefix_with_whdboot_path("WHDLoad");
 		write_log("Downloading %s ...\n", destination.c_str());
-		download_file("https://github.com/midwan/amiberry/blob/master/whdboot/WHDLoad?raw=true", destination);
+		download_file("https://github.com/midwan/amiberry/blob/master/whdboot/WHDLoad?raw=true", destination, false);
 
 		//  download boot-data.zip
 		destination = prefix_with_whdboot_path("boot-data.zip");
 		write_log("Downloading %s ...\n", destination.c_str());
-		download_file("https://github.com/midwan/amiberry/blob/master/whdboot/boot-data.zip?raw=true", destination);
+		download_file("https://github.com/midwan/amiberry/blob/master/whdboot/boot-data.zip?raw=true", destination, false);
 
 		// download kickstart RTB files for maximum compatibility
 		download_rtb("kick33180.A500.RTB");
@@ -231,7 +231,7 @@ class DownloadXMLButtonActionListener : public gcn::ActionListener
 		destination = prefix_with_whdboot_path("game-data/whdload_db.xml");
 		const auto old_timestamp = get_xml_timestamp(destination);
 		write_log("Downloading %s ...\n", destination.c_str());
-		const auto result = download_file("https://github.com/HoraceAndTheSpider/Amiberry-XML-Builder/blob/master/whdload_db.xml?raw=true", destination);
+		const auto result = download_file("https://github.com/HoraceAndTheSpider/Amiberry-XML-Builder/blob/master/whdload_db.xml?raw=true", destination, true);
 
 		if (result)
 		{
@@ -258,7 +258,7 @@ class DownloadControllerDbActionListener : public gcn::ActionListener
 		destination += "gamecontrollerdb.txt";
 		write_log("Downloading % ...\n", destination.c_str());
 		const auto* const url = "https://raw.githubusercontent.com/gabomdq/SDL_GameControllerDB/master/gamecontrollerdb.txt";
-		const auto result = download_file(url, destination);
+		const auto result = download_file(url, destination, true);
 
 		if (result)
 		{

src/osdep/gui/gui_handling.h

@@ -369,8 +369,8 @@ extern void init_dispmanx_gui();
 extern void update_gui_screen();
 extern void cap_fps(Uint64 start);
 extern long get_file_size(const std::string& filename);
-extern bool download_file(const std::string& source, const std::string& destination);
-extern void download_rtb(std::string filename);
+extern bool download_file(const std::string& source, const std::string& destination, bool keep_backup);
+extern void download_rtb(const std::string& filename);
 
 extern int fromdfxtype(int num, int dfx, int subtype);
 extern int todfxtype(int num, int dfx, int* subtype);