Codechange: use fmt::format to create dummy scripts

src/script/script_info_dummy.cpp

@@ -12,6 +12,7 @@
 
 #include "../string_func.h"
 #include "../strings_func.h"
+#include "../3rdparty/fmt/format.h"
 
 #include "../safeguards.h"
 
@@ -27,24 +28,21 @@
 /** Run the dummy info.nut. */
 void Script_CreateDummyInfo(HSQUIRRELVM vm, const char *type, const char *dir)
 {
-	char dummy_script[4096];
+	std::string dummy_script = fmt::format(
-	char *dp = dummy_script;
+			"class Dummy{0} extends {0}Info {{\n"
-	dp += seprintf(dp, lastof(dummy_script), "class Dummy%s extends %sInfo {\n", type, type);
+			"function GetAuthor()      {{ return \"OpenTTD Developers Team\"; }}\n"
-	dp += seprintf(dp, lastof(dummy_script), "function GetAuthor()      { return \"OpenTTD Developers Team\"; }\n");
+			"function GetName()        {{ return \"Dummy{0}\"; }}\n"
-	dp += seprintf(dp, lastof(dummy_script), "function GetName()        { return \"Dummy%s\"; }\n", type);
+			"function GetShortName()   {{ return \"DUMM\"; }}\n"
-	dp += seprintf(dp, lastof(dummy_script), "function GetShortName()   { return \"DUMM\"; }\n");
+			"function GetDescription() {{ return \"A Dummy {0} that is loaded when your {1}/ dir is empty\"; }}\n"
-	dp += seprintf(dp, lastof(dummy_script), "function GetDescription() { return \"A Dummy %s that is loaded when your %s/ dir is empty\"; }\n", type, dir);
+			"function GetVersion()     {{ return 1; }}\n"
-	dp += seprintf(dp, lastof(dummy_script), "function GetVersion()     { return 1; }\n");
+			"function GetDate()        {{ return \"2008-07-26\"; }}\n"
-	dp += seprintf(dp, lastof(dummy_script), "function GetDate()        { return \"2008-07-26\"; }\n");
+			"function CreateInstance() {{ return \"Dummy{0}\"; }}\n"
-	dp += seprintf(dp, lastof(dummy_script), "function CreateInstance() { return \"Dummy%s\"; }\n", type);
+			"}} RegisterDummy{0}(Dummy{0}());\n", type, dir);
-	dp += seprintf(dp, lastof(dummy_script), "} RegisterDummy%s(Dummy%s());\n", type, type);
-
-	const SQChar *sq_dummy_script = dummy_script;
 
 	sq_pushroottable(vm);
 
 	/* Load and run the script */
-	if (SQ_SUCCEEDED(sq_compilebuffer(vm, sq_dummy_script, strlen(sq_dummy_script), "dummy", SQTrue))) {
+	if (SQ_SUCCEEDED(sq_compilebuffer(vm, dummy_script.c_str(), dummy_script.size(), "dummy", SQTrue))) {
 		sq_push(vm, -2);
 		if (SQ_SUCCEEDED(sq_call(vm, 1, SQFalse, SQTrue))) {
 			sq_pop(vm, 1);
@@ -54,52 +52,56 @@ void Script_CreateDummyInfo(HSQUIRRELVM vm, const char *type, const char *dir)
 	NOT_REACHED();
 }
 
+/**
+ * Split the given message on newlines ('\n') and escape quotes and (back)slashes,
+ * so they can be properly interpreted as string constants by the Squirrel compiler.
+ * @param message The message that we want to sanitize for use in Squirrel code.
+ * @return Vector with sanitized strings to use as string constant in Squirrel code.
+ */
+static std::vector<std::string> EscapeQuotesAndSlashesAndSplitOnNewLines(const std::string &message)
+{
+	std::vector<std::string> messages;
+
+	std::string safe_message;
+	for (auto c : message) {
+		if (c == '\n') {
+			messages.emplace_back(std::move(safe_message));
+			continue;
+		}
+
+		if (c == '"' || c == '\\') safe_message.push_back('\\');
+		safe_message.push_back(c);
+	}
+	messages.emplace_back(std::move(safe_message));
+	return messages;
+}
+
 /** Run the dummy AI and let it generate an error message. */
 void Script_CreateDummy(HSQUIRRELVM vm, StringID string, const char *type)
 {
 	/* We want to translate the error message.
 	 * We do this in three steps:
-	 * 1) We get the error message
+	 * 1) We get the error message, escape quotes and slashes, and split on
+	 *    newlines because Log.Error terminates passed strings at newlines.
 	 */
-	char error_message[1024];
+	std::string error_message = GetString(string);
-	GetString(error_message, string, lastof(error_message));
+	std::vector<std::string> messages = EscapeQuotesAndSlashesAndSplitOnNewLines(error_message);
-
-	/* Make escapes for all quotes and slashes. */
-	char safe_error_message[1024];
-	char *q = safe_error_message;
-	for (const char *p = error_message; *p != '\0' && q < lastof(safe_error_message) - 2; p++, q++) {
-		if (*p == '"' || *p == '\\') *q++ = '\\';
-		*q = *p;
-	}
-	*q = '\0';
 
 	/* 2) We construct the AI's code. This is done by merging a header, body and footer */
-	char dummy_script[4096];
+	std::string dummy_script;
-	char *dp = dummy_script;
+	auto back_inserter = std::back_inserter(dummy_script);
-	dp += seprintf(dp, lastof(dummy_script), "class Dummy%s extends %sController {\n  function Start()\n  {\n", type, type);
+	/* Just a rough ballpark estimate. */
+	dummy_script.reserve(error_message.size() + 128 + 64 * messages.size());
 
-	/* As special trick we need to split the error message on newlines and
+	fmt::format_to(back_inserter, "class Dummy{0} extends {0}Controller {{\n  function Start()\n  {{\n", type);
-	 * emit each newline as a separate error printing string. */
+	for (std::string &message : messages) {
-	char *newline;
+		fmt::format_to(back_inserter, "    {}Log.Error(\"{}\");\n", type, message);
-	char *p = safe_error_message;
+	}
-	do {
+	dummy_script += "  }\n}\n";
-		newline = strchr(p, '\n');
-		if (newline != nullptr) *newline = '\0';
 
-		dp += seprintf(dp, lastof(dummy_script), "    %sLog.Error(\"%s\");\n", type, p);
+	/* 3) Finally we load and run the script */
-		p = newline + 1;
-	} while (newline != nullptr);
-
-	strecpy(dp, "  }\n}\n", lastof(dummy_script));
-
-	/* 3) We translate the error message in the character format that Squirrel wants.
-	 *    We can use the fact that the wchar string printing also uses %s to print
-	 *    old style char strings, which is what was generated during the script generation. */
-	const SQChar *sq_dummy_script = dummy_script;
-
-	/* And finally we load and run the script */
 	sq_pushroottable(vm);
-	if (SQ_SUCCEEDED(sq_compilebuffer(vm, sq_dummy_script, strlen(sq_dummy_script), "dummy", SQTrue))) {
+	if (SQ_SUCCEEDED(sq_compilebuffer(vm, dummy_script.c_str(), dummy_script.size(), "dummy", SQTrue))) {
 		sq_push(vm, -2);
 		if (SQ_SUCCEEDED(sq_call(vm, 1, SQFalse, SQTrue))) {
 			sq_pop(vm, 1);