Don't overwrite persistent property files

This fixes a bug introduced by I81b6bd984aad8f7ddec93ce74f4543e4f71be508

In the original CL, setting a sysprop `next_boot.<name>` and then
rebooting the device could remove all the persistent properties stored
in /data/property/persistent_properties. It happened because the
function `WritePersistentProperty` is called with a