[C++] Don't use iostream, use static libstdc++

Implement file_reader class (simple fd->container).
Implement concat class for simple formatting strings.
Some options allow significantly reduce executable size.
Static part of libstdc++ now is only 130~150 Kb.

Makefile

@@ -39,6 +39,8 @@ CXXFLAGS:=-DVERSION=\"v$(VERSION)\ \($(COMMIT)\)\" \
 	-D_FORTIFY_SOURCE=2 \
 	-D_DEFAULT_SOURCE \
 	-Werror=format-security \
+	-fdata-sections -ffunction-sections \
+	-static-libgcc -static-libstdc++\
 	$(CXXFLAGS)
 
 platform=$(shell uname -s)
@@ -53,7 +55,7 @@ endif
 all: compose man
 	mkdir -p bin
 	cp scripts/keyd-application-mapper bin/
-	$(CXX) $(CXXFLAGS) -O3 $(COMPAT_FILES) src/*.cpp src/vkbd/$(VKBD).cpp -lpthread -o bin/keyd $(LDFLAGS)
+	$(CXX) $(CXXFLAGS) -O3 $(COMPAT_FILES) src/*.cpp src/vkbd/$(VKBD).cpp -lpthread -Wl,--gc-sections -o bin/keyd $(LDFLAGS)
 debug:
 	CFLAGS="-g -fsanitize=address -Wunused" $(MAKE)
 compose:

keyd.service.in

@@ -6,6 +6,7 @@ Documentation=man:keyd(1)
 Type=simple
 ExecStart=@PREFIX@/bin/keyd
 KillMode=process
+Environment="GLIBCXX_TUNABLES=glibcxx.eh_pool.obj_count=2:glibcxx.eh_pool.obj_size=4"
 
 [Install]
 WantedBy=multi-user.target

src/config.cpp

@@ -26,8 +26,6 @@
 #include <limits>
 #include <string>
 #include <string_view>
-#include <iostream>
-#include <fstream>
 #include <algorithm>
 #include <numeric>
 
@@ -186,40 +184,33 @@ static std::string resolve_include_path(const char *path, std::string_view inclu
 	return resolved_path;
 }
 
-static std::string read_file(const char *path)
+static std::string read_file(const char *path, size_t recursion_depth = 0)
 {
-	constexpr std::string_view include_prefix = "include ";
+	std::string buf;
 
-	std::string buf, line;
-
-	std::ifstream file(path);
-	if (!file.is_open()) {
+	std::string file = file_reader(open(path, O_RDONLY), 4096, [&] {
 		err("failed to open %s", path);
-		return {};
-	}
+		perror("open");
+	});
 
-	while (std::getline(file, line)) {
-		if (line.starts_with(include_prefix)) {
-			std::string_view include_path = line;
-			include_path.remove_prefix(include_prefix.size());
-			while (include_path.starts_with(' '))
-				include_path.remove_prefix(1);
+	for (auto line : split_char<'\n'>(file)) {
+		if (line.starts_with("include ") || line.starts_with("include\t")) {
+			auto include_path = line.substr(8);
 
-			auto resolved_path = resolve_include_path(path, include_path);
+			std::string resolved_path = resolve_include_path(path, include_path);
 			if (resolved_path.empty()) {
-				warn("failed to resolve include path: %s", include_path.data());
+				warn("failed to resolve include path: %.*s", (int)include_path.size(), include_path.data());
 				continue;
 			}
 
-			std::ifstream file(resolved_path);
-			if (!file.is_open()) {
-				warn("failed to %s", line.c_str());
-				perror("open");
-			} else {
-				buf.append(std::istreambuf_iterator<char>(file), std::istreambuf_iterator<char>());
+			if (recursion_depth >= 10) {
+				warn("include depth too big or cyclic: %.*s", (int)include_path.size(), include_path.data());
+				continue;
 			}
+
+			buf += read_file(resolved_path.c_str(), recursion_depth + 1);
 		} else {
-			buf += line;
+			buf.append(line);
 			buf += '\n';
 		}
 	}
@@ -1098,3 +1089,11 @@ void config_backup::restore(struct config& cfg)
 	cfg.macros.resize(macro_count);
 	cfg.commands.resize(cmd_count);
 }
+
+config::~config()
+{
+}
+
+config_backup::~config_backup()
+{
+}

src/config.h

@@ -183,6 +183,7 @@ struct config {
 	config() = default;
 	config(const config&) = delete;
 	config& operator=(const config&) = delete;
+	~config();
 };
 
 struct config_backup {
@@ -199,6 +200,7 @@ struct config_backup {
 	std::vector<layer_backup> layers;
 
 	explicit config_backup(const struct config& cfg);
+	~config_backup();
 
 	void restore(struct config& cfg);
 };

src/daemon.cpp

@@ -2,7 +2,6 @@
 #include "log.h"
 #include <memory>
 #include <utility>
-#include <fstream>
 
