Introduce `std::string_view` into wider use (#14368)

doc/lua_api.md

@@ -5459,7 +5459,7 @@ Utilities
   You can use `colorspec_to_bytes` to generate raw RGBA values.
   Palettes are not supported at the moment.
   You may use this to procedurally generate textures during server init.
-* `minetest.urlencode(str)`: Encodes non-unreserved URI characters by a
+* `minetest.urlencode(str)`: Encodes reserved URI characters by a
   percent sign followed by two hex digits. See
   [RFC 3986, section 2.3](https://datatracker.ietf.org/doc/html/rfc3986#section-2.3).
 

games/devtest/mods/unittests/misc.lua

@@ -133,6 +133,12 @@ local function test_compress()
 end
 unittests.register("test_compress", test_compress)
 
+local function test_urlencode()
+	-- checks that API code handles null bytes
+	assert(core.urlencode("foo\000bar!") == "foo%00bar%21")
+end
+unittests.register("test_urlencode", test_urlencode)
+
 local function test_game_info()
 	local info = minetest.get_game_info()
 	local game_conf = Settings(info.path .. "/game.conf")

src/activeobject.h

@@ -46,7 +46,7 @@ enum ActiveObjectType {
 
 struct ActiveObjectMessage
 {
-	ActiveObjectMessage(u16 id_, bool reliable_=true, const std::string &data_ = "") :
+	ActiveObjectMessage(u16 id_, bool reliable_=true, std::string_view data_ = "") :
 		id(id_),
 		reliable(reliable_),
 		datastring(data_)

src/chat.cpp

@@ -577,6 +577,7 @@ void ChatPrompt::historyNext()
 
 void ChatPrompt::nickCompletion(const std::set<std::string> &names, bool backwards)
 {
+	const std::wstring_view line(getLineRef());
 	// Two cases:
 	// (a) m_nick_completion_start == m_nick_completion_end == 0
 	//     Then no previous nick completion is active.
@@ -586,7 +587,6 @@ void ChatPrompt::nickCompletion(const std::set<std::string> &names, bool backwar
 	//     m_nick_completion_start..m_nick_completion_end are the
 	//     interval where the originally used prefix was. Cycle
 	//     through the list of completions of that prefix.
-	const std::wstring &line = getLineRef();
 	u32 prefix_start = m_nick_completion_start;
 	u32 prefix_end = m_nick_completion_end;
 	bool initial = (prefix_end == 0);
@@ -601,7 +601,7 @@ void ChatPrompt::nickCompletion(const std::set<std::string> &names, bool backwar
 		if (prefix_start == prefix_end)
 			return;
 	}
-	std::wstring prefix = line.substr(prefix_start, prefix_end - prefix_start);
+	auto prefix = line.substr(prefix_start, prefix_end - prefix_start);
 
 	// find all names that start with the selected prefix
 	std::vector<std::wstring> completions;
@@ -624,7 +624,7 @@ void ChatPrompt::nickCompletion(const std::set<std::string> &names, bool backwar
 	{
 		while (word_end < line.size() && !iswspace(line[word_end]))
 			++word_end;
-		std::wstring word = line.substr(prefix_start, word_end - prefix_start);
+		auto word = line.substr(prefix_start, word_end - prefix_start);
 
 		// cycle through completions
 		for (u32 i = 0; i < completions.size(); ++i)
@@ -640,7 +640,7 @@ void ChatPrompt::nickCompletion(const std::set<std::string> &names, bool backwar
 			}
 		}
 	}
-	std::wstring replacement = completions[replacement_index];
+	const auto &replacement = completions[replacement_index];
 	if (word_end < line.size() && iswspace(line[word_end]))
 		++word_end;
 

src/client/clientmedia.cpp

@@ -541,11 +541,9 @@ bool IClientMediaDownloader::checkAndLoad(
 	// Compute actual checksum of data
 	std::string data_sha1;
 	{
-		SHA1 data_sha1_calculator;
-		data_sha1_calculator.addBytes(data.c_str(), data.size());
-		unsigned char *data_tmpdigest = data_sha1_calculator.getDigest();
-		data_sha1.assign((char*) data_tmpdigest, 20);
-		free(data_tmpdigest);
+		SHA1 ctx;
+		ctx.addBytes(data);
+		data_sha1 = ctx.getDigest();
 	}
 
 	// Check that received file matches announced checksum

src/client/filecache.cpp

@@ -67,7 +67,7 @@ bool FileCache::loadByPath(const std::string &path, std::ostream &os)
 	return !bad;
 }
 
-bool FileCache::updateByPath(const std::string &path, const std::string &data)
+bool FileCache::updateByPath(const std::string &path, std::string_view data)
 {
 	createDir();
 	std::ofstream file(path.c_str(), std::ios_base::binary |
@@ -80,13 +80,13 @@ bool FileCache::updateByPath(const std::string &path, const std::string &data)
 		return false;
 	}
 
-	file.write(data.c_str(), data.length());
+	file << data;
 	file.close();
 
 	return !file.fail();
 }
 
-bool FileCache::update(const std::string &name, const std::string &data)
+bool FileCache::update(const std::string &name, std::string_view data)
 {
 	std::string path = m_dir + DIR_DELIM + name;
 	return updateByPath(path, data);

src/client/filecache.h

@@ -22,6 +22,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 
 #include <iostream>
 #include <string>
+#include <string_view>
 
 class FileCache
 {
@@ -31,7 +32,7 @@ public:
 	*/
 	FileCache(const std::string &dir) : m_dir(dir) {}
 
-	bool update(const std::string &name, const std::string &data);
+	bool update(const std::string &name, std::string_view data);
 	bool load(const std::string &name, std::ostream &os);
 	bool exists(const std::string &name);
 
@@ -43,5 +44,5 @@ private:
 
 	void createDir();
 	bool loadByPath(const std::string &path, std::ostream &os);
-	bool updateByPath(const std::string &path, const std::string &data);
+	bool updateByPath(const std::string &path, std::string_view data);
 };

src/client/shader.cpp

@@ -804,7 +804,7 @@ ShaderInfo ShaderSource::generateShader(const std::string &name,
 }
 
 void dumpShaderProgram(std::ostream &output_stream,
-		const std::string &program_type, const std::string &program)
+		const std::string &program_type, std::string_view program)
 {
 	output_stream << program_type << " shader program:" << std::endl <<
 		"----------------------------------" << std::endl;

src/client/shader.h

@@ -192,4 +192,4 @@ public:
 IWritableShaderSource *createShaderSource();
 
 void dumpShaderProgram(std::ostream &output_stream,
-	const std::string &program_type, const std::string &program);
+	const std::string &program_type, std::string_view program);

src/client/tile.cpp

@@ -404,7 +404,7 @@ private:
 	// Generate image based on a string like "stone.png" or "[crack:1:0".
 	// if baseimg is NULL, it is created. Otherwise stuff is made on it.
 	// source_image_names is important to determine when to flush the image from a cache (dynamic media)
-	bool generateImagePart(std::string part_of_name, video::IImage *& baseimg, std::set<std::string> &source_image_names);
+	bool generateImagePart(std::string_view part_of_name, video::IImage *& baseimg, std::set<std::string> &source_image_names);
 
 	/*! Generates an image from a full string like
 	 * "stone.png^mineral_coal.png^[crack:1:0".
@@ -412,7 +412,7 @@ private:
 	 * The returned Image should be dropped.
 	 * source_image_names is important to determine when to flush the image from a cache (dynamic media)
 	 */
-	video::IImage* generateImage(const std::string &name, std::set<std::string> &source_image_names);
+	video::IImage* generateImage(std::string_view name, std::set<std::string> &source_image_names);
 
 	// Thread-safe cache of what source images are known (true = known)
 	MutexedMap<std::string, bool> m_source_image_existence;
@@ -593,7 +593,7 @@ static void draw_crack(video::IImage *crack, video::IImage *dst,
 // Brighten image
 void brighten(video::IImage *image);
 // Parse a transform name
-u32 parseImageTransform(const std::string& s);
+u32 parseImageTransform(std::string_view s);
 // Apply transform to image dimension
 core::dimension2d<u32> imageTransformDimension(u32 transform, core::dimension2d<u32> dim);
 // Apply transform to image data
@@ -963,7 +963,8 @@ static video::IImage *createInventoryCubeImage(
 	return result;
 }
 
-video::IImage* TextureSource::generateImage(const std::string &name, std::set<std::string> &source_image_names)
+video::IImage* TextureSource::generateImage(std::string_view name,
+		std::set<std::string> &source_image_names)
 {
 	// Get the base image
 
@@ -1024,15 +1025,15 @@ video::IImage* TextureSource::generateImage(const std::string &name, std::set<st
 		according to it
 	*/
 
-	std::string last_part_of_name = name.substr(last_separator_pos + 1);
+	auto last_part_of_name = name.substr(last_separator_pos + 1);
 
 	/*
 		If this name is enclosed in parentheses, generate it
 		and blit it onto the base image
 	*/
 	if (last_part_of_name[0] == paren_open
-			&& last_part_of_name[last_part_of_name.size() - 1] == paren_close) {
-		std::string name2 = last_part_of_name.substr(1,
+			&& last_part_of_name.back() == paren_close) {
+		auto name2 = last_part_of_name.substr(1,
 				last_part_of_name.size() - 2);
 		video::IImage *tmp = generateImage(name2, source_image_names);
 		if (!tmp) {
@@ -1199,7 +1200,7 @@ void blitBaseImage(video::IImage* &src, video::IImage* &dst)
 		} \
 	} while(0)
 
-bool TextureSource::generateImagePart(std::string part_of_name,
+bool TextureSource::generateImagePart(std::string_view part_of_name,
 		video::IImage *& baseimg, std::set<std::string> &source_image_names)
 {
 	const char escape = '\\'; // same as in generateImage()
@@ -1216,8 +1217,9 @@ bool TextureSource::generateImagePart(std::string part_of_name,
 
 	// Stuff starting with [ are special commands
 	if (part_of_name.empty() || part_of_name[0] != '[') {
-		source_image_names.insert(part_of_name);
-		video::IImage *image = m_sourcecache.getOrLoad(part_of_name);
+		std::string part_s(part_of_name);
+		source_image_names.insert(part_s);
+		video::IImage *image = m_sourcecache.getOrLoad(part_s);
 		if (!image) {
 			// Do not create the dummy texture
 			if (part_of_name.empty())
@@ -1516,8 +1518,10 @@ bool TextureSource::generateImagePart(std::string part_of_name,
 				return false;
 			}
 
-			str_replace(part_of_name, '&', '^');
-			Strfnd sf(part_of_name);
+			std::string part_s(part_of_name);
+			str_replace(part_s, '&', '^');
+
+			Strfnd sf(part_s);
 			sf.next("{");
 			std::string imagename_top = sf.next("{");
 			std::string imagename_left = sf.next("{");
@@ -1873,7 +1877,7 @@ bool TextureSource::generateImagePart(std::string part_of_name,
 		else if (str_starts_with(part_of_name, "[png:")) {
 			std::string png;
 			{
-				std::string blob = part_of_name.substr(5);
+				auto blob = part_of_name.substr(5);
 				if (!base64_is_valid(blob)) {
 					errorstream << "generateImagePart(): "
 								<< "malformed base64 in [png" << std::endl;
@@ -2433,7 +2437,7 @@ void brighten(video::IImage *image)
 	}
 }
 
-u32 parseImageTransform(const std::string& s)
+u32 parseImageTransform(std::string_view s)
 {
 	int total_transform = 0;
 

src/content/mod_configuration.cpp

@@ -22,6 +22,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "settings.h"
 #include "filesys.h"
 #include "gettext.h"
+#include "exceptions.h"
 
 
 std::string ModConfiguration::getUnsatisfiedModsError() const

src/content/mods.cpp

@@ -228,7 +228,7 @@ bool ModStorage::contains(const std::string &name) const
 	return m_database->hasModEntry(m_mod_name, name);
 }
 
-bool ModStorage::setString(const std::string &name, const std::string &var)
+bool ModStorage::setString(const std::string &name, std::string_view var)
 {
 	if (var.empty())
 		return m_database->removeModEntry(m_mod_name, name);

src/content/mods.h

@@ -123,7 +123,7 @@ public:
 
 	bool contains(const std::string &name) const override;
 
-	bool setString(const std::string &name, const std::string &var) override;
+	bool setString(const std::string &name, std::string_view var) override;
 
 	const StringMap &getStrings(StringMap *place) const override;
 

src/content/subgames.cpp

@@ -239,9 +239,9 @@ std::set<std::string> getAvailableGameIds()
 
 			// Add it to result
 			const char *ends[] = {"_game", NULL};
-			std::string shorter = removeStringEnd(dln.name, ends);
+			auto shorter = removeStringEnd(dln.name, ends);
 			if (!shorter.empty())
-				gameids.insert(shorter);
+				gameids.emplace(shorter);
 			else
 				gameids.insert(dln.name);
 		}

src/craftdef.cpp

@@ -34,7 +34,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 
 inline bool isGroupRecipeStr(const std::string &rec_name)
 {
-	return str_starts_with(rec_name, std::string("group:"));
+	return str_starts_with(rec_name, "group:");
 }
 
 static bool hasGroupItem(const std::vector<std::string> &recipe)

src/database/database-dummy.cpp

@@ -25,7 +25,7 @@ Dummy database class
 #include "remoteplayer.h"
 
