Magisk/native/jni/resetprop/resetprop.cpp

#include <dlfcn.h>
#include <sys/types.h>
#include <vector>
#include <map>

#include <logging.hpp>
#include <resetprop.hpp>
#include <utils.hpp>

#define _REALLY_INCLUDE_SYS__SYSTEM_PROPERTIES_H_
#include <_system_properties.h>

#include "_resetprop.hpp"

using namespace std;

static bool verbose = false;

static int (*system_property_get)(const char*, char*);
static int (*system_property_set)(const char*, const char*);

[[noreturn]] static void usage(char* arg0) {
	fprintf(stderr,
R"EOF("resetprop - System Props Modification Tool

Usage: %s [flags] [options...]

Options:
   -h, --help        show this message
   (no arguments)    print all properties
   NAME              get property
   NAME VALUE        set property entry NAME with VALUE
   --file FILE       load props from FILE
   --delete NAME     delete property

Flags:
   -v      print verbose output to stderr
   -n      set properties without going through init
           affects setprop and prop file loading
   -p      also access props directly from persist storage
           affects getprop and delprop

)EOF", arg0);
	exit(1);
}

static bool check_legal_property_name(const char *name) {
	int namelen = strlen(name);

	if (namelen < 1) goto illegal;
	if (name[0] == '.') goto illegal;
	if (name[namelen - 1] == '.') goto illegal;

	/* Only allow alphanumeric, plus '.', '-', '@', ':', or '_' */
	/* Don't allow ".." to appear in a property name */
	for (size_t i = 0; i < namelen; i++) {
		if (name[i] == '.') {
			// i=0 is guaranteed to never have a dot. See above.
			if (name[i-1] == '.') goto illegal;
			continue;
		}
		if (name[i] == '_' || name[i] == '-' || name[i] == '@' || name[i] == ':') continue;
		if (name[i] >= 'a' && name[i] <= 'z') continue;
		if (name[i] >= 'A' && name[i] <= 'Z') continue;
		if (name[i] >= '0' && name[i] <= '9') continue;
		goto illegal;
	}

	return true;

	illegal:
	LOGE("Illegal property name: [%s]\n", name);
	return false;
}

static void read_prop(const prop_info *pi, void *cb) {
	__system_property_read_callback(
			pi, [](auto cb, auto name, auto value, auto) {
				reinterpret_cast<prop_cb*>(cb)->exec(name, value);
			}, cb);
}

static void print_props(bool persist) {
	getprops([](auto name, auto value, auto) {
		printf("[%s]: [%s]\n", name, value);
	}, nullptr, persist);
}

struct sysprop {
	virtual int setprop(const char *name, const char *value, bool trigger) { return 1; }
	virtual string getprop(const char *name, bool persist) { return ""; }
	virtual void getprops(void (*callback)(const char *, const char *, void *),
			void *cookie, bool persist) {}
	virtual int delprop(const char *name, bool persist) { return 1; }
};

struct stock_sysprop : public sysprop {
	int setprop(const char *name, const char *value, bool) override {
		return system_property_set(name, value);
	}
	string getprop(const char *name, bool) override {
		char buf[PROP_VALUE_MAX];
		buf[0] = '\0';
		system_property_get(name, buf);
		return buf;
	}
};

struct resetprop : public sysprop {
	int setprop(const char *name, const char *value, bool trigger) override {
		if (!check_legal_property_name(name))
			return 1;

		int ret;
		auto pi = const_cast<prop_info *>(__system_property_find(name));
		if (pi != nullptr) {
			if (trigger) {
				if (strncmp(name, "ro.", 3) == 0)
					delprop(name, false);
				ret = system_property_set(name, value);
			} else {
				ret = __system_property_update(pi, value, strlen(value));
			}
			LOGD("resetprop: update prop [%s]: [%s] by %s\n", name, value,
				 trigger ? "property_service" : "modifying prop data structure");
		} else {
			if (trigger) {
				ret = system_property_set(name, value);
			} else {
				ret = __system_property_add(name, strlen(name), value, strlen(value));
			}
			LOGD("resetprop: create prop [%s]: [%s] by %s\n", name, value,
				 trigger ? "property_service" : "modifying prop data structure");
		}

		if (ret)
			LOGE("resetprop: setprop error\n");

