Escape backslashes when passing cwd to Python on Windows

Author: Dominic Price

frontend/gtkmm/NotebookWindow.cc

@@ -648,9 +648,9 @@ void NotebookWindow::on_connect()
 	// prefs.python_path might end in a backslash which will raise an EOF syntax error, so we add a
 	// semicolon to the end of it and then remove the (empty) last element of the resulting list
 	if (!trim(prefs.python_path).empty())
-		console.send_input("sys.path = r'''" + prefs.python_path + ";'''.split(';')[:-1] + sys.path");
+		console.send_input("sys.path = r'''" + escape_backslashes(prefs.python_path) + ";'''.split(';')[:-1] + sys.path");
 	if (!name.empty()) {
-		console.send_input("sys.path.insert(0, '''" + name.substr(0, name.find_last_of("\\/")) + "''')");
+		console.send_input("sys.path.insert(0, '''" + escape_backslashes(name.substr(0, name.find_last_of("\\/"))) + "''')");
 		}
 	}
 
@@ -1564,7 +1564,7 @@ void NotebookWindow::on_file_save_as()
 			else {
 				modified=false;
 				update_title();
-				console.send_input("sys.path.insert(0, r'''" + name.substr(0, name.find_last_of("\\/")) + "''')");
+				console.send_input("sys.path.insert(0, r'''" + escape_backslashes(name.substr(0, name.find_last_of("\\/"))) + "''')");
 				}
 			break;
 			}

libs/internal/include/internal/string_tools.h

@@ -49,3 +49,13 @@ inline std::string nth_line(const std::string& s, size_t n)
 	}
 	return s.substr(pos, s.find('\n', pos) - pos);
 }
+
+inline std::string escape_backslashes(std::string s)
+{
+	size_t start = 0;
+	while ((start = s.find('\\', start)) != std::string::npos) {
+		s.replace(start, 1, "\\\\");
+		start += 2;
+	}
+	return s;
+}