 
-bool Database_Dummy::saveBlock(const v3s16 &pos, const std::string &data)
+bool Database_Dummy::saveBlock(const v3s16 &pos, std::string_view data)
 {
 	m_database[getBlockAsInteger(pos)] = data;
 	return true;
@@ -128,11 +128,12 @@ bool Database_Dummy::hasModEntry(const std::string &modname, const std::string &
 }
 
 bool Database_Dummy::setModEntry(const std::string &modname,
-	const std::string &key, const std::string &value)
+	const std::string &key, std::string_view value)
 {
 	auto mod_pair = m_mod_storage_database.find(modname);
 	if (mod_pair == m_mod_storage_database.end()) {
-		m_mod_storage_database[modname] = StringMap({{key, value}});
+		auto &map = m_mod_storage_database[modname];
+		map[key] = value;
 	} else {
 		mod_pair->second[key] = value;
 	}

src/database/database-dummy.h

@@ -20,6 +20,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #pragma once
 
 #include <map>
+#include <set>
 #include <string>
 #include "database.h"
 #include "irrlichttypes.h"
@@ -27,7 +28,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 class Database_Dummy : public MapDatabase, public PlayerDatabase, public ModStorageDatabase
 {
 public:
-	bool saveBlock(const v3s16 &pos, const std::string &data);
+	bool saveBlock(const v3s16 &pos, std::string_view data);
 	void loadBlock(const v3s16 &pos, std::string *block);
 	bool deleteBlock(const v3s16 &pos);
 	void listAllLoadableBlocks(std::vector<v3s16> &dst);
@@ -43,7 +44,7 @@ public:
 			const std::string &key, std::string *value);
 	bool hasModEntry(const std::string &modname, const std::string &key);
 	bool setModEntry(const std::string &modname,
-			const std::string &key, const std::string &value);
+			const std::string &key,std::string_view value);
 	bool removeModEntry(const std::string &modname, const std::string &key);
 	bool removeModEntries(const std::string &modname);
 	void listMods(std::vector<std::string> *res);

src/database/database-files.cpp

@@ -428,13 +428,14 @@ bool ModStorageDatabaseFiles::hasModEntry(const std::string &modname, const std:
 }
 
 bool ModStorageDatabaseFiles::setModEntry(const std::string &modname,
-	const std::string &key, const std::string &value)
+	const std::string &key, std::string_view value)
 {
 	Json::Value *meta = getOrCreateJson(modname);
 	if (!meta)
 		return false;
 
-	(*meta)[key] = Json::Value(value);
+	Json::Value value_v(value.data(), value.data() + value.size());
+	(*meta)[key] = std::move(value_v);
 	m_modified.insert(modname);
 
 	return true;

src/database/database-files.h

@@ -84,7 +84,7 @@ public:
 		const std::string &key, std::string *value);
 	virtual bool hasModEntry(const std::string &modname, const std::string &key);
 	virtual bool setModEntry(const std::string &modname,
-		const std::string &key, const std::string &value);
+		const std::string &key, std::string_view value);
 	virtual bool removeModEntry(const std::string &modname, const std::string &key);
 	virtual bool removeModEntries(const std::string &modname);
 	virtual void listMods(std::vector<std::string> *res);

src/database/database-leveldb.cpp

@@ -53,10 +53,11 @@ Database_LevelDB::Database_LevelDB(const std::string &savedir)
 	m_database.reset(db);
 }
 
-bool Database_LevelDB::saveBlock(const v3s16 &pos, const std::string &data)
+bool Database_LevelDB::saveBlock(const v3s16 &pos, std::string_view data)
 {
+	leveldb::Slice data_s(data.data(), data.size());
 	leveldb::Status status = m_database->Put(leveldb::WriteOptions(),
-			i64tos(getBlockAsInteger(pos)), data);
+			i64tos(getBlockAsInteger(pos)), data_s);
 	if (!status.ok()) {
 		warningstream << "saveBlock: LevelDB error saving block "
 			<< pos << ": " << status.ToString() << std::endl;

src/database/database-leveldb.h

@@ -34,7 +34,7 @@ public:
 	Database_LevelDB(const std::string &savedir);
 	~Database_LevelDB() = default;
 
-	bool saveBlock(const v3s16 &pos, const std::string &data);
+	bool saveBlock(const v3s16 &pos, std::string_view data);
 	void loadBlock(const v3s16 &pos, std::string *block);
 	bool deleteBlock(const v3s16 &pos);
 	void listAllLoadableBlocks(std::vector<v3s16> &dst);

src/database/database-postgresql.cpp

@@ -223,7 +223,7 @@ void MapDatabasePostgreSQL::initStatements()
 		"SELECT posX, posY, posZ FROM blocks");
 }
 
-bool MapDatabasePostgreSQL::saveBlock(const v3s16 &pos, const std::string &data)
+bool MapDatabasePostgreSQL::saveBlock(const v3s16 &pos, std::string_view data)
 {
 	// Verify if we don't overflow the platform integer with the mapblock size
 	if (data.size() > INT_MAX) {
@@ -240,7 +240,7 @@ bool MapDatabasePostgreSQL::saveBlock(const v3s16 &pos, const std::string &data)
 	y = htonl(pos.Y);
 	z = htonl(pos.Z);
 
-	const void *args[] = { &x, &y, &z, data.c_str() };
+	const void *args[] = { &x, &y, &z, data.data() };
 	const int argLen[] = {
 		sizeof(x), sizeof(y), sizeof(z), (int)data.size()
 	};
@@ -940,11 +940,11 @@ bool ModStorageDatabasePostgreSQL::hasModEntry(const std::string &modname,
 }
 
 bool ModStorageDatabasePostgreSQL::setModEntry(const std::string &modname,
-	const std::string &key, const std::string &value)
+	const std::string &key, std::string_view value)
 {
 	verifyDatabase();
 
-	const void *args[] = { modname.c_str(), key.c_str(), value.c_str() };
+	const void *args[] = { modname.c_str(), key.c_str(), value.data() };
 	const int argLen[] = {
 		-1,
 		(int)MYMIN(key.size(), INT_MAX),

src/database/database-postgresql.h

@@ -120,7 +120,7 @@ public:
 	MapDatabasePostgreSQL(const std::string &connect_string);
 	virtual ~MapDatabasePostgreSQL() = default;
 
-	bool saveBlock(const v3s16 &pos, const std::string &data);
+	bool saveBlock(const v3s16 &pos, std::string_view data);
 	void loadBlock(const v3s16 &pos, std::string *block);
 	bool deleteBlock(const v3s16 &pos);
 	void listAllLoadableBlocks(std::vector<v3s16> &dst);
@@ -186,7 +186,7 @@ public:
 	bool getModEntry(const std::string &modname, const std::string &key, std::string *value);
 	bool hasModEntry(const std::string &modname, const std::string &key);
 	bool setModEntry(const std::string &modname,
-			const std::string &key, const std::string &value);
+			const std::string &key, std::string_view value);
 	bool removeModEntry(const std::string &modname, const std::string &key);
 	bool removeModEntries(const std::string &modname);
 	void listMods(std::vector<std::string> *res);

src/database/database-redis.cpp

@@ -91,12 +91,12 @@ void Database_Redis::endSave() {
 	freeReplyObject(reply);
 }
 
-bool Database_Redis::saveBlock(const v3s16 &pos, const std::string &data)
+bool Database_Redis::saveBlock(const v3s16 &pos, std::string_view data)
 {
 	std::string tmp = i64tos(getBlockAsInteger(pos));
 
 	redisReply *reply = static_cast<redisReply *>(redisCommand(ctx, "HSET %s %s %b",
-			hash.c_str(), tmp.c_str(), data.c_str(), data.size()));
+			hash.c_str(), tmp.c_str(), data.data(), data.size()));
 	if (!reply) {
 		warningstream << "saveBlock: redis command 'HSET' failed on "
 			"block " << pos << ": " << ctx->errstr << std::endl;

src/database/database-redis.h

@@ -38,7 +38,7 @@ public:
 	void beginSave();
 	void endSave();
 
-	bool saveBlock(const v3s16 &pos, const std::string &data);
+	bool saveBlock(const v3s16 &pos, std::string_view data);
 	void loadBlock(const v3s16 &pos, std::string *block);
 	bool deleteBlock(const v3s16 &pos);
 	void listAllLoadableBlocks(std::vector<v3s16> &dst);

src/database/database-sqlite3.cpp

@@ -258,7 +258,7 @@ bool MapDatabaseSQLite3::deleteBlock(const v3s16 &pos)
 	return good;
 }
 
-bool MapDatabaseSQLite3::saveBlock(const v3s16 &pos, const std::string &data)
+bool MapDatabaseSQLite3::saveBlock(const v3s16 &pos, std::string_view data)
 {
 	verifyDatabase();
 
@@ -283,13 +283,8 @@ void MapDatabaseSQLite3::loadBlock(const v3s16 &pos, std::string *block)
 		return;
 	}
 
-	const char *data = (const char *) sqlite3_column_blob(m_stmt_read, 0);
-	size_t len = sqlite3_column_bytes(m_stmt_read, 0);
-
-	if (data)
-		block->assign(data, len);
-	else
-		block->clear();
+	auto data = sqlite_to_blob(m_stmt_read, 0);
+	block->assign(data);
 
 	sqlite3_step(m_stmt_read);
 	// We should never get more than 1 row, so ok to reset
@@ -553,7 +548,7 @@ bool PlayerDatabaseSQLite3::loadPlayer(RemotePlayer *player, PlayerSAO *sao)
 		int_to_sqlite(m_stmt_player_load_inventory_items, 2, invId);
 		while (sqlite3_step(m_stmt_player_load_inventory_items) == SQLITE_ROW) {
 			const std::string itemStr = sqlite_to_string(m_stmt_player_load_inventory_items, 1);
-			if (itemStr.length() > 0) {
+			if (!itemStr.empty()) {
 				ItemStack stack;
 				stack.deSerialize(itemStr);
 				invList->changeItem(sqlite_to_uint(m_stmt_player_load_inventory_items, 0), stack);
@@ -567,7 +562,7 @@ bool PlayerDatabaseSQLite3::loadPlayer(RemotePlayer *player, PlayerSAO *sao)
 	str_to_sqlite(m_stmt_player_metadata_load, 1, sao->getPlayer()->getName());
 	while (sqlite3_step(m_stmt_player_metadata_load) == SQLITE_ROW) {
 		std::string attr = sqlite_to_string(m_stmt_player_metadata_load, 0);
-		std::string value = sqlite_to_string(m_stmt_player_metadata_load, 1);
+		auto value = sqlite_to_string_view(m_stmt_player_metadata_load, 1);
 
 		sao->getMeta().setString(attr, value);
 	}
@@ -592,7 +587,7 @@ void PlayerDatabaseSQLite3::listPlayers(std::vector<std::string> &res)
 	verifyDatabase();
 
 	while (sqlite3_step(m_stmt_player_list) == SQLITE_ROW)
-		res.push_back(sqlite_to_string(m_stmt_player_list, 0));
+		res.emplace_back(sqlite_to_string_view(m_stmt_player_list, 0));
 
 	sqlite3_reset(m_stmt_player_list);
 }
@@ -669,14 +664,14 @@ bool AuthDatabaseSQLite3::getAuth(const std::string &name, AuthEntry &res)
 		return false;
 	}
 	res.id = sqlite_to_uint(m_stmt_read, 0);
-	res.name = sqlite_to_string(m_stmt_read, 1);
-	res.password = sqlite_to_string(m_stmt_read, 2);
+	res.name = sqlite_to_string_view(m_stmt_read, 1);
+	res.password = sqlite_to_string_view(m_stmt_read, 2);
 	res.last_login = sqlite_to_int64(m_stmt_read, 3);
 	sqlite3_reset(m_stmt_read);
 
 	int64_to_sqlite(m_stmt_read_privs, 1, res.id);
 	while (sqlite3_step(m_stmt_read_privs) == SQLITE_ROW) {
-		res.privileges.emplace_back(sqlite_to_string(m_stmt_read_privs, 0));
+		res.privileges.emplace_back(sqlite_to_string_view(m_stmt_read_privs, 0));
 	}
 	sqlite3_reset(m_stmt_read_privs);
 
@@ -741,7 +736,7 @@ void AuthDatabaseSQLite3::listNames(std::vector<std::string> &res)
 	verifyDatabase();
 
 	while (sqlite3_step(m_stmt_list_names) == SQLITE_ROW) {
-		res.push_back(sqlite_to_string(m_stmt_list_names, 0));
+		res.emplace_back(sqlite_to_string_view(m_stmt_list_names, 0));
 	}
 	sqlite3_reset(m_stmt_list_names);
 }
@@ -815,11 +810,9 @@ void ModStorageDatabaseSQLite3::getModEntries(const std::string &modname, String
 
 	str_to_sqlite(m_stmt_get_all, 1, modname);
 	while (sqlite3_step(m_stmt_get_all) == SQLITE_ROW) {
-		const char *key_data = (const char *) sqlite3_column_blob(m_stmt_get_all, 0);
-		size_t key_len = sqlite3_column_bytes(m_stmt_get_all, 0);
-		const char *value_data = (const char *) sqlite3_column_blob(m_stmt_get_all, 1);
-		size_t value_len = sqlite3_column_bytes(m_stmt_get_all, 1);
-		(*storage)[std::string(key_data, key_len)] = std::string(value_data, value_len);
+		auto key = sqlite_to_blob(m_stmt_get_all, 0);
+		auto value = sqlite_to_blob(m_stmt_get_all, 1);
+		(*storage)[std::string(key)].assign(value);
 	}
 	sqlite3_vrfy(sqlite3_errcode(m_database), SQLITE_DONE);
 
@@ -833,9 +826,8 @@ void ModStorageDatabaseSQLite3::getModKeys(const std::string &modname,
 
 	str_to_sqlite(m_stmt_get_keys, 1, modname);
 	while (sqlite3_step(m_stmt_get_keys) == SQLITE_ROW) {
-		const char *key_data = (const char *) sqlite3_column_blob(m_stmt_get_keys, 0);
-		size_t key_len = sqlite3_column_bytes(m_stmt_get_keys, 0);
-		storage->emplace_back(key_data, key_len);
+		auto key = sqlite_to_blob(m_stmt_get_keys, 0);
+		storage->emplace_back(key);
 	}
 	sqlite3_vrfy(sqlite3_errcode(m_database), SQLITE_DONE);
 