		return ret;
	}

	string getprop(const char *name, bool persist) override {
		if (!check_legal_property_name(name))
			return string();
		auto pi = __system_property_find(name);
		if (pi == nullptr) {
			if (persist && strncmp(name, "persist.", 8) == 0) {
				auto value = persist_getprop(name);
				if (value.empty())
					goto not_found;
				return value;
			}
			not_found:
			LOGD("resetprop: prop [%s] does not exist\n", name);
			return string();
		} else {
			string val;
			auto reader = make_prop_cb(val, [](auto, auto value, auto str){ str = value; });
			read_prop(pi, &reader);
			LOGD("resetprop: getprop [%s]: [%s]\n", name, val.data());
			return val;
		}
	}

	void getprops(void (*callback)(const char *, const char *, void *),
			void *cookie, bool persist) override {
		prop_list list;
		prop_collector collector(list);
		__system_property_foreach(read_prop, &collector);
		if (persist)
			persist_getprops(&collector);
		for (auto &[key, val] : list)
			callback(key.data(), val.data(), cookie);
		if (persist)
			persist_cleanup();
	}

	int delprop(const char *name, bool persist) override {
		if (!check_legal_property_name(name))
			return 1;
		LOGD("resetprop: delete prop [%s]\n", name);
		if (persist && strncmp(name, "persist.", 8) == 0)
			persist = persist_deleteprop(name);
		return __system_property_delete(name) && !(persist && strncmp(name, "persist.", 8) == 0);
	}
};

#define DLOAD(name) \
*(void **) &name = dlsym(RTLD_DEFAULT, "__" #name)

static sysprop *get_impl() {
	static sysprop *impl = nullptr;
	if (impl == nullptr) {
		use_pb = access(PERSISTENT_PROPERTY_DIR "/persistent_properties", R_OK) == 0;
#ifdef APPLET_STUB_MAIN
		if (__system_properties_init()) {
			LOGE("resetprop: __system_properties_init error\n");
			exit(1);
		}
		impl = new resetprop();
		system_property_set = &__system_property_set;
#else
		DLOAD(system_property_set);  /* Always prefer to use setprop from platform */
		if (__system_properties_init()) {
			LOGW("resetprop: __system_properties_init error\n");
			DLOAD(system_property_get);
			impl = system_property_get ? new stock_sysprop() : new sysprop();
		} else {
			impl = new resetprop();
		}
#endif
	}
	return impl;
}

/*********************************
 * Implementation of public APIs
 *********************************/

string getprop(const char *name, bool persist) {
	return get_impl()->getprop(name, persist);
}

void getprops(void (*callback)(const char *, const char *, void *), void *cookie, bool persist) {
	get_impl()->getprops(callback, cookie, persist);
}

int setprop(const char *name, const char *value, bool trigger) {
	return get_impl()->setprop(name, value, trigger);
}

int delprop(const char *name, bool persist) {
	return get_impl()->delprop(name, persist);
}

void load_prop_file(const char *filename, bool trigger) {
	auto impl = get_impl();
	LOGD("resetprop: Parse prop file [%s]\n", filename);
	parse_prop_file(filename, [=](auto key, auto val) -> bool {
		impl->setprop(key.data(), val.data(), trigger);
		return true;
	});
}

int resetprop_main(int argc, char *argv[]) {
	log_cb.d = [](auto fmt, auto ap) -> int { return verbose ? vfprintf(stderr, fmt, ap) : 0; };

	bool trigger = true, persist = false;
	char *argv0 = argv[0];
	string prop;

	--argc;
	++argv;

	// Parse flags and -- options
	while (argc && argv[0][0] == '-') {
		for (int idx = 1; true; ++idx) {
			switch (argv[0][idx]) {
			case '-':
				if (strcmp(argv[0], "--file") == 0 && argc == 2) {
					load_prop_file(argv[1], trigger);
					return 0;
				} else if (strcmp(argv[0], "--delete") == 0 && argc == 2) {
					return delprop(argv[1], persist);
				} else if (strcmp(argv[0], "--help") == 0) {
					usage(argv0);
				}
			case 'v':
				verbose = true;
				continue;
			case 'p':
				persist = true;
				continue;
			case 'n':
				trigger = false;
				continue;
			case '\0':
				break;
			case 'h':
			default:
				usage(argv0);
			}
			break;
		}
		--argc;
		++argv;
	}

	switch (argc) {
	case 0:
		print_props(persist);
		return 0;
	case 1:
		prop = getprop(argv[0], persist);
		if (prop.empty()) return 1;
		printf("%s\n", prop.data());
		return 0;
	case 2:
		return setprop(argv[0], argv[1], trigger);
	default:
		usage(argv0);
	}
}