Export get_prop to Rust

native/src/base/Android.mk

@@ -4,7 +4,11 @@ LOCAL_PATH := $(call my-dir)
 
 include $(CLEAR_VARS)
 LOCAL_MODULE := libbase
-LOCAL_C_INCLUDES := src/include $(LOCAL_PATH)/include out/generated
+LOCAL_C_INCLUDES := \
+    src/include \
+    $(LOCAL_PATH)/include \
+    $(LOCAL_PATH)/../external/cxx-rs/include \
+    out/generated
 LOCAL_EXPORT_C_INCLUDES := $(LOCAL_C_INCLUDES)
 LOCAL_EXPORT_STATIC_LIBRARIES := libcxx
 LOCAL_STATIC_LIBRARIES := libcxx

native/src/core/core.hpp

@@ -2,6 +2,7 @@
 
 #include <string>
 #include <vector>
+#include <cxx.h>
 
 extern bool RECOVERY_MODE;
 extern std::atomic<ino_t> pkg_xml_ino;
@@ -28,6 +29,7 @@ void clear_pkg(const char *pkg, int user_id);
 [[noreturn]] void install_module(const char *file);
 
 // System properties
+rust::String get_prop_rs(const char *name, bool persist);
 std::string get_prop(const char *name, bool persist = false);
 int delete_prop(const char *name, bool persist = false);
 int set_prop(const char *name, const char *value, bool skip_svc = false);

native/src/core/lib.rs

@@ -1,12 +1,18 @@
 pub use base;
 use daemon::*;
 use logging::*;
+use std::ffi::CStr;
 
 mod daemon;
 mod logging;
 
 #[cxx::bridge]
 pub mod ffi {
+    extern "C++" {
+        include!("core.hpp");
+        unsafe fn get_prop_rs(name: *const c_char, persist: bool) -> String;
+    }
+
     extern "Rust" {
         fn rust_test_entry();
         fn android_logging();
@@ -28,3 +34,7 @@ pub mod ffi {
 }
 
 fn rust_test_entry() {}
+
+pub fn get_prop(name: &CStr, persist: bool) -> String {
+    unsafe { ffi::get_prop_rs(name.as_ptr(), persist) }
+}

native/src/core/resetprop/persist.cpp

@@ -223,23 +223,22 @@ private:
     string_view _name;
 };
 
-string persist_get_prop(const char *name) {
+void persist_get_prop(const char *name, prop_cb *prop_cb) {
     if (check_pb()) {
         match_prop_name cb(name);
         pb_get_prop(&cb);
         if (cb.value[0]) {
             LOGD("resetprop: get prop (persist) [%s]: [%s]\n", name, cb.value);
-            return cb.value;
+            prop_cb->exec(name, cb.value);
         }
     } else {
         // Try to read from file
         char value[PROP_VALUE_MAX];
         if (file_get_prop(name, value)) {
             LOGD("resetprop: get prop (persist) [%s]: [%s]\n", name, value);
-            return value;
+            prop_cb->exec(name, value);
         }
     }
-    return "";
 }
 
 bool persist_delete_prop(const char *name) {

native/src/core/resetprop/resetprop.cpp

@@ -115,15 +115,19 @@ static void read_prop_with_cb(const prop_info *pi, void *cb) {
     }
 }
 
+template<class StringType>
 struct prop_to_string : prop_cb {
-    explicit prop_to_string(string &s) : val(s) {}
     void exec(const char *, const char *value) override {
         val = value;
     }
-private:
+    StringType val;
-    string &val;
 };
 
+template<> void prop_to_string<rust::String>::exec(const char *, const char *value) {
+    // We do not want to crash when values are not UTF-8
+    val = rust::String::lossy(value);
+}
+
 static int set_prop(const char *name, const char *value, PropFlags flags) {
     if (!check_legal_property_name(name))
         return 1;
@@ -170,31 +174,33 @@ static int set_prop(const char *name, const char *value, PropFlags flags) {
     return ret;
 }
 
-static string get_prop(const char *name, PropFlags flags) {
+template<class StringType>
+static StringType get_prop(const char *name, PropFlags flags) {
     if (!check_legal_property_name(name))
-        return "";
+        return {};
+
+    prop_to_string<StringType> cb;
 
     if (flags.isContext()) {
-        auto val = __system_property_get_context(name) ?: "";
+        auto context = __system_property_get_context(name) ?: "";
-        LOGD("resetprop: prop context [%s]: [%s]\n", name, val);
+        LOGD("resetprop: prop context [%s]: [%s]\n", name, context);
-        return val;
+        cb.exec(name, context);
+        return cb.val;
     }
 
-    string val;
     if (!flags.isPersistOnly()) {
         if (auto pi = system_property_find(name)) {
-            prop_to_string cb(val);
             read_prop_with_cb(pi, &cb);
-            LOGD("resetprop: get prop [%s]: [%s]\n", name, val.data());
+            LOGD("resetprop: get prop [%s]: [%s]\n", name, cb.val.c_str());
         }
     }
 
-    if (val.empty() && flags.isPersist() && str_starts(name, "persist."))
+    if (cb.val.empty() && flags.isPersist() && str_starts(name, "persist."))
-        val = persist_get_prop(name);
+        persist_get_prop(name, &cb);
-
+    if (cb.val.empty())
-    if (val.empty())
         LOGD("resetprop: prop [%s] does not exist\n", name);
-    return val;
+
+    return cb.val;
 }
 
 static void print_props(PropFlags flags) {
@@ -335,7 +341,7 @@ int resetprop_main(int argc, char *argv[]) {
         print_props(flags);
         return 0;
     case 1: {
-        string val = get_prop(argv[0], flags);
+        auto val = get_prop<string>(argv[0], flags);
         if (val.empty())
             return 1;
         printf("%s\n", val.data());
@@ -352,11 +358,20 @@ int resetprop_main(int argc, char *argv[]) {
  * Public APIs
  ****************/
 
-string get_prop(const char *name, bool persist) {
+template<class StringType>
+static StringType get_prop_impl(const char *name, bool persist) {
     InitOnce();
     PropFlags flags;
     if (persist) flags.setPersist();
-    return get_prop(name, flags);
+    return get_prop<StringType>(name, flags);
+}
+
+rust::String get_prop_rs(const char *name, bool persist) {
+    return get_prop_impl<rust::String>(name, persist);
+}
+
+string get_prop(const char *name, bool persist) {
+    return get_prop_impl<string>(name, persist);
 }
 
 int delete_prop(const char *name, bool persist) {

native/src/core/resetprop/resetprop.hpp

@@ -21,7 +21,7 @@ private:
     prop_list &list;
 };
 
-std::string persist_get_prop(const char *name);
+void persist_get_prop(const char *name, prop_cb *prop_cb);
 void persist_get_props(prop_cb *prop_cb);
 bool persist_delete_prop(const char *name);
 bool persist_set_prop(const char *name, const char *value);