@@ -852,9 +844,8 @@ bool ModStorageDatabaseSQLite3::getModEntry(const std::string &modname,
 		"Internal error: failed to bind query at " __FILE__ ":" TOSTRING(__LINE__));
 	bool found = sqlite3_step(m_stmt_get) == SQLITE_ROW;
 	if (found) {
-		const char *value_data = (const char *) sqlite3_column_blob(m_stmt_get, 0);
-		size_t value_len = sqlite3_column_bytes(m_stmt_get, 0);
-		value->assign(value_data, value_len);
+		auto sv = sqlite_to_blob(m_stmt_get, 0);
+		value->assign(sv);
 		sqlite3_step(m_stmt_get);
 	}
 
@@ -881,7 +872,7 @@ bool ModStorageDatabaseSQLite3::hasModEntry(const std::string &modname,
 }
 
 bool ModStorageDatabaseSQLite3::setModEntry(const std::string &modname,
-	const std::string &key, const std::string &value)
+	const std::string &key, std::string_view value)
 {
 	verifyDatabase();
 

src/database/database-sqlite3.h

@@ -44,14 +44,9 @@ protected:
 	void verifyDatabase();
 
 	// Convertors
-	inline void str_to_sqlite(sqlite3_stmt *s, int iCol, const std::string &str) const
+	inline void str_to_sqlite(sqlite3_stmt *s, int iCol, std::string_view str) const
 	{
-		sqlite3_vrfy(sqlite3_bind_text(s, iCol, str.c_str(), str.size(), NULL));
-	}
-
-	inline void str_to_sqlite(sqlite3_stmt *s, int iCol, const char *str) const
-	{
-		sqlite3_vrfy(sqlite3_bind_text(s, iCol, str, strlen(str), NULL));
+		sqlite3_vrfy(sqlite3_bind_text(s, iCol, str.data(), str.size(), NULL));
 	}
 
 	inline void int_to_sqlite(sqlite3_stmt *s, int iCol, int val) const
@@ -69,10 +64,28 @@ protected:
 		sqlite3_vrfy(sqlite3_bind_double(s, iCol, val));
 	}
 
-	inline std::string sqlite_to_string(sqlite3_stmt *s, int iCol)
+	// Note that the return value is only valid until the statement is stepped or reset.
+	inline std::string_view sqlite_to_string_view(sqlite3_stmt *s, int iCol)
 	{
 		const char* text = reinterpret_cast<const char*>(sqlite3_column_text(s, iCol));
-		return std::string(text ? text : "");
+		return text ? std::string_view(text) : std::string_view();
+	}
+
+	// Avoid using this in favor of `sqlite_to_string_view`.
+	inline std::string sqlite_to_string(sqlite3_stmt *s, int iCol)
+	{
+		return std::string(sqlite_to_string_view(s, iCol));
+	}
+
+	// Converts a BLOB-type column into a string_view (null byte safe).
+	// Note that the return value is only valid until the statement is stepped or reset.
+	inline std::string_view sqlite_to_blob(sqlite3_stmt *s, int iCol)
+	{
+		const char *data = reinterpret_cast<const char*>(sqlite3_column_blob(s, iCol));
+		if (!data)
+			return std::string_view();
+		size_t len = sqlite3_column_bytes(s, iCol);
+		return std::string_view(data, len);
 	}
 
 	inline s32 sqlite_to_int(sqlite3_stmt *s, int iCol)
@@ -107,13 +120,16 @@ protected:
 	}
 
 	// Query verifiers helpers
-	inline void sqlite3_vrfy(int s, const std::string &m = "", int r = SQLITE_OK) const
+	inline void sqlite3_vrfy(int s, std::string_view m = "", int r = SQLITE_OK) const
 	{
-		if (s != r)
-			throw DatabaseException(m + ": " + sqlite3_errmsg(m_database));
+		if (s != r) {
+			std::string msg(m);
+			msg.append(": ").append(sqlite3_errmsg(m_database));
+			throw DatabaseException(msg);
+		}
 	}
 
-	inline void sqlite3_vrfy(const int s, const int r, const std::string &m = "") const
+	inline void sqlite3_vrfy(const int s, const int r, std::string_view m = "") const
 	{
 		sqlite3_vrfy(s, m, r);
 	}
@@ -146,7 +162,7 @@ public:
 	MapDatabaseSQLite3(const std::string &savedir);
 	virtual ~MapDatabaseSQLite3();
 
-	bool saveBlock(const v3s16 &pos, const std::string &data);
+	bool saveBlock(const v3s16 &pos, std::string_view data);
 	void loadBlock(const v3s16 &pos, std::string *block);
 	bool deleteBlock(const v3s16 &pos);
 	void listAllLoadableBlocks(std::vector<v3s16> &dst);
@@ -245,7 +261,7 @@ public:
 		const std::string &key, std::string *value);
 	virtual bool hasModEntry(const std::string &modname, const std::string &key);
 	virtual bool setModEntry(const std::string &modname,
-		const std::string &key, const std::string &value);
+		const std::string &key,std::string_view value);
 	virtual bool removeModEntry(const std::string &modname, const std::string &key);
 	virtual bool removeModEntries(const std::string &modname);
 	virtual void listMods(std::vector<std::string> *res);

src/database/database.h

@@ -19,12 +19,11 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 
 #pragma once
 
-#include <set>
 #include <string>
+#include <string_view>
 #include <vector>
 #include "irr_v3d.h"
 #include "irrlichttypes.h"
-#include "util/basic_macros.h"
 #include "util/string.h"
 
 class Database
@@ -40,7 +39,7 @@ class MapDatabase : public Database
 public:
 	virtual ~MapDatabase() = default;
 
-	virtual bool saveBlock(const v3s16 &pos, const std::string &data) = 0;
+	virtual bool saveBlock(const v3s16 &pos, std::string_view data) = 0;
 	virtual void loadBlock(const v3s16 &pos, std::string *block) = 0;
 	virtual bool deleteBlock(const v3s16 &pos) = 0;
 
@@ -97,7 +96,7 @@ public:
 	virtual bool getModEntry(const std::string &modname,
 		const std::string &key, std::string *value) = 0;
 	virtual bool setModEntry(const std::string &modname,
-		const std::string &key, const std::string &value) = 0;
+		const std::string &key, std::string_view value) = 0;
 	virtual bool removeModEntry(const std::string &modname, const std::string &key) = 0;
 	virtual bool removeModEntries(const std::string &modname) = 0;
 	virtual void listMods(std::vector<std::string> *res) = 0;

src/filesys.cpp

@@ -828,7 +828,7 @@ const char *GetFilenameFromPath(const char *path)
 	return filename ? filename + 1 : path;
 }
 
-bool safeWriteToFile(const std::string &path, const std::string &content)
+bool safeWriteToFile(const std::string &path, std::string_view content)
 {
 	std::string tmp_file = path + ".~mt";
 
@@ -844,7 +844,7 @@ bool safeWriteToFile(const std::string &path, const std::string &content)
 		return false;
 	}
 	DWORD bytes_written;
-	tmp_success = (WriteFile(tmp_handle, content.c_str(), content.size(), &bytes_written, nullptr) &&
+	tmp_success = (WriteFile(tmp_handle, content.data(), content.size(), &bytes_written, nullptr) &&
 					FlushFileBuffers(tmp_handle));
 	CloseHandle(tmp_handle);
 #else

src/filesys.h

@@ -21,8 +21,8 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 
 #include <set>
 #include <string>
+#include <string_view>
 #include <vector>
-#include "exceptions.h"
 
 #ifdef _WIN32
 #define DIR_DELIM "\\"
@@ -142,7 +142,7 @@ std::string AbsolutePath(const std::string &path);
 // delimiter is found.
 const char *GetFilenameFromPath(const char *path);
 
-bool safeWriteToFile(const std::string &path, const std::string &content);
+bool safeWriteToFile(const std::string &path, std::string_view content);
 
 #ifndef SERVER
 bool extractZipFile(irr::io::IFileSystem *fs, const char *filename, const std::string &destination);

src/gui/guiFormSpecMenu.cpp

@@ -755,7 +755,7 @@ void GUIFormSpecMenu::parseScrollBarOptions(parserData* data, const std::string
 			data->scrollbar_options.thumb_size = value <= 0 ? 1 : value;
 			continue;
 		} else if (options[0] == "arrows") {
-			std::string value = trim(options[1]);
+			auto value = trim(options[1]);
 			if (value == "hide")
 				data->scrollbar_options.arrow_visiblity = GUIScrollBar::HIDE;
 			else if (value == "show")
@@ -2449,8 +2449,8 @@ bool GUIFormSpecMenu::parseSizeDirect(parserData* data, const std::string &eleme
 	if (parts.size() < 2)
 		return false;
 
-	std::string type = trim(parts[0]);
-	std::string description = trim(parts[1]);
+	auto type = trim(parts[0]);
+	std::string description(trim(parts[1]));
 
 	if (type != "size" && type != "invsize")
 		return false;
@@ -2473,8 +2473,8 @@ bool GUIFormSpecMenu::parsePositionDirect(parserData *data, const std::string &e
 	if (parts.size() != 2)
 		return false;
 
-	std::string type = trim(parts[0]);
-	std::string description = trim(parts[1]);
+	auto type = trim(parts[0]);
+	std::string description(trim(parts[1]));
 
 	if (type != "position")
 		return false;
@@ -2512,8 +2512,8 @@ bool GUIFormSpecMenu::parseAnchorDirect(parserData *data, const std::string &ele
 	if (parts.size() != 2)
 		return false;
 
-	std::string type = trim(parts[0]);
-	std::string description = trim(parts[1]);
+	auto type = trim(parts[0]);
+	std::string description(trim(parts[1]));
 
 	if (type != "anchor")
 		return false;
@@ -2552,8 +2552,8 @@ bool GUIFormSpecMenu::parsePaddingDirect(parserData *data, const std::string &el
 	if (parts.size() != 2)
 		return false;
 
-	std::string type = trim(parts[0]);
-	std::string description = trim(parts[1]);
+	auto type = trim(parts[0]);
+	std::string description(trim(parts[1]));
 
 	if (type != "padding")
 		return false;
@@ -2624,7 +2624,7 @@ bool GUIFormSpecMenu::parseStyle(parserData *data, const std::string &element, b
 
 	std::vector<std::string> selectors = split(parts[0], ',');
 	for (size_t sel = 0; sel < selectors.size(); sel++) {
-		std::string selector = trim(selectors[sel]);
+		std::string selector(trim(selectors[sel]));
 
 		// Copy the style properties to a new StyleSpec
 		// This allows a separate state mask per-selector
@@ -3216,7 +3216,7 @@ void GUIFormSpecMenu::regenerateGui(v2u32 screensize)
 	mydata.real_coordinates = m_formspec_version >= 2;
 	for (; i < elements.size(); i++) {
 		std::vector<std::string> parts = split(elements[i], '[');
-		std::string name = trim(parts[0]);
+		auto name = trim(parts[0]);
 		if (name != "real_coordinates" || parts.size() != 2)
 			break; // Invalid format
 

src/itemstackmetadata.cpp

@@ -49,10 +49,10 @@ static void sanitize_string(std::string &str)
 	str.erase(std::remove(str.begin(), str.end(), DESERIALIZE_PAIR_DELIM), str.end());
 }
 
-bool ItemStackMetadata::setString(const std::string &name, const std::string &var)
+bool ItemStackMetadata::setString(const std::string &name, std::string_view var)
 {
 	std::string clean_name = name;
-	std::string clean_var = var;
+	std::string clean_var(var);
 	sanitize_string(clean_name);
 	sanitize_string(clean_var);
 

src/itemstackmetadata.h

@@ -36,7 +36,7 @@ public:
 
 	// Overrides
 	void clear() override;
-	bool setString(const std::string &name, const std::string &var) override;
+	bool setString(const std::string &name, std::string_view var) override;
 
 	void serialize(std::ostream &os) const;
 	void deSerialize(std::istream &is);

src/map.cpp

@@ -1798,6 +1798,7 @@ bool ServerMap::saveBlock(MapBlock *block, MapDatabase *db, int compression_leve
 	o.write((char*) &version, 1);
 	block->serialize(o, version, true, compression_level);
 
+	// FIXME: zero copy possible in c++20 or with custom rdbuf
 	bool ret = db->saveBlock(p3d, o.str());
 	if (ret) {
 		// We just wrote it to the disk so clear modified flag

src/mapblock.cpp

@@ -382,7 +382,7 @@ void MapBlock::serialize(std::ostream &os_compressed, u8 version, bool disk, int
 		Bulk node data
 	*/
 	NameIdMapping nimap;
-	SharedBuffer<u8> buf;
+	Buffer<u8> buf;
 	const u8 content_width = 2;
 	const u8 params_width = 2;
  	if(disk)
@@ -653,7 +653,7 @@ void MapBlock::deSerialize_pre22(std::istream &is, u8 version, bool disk)
 
 	// Make a temporary buffer
 	u32 ser_length = MapNode::serializedLength(version);
-	SharedBuffer<u8> databuf_nodelist(nodecount * ser_length);
+	Buffer<u8> databuf_nodelist(nodecount * ser_length);
 
 	// These have no compression
 	if (version <= 3 || version == 5 || version == 6) {

src/mapgen/mg_schematic.cpp

@@ -384,7 +384,7 @@ bool Schematic::serializeToMts(std::ostream *os) const
 	}
 
 	// compressed bulk node data
-	SharedBuffer<u8> buf = MapNode::serializeBulk(MTSCHEM_MAPNODE_SER_FMT_VER,
+	auto buf = MapNode::serializeBulk(MTSCHEM_MAPNODE_SER_FMT_VER,
 		schemdata, size.X * size.Y * size.Z, 2, 2);
 	compress(buf, ss, MTSCHEM_MAPNODE_SER_FMT_VER);
 

src/mapnode.cpp

@@ -690,7 +690,7 @@ void MapNode::deSerialize(u8 *source, u8 version)
 	}
 }
 
-SharedBuffer<u8> MapNode::serializeBulk(int version,
+Buffer<u8> MapNode::serializeBulk(int version,
 		const MapNode *nodes, u32 nodecount,
 		u8 content_width, u8 params_width)
 {
@@ -706,7 +706,7 @@ SharedBuffer<u8> MapNode::serializeBulk(int version,
 		throw SerializationError("MapNode::serializeBulk: serialization to "
 				"version < 24 not possible");
 