 #ifndef CONFIG_DIR
 #define CONFIG_DIR ""
@@ -183,7 +182,6 @@ static void on_layer_change(const struct keyboard *kbd, struct layer *layer, uin
 static void load_configs()
 {
 	DIR *dh = opendir(CONFIG_DIR);
-	struct dirent *dirent;
 
 	if (!dh) {
 		perror("opendir");
@@ -192,22 +190,18 @@ static void load_configs()
 
 	configs.reset();
 
-	while ((dirent = readdir(dh))) {
-		char path[1024];
-		int len;
-
+	while (struct dirent* dirent = readdir(dh)) {
 		if (dirent->d_type == DT_DIR)
 			continue;
 
-		len = snprintf(path, sizeof path, "%s/%s", CONFIG_DIR, dirent->d_name);
-
-		if (len >= 5 && !strcmp(path + len - 5, ".conf")) {
+		auto name = concat(CONFIG_DIR "/", dirent->d_name);
+		if (name.ends_with(".conf")) {
 			auto ent = std::make_unique<config_ent>();
 
-			keyd_log("CONFIG: parsing b{%s}\n", path);
+			keyd_log("CONFIG: parsing b{%s}\n", name.c_str());
 
 			auto kbd = std::make_unique<keyboard>();
-			if (!config_parse(&kbd->config, path)) {
+			if (!config_parse(&kbd->config, name.c_str())) {
 				kbd->output = {
 					.send_key = send_key,
 					.on_layer_change = on_layer_change,
@@ -220,7 +214,7 @@ static void load_configs()
 				ent->next = std::move(configs);
 				configs = std::move(ent);
 			} else {
-				keyd_log("DEVICE: y{WARNING} failed to parse %s\n", path);
+				keyd_log("DEVICE: y{WARNING} failed to parse %s\n", name.c_str());
 			}
 
 		}
@@ -266,7 +260,7 @@ static void manage_device(struct device *dev)
 
 	if ((ent = lookup_config_ent(dev->id, flags))) {
 		if (device_grab(dev)) {
-			keyd_log("DEVICE: y{WARNING} Failed to grab %s\n", dev->path);
+			keyd_log("DEVICE: y{WARNING} Failed to grab /dev/input/%u\n", dev->num);
 			dev->data = NULL;
 			return;
 		}
@@ -287,7 +281,6 @@ static void manage_device(struct device *dev)
 static void reload(std::shared_ptr<env_pack> env)
 {
 	restore_leds();
-	configs.reset();
 	load_configs();
 
 	for (size_t i = 0; i < device_table_sz; i++)
@@ -307,12 +300,13 @@ static void reload(std::shared_ptr<env_pack> env)
 		else
 			buf.clear();
 		buf += "keyd/bindings.conf";
-		std::ifstream file(buf, std::ios::binary);
-		if (!file.is_open()) {
+		buf = std::string(file_reader(open(buf.c_str(), O_RDONLY), 4096, []{
 			keyd_log("Unable to open %s\n", buf.c_str());
+			perror("open");
+		}));
+
+		if (buf.empty())
 			return;
-		}
-		buf.assign(std::istreambuf_iterator(file), std::istreambuf_iterator<char>());
 
 		for (auto ent = configs.get(); ent; ent = ent->next.get()) {
 			ent->kbd->config.cfg_use_uid = env->uid;
@@ -517,10 +511,10 @@ static void handle_client(int con)
 	if (getuid() < 1000)
 	{
 		// Copy initial environment variables from caller process
-		std::ifstream envf(("/proc/" + std::to_string(cred.pid) + "/environ").c_str(), std::ios::binary);
-		if (envf.is_open()) {
-			std::vector<char> buf;
-			buf.assign(std::istreambuf_iterator<char>(envf), std::istreambuf_iterator<char>());
+		std::vector<char> buf = file_reader(open(concat("/proc/", cred.pid, "/environ").c_str(), O_RDONLY), 8192, [] {
+			perror("environ");
+		});
+		if (!buf.empty()) {
 			if (prev && prev->buf == buf) {
 				// Share previous environment variables
 				ephemeral_config.env = prev;
@@ -543,6 +537,7 @@ static void handle_client(int con)
 
 	size_t msg_count = 0;
 	while (handle_message(con, &ephemeral_config, prev ? prev : std::make_shared<env_pack>())) {
+		ephemeral_config.commands.clear();
 		msg_count++;
 	}
 	dbg2("%zu messages processed", msg_count);
@@ -692,11 +687,15 @@ static int event_handler(struct event *ev)
 	return timeout;
 }
 
+#ifndef VERSION
+#define VERSION "unknown"
+#endif
+
 int run_daemon(int, char *[])
 {
-	ipcfd = ipc_create_server(/* SOCKET_PATH */);
+	ipcfd = ipc_create_server();
 	if (ipcfd < 0)
-		die("failed to create %s (another instance already running?)", SOCKET_PATH);
+		die("failed to create socket (another instance already running?)");
 
 	vkbd = vkbd_init(VKBD_NAME);
 

src/device.cpp

@@ -143,8 +143,8 @@ static int device_init(const char *path, struct device *dev)
 
 	capabilities = resolve_device_capabilities(fd, &num_keys, &relmask, &absmask);
 
