Changed a few zippath related functions to return their strings as a return value, as opposed to passing in a destination buffer

src/emu/diimage.cpp

@@ -156,7 +156,7 @@ void device_image_interface::device_compute_hash(hash_collection &hashes, const
 image_error_t device_image_interface::set_image_filename(const char *filename)
 {
 	m_image_name = filename;
-	util::zippath_parent(m_working_directory, filename);
+	m_working_directory = util::zippath_parent(filename);
 	m_basename.assign(m_image_name);
 
 	int loc1 = m_image_name.find_last_of('\\');
@@ -316,7 +316,7 @@ bool device_image_interface::try_change_working_directory(const char *subdir)
 
 	/* did we successfully identify the directory? */
 	if (success)
-		util::zippath_combine(m_working_directory, m_working_directory.c_str(), subdir);
+		m_working_directory = util::zippath_combine(m_working_directory.c_str(), subdir);
 
 	return success;
 }

src/frontend/mame/ui/filesel.cpp

@@ -228,7 +228,7 @@ menu_file_selector::file_selector_entry *menu_file_selector::append_dirent_entry
 	}
 
 	// determine the full path
-	util::zippath_combine(buffer, m_current_directory.c_str(), dirent->name);
+	buffer = util::zippath_combine(m_current_directory.c_str(), dirent->name);
 
 	// create the file selector entry
 	entry = &append_entry(

src/frontend/mame/ui/floppycntrl.cpp

@@ -131,7 +131,7 @@ void menu_control_floppy_image::handle()
 			state = START_FILE;
 			handle();
 		} else {
-			util::zippath_combine(output_filename, current_directory.c_str(), current_file.c_str());
+			output_filename = util::zippath_combine(current_directory.c_str(), current_file.c_str());
 			output_format = format_array[submenu_result];
 			do_load_create();
 			menu::stack_pop(machine());

src/frontend/mame/ui/imgcntrl.cpp

@@ -61,7 +61,7 @@ menu_control_device_image::menu_control_device_image(mame_ui_manager &mui, rende
 		if (image->exists())
 		{
 			current_file.assign(image->filename());
-			util::zippath_parent(current_directory, current_file.c_str());
+			current_directory = util::zippath_parent(current_file.c_str());
 		} else
 			current_directory.assign(image->working_directory());
 
@@ -87,11 +87,10 @@ menu_control_device_image::~menu_control_device_image()
 
 void menu_control_device_image::test_create(bool &can_create, bool &need_confirm)
 {
-	std::string path;
 	osd::directory::entry::entry_type file_type;
 
 	/* assemble the full path */
-	util::zippath_combine(path, current_directory.c_str(), current_file.c_str());
+	auto path = util::zippath_combine(current_directory.c_str(), current_file.c_str());
 
 	/* does a file or a directory exist at the path */
 	auto entry = osd_stat(path.c_str());
@@ -323,8 +322,7 @@ void menu_control_device_image::handle()
 		break;
 
 	case DO_CREATE: {
-		std::string path;
+		auto path = util::zippath_combine(current_directory.c_str(), current_file.c_str());
-		util::zippath_combine(path, current_directory.c_str(), current_file.c_str());
 		int err = image->create(path.c_str(), nullptr, nullptr);
 		if (err != 0)
 			machine().popmessage("Error: %s", image->error());

src/lib/util/zippath.cpp

@@ -140,11 +140,12 @@ static void parse_parent_path(const char *path, int *beginpos, int *endpos)
 //	zippath_parent - retrieves the parent directory
 // -------------------------------------------------
 
-std::string &zippath_parent(std::string &dst, const char *path)
+std::string zippath_parent(const char *path)
 {
 	int pos;
 	parse_parent_path(path, &pos, nullptr);
 
+	std::string dst;
 	if (pos >= 0)
 		dst.assign(path, pos + 1);
 	else
@@ -170,8 +171,9 @@ std::string &zippath_parent(std::string &dst, const char *path)
  * @return  A std::string&
  */
 
-std::string &zippath_parent_basename(std::string &dst, const char *path)
+std::string zippath_parent_basename(const char *path)
 {
+	std::string dst;
 	int beginpos, endpos;
 	parse_parent_path(path, &beginpos, &endpos);
 	dst.copy((char*)(path + beginpos + 1), endpos - beginpos);
@@ -196,15 +198,16 @@ std::string &zippath_parent_basename(std::string &dst, const char *path)
  * @return  A std::string&
  */
 
-std::string &zippath_combine(std::string &dst, const char *path1, const char *path2)
+std::string zippath_combine(const char *path1, const char *path2)
 {
+	std::string dst;
 	if (!strcmp(path2, "."))
 	{
 		dst.assign(path1);
 	}
 	else if (!strcmp(path2, ".."))
 	{
-		zippath_parent(dst, path1);
+		dst = zippath_parent(path1);
 	}
 	else if (osd_is_absolute_path(path2))
 	{
@@ -401,8 +404,7 @@ osd_file::error zippath_fopen(const char *filename, UINT32 openflags, util::core
 		if (filerr != osd_file::error::NONE)
 		{
 			/* go up a directory */
-			std::string temp;
+			auto temp = zippath_parent(mainpath.c_str());
-			zippath_parent(temp, mainpath.c_str());
 
 			/* append to the sub path */
 			if (subpath.length() > 0)
@@ -714,8 +716,7 @@ static osd_file::error zippath_resolve(const char *path, osd::directory::entry::
 			// if we have not found the file or directory, go up
 			current_entry_type = osd::directory::entry::entry_type::NONE;
 			went_up = true;
-			std::string parent;
+			apath = zippath_parent(apath.c_str());
-			apath = zippath_parent(parent, apath.c_str());
 		}
 	}
 	while ((current_entry_type == osd::directory::entry::entry_type::NONE) && !is_root(apath.c_str()));

src/lib/util/zippath.h

@@ -34,13 +34,13 @@ class zippath_directory;
 // ----- path operations -----
 
 // retrieves the parent directory
-std::string &zippath_parent(std::string &dst, const char *path);
+std::string zippath_parent(const char *path);
 
 // retrieves the parent directory basename
-std::string &zippath_parent_basename(std::string &dst, const char *path);
+std::string zippath_parent_basename(const char *path);
 
 // combines two paths
-std::string &zippath_combine(std::string &dst, const char *path1, const char *path2);
+std::string zippath_combine(const char *path1, const char *path2);
 
 
 // ----- file operations -----