-	SharedBuffer<u8> databuf(nodecount * (content_width + params_width));
+	Buffer<u8> databuf(nodecount * (content_width + params_width));
 
 	u32 start1 = content_width * nodecount;
 	u32 start2 = (content_width + 1) * nodecount;

src/mapnode.h

@@ -316,7 +316,7 @@ struct alignas(u32) MapNode
 	//   content_width = the number of bytes of content per node
 	//   params_width = the number of bytes of params per node
 	//   compressed = true to zlib-compress output
-	static SharedBuffer<u8> serializeBulk(int version,
+	static Buffer<u8> serializeBulk(int version,
 			const MapNode *nodes, u32 nodecount,
 			u8 content_width, u8 params_width);
 	static void deSerializeBulk(std::istream &is, int version,

src/metadata.cpp

@@ -70,7 +70,7 @@ bool IMetadata::getStringToRef(const std::string &name,
 const std::string &IMetadata::resolveString(const std::string &str, std::string *place,
 		u16 recursion, bool deprecated) const
 {
-	if (recursion <= 1 && str.substr(0, 2) == "${" && str[str.length() - 1] == '}') {
+	if (recursion <= 1 && str_starts_with(str, "${") && str.back() == '}') {
 		if (deprecated) {
 			warningstream << "Deprecated use of recursive resolution syntax in metadata: ";
 			safe_print_string(warningstream, str);
@@ -128,7 +128,7 @@ const std::string *SimpleMetadata::getStringRaw(const std::string &name, std::st
 	return found != m_stringvars.cend() ? &found->second : nullptr;
 }
 
-bool SimpleMetadata::setString(const std::string &name, const std::string &var)
+bool SimpleMetadata::setString(const std::string &name, std::string_view var)
 {
 	if (var.empty()) {
 		if (m_stringvars.erase(name) == 0)
@@ -137,7 +137,7 @@ bool SimpleMetadata::setString(const std::string &name, const std::string &var)
 		StringMap::iterator it = m_stringvars.find(name);
 		if (it != m_stringvars.end() && it->second == var)
 			return false;
-		m_stringvars[name] = var;
+		m_stringvars[name].assign(var);
 	}
 	m_modified = true;
 	return true;

src/metadata.h

@@ -53,7 +53,7 @@ public:
 	bool getStringToRef(const std::string &name, std::string &str, u16 recursion = 0) const;
 
 	// Returns whether the metadata was (potentially) changed.
-	virtual bool setString(const std::string &name, const std::string &var) = 0;
+	virtual bool setString(const std::string &name, std::string_view var) = 0;
 
 	inline bool removeString(const std::string &name) { return setString(name, ""); }
 
@@ -89,7 +89,7 @@ public:
 
 	size_t size() const;
 	bool contains(const std::string &name) const override;
-	virtual bool setString(const std::string &name, const std::string &var) override;
+	virtual bool setString(const std::string &name, std::string_view var) override;
 	const StringMap &getStrings(StringMap *) const override final;
 	const std::vector<std::string> &getKeys(std::vector<std::string> *place)
 		const override final;

src/network/clientpackethandler.cpp

@@ -1651,10 +1651,8 @@ void Client::handleCommand_MediaPush(NetworkPacket *pkt)
 		std::string computed_hash;
 		{
 			SHA1 ctx;
-			ctx.addBytes(filedata.c_str(), filedata.size());
-			unsigned char *buf = ctx.getDigest();
-			computed_hash.assign((char*) buf, 20);
-			free(buf);
+			ctx.addBytes(filedata);
+			computed_hash = ctx.getDigest();
 		}
 		if (raw_hash != computed_hash) {
 			verbosestream << "Hash of file data mismatches, ignoring." << std::endl;

src/network/networkpacket.cpp

@@ -99,7 +99,7 @@ NetworkPacket& NetworkPacket::operator>>(std::string& dst)
 	return *this;
 }
 
-NetworkPacket& NetworkPacket::operator<<(const std::string &src)
+NetworkPacket& NetworkPacket::operator<<(std::string_view src)
 {
 	if (src.size() > STRING_MAX_LEN) {
 		throw PacketError("String too long");
@@ -109,12 +109,12 @@ NetworkPacket& NetworkPacket::operator<<(const std::string &src)
 
 	*this << msgsize;
 
-	putRawString(src.c_str(), (u32)msgsize);
+	putRawString(src.data(), (u32)msgsize);
 
 	return *this;
 }
 
-void NetworkPacket::putLongString(const std::string &src)
+void NetworkPacket::putLongString(std::string_view src)
 {
 	if (src.size() > LONG_STRING_MAX_LEN) {
 		throw PacketError("String too long");
@@ -124,7 +124,7 @@ void NetworkPacket::putLongString(const std::string &src)
 
 	*this << msgsize;
 
-	putRawString(src.c_str(), msgsize);
+	putRawString(src.data(), msgsize);
 }
 
 static constexpr bool NEED_SURROGATE_CODING = sizeof(wchar_t) > 2;
@@ -160,7 +160,7 @@ NetworkPacket& NetworkPacket::operator>>(std::wstring& dst)
 	return *this;
 }
 
-NetworkPacket& NetworkPacket::operator<<(const std::wstring &src)
+NetworkPacket& NetworkPacket::operator<<(std::wstring_view src)
 {
 	if (src.size() > WIDE_STRING_MAX_LEN) {
 		throw PacketError("String too long");

src/network/networkpacket.h

@@ -55,18 +55,18 @@ public:
 	const char *getString(u32 from_offset) const;
 	// major difference to putCString(): doesn't write len into the buffer
 	void putRawString(const char *src, u32 len);
-	void putRawString(const std::string &src)
+	void putRawString(std::string_view src)
 	{
-		putRawString(src.c_str(), src.size());
+		putRawString(src.data(), src.size());
 	}
 
 	NetworkPacket &operator>>(std::string &dst);
-	NetworkPacket &operator<<(const std::string &src);
+	NetworkPacket &operator<<(std::string_view src);
 
-	void putLongString(const std::string &src);
+	void putLongString(std::string_view src);
 
 	NetworkPacket &operator>>(std::wstring &dst);
-	NetworkPacket &operator<<(const std::wstring &src);
+	NetworkPacket &operator<<(std::wstring_view src);
 
 	std::string readLongString();
 

src/nodedef.cpp

@@ -1142,17 +1142,16 @@ bool NodeDefManager::getIds(const std::string &name,
 		std::vector<content_t> &result) const
 {
 	//TimeTaker t("getIds", NULL, PRECISION_MICRO);
-	if (name.substr(0,6) != "group:") {
+	if (!str_starts_with(name, "group:")) {
 		content_t id = CONTENT_IGNORE;
 		bool exists = getId(name, id);
 		if (exists)
 			result.push_back(id);
 		return exists;
 	}
-	std::string group = name.substr(6);
 
-	std::unordered_map<std::string, std::vector<content_t>>::const_iterator
-		i = m_group_to_items.find(group);
+	std::string group = name.substr(6);
+	auto i = m_group_to_items.find(group);
 	if (i == m_group_to_items.end())
 		return true;
 
@@ -1847,7 +1846,7 @@ bool NodeResolver::getIdsFromNrBacklog(std::vector<content_t> *result_out,
 		content_t c;
 		std::string &name = m_nodenames[m_nodenames_idx++];
 
-		if (name.substr(0,6) != "group:") {
+		if (!str_starts_with(name, "group:")) {
 			if (m_ndef->getId(name, c)) {
 				result_out->push_back(c);
 			} else if (all_required) {

src/nodemetadata.h

@@ -20,6 +20,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #pragma once
 
 #include <unordered_set>
+#include <map>
 #include "metadata.h"
 
 /*

src/porting.cpp

@@ -832,7 +832,7 @@ static bool open_uri(const std::string &uri)
 
 bool open_url(const std::string &url)
 {
-	if (url.substr(0, 7) != "http://" && url.substr(0, 8) != "https://") {
+	if (!str_starts_with(url, "http://") && !str_starts_with(url, "https://")) {
 		errorstream << "Unable to open browser as URL is missing schema: " << url << std::endl;
 		return false;
 	}

src/script/common/c_content.cpp

@@ -1664,7 +1664,7 @@ Pointabilities read_pointabilities(lua_State *L, int index)
 			std::string name = luaL_checkstring(L, -2);
 
 			// handle groups
-			if(std::string_view(name).substr(0,6)=="group:") {
+			if (str_starts_with(name, "group:")) {
 				pointabilities.node_groups[name.substr(6)] = read_pointability_type(L, -1);
 			} else {
 				pointabilities.nodes[name] = read_pointability_type(L, -1);
@@ -1685,7 +1685,7 @@ Pointabilities read_pointabilities(lua_State *L, int index)
 			std::string name = luaL_checkstring(L, -2);
 
 			// handle groups
-			if(std::string_view(name).substr(0,6)=="group:") {
+			if (str_starts_with(name, "group:")) {
 				pointabilities.object_groups[name.substr(6)] = read_pointability_type(L, -1);
 			} else {
 				pointabilities.objects[name] = read_pointability_type(L, -1);

src/script/common/helper.cpp

@@ -25,6 +25,7 @@ extern "C" {
 #include <cmath>
 #include <irr_v2d.h>
 #include <irr_v3d.h>
+#include <string_view>
 #include "c_converter.h"
 #include "c_types.h"
 
@@ -78,11 +79,16 @@ v3f LuaHelper::readParam(lua_State *L, int index)
 }
 
 template <>
-std::string LuaHelper::readParam(lua_State *L, int index)
+std::string_view LuaHelper::readParam(lua_State *L, int index)
 {
 	size_t length;
-	std::string result;
 	const char *str = luaL_checklstring(L, index, &length);
-	result.assign(str, length);
-	return result;
+	return std::string_view(str, length);
+}
+
+template <>
+std::string LuaHelper::readParam(lua_State *L, int index)
+{
+	auto sv = readParam<std::string_view>(L, index);
+	return std::string(sv); // a copy
 }

src/script/common/helper.h

@@ -19,6 +19,8 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 
 #pragma once
 
+#include <string_view>
+
 extern "C" {
 #include <lua.h>
 }
@@ -27,23 +29,22 @@ class LuaHelper
 {
 protected:
 	/**
-	 * Read a value using a template type T from Lua State L and index
-	 *
+	 * Read a value using a template type T from Lua state L at index
 	 *
 	 * @tparam T type to read from Lua
 	 * @param L Lua state
-	 * @param index Lua Index to read
+	 * @param index Lua index to read
 	 * @return read value from Lua
 	 */
 	template <typename T>
 	static T readParam(lua_State *L, int index);
 
 	/**
-	 * Read a value using a template type T from Lua State L and index
+	 * Read a value using a template type T from Lua state L at index
 	 *
 	 * @tparam T type to read from Lua
 	 * @param L Lua state
-	 * @param index Lua Index to read
+	 * @param index Lua index to read
 	 * @param default_value default value to apply if nil
 	 * @return read value from Lua or default value if nil
 	 */
@@ -53,3 +54,18 @@ protected:
 		return lua_isnoneornil(L, index) ? default_value : readParam<T>(L, index);
 	}
 };
+
+// (only declared for documentation purposes:)
+
+/**
+ * Read a string from Lua state L at index without copying it.
+ *
+ * Note that the returned string view is only valid as long as the value is on
+ * the stack and has not been modified. Be careful.
+ *
+ * @param L Lua state
+ * @param index Lua index to read
+ * @return string view
+ */
+template <>
+std::string_view LuaHelper::readParam(lua_State *L, int index);

src/script/lua_api/l_item.cpp

@@ -163,6 +163,9 @@ int LuaItemStack::l_get_metadata(lua_State *L)
 	NO_MAP_LOCK_REQUIRED;
 	LuaItemStack *o = checkObject<LuaItemStack>(L, 1);
 	ItemStack &item = o->m_stack;
+
+	log_deprecated(L, "ItemStack:get_metadata is deprecated", 1, true);
+
 	const std::string &value = item.metadata.getString("");
 	lua_pushlstring(L, value.c_str(), value.size());
 	return 1;
@@ -176,6 +179,8 @@ int LuaItemStack::l_set_metadata(lua_State *L)
 	LuaItemStack *o = checkObject<LuaItemStack>(L, 1);
 	ItemStack &item = o->m_stack;
 
+	log_deprecated(L, "ItemStack:set_metadata is deprecated", 1, true);
+
 	size_t len = 0;
 	const char *ptr = luaL_checklstring(L, 2, &len);
 	item.metadata.setString("", std::string(ptr, len));

src/script/lua_api/l_metadata.cpp

@@ -115,9 +115,7 @@ int MetaDataRef::l_set_string(lua_State *L)
 
 	MetaDataRef *ref = checkAnyMetadata(L, 1);
 	std::string name = luaL_checkstring(L, 2);
-	size_t len = 0;
-	const char *s = lua_tolstring(L, 3, &len);
-	std::string str(s, len);
+	auto str = readParam<std::string_view>(L, 3);
 
 	IMetadata *meta = ref->getmeta(!str.empty());
 	if (meta != NULL && meta->setString(name, str))
@@ -300,9 +298,8 @@ bool MetaDataRef::handleFromTable(lua_State *L, int table, IMetadata *meta)
 		while (lua_next(L, fieldstable) != 0) {
 			// key at index -2 and value at index -1
 			std::string name = readParam<std::string>(L, -2);
-			size_t cl;
-			const char *cs = lua_tolstring(L, -1, &cl);
-			meta->setString(name, std::string(cs, cl));
+			auto value = readParam<std::string_view>(L, -1);
+			meta->setString(name, value);
 			lua_pop(L, 1); // Remove value, keep key for next iteration
 		}
 		lua_pop(L, 1);

src/script/lua_api/l_util.cpp

@@ -318,8 +318,7 @@ int ModApiUtil::l_compress(lua_State *L)
 {
 	NO_MAP_LOCK_REQUIRED;
 