-	if (ioctl(fd, EVIOCGNAME(sizeof(dev->name)), dev->name) == -1) {
-		keyd_log("ERROR: could not fetch device name of %s\n", dev->path);
+	if (ioctl(fd, EVIOCGNAME(sizeof(dev->name) - 1), dev->name) == -1) {
+		keyd_log("ERROR: could not fetch device name of /dev/input/event%u\n", dev->num);
 		return -1;
 	}
 
@@ -176,8 +176,7 @@ static int device_init(const char *path, struct device *dev)
 			return -1;
 		}
 
-		strncpy(dev->path, path, sizeof(dev->path)-1);
-		dev->path[sizeof(dev->path)-1] = 0;
+		dev->num = atoi(path + strlen("/dev/input/event"));
 
 		/*
 		 * Attempt to generate a reproducible unique identifier for each device.

src/device.h

@@ -26,11 +26,11 @@ struct device {
 	uint8_t capabilities;
 	uint8_t is_virtual;
 
-	uint8_t led_state[LED_CNT];
+	char id[25];
+	uint32_t num;
+	char name[96];
 
-	char id[64];
-	char name[64];
-	char path[256];
+	uint8_t led_state[LED_CNT];
 
 	/* Internal. */
 	uint32_t _maxx;

src/ipc.cpp

@@ -8,6 +8,10 @@
 
 /* TODO (maybe): settle on an API and publish the protocol. */
 
+#ifndef SOCKET_PATH
+#define SOCKET_PATH "/var/run/keyd.socket"
+#endif
+
 static void chgid()
 {
 	struct group *g = getgrnam("keyd");

src/keyd.cpp

@@ -36,6 +36,10 @@ static int ipc_exec(enum ipc_msg_type_e type, const char *data, size_t sz, uint3
 	return msg.type == IPC_FAIL;
 }
 
+#ifndef VERSION
+#define VERSION "unknown"
+#endif
+
 static int version(int, char *[])
 {
 	printf("keyd " VERSION "\n");

src/keyd.h

@@ -106,4 +106,53 @@ int ipc_connect();
 extern struct device device_table[MAX_DEVICES];
 extern size_t device_table_sz;
 
+// One-time file reader
+struct file_reader
+{
+	explicit file_reader(int fd, unsigned reserve, auto on_fail)
+		: fd(fd)
+		, reserve(reserve)
+	{
+		if (fd < 0) {
+			on_fail();
+		}
+	}
+
+	file_reader(const file_reader&) = delete;
+	file_reader& operator=(const file_reader&) = delete;
+
+	// Read full file
+	template <typename T, typename V = typename T::value_type>
+	operator T()
+	{
+		T result;
+		size_t rd = 0;
+		V buf[4096];
+		while ((rd = read(this->fd, buf, sizeof(buf))) <= sizeof(buf)) {
+			if (rd == 0)
+				break;
+			// Unimplemented, but won't happen for single-byte types
+			if (rd % sizeof(V))
+				throw buf[0];
+			result.insert(result.end(), buf, buf + rd / sizeof(V));
+		}
+		return result;
+	}
+
+	void reset()
+	{
+		if (lseek(fd, 0, SEEK_SET) < 0)
+			perror("file_reader::lseek");
+	}
+
+	~file_reader()
+	{
+		if (fd >= 0)
+			close(fd);
+	}
+private:
+	int fd;
+	unsigned reserve;
+};
+
 #endif

src/macro.cpp

@@ -33,10 +33,6 @@ int macro_parse(std::string_view s, macro& macro, struct config* config)
 				err("incomplete macro command found");
 				return -1;
 			}
-			if (is_cmd && !config) {
-				err("commands are not allowed in this context");
-				return -1;
-			}
 			if (is_cmd && config->commands.size() > std::numeric_limits<decltype(descriptor_arg::idx)>::max()) {
 				err("max commands exceeded");
 				return -1;

src/monitor.cpp

@@ -38,12 +38,10 @@ int event_handler(struct event *ev)
 	const char *name;
 
 	case EV_DEV_ADD:
-		keyd_log("device added: %s %s (%s)\n",
-			  ev->dev->id, ev->dev->name, ev->dev->path);
+		keyd_log("device added: %s %s (/dev/input/event%u)\n", ev->dev->id, ev->dev->name, ev->dev->num);
 		break;
 	case EV_DEV_REMOVE:
-		keyd_log("device removed: %s %s (%s)\n",
-			  ev->dev->id, ev->dev->name, ev->dev->path);
+		keyd_log("device removed: %s %s (/dev/input/event%u)\n", ev->dev->id, ev->dev->name, ev->dev->num);
 		break;
 	case EV_DEV_EVENT:
 		switch (ev->devev->type) {