-	size_t size;
-	const char *data = luaL_checklstring(L, 1, &size);
+	auto data = readParam<std::string_view>(L, 1);
 
 	LuaCompressMethod method = get_compress_method(L, 2);
 
@@ -330,13 +329,13 @@ int ModApiUtil::l_compress(lua_State *L)
 		if (!lua_isnoneornil(L, 3))
 			level = readParam<int>(L, 3);
 
-		compressZlib(reinterpret_cast<const u8 *>(data), size, os, level);
+		compressZlib(data, os, level);
 	} else if (method == LUA_COMPRESS_METHOD_ZSTD) {
 		int level = ZSTD_CLEVEL_DEFAULT;
 		if (!lua_isnoneornil(L, 3))
 			level = readParam<int>(L, 3);
 
-		compressZstd(reinterpret_cast<const u8 *>(data), size, os, level);
+		compressZstd(data, os, level);
 	}
 
 	std::string out = os.str();
@@ -350,12 +349,12 @@ int ModApiUtil::l_decompress(lua_State *L)
 {
 	NO_MAP_LOCK_REQUIRED;
 
-	size_t size;
-	const char *data = luaL_checklstring(L, 1, &size);
+	auto data = readParam<std::string_view>(L, 1);
 
 	LuaCompressMethod method = get_compress_method(L, 2);
 
-	std::istringstream is(std::string(data, size), std::ios_base::binary);
+	// FIXME: zero copy possible in c++26 or with custom rdbuf
+	std::istringstream is(std::string(data), std::ios_base::binary);
 	std::ostringstream os(std::ios_base::binary);
 
 	if (method == LUA_COMPRESS_METHOD_DEFLATE) {
@@ -375,10 +374,9 @@ int ModApiUtil::l_encode_base64(lua_State *L)
 {
 	NO_MAP_LOCK_REQUIRED;
 
-	size_t size;
-	const char *data = luaL_checklstring(L, 1, &size);
+	auto data = readParam<std::string_view>(L, 1);
 
-	std::string out = base64_encode((const unsigned char *)(data), size);
+	std::string out = base64_encode(data);
 
 	lua_pushlstring(L, out.data(), out.size());
 	return 1;
@@ -389,9 +387,7 @@ int ModApiUtil::l_decode_base64(lua_State *L)
 {
 	NO_MAP_LOCK_REQUIRED;
 
-	size_t size;
-	const char *d = luaL_checklstring(L, 1, &size);
-	const std::string data = std::string(d, size);
+	auto data = readParam<std::string_view>(L, 1);
 
 	if (!base64_is_valid(data)) {
 		lua_pushnil(L);
@@ -487,12 +483,11 @@ int ModApiUtil::l_safe_file_write(lua_State *L)
 {
 	NO_MAP_LOCK_REQUIRED;
 	const char *path = luaL_checkstring(L, 1);
-	size_t size;
-	const char *content = luaL_checklstring(L, 2, &size);
+	auto content = readParam<std::string_view>(L, 2);
 
 	CHECK_SECURE_PATH(L, path, true);
 
-	bool ret = fs::safeWriteToFile(path, std::string(content, size));
+	bool ret = fs::safeWriteToFile(path, content);
 	lua_pushboolean(L, ret);
 
 	return 1;
@@ -549,18 +544,16 @@ int ModApiUtil::l_get_version(lua_State *L)
 int ModApiUtil::l_sha1(lua_State *L)
 {
 	NO_MAP_LOCK_REQUIRED;
-	size_t size;
-	const char *data = luaL_checklstring(L, 1, &size);
+
+	auto data = readParam<std::string_view>(L, 1);
 	bool hex = !lua_isboolean(L, 2) || !readParam<bool>(L, 2);
 
 	// Compute actual checksum of data
 	std::string data_sha1;
 	{
 		SHA1 ctx;
-		ctx.addBytes(data, size);
-		unsigned char *data_tmpdigest = ctx.getDigest();
-		data_sha1.assign((char*) data_tmpdigest, 20);
-		free(data_tmpdigest);
+		ctx.addBytes(data);
+		data_sha1 = ctx.getDigest();
 	}
 
 	if (hex) {
@@ -654,8 +647,8 @@ int ModApiUtil::l_urlencode(lua_State *L)
 {
 	NO_MAP_LOCK_REQUIRED;
 
-	const char *value = luaL_checkstring(L, 1);
-	lua_pushstring(L, urlencode(value).c_str());
+	auto s = readParam<std::string_view>(L, 1);
+	lua_pushstring(L, urlencode(s).c_str());
 	return 1;
 }
 

src/serialization.cpp

@@ -106,11 +106,6 @@ void compressZlib(const u8 *data, size_t data_size, std::ostream &os, int level)
 	}
 }
 
-void compressZlib(const std::string &data, std::ostream &os, int level)
-{
-	compressZlib((u8*)data.c_str(), data.size(), os, level);
-}
-
 void decompressZlib(std::istream &is, std::ostream &os, size_t limit)
 {
 	z_stream z;
@@ -211,7 +206,6 @@ void compressZstd(const u8 *data, size_t data_size, std::ostream &os, int level)
 	// it will be destroyed when the thread ends
 	thread_local std::unique_ptr<ZSTD_CStream, ZSTD_Deleter> stream(ZSTD_createCStream());
 
-
 	ZSTD_initCStream(stream.get(), level);
 
 	const size_t bufsize = 16384;
@@ -247,11 +241,6 @@ void compressZstd(const u8 *data, size_t data_size, std::ostream &os, int level)
 
 }
 
-void compressZstd(const std::string &data, std::ostream &os, int level)
-{
-	compressZstd((u8*)data.c_str(), data.size(), os, level);
-}
-
 void decompressZstd(std::istream &is, std::ostream &os)
 {
 	// reusing the context is recommended for performance
@@ -295,7 +284,7 @@ void decompressZstd(std::istream &is, std::ostream &os)
 	}
 }
 
-void compress(u8 *data, u32 size, std::ostream &os, u8 version, int level)
+void compress(const u8 *data, u32 size, std::ostream &os, u8 version, int level)
 {
 	if(version >= 29)
 	{
@@ -345,16 +334,6 @@ void compress(u8 *data, u32 size, std::ostream &os, u8 version, int level)
 	os.write((char*)&current_byte, 1);
 }
 
-void compress(const SharedBuffer<u8> &data, std::ostream &os, u8 version, int level)
-{
-	compress(*data, data.getSize(), os, version, level);
-}
-
-void compress(const std::string &data, std::ostream &os, u8 version, int level)
-{
-	compress((u8*)data.c_str(), data.size(), os, version, level);
-}
-
 void decompress(std::istream &is, std::ostream &os, u8 version)
 {
 	if(version >= 29)

src/serialization.h

@@ -22,7 +22,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "irrlichttypes.h"
 #include "exceptions.h"
 #include <iostream>
-#include "util/pointer.h"
+#include <string_view>
 
 /*
 	Map format serialization version
@@ -83,19 +83,27 @@ inline bool ser_ver_supported(s32 v) {
 }
 
 /*
-	Misc. serialization functions
+	Compression functions
 */
 
 void compressZlib(const u8 *data, size_t data_size, std::ostream &os, int level = -1);
-void compressZlib(const std::string &data, std::ostream &os, int level = -1);
+inline void compressZlib(std::string_view data, std::ostream &os, int level = -1)
+{
+	compressZlib(reinterpret_cast<const u8*>(data.data()), data.size(), os, level);
+}
 void decompressZlib(std::istream &is, std::ostream &os, size_t limit = 0);
 
 void compressZstd(const u8 *data, size_t data_size, std::ostream &os, int level = 0);
-void compressZstd(const std::string &data, std::ostream &os, int level = 0);
+inline void compressZstd(std::string_view data, std::ostream &os, int level = 0)
+{
+	compressZstd(reinterpret_cast<const u8*>(data.data()), data.size(), os, level);
+}
 void decompressZstd(std::istream &is, std::ostream &os);
 
-// These choose between zlib and a self-made one according to version
-void compress(const SharedBuffer<u8> &data, std::ostream &os, u8 version, int level = -1);
-void compress(const std::string &data, std::ostream &os, u8 version, int level = -1);
-void compress(u8 *data, u32 size, std::ostream &os, u8 version, int level = -1);
+// These choose between zstd, zlib and a self-made one according to version
+void compress(const u8 *data, u32 size, std::ostream &os, u8 version, int level = -1);
+inline void compress(std::string_view data, std::ostream &os, u8 version, int level = -1)
+{
+	compress(reinterpret_cast<const u8*>(data.data()), data.size(), os, version, level);
+}
 void decompress(std::istream &is, std::ostream &os, u8 version);

src/server.cpp

@@ -2534,14 +2534,13 @@ bool Server::addMediaFile(const std::string &filename,
 	}
 
 	SHA1 sha1;
-	sha1.addBytes(filedata.c_str(), filedata.length());
+	sha1.addBytes(filedata);
 
-	unsigned char *digest = sha1.getDigest();
-	std::string sha1_base64 = base64_encode(digest, 20);
-	std::string sha1_hex = hex_encode((char*) digest, 20);
+	std::string digest = sha1.getDigest();
+	std::string sha1_base64 = base64_encode(digest);
+	std::string sha1_hex = hex_encode(digest);
 	if (digest_to)
-		*digest_to = std::string((char*) digest, 20);
-	free(digest);
+		*digest_to = digest;
 
 	// Put in list
 	m_media[filename] = MediaInfo(filepath, sha1_base64);

src/server.h

@@ -93,8 +93,8 @@ struct MediaInfo
 	// does what it says. used by some cases of dynamic media.
 	bool delete_at_shutdown;
 
-	MediaInfo(const std::string &path_="",
-	          const std::string &sha1_digest_=""):
+	MediaInfo(std::string_view path_ = "",
+	          std::string_view sha1_digest_ = ""):
 		path(path_),
 		sha1_digest(sha1_digest_),
 		no_announce(false),

src/settings.cpp

@@ -97,7 +97,7 @@ void SettingsHierarchy::onLayerRemoved(int layer)
 
 /* Settings implementation */
 
-Settings *Settings::createLayer(SettingsLayer sl, const std::string &end_tag)
+Settings *Settings::createLayer(SettingsLayer sl, std::string_view end_tag)
 {
 	return new Settings(end_tag, &g_hierarchy, (int)sl);
 }
@@ -109,7 +109,7 @@ Settings *Settings::getLayer(SettingsLayer sl)
 }
 
 
-Settings::Settings(const std::string &end_tag, SettingsHierarchy *h,
+Settings::Settings(std::string_view end_tag, SettingsHierarchy *h,
 		int settings_layer) :
 	m_end_tag(end_tag),
 	m_hierarchy(h),
@@ -131,7 +131,7 @@ Settings::~Settings()
 }
 
 
-Settings & Settings::operator = (const Settings &other)
+Settings & Settings::operator=(const Settings &other)
 {
 	if (&other == this)
 		return *this;
@@ -151,7 +151,7 @@ Settings & Settings::operator = (const Settings &other)
 }
 
 
-bool Settings::checkNameValid(const std::string &name)
+bool Settings::checkNameValid(std::string_view name)
 {
 	bool valid = name.find_first_of("=\"{}#") == std::string::npos;
 	if (valid)
@@ -166,7 +166,7 @@ bool Settings::checkNameValid(const std::string &name)
 }
 
 
-bool Settings::checkValueValid(const std::string &value)
+bool Settings::checkValueValid(std::string_view value)
 {
 	if (value.substr(0, 3) == "\"\"\"" ||
 		value.find("\n\"\"\"") != std::string::npos) {
@@ -407,13 +407,13 @@ bool Settings::parseCommandLine(int argc, char *argv[],
 {
 	int nonopt_index = 0;
 	for (int i = 1; i < argc; i++) {
-		std::string arg_name = argv[i];
+		std::string_view arg_name(argv[i]);
 		if (arg_name.substr(0, 2) != "--") {
 			// If option doesn't start with -, read it in as nonoptX
-			if (arg_name[0] != '-'){
+			if (arg_name[0] != '-') {
 				std::string name = "nonopt";
 				name += itos(nonopt_index);
-				set(name, arg_name);
+				set(name, std::string(arg_name));
 				nonopt_index++;
 				continue;
 			}
@@ -422,7 +422,7 @@ bool Settings::parseCommandLine(int argc, char *argv[],
 			return false;
 		}
 
-		std::string name = arg_name.substr(2);
+		std::string name(arg_name.substr(2));
 
 		auto n = allowed_options.find(name);
 		if (n == allowed_options.end()) {
@@ -997,7 +997,7 @@ bool Settings::remove(const std::string &name)
 SettingsParseEvent Settings::parseConfigObject(const std::string &line,
 	std::string &name, std::string &value)
 {
-	std::string trimmed_line = trim(line);
+	auto trimmed_line = trim(line);
 
 	if (trimmed_line.empty())
 		return SPE_NONE;

src/settings.h

@@ -23,8 +23,8 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "util/string.h"
 #include "util/basic_macros.h"
 #include <string>
-#include <list>
 #include <set>
+#include <map>
 #include <mutex>
 
 class Settings;
@@ -124,18 +124,17 @@ typedef std::unordered_map<std::string, SettingsEntry> SettingEntries;
 class Settings {
 public:
 	/* These functions operate on the global hierarchy! */
-	static Settings *createLayer(SettingsLayer sl, const std::string &end_tag = "");
+	static Settings *createLayer(SettingsLayer sl, std::string_view end_tag = "");
 	static Settings *getLayer(SettingsLayer sl);
 	/**/
 
-	Settings(const std::string &end_tag = "") :
+	Settings(std::string_view end_tag = "") :
 		m_end_tag(end_tag)
 	{}
-	Settings(const std::string &end_tag, SettingsHierarchy *h, int settings_layer);
+	Settings(std::string_view end_tag, SettingsHierarchy *h, int settings_layer);
 	~Settings();
 
-	Settings & operator += (const Settings &other);
-	Settings & operator = (const Settings &other);
+	Settings & operator=(const Settings &other);
 
 	/***********************
 	 * Reading and writing *
@@ -258,8 +257,8 @@ private:
 	bool updateConfigObject(std::istream &is, std::ostream &os,
 		u32 tab_depth=0);
 
-	static bool checkNameValid(const std::string &name);
-	static bool checkValueValid(const std::string &value);
+	static bool checkNameValid(std::string_view name);
+	static bool checkValueValid(std::string_view value);
 	static std::string getMultiline(std::istream &is, size_t *num_lines=NULL);
 	static void printEntry(std::ostream &os, const std::string &name,
 		const SettingsEntry &entry, u32 tab_depth=0);
@@ -276,9 +275,7 @@ private:
 	// For sane mutex locking when iterating
 	friend class LuaSettings;
 
-	void updateNoLock(const Settings &other);
 	void clearNoLock();
-	void clearDefaultsNoLock();
 
 	void doCallbacks(const std::string &name) const;
 

src/sound.h

@@ -33,7 +33,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 */
 struct SoundSpec
 {
-	SoundSpec(const std::string &name = "", float gain = 1.0f,
+	SoundSpec(std::string_view name = "", float gain = 1.0f,
 			bool loop = false, float fade = 0.0f, float pitch = 1.0f,
 			float start_time = 0.0f) :
 			name(name), gain(gain), fade(fade), pitch(pitch), start_time(start_time),

src/unittest/test_compression.cpp

@@ -57,7 +57,7 @@ void TestCompression::runTests(IGameDef *gamedef)
 
 void TestCompression::testRLECompression()
 {
-	SharedBuffer<u8> fromdata(4);
+	Buffer<u8> fromdata(4);
 	fromdata[0]=1;
 	fromdata[1]=5;
 	fromdata[2]=5;
@@ -106,7 +106,7 @@ void TestCompression::testRLECompression()
 
 void TestCompression::testZlibCompression()
 {
-	SharedBuffer<u8> fromdata(4);
+	Buffer<u8> fromdata(4);
 	fromdata[0]=1;
 	fromdata[1]=5;
 	fromdata[2]=5;

src/unittest/test_map_settings_manager.cpp

@@ -189,10 +189,9 @@ void TestMapSettingsManager::testMapSettingsManager()
 	SHA1 ctx;
 	std::string metafile_contents;
 	UASSERT(fs::ReadFile(test_mapmeta_path, metafile_contents));
-	ctx.addBytes(&metafile_contents[0], metafile_contents.size());
-	unsigned char *sha1_result = ctx.getDigest();
-	int resultdiff = memcmp(sha1_result, expected_contents_hash, 20);
-	free(sha1_result);
+	ctx.addBytes(metafile_contents);
+	std::string sha1_result = ctx.getDigest();
+	int resultdiff = memcmp(sha1_result.data(), expected_contents_hash, 20);
 
 	UASSERT(!resultdiff);
 #endif

src/unittest/test_utilities.cpp

@@ -240,20 +240,26 @@ void TestUtilities::testPadString()
 
 void TestUtilities::testStartsWith()
 {
-	UASSERT(str_starts_with(std::string(), std::string()) == true);
+	std::string the("the");
+	UASSERT(str_starts_with(std::string(), "") == true);
 	UASSERT(str_starts_with(std::string("the sharp pickaxe"),
 		std::string()) == true);
 	UASSERT(str_starts_with(std::string("the sharp pickaxe"),
-		std::string("the")) == true);
+		std::string_view(the)) == true);
 	UASSERT(str_starts_with(std::string("the sharp pickaxe"),
 		std::string("The")) == false);
 	UASSERT(str_starts_with(std::string("the sharp pickaxe"),
 		std::string("The"), true) == true);
-	UASSERT(str_starts_with(std::string("T"), std::string("The")) == false);
+	UASSERT(str_starts_with(std::string("T"), "The") == false);
 }
 
 void TestUtilities::testStrEqual()
 {
+	std::string foo("foo");
+	UASSERT(str_equal(foo, std::string_view(foo)));
+	UASSERT(!str_equal(foo, std::string("bar")));
+	UASSERT(str_equal(std::string_view(foo), std::string_view(foo)));
+	UASSERT(str_equal(std::wstring(L"FOO"), std::wstring(L"foo"), true));
 	UASSERT(str_equal(utf8_to_wide("abc"), utf8_to_wide("abc")));
 	UASSERT(str_equal(utf8_to_wide("ABC"), utf8_to_wide("abc"), true));
 }
@@ -629,14 +635,14 @@ void TestUtilities::testBase64()
 
 void TestUtilities::testSanitizeDirName()
 {
-	UASSERT(sanitizeDirName("a", "~") == "a");
-	UASSERT(sanitizeDirName("  ", "~") == "__");
-	UASSERT(sanitizeDirName(" a ", "~") == "_a_");
-	UASSERT(sanitizeDirName("COM1", "~") == "~COM1");
-	UASSERT(sanitizeDirName("COM1", ":") == "_COM1");
-	UASSERT(sanitizeDirName("cOm\u00B2", "~") == "~cOm\u00B2");
-	UASSERT(sanitizeDirName("cOnIn$", "~") == "~cOnIn$");
-	UASSERT(sanitizeDirName(" cOnIn$ ", "~") == "_cOnIn$_");
+	UASSERTEQ(auto, sanitizeDirName("a", "~"), "a");
+	UASSERTEQ(auto, sanitizeDirName("  ", "~"), "__");
+	UASSERTEQ(auto, sanitizeDirName(" a ", "~"), "_a_");
+	UASSERTEQ(auto, sanitizeDirName("COM1", "~"), "~COM1");
+	UASSERTEQ(auto, sanitizeDirName("COM1", ":"), "_COM1");
+	UASSERTEQ(auto, sanitizeDirName("cOm\u00B2", "~"), "~cOm\u00B2");
+	UASSERTEQ(auto, sanitizeDirName("cOnIn$", "~"), "~cOnIn$");
+	UASSERTEQ(auto, sanitizeDirName(" cOnIn$ ", "~"), "_cOnIn$_");
 }
 
 template <typename F, typename C>

src/util/auth.cpp

@@ -39,10 +39,9 @@ std::string translate_password(const std::string &name,
 
 	std::string slt = name + password;
 	SHA1 sha1;
-	sha1.addBytes(slt.c_str(), slt.length());
-	unsigned char *digest = sha1.getDigest();
-	std::string pwd = base64_encode(digest, 20);
-	free(digest);
+	sha1.addBytes(slt);
+	std::string digest = sha1.getDigest();
+	std::string pwd = base64_encode(digest);
 	return pwd;
 }
 
@@ -112,8 +111,8 @@ std::string encode_srp_verifier(const std::string &verifier,
 {
 	std::ostringstream ret_str;
 	ret_str << "#1#"
-		<< base64_encode((unsigned char *)salt.c_str(), salt.size()) << "#"
-		<< base64_encode((unsigned char *)verifier.c_str(), verifier.size());
+		<< base64_encode(salt) << "#"
+		<< base64_encode(verifier);
 	return ret_str.str();
 }
 

src/util/base64.cpp

@@ -45,15 +45,15 @@ static inline bool is_base64(unsigned char c)
 			|| c == '+' || c == '/';
 }
 
-bool base64_is_valid(std::string const& s)
+bool base64_is_valid(std::string_view s)
 {
 	size_t i = 0;
 	for (; i < s.size(); ++i)
 		if (!is_base64(s[i]))
 			break;
 	unsigned char padding = 3 - ((i + 3) % 4);
-	if ((padding == 1 && base64_chars_padding_1.find(s[i - 1]) == std::string::npos)
-			|| (padding == 2 && base64_chars_padding_2.find(s[i - 1]) == std::string::npos)
+	if ((padding == 1 && base64_chars_padding_1.find(s[i - 1]) == s.npos)
+			|| (padding == 2 && base64_chars_padding_2.find(s[i - 1]) == s.npos)
 			|| padding == 3)
 		return false;
 	int actual_padding = s.size() - i;
@@ -69,8 +69,14 @@ bool base64_is_valid(std::string const& s)
 	return padding == actual_padding;
 }
 
-std::string base64_encode(unsigned char const* bytes_to_encode, unsigned int in_len) {
+std::string base64_encode(std::string_view s)
+{
+	const unsigned char *bytes_to_encode = reinterpret_cast<const unsigned char*>(s.data());
+	size_t in_len = s.size();
+
 	std::string ret;
+	ret.reserve(in_len + in_len / 3);
+
 	int i = 0;
 	int j = 0;
 	unsigned char char_array_3[3];
@@ -110,16 +116,17 @@ std::string base64_encode(unsigned char const* bytes_to_encode, unsigned int in_
 	}
 
 	return ret;
-
 }
 
-std::string base64_decode(std::string const& encoded_string) {
+std::string base64_decode(std::string_view encoded_string)
+{
 	int in_len = encoded_string.size();
 	int i = 0;
 	int j = 0;
 	int in_ = 0;
 	unsigned char char_array_4[4], char_array_3[3];
 	std::string ret;
+	ret.reserve(in_len / 4 * 3);
 
 	while (in_len-- && ( encoded_string[in_] != '=') && is_base64(encoded_string[in_])) {
 		char_array_4[i++] = encoded_string[in_]; in_++;

src/util/base64.h

@@ -29,7 +29,8 @@ René Nyffenegger rene.nyffenegger@adp-gmbh.ch
 #pragma once
 
 #include <string>
+#include <string_view>
 
-bool base64_is_valid(std::string const& s);
-std::string base64_encode(unsigned char const* , unsigned int len);
-std::string base64_decode(std::string const& s);
+bool base64_is_valid(std::string_view s);
+std::string base64_encode(std::string_view s);
+std::string base64_decode(std::string_view s);

src/util/hex.h

@@ -20,6 +20,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #pragma once
 
 #include <string>
+#include <string_view>
 
 static const char hex_chars[] = "0123456789abcdef";
 
@@ -41,9 +42,9 @@ static inline std::string hex_encode(const char *data, unsigned int data_size)
 	return ret;
 }
 
-static inline std::string hex_encode(const std::string &data)
+static inline std::string hex_encode(std::string_view data)
 {
-	return hex_encode(data.c_str(), data.size());
+	return hex_encode(data.data(), data.size());
 }
 
 static inline bool hex_digit_decode(char hexdigit, unsigned char &value)

src/util/pointer.h

@@ -23,6 +23,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "debug.h" // For assert()
 #include <cstring>
 #include <memory> // std::shared_ptr
+#include <string_view>
 
 
 template<typename T> class ConstSharedPtr {
@@ -133,6 +134,13 @@ public:
 		return m_size;
 	}
 
+	operator std::string_view() const
+	{
+		if (!data)
+			return std::string_view();
+		return std::string_view(reinterpret_cast<char*>(data), m_size);
+	}
+
 private:
 	void drop()
 	{

src/util/serialize.cpp

@@ -34,7 +34,7 @@ FloatType g_serialize_f32_type = FLOATTYPE_UNKNOWN;
 //// String
 ////
 
-std::string serializeString16(const std::string &plain)
+std::string serializeString16(std::string_view plain)
 {
 	std::string s;
 	char buf[2];
@@ -76,7 +76,7 @@ std::string deSerializeString16(std::istream &is)
 //// Long String
 ////
 
-std::string serializeString32(const std::string &plain)
+std::string serializeString32(std::string_view plain)
 {
 	std::string s;
 	char buf[4];
@@ -122,7 +122,7 @@ std::string deSerializeString32(std::istream &is)
 //// JSON-like strings
 ////
 
-std::string serializeJsonString(const std::string &plain)
+std::string serializeJsonString(std::string_view plain)
 {
 	std::string tmp;
 
@@ -263,13 +263,13 @@ std::string deSerializeJsonString(std::istream &is)
 	return tmp;
 }
 
-std::string serializeJsonStringIfNeeded(const std::string &s)
+std::string serializeJsonStringIfNeeded(std::string_view s)
 {
 	for (size_t i = 0; i < s.size(); ++i) {
 		if (s[i] <= 0x1f || s[i] >= 0x7f || s[i] == ' ' || s[i] == '\"')
 			return serializeJsonString(s);
 	}
-	return s;
+	return std::string(s);
 }
 
 std::string deSerializeJsonStringIfNeeded(std::istream &is)

src/util/serialize.h

@@ -41,7 +41,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include <cstring> // for memcpy
 #include <iostream>
 #include <string>
-#include <vector>
+#include <string_view>
 
 #define FIXEDPOINT_FACTOR 1000.0f
 
@@ -450,26 +450,26 @@ inline v3f clampToF1000(v3f v)
 }
 
 // Creates a string with the length as the first two bytes
-std::string serializeString16(const std::string &plain);
+std::string serializeString16(std::string_view plain);
 
 // Reads a string with the length as the first two bytes
 std::string deSerializeString16(std::istream &is);
 
 // Creates a string with the length as the first four bytes
-std::string serializeString32(const std::string &plain);
+std::string serializeString32(std::string_view plain);
 
 // Reads a string with the length as the first four bytes
 std::string deSerializeString32(std::istream &is);
 
 // Creates a string encoded in JSON format (almost equivalent to a C string literal)
-std::string serializeJsonString(const std::string &plain);
+std::string serializeJsonString(std::string_view plain);
 
 // Reads a string encoded in JSON format
 std::string deSerializeJsonString(std::istream &is);
 
 // If the string contains spaces, quotes or control characters, encodes as JSON.
 // Else returns the string unmodified.
-std::string serializeJsonStringIfNeeded(const std::string &s);
+std::string serializeJsonStringIfNeeded(std::string_view s);
 
 // Parses a string serialized by serializeJsonStringIfNeeded.
 std::string deSerializeJsonStringIfNeeded(std::istream &is);

src/util/sha1.cpp

@@ -65,7 +65,7 @@ void SHA1::storeBigEndianUint32( unsigned char* byte, Uint32 num )
 SHA1::SHA1()
 {
 	// make sure that the data type is the right size
-	assert( sizeof( Uint32 ) * 5 == 20 );
+	static_assert( sizeof( Uint32 ) * 5 == 20 );
 }
 
 // Destructor ********************************************************
@@ -134,20 +134,19 @@ void SHA1::process()
 }
 
 // addBytes **********************************************************
-void SHA1::addBytes( const char* data, int num )
+void SHA1::addBytes( const char* data, Uint32 num )
 {
 	assert( data );
-	assert( num >= 0 );
 	// add these bytes to the running total
 	size += num;
 	// repeat until all data is processed
 	while( num > 0 )
 	{
 		// number of bytes required to complete block
-		int needed = 64 - unprocessedBytes;
-		assert( needed > 0 );
+		Uint32 needed = 64 - unprocessedBytes;
+		assert( needed <= 64 );
 		// number of bytes to copy (use smaller of two)
-		int toCopy = (num < needed) ? num : needed;
+		Uint32 toCopy = (num < needed) ? num : needed;
 		// Copy the bytes
 		memcpy( bytes + unprocessedBytes, data, toCopy );
 		// Bytes have been copied
@@ -161,7 +160,7 @@ void SHA1::addBytes( const char* data, int num )
 }
 
 // digest ************************************************************
-unsigned char* SHA1::getDigest()
+void SHA1::getDigest(unsigned char *digest)
 {
 	// save the message size
 	Uint32 totalBitsL = size << 3;
@@ -179,20 +178,16 @@ unsigned char* SHA1::getDigest()
 		addBytes( (char*)footer, 64 - unprocessedBytes);
 	assert( unprocessedBytes <= 56 );
 	// how many zeros do we need
-	int neededZeros = 56 - unprocessedBytes;
+	Uint32 neededZeros = 56 - unprocessedBytes;
 	// store file size (in bits) in big-endian format
 	storeBigEndianUint32( footer + neededZeros    , totalBitsH );
 	storeBigEndianUint32( footer + neededZeros + 4, totalBitsL );
 	// finish the final block
 	addBytes( (char*)footer, neededZeros + 8 );
-	// allocate memory for the digest bytes
-	unsigned char* digest = (unsigned char*)malloc( 20 );
 	// copy the digest bytes
 	storeBigEndianUint32( digest, H0 );
 	storeBigEndianUint32( digest + 4, H1 );
 	storeBigEndianUint32( digest + 8, H2 );
 	storeBigEndianUint32( digest + 12, H3 );
 	storeBigEndianUint32( digest + 16, H4 );
-	// return the digest
-	return digest;
 }

src/util/sha1.h

@@ -26,7 +26,11 @@ SOFTWARE.
 
 #pragma once
 
-typedef unsigned int Uint32;
+#include <cstdint>
+#include <string>
+#include <string_view>
+
+typedef uint32_t Uint32;
 
 class SHA1
 {
@@ -38,15 +42,24 @@ private:
 	Uint32 H3 = 0x10325476;
 	Uint32 H4 = 0xc3d2e1f0;
 	unsigned char bytes[64];
-	int unprocessedBytes = 0;
+	Uint32 unprocessedBytes = 0;
 	Uint32 size = 0;
 	void process();
 
 public:
 	SHA1();
 	~SHA1();
-	void addBytes(const char *data, int num);
-	unsigned char *getDigest();
+	void addBytes(const char *data, Uint32 num);
+	inline void addBytes(std::string_view data) {
+		addBytes(data.data(), data.size());
+	}
+	void getDigest(unsigned char *to);
+	inline std::string getDigest() {
+		std::string ret(20, '\000');
+		getDigest(reinterpret_cast<unsigned char*>(ret.data()));
+		return ret;
+	}
+
 	// utility methods
 	static Uint32 lrot(Uint32 x, int bits);
 	static void storeBigEndianUint32(unsigned char *byte, Uint32 num);

src/util/strfnd.h

@@ -20,14 +20,19 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #pragma once
 
 #include <string>
+#include <string_view>
 
+// FIXME: convert this class to string_view
 template <typename T>
 class BasicStrfnd {
 	typedef std::basic_string<T> String;
 	String str;
 	size_t pos;
 public:
-	BasicStrfnd(const String &s) : str(s), pos(0) {}
+	BasicStrfnd(const String &s) { start(s); }
+	BasicStrfnd(const T *ptr) { str = ptr; pos = 0; }
+	BasicStrfnd(std::basic_string_view<T> sv) { str = sv; pos = 0; }
+
 	void start(const String &s) { str = s; pos = 0; }
 	size_t where() { return pos; }
 	void to(size_t i) { pos = i; }

src/util/string.cpp

@@ -82,14 +82,14 @@ const char *DEFAULT_ENCODING = "UTF-32LE";
 const char *DEFAULT_ENCODING = "WCHAR_T";
 #endif
 
-std::wstring utf8_to_wide(const std::string &input)
+std::wstring utf8_to_wide(std::string_view input)
 {
 	const size_t inbuf_size = input.length();
 	// maximum possible size, every character is sizeof(wchar_t) bytes
 	size_t outbuf_size = input.length() * sizeof(wchar_t);
 
 	char *inbuf = new char[inbuf_size]; // intentionally NOT null-terminated
-	memcpy(inbuf, input.c_str(), inbuf_size);
+	memcpy(inbuf, input.data(), inbuf_size);
 	std::wstring out;
 	out.resize(outbuf_size / sizeof(wchar_t));
 
@@ -110,14 +110,14 @@ std::wstring utf8_to_wide(const std::string &input)
 	return out;
 }
 
-std::string wide_to_utf8(const std::wstring &input)
+std::string wide_to_utf8(std::wstring_view input)
 {
 	const size_t inbuf_size = input.length() * sizeof(wchar_t);
 	// maximum possible size: utf-8 encodes codepoints using 1 up to 4 bytes
 	size_t outbuf_size = input.length() * 4;
 
 	char *inbuf = new char[inbuf_size]; // intentionally NOT null-terminated
-	memcpy(inbuf, input.c_str(), inbuf_size);
+	memcpy(inbuf, input.data(), inbuf_size);
 	std::string out;
 	out.resize(outbuf_size);
 
@@ -135,24 +135,24 @@ std::string wide_to_utf8(const std::wstring &input)
 
 #else // _WIN32
 
-std::wstring utf8_to_wide(const std::string &input)
+std::wstring utf8_to_wide(std::string_view input)
 {
 	size_t outbuf_size = input.size() + 1;
 	wchar_t *outbuf = new wchar_t[outbuf_size];
 	memset(outbuf, 0, outbuf_size * sizeof(wchar_t));
-	MultiByteToWideChar(CP_UTF8, 0, input.c_str(), input.size(),
+	MultiByteToWideChar(CP_UTF8, 0, input.data(), input.size(),
 		outbuf, outbuf_size);
 	std::wstring out(outbuf);
 	delete[] outbuf;
 	return out;
 }
 
-std::string wide_to_utf8(const std::wstring &input)
+std::string wide_to_utf8(std::wstring_view input)
 {
 	size_t outbuf_size = (input.size() + 1) * 6;
 	char *outbuf = new char[outbuf_size];
 	memset(outbuf, 0, outbuf_size);
-	WideCharToMultiByte(CP_UTF8, 0, input.c_str(), input.size(),
+	WideCharToMultiByte(CP_UTF8, 0, input.data(), input.size(),
 		outbuf, outbuf_size, NULL, NULL);
 	std::string out(outbuf);
 	delete[] outbuf;
@@ -162,9 +162,9 @@ std::string wide_to_utf8(const std::wstring &input)
 #endif // _WIN32
 
 
-std::string urlencode(const std::string &str)
+std::string urlencode(std::string_view str)
 {
-	// Encodes non-unreserved URI characters by a percent sign
+	// Encodes reserved URI characters by a percent sign
 	// followed by two hex digits. See RFC 3986, section 2.3.
 	static const char url_hex_chars[] = "0123456789ABCDEF";
 	std::ostringstream oss(std::ios::binary);
@@ -180,7 +180,7 @@ std::string urlencode(const std::string &str)
 	return oss.str();
 }
 
-std::string urldecode(const std::string &str)
+std::string urldecode(std::string_view str)
 {
 	// Inverse of urlencode
 	std::ostringstream oss(std::ios::binary);
@@ -615,10 +615,10 @@ void str_replace(std::string &str, char from, char to)
  * before filling it again.
  */
 
-void translate_all(const std::wstring &s, size_t &i,
+static void translate_all(const std::wstring &s, size_t &i,
 		Translations *translations, std::wstring &res);
 
-void translate_string(const std::wstring &s, Translations *translations,
+static void translate_string(const std::wstring &s, Translations *translations,
 		const std::wstring &textdomain, size_t &i, std::wstring &res)
 {
 	std::wostringstream output;
@@ -732,14 +732,15 @@ void translate_string(const std::wstring &s, Translations *translations,
 	res = result.str();
 }
 
-void translate_all(const std::wstring &s, size_t &i,
+static void translate_all(const std::wstring &s, size_t &i,
 		Translations *translations, std::wstring &res)
 {
-	std::wostringstream output;
+	res.clear();
+	res.reserve(s.length());
 	while (i < s.length()) {
 		// Not an escape sequence: just add the character.
 		if (s[i] != '\x1b') {
-			output.put(s[i]);
+			res.append(1, s[i]);
 			++i;
 			continue;
 		}
@@ -747,7 +748,7 @@ void translate_all(const std::wstring &s, size_t &i,
 		// We have an escape sequence: locate it and its data
 		// It is either a single character, or it begins with '('
 		// and extends up to the following ')', with '\' as an escape character.
-		size_t escape_start = i;
+		const size_t escape_start = i;
 		++i;
 		size_t start_index = i;
 		size_t length;
@@ -784,14 +785,12 @@ void translate_all(const std::wstring &s, size_t &i,
 				textdomain = parts[1];
 			std::wstring translated;
 			translate_string(s, translations, textdomain, i, translated);
-			output << translated;
+			res.append(translated);
 		} else {
 			// Another escape sequence, such as colors. Preserve it.
-			output << std::wstring(s, escape_start, i - escape_start);
+			res.append(&s[escape_start], i - escape_start);
 		}
 	}
-
-	res = output.str();
 }
 
 // Translate string server side
@@ -813,7 +812,7 @@ std::wstring translate_string(const std::wstring &s)
 #endif
 }
 
-static const std::array<std::wstring, 30> disallowed_dir_names = {
+static const std::array<std::wstring_view, 30> disallowed_dir_names = {
 	// Problematic filenames from here:
 	// https://docs.microsoft.com/en-us/windows/win32/fileio/naming-a-file#file-and-directory-names
 	// Plus undocumented values from here:
@@ -853,10 +852,10 @@ static const std::array<std::wstring, 30> disallowed_dir_names = {
 /**
  * List of characters that are blacklisted from created directories
  */
-static const std::wstring disallowed_path_chars = L"<>:\"/\\|?*.";
+static const std::wstring_view disallowed_path_chars = L"<>:\"/\\|?*.";
 
 
-std::string sanitizeDirName(const std::string &str, const std::string &optional_prefix)
+std::string sanitizeDirName(std::string_view str, std::string_view optional_prefix)
 {
 	std::wstring safe_name = utf8_to_wide(str);
 
@@ -897,7 +896,7 @@ std::string sanitizeDirName(const std::string &str, const std::string &optional_
 }
 
 
-void safe_print_string(std::ostream &os, const std::string &str)
+void safe_print_string(std::ostream &os, std::string_view str)
 {
 	std::ostream::fmtflags flags = os.flags();
 	os << std::hex;
@@ -913,7 +912,7 @@ void safe_print_string(std::ostream &os, const std::string &str)
 }
 
 
-v3f str_to_v3f(const std::string &str)
+v3f str_to_v3f(std::string_view str)
 {
 	v3f value;
 	Strfnd f(str);

src/util/string.h

@@ -23,10 +23,10 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "irrString.h"
 #include <cstdlib>
 #include <string>
+#include <string_view>
 #include <cstring>
 #include <vector>
 #include <limits>
-#include <map>
 #include <sstream>
 #include <iomanip>
 #include <cctype>
@@ -76,15 +76,18 @@ struct FlagDesc {
 
 // Try to avoid converting between wide and UTF-8 unless you need to
 // input/output stuff via Irrlicht
-std::wstring utf8_to_wide(const std::string &input);
-std::string wide_to_utf8(const std::wstring &input);
+std::wstring utf8_to_wide(std::string_view input);
+std::string wide_to_utf8(std::wstring_view input);
+
+std::string urlencode(std::string_view str);
+std::string urldecode(std::string_view str);
 
-std::string urlencode(const std::string &str);
-std::string urldecode(const std::string &str);
 u32 readFlagString(std::string str, const FlagDesc *flagdesc, u32 *flagmask);
 std::string writeFlagString(u32 flags, const FlagDesc *flagdesc, u32 flagmask);
+
 size_t mystrlcpy(char *dst, const char *src, size_t size) noexcept;
 char *mystrtok_r(char *s, const char *sep, char **lasts) noexcept;
+
 u64 read_seed(const char *str);
 bool parseColorString(const std::string &value, video::SColor &color, bool quiet,
 		unsigned char default_alpha = 0xff);
@@ -115,23 +118,32 @@ inline std::string padStringRight(std::string str, size_t len)
  *
  * @return If no end could be removed then "" is returned.
  */
-inline std::string removeStringEnd(const std::string &str,
+inline std::string_view removeStringEnd(std::string_view str,
 		const char *ends[])
 {
 	const char **p = ends;
 
 	for (; *p && (*p)[0] != '\0'; p++) {
-		std::string end = *p;
+		std::string_view end(*p);
 		if (str.size() < end.size())
 			continue;
 		if (str.compare(str.size() - end.size(), end.size(), end) == 0)
 			return str.substr(0, str.size() - end.size());
 	}
 
-	return "";
+	return std::string_view();
 }
 
 
+#define MAKE_VARIANT(_name, _t0, _t1) \
+	template <typename T, typename... Args> \
+	inline auto _name(_t0 arg1, _t1 arg2, Args&&... args) \
+	{ \
+		return (_name)(std::basic_string_view<T>(arg1), std::basic_string_view<T>(arg2), \
+			std::forward<Args>(args)...); \
+	}
+
+
 /**
  * Check two strings for equivalence.  If \p case_insensitive is true
  * then the case of the strings is ignored (default is false).
@@ -142,8 +154,8 @@ inline std::string removeStringEnd(const std::string &str,
  * @return true if the strings match
  */
 template <typename T>
-inline bool str_equal(const std::basic_string<T> &s1,
-		const std::basic_string<T> &s2,
+inline bool str_equal(std::basic_string_view<T> s1,
+		std::basic_string_view<T> s2,
 		bool case_insensitive = false)
 {
 	if (!case_insensitive)
@@ -159,6 +171,16 @@ inline bool str_equal(const std::basic_string<T> &s1,
 	return true;
 }
 
+// For some reason an std::string will not implicitly get converted
+// to an std::basic_string_view<char> in the template case above, so we need
+// these three wrappers. It works if you take out the template parameters.
+// see also <https://stackoverflow.com/questions/68380141/>
+MAKE_VARIANT(str_equal, const std::basic_string<T> &, const std::basic_string<T> &)
+
+MAKE_VARIANT(str_equal, std::basic_string_view<T>, const std::basic_string<T> &)
+
+MAKE_VARIANT(str_equal, const std::basic_string<T> &, std::basic_string_view<T>)
+
 
 /**
  * Check whether \p str begins with the string prefix. If \p case_insensitive
@@ -171,8 +193,8 @@ inline bool str_equal(const std::basic_string<T> &s1,
  * @return true if the str begins with prefix
  */
 template <typename T>
-inline bool str_starts_with(const std::basic_string<T> &str,
-		const std::basic_string<T> &prefix,
+inline bool str_starts_with(std::basic_string_view<T> str,
+		std::basic_string_view<T> prefix,
 		bool case_insensitive = false)
 {
 	if (str.size() < prefix.size())
@@ -187,24 +209,17 @@ inline bool str_starts_with(const std::basic_string<T> &str,
 	return true;
 }
 
-/**
- * Check whether \p str begins with the string prefix. If \p case_insensitive
- * is true then the check is case insensitve (default is false; i.e. case is
- * significant).
- *
- * @param str
- * @param prefix
- * @param case_insensitive
- * @return true if the str begins with prefix
- */
-template <typename T>
-inline bool str_starts_with(const std::basic_string<T> &str,
-		const T *prefix,
-		bool case_insensitive = false)
-{
-	return str_starts_with(str, std::basic_string<T>(prefix),
-			case_insensitive);
-}
+// (same conversion issue here)
+MAKE_VARIANT(str_starts_with, const std::basic_string<T> &, const std::basic_string<T> &)
+
+MAKE_VARIANT(str_starts_with, std::basic_string_view<T>, const std::basic_string<T> &)
+
+MAKE_VARIANT(str_starts_with, const std::basic_string<T> &, std::basic_string_view<T>)
+
+// (the same but with char pointers, only for the prefix argument)
+MAKE_VARIANT(str_starts_with, const std::basic_string<T> &, const T*)
+
+MAKE_VARIANT(str_starts_with, std::basic_string_view<T>, const T*)
 
 
 /**
@@ -218,8 +233,8 @@ inline bool str_starts_with(const std::basic_string<T> &str,
  * @return true if the str begins with suffix
  */
 template <typename T>
-inline bool str_ends_with(const std::basic_string<T> &str,
-		const std::basic_string<T> &suffix,
+inline bool str_ends_with(std::basic_string_view<T> str,
+		std::basic_string_view<T> suffix,
 		bool case_insensitive = false)
 {
 	if (str.size() < suffix.size())
@@ -235,25 +250,20 @@ inline bool str_ends_with(const std::basic_string<T> &str,
 	return true;
 }
 
+// (same conversion issue here)
+MAKE_VARIANT(str_ends_with, const std::basic_string<T> &, const std::basic_string<T> &)
 
-/**
- * Check whether \p str ends with the string suffix. If \p case_insensitive
- * is true then the check is case insensitve (default is false; i.e. case is
- * significant).
- *
- * @param str
- * @param suffix
- * @param case_insensitive
- * @return true if the str begins with suffix
- */
-template <typename T>
-inline bool str_ends_with(const std::basic_string<T> &str,
-		const T *suffix,
-		bool case_insensitive = false)
-{
-	return str_ends_with(str, std::basic_string<T>(suffix),
-			case_insensitive);
-}
+MAKE_VARIANT(str_ends_with, std::basic_string_view<T>, const std::basic_string<T> &)
+
+MAKE_VARIANT(str_ends_with, const std::basic_string<T> &, std::basic_string_view<T>)
+
+// (the same but with char pointers, only for the suffix argument)
+MAKE_VARIANT(str_ends_with, const std::basic_string<T> &, const T*)
+
+MAKE_VARIANT(str_ends_with, std::basic_string_view<T>, const T*)
+
+
+#undef MAKE_VARIANT
 
 
 /**
@@ -282,24 +292,21 @@ inline std::vector<std::basic_string<T> > str_split(
  * @param str
  * @return A copy of \p str converted to all lowercase characters.
  */
-inline std::string lowercase(const std::string &str)
+inline std::string lowercase(std::string_view str)
 {
 	std::string s2;
-
-	s2.reserve(str.size());
-
-	for (char i : str)
-		s2 += tolower(i);
-
+	s2.resize(str.size());
+	for (size_t i = 0; i < str.size(); i++)
+		s2[i] = tolower(str[i]);
 	return s2;
 }
 
 
 /**
  * @param str
- * @return A copy of \p str with leading and trailing whitespace removed.
+ * @return A view of \p str with leading and trailing whitespace removed.
  */
-inline std::string trim(const std::string &str)
+inline std::string_view trim(std::string_view str)
 {
 	size_t front = 0;
 	size_t back = str.size();
@@ -313,6 +320,26 @@ inline std::string trim(const std::string &str)
 	return str.substr(front, back - front);
 }
 
+// If input was a temporary string keep it one to make sure patterns like
+// trim(func_that_returns_str()) are predictable regarding memory allocation
+// and don't lead to UAF. ↓ ↓ ↓
+
+/**
+ * @param str
+ * @return A copy of \p str with leading and trailing whitespace removed.
+ */
+inline std::string trim(std::string &&str)
+{
+	std::string ret(trim(std::string_view(str)));
+	return ret;
+}
+
+// The above declaration causes ambiguity with char pointers so we have to fix that:
+inline std::string_view trim(const char *str)
+{
+	return trim(std::string_view(str));
+}
+
 
 /**
  * Returns whether \p str should be regarded as (bool) true.  Case and leading
@@ -320,7 +347,7 @@ inline std::string trim(const std::string &str)
  * true are "y", "yes", "true" and any number that is not 0.
  * @param str
  */
-inline bool is_yes(const std::string &str)
+inline bool is_yes(std::string_view str)
 {
 	std::string s2 = lowercase(trim(str));
 
@@ -377,7 +404,7 @@ inline float mystof(const std::string &str)
 template <typename T>
 inline T from_string(const std::string &str)
 {
-	std::stringstream tmp(str);
+	std::istringstream tmp(str);
 	T t;
 	tmp >> t;
 	return t;
@@ -386,42 +413,6 @@ inline T from_string(const std::string &str)
 /// Returns a 64-bit signed value represented by the string \p str (decimal).
 inline s64 stoi64(const std::string &str) { return from_string<s64>(str); }
 
-#if __cplusplus < 201103L
-namespace std {
-
-/// Returns a string representing the value \p val.
-template <typename T>
-inline string to_string(T val)
-{
-	ostringstream oss;
-	oss << val;
-	return oss.str();
-}
-#define DEFINE_STD_TOSTRING_FLOATINGPOINT(T)		\
-	template <>					\
-	inline string to_string<T>(T val)		\
-	{						\
-		ostringstream oss;			\
-		oss << std::fixed			\
-			<< std::setprecision(6)		\
-			<< val;				\
-		return oss.str();			\
-	}
-DEFINE_STD_TOSTRING_FLOATINGPOINT(float)
-DEFINE_STD_TOSTRING_FLOATINGPOINT(double)
-DEFINE_STD_TOSTRING_FLOATINGPOINT(long double)
-
-#undef DEFINE_STD_TOSTRING_FLOATINGPOINT
-
-/// Returns a wide string representing the value \p val
-template <typename T>
-inline wstring to_wstring(T val)
-{
-	return utf8_to_wide(to_string(val));
-}
-}
-#endif
-
 /// Returns a string representing the decimal value of the 32-bit value \p i.
 inline std::string itos(s32 i) { return std::to_string(i); }
 /// Returns a string representing the decimal value of the 64-bit value \p i.
@@ -443,8 +434,8 @@ inline std::string ftos(float f)
  * @param pattern The pattern to replace.
  * @param replacement What to replace the pattern with.
  */
-inline void str_replace(std::string &str, const std::string &pattern,
-		const std::string &replacement)
+inline void str_replace(std::string &str, std::string_view pattern,
+		std::string_view replacement)
 {
 	std::string::size_type start = str.find(pattern, 0);
 	while (start != str.npos) {
@@ -454,7 +445,7 @@ inline void str_replace(std::string &str, const std::string &pattern,
 }
 
 /**
- * Escapes characters [ ] \ , ; that cannot be used in formspecs
+ * Escapes characters that cannot be used in formspecs
  */
 inline void str_formspec_escape(std::string &str)
 {
@@ -486,7 +477,7 @@ void str_replace(std::string &str, char from, char to);
  *
  * @see string_allowed_blacklist()
  */
-inline bool string_allowed(const std::string &str, const std::string &allowed_chars)
+inline bool string_allowed(std::string_view str, std::string_view allowed_chars)
 {
 	return str.find_first_not_of(allowed_chars) == str.npos;
 }
@@ -502,8 +493,8 @@ inline bool string_allowed(const std::string &str, const std::string &allowed_ch
 
  * @see string_allowed()
  */
-inline bool string_allowed_blacklist(const std::string &str,
-		const std::string &blacklisted_chars)
+inline bool string_allowed_blacklist(std::string_view str,
+		std::string_view blacklisted_chars)
 {
 	return str.find_first_of(blacklisted_chars) == str.npos;
 }
@@ -524,12 +515,12 @@ inline bool string_allowed_blacklist(const std::string &str,
  * @param row_len The row length (in characters).
  * @return A new string with the wrapping applied.
  */
-inline std::string wrap_rows(const std::string &from,
-		unsigned row_len)
+inline std::string wrap_rows(std::string_view from, unsigned row_len)
 {
 	std::string to;
+	to.reserve(from.size());
 
-	size_t character_idx = 0;
+	unsigned character_idx = 0;
 	for (size_t i = 0; i < from.size(); i++) {
 		if (!IS_UTF8_MULTB_INNER(from[i])) {
 			// Wrap string after last inner byte of char
@@ -551,6 +542,7 @@ template <typename T>
 inline std::basic_string<T> unescape_string(const std::basic_string<T> &s)
 {
 	std::basic_string<T> res;
+	res.reserve(s.size());
 
 	for (size_t i = 0; i < s.length(); i++) {
 		if (s[i] == '\\') {
@@ -574,6 +566,7 @@ template <typename T>
 std::basic_string<T> unescape_enriched(const std::basic_string<T> &s)
 {
 	std::basic_string<T> output;
+	output.reserve(s.size());
 	size_t i = 0;
 	while (i < s.length()) {
 		if (s[i] == '\x1b') {
@@ -646,7 +639,7 @@ inline std::wstring unescape_translate(const std::wstring &s) {
  * @return true if to_check is not empty and all characters in to_check are
  *	decimal digits, otherwise false
  */
-inline bool is_number(const std::string &to_check)
+inline bool is_number(std::string_view to_check)
 {
 	for (char i : to_check)
 		if (!std::isdigit(i))
@@ -720,7 +713,7 @@ inline const std::string duration_to_string(int sec)
  * @return A std::string
  */
 inline std::string str_join(const std::vector<std::string> &list,
-		const std::string &delimiter)
+		std::string_view delimiter)
 {
 	std::ostringstream oss;
 	bool first = true;
@@ -738,17 +731,17 @@ inline std::string str_join(const std::vector<std::string> &list,
  */
 inline std::string stringw_to_utf8(const irr::core::stringw &input)
 {
-	std::wstring str(input.c_str());
-	return wide_to_utf8(str);
+	std::wstring_view sv(input.c_str(), input.size());
+	return wide_to_utf8(sv);
 }
 
  /**
   * Create an irr::core:stringw from a UTF8 std::string.
   */
-inline irr::core::stringw utf8_to_stringw(const std::string &input)
+inline irr::core::stringw utf8_to_stringw(std::string_view input)
 {
 	std::wstring str = utf8_to_wide(input);
-	return irr::core::stringw(str.c_str());
+	return irr::core::stringw(str.c_str(), str.size());
 }
 
 /**
@@ -757,7 +750,7 @@ inline irr::core::stringw utf8_to_stringw(const std::string &input)
  *    and add a prefix to them
  * 2. Remove 'unsafe' characters from the name by replacing them with '_'
  */
-std::string sanitizeDirName(const std::string &str, const std::string &optional_prefix);
+std::string sanitizeDirName(std::string_view str, std::string_view optional_prefix);
 
 /**
  * Prints a sanitized version of a string without control characters.
@@ -765,12 +758,12 @@ std::string sanitizeDirName(const std::string &str, const std::string &optional_
  * ASCII control characters are replaced with their hex encoding in angle
  * brackets (e.g. "a\x1eb" -> "a<1e>b").
  */
-void safe_print_string(std::ostream &os, const std::string &str);
+void safe_print_string(std::ostream &os, std::string_view str);
 
 /**
  * Parses a string of form `(1, 2, 3)` to a v3f
  *
- * @param str String
- * @return
+ * @param str string
+ * @return float vector
  */
-v3f str_to_v3f(const std::string &str);
+v3f str_to_v3f(std::string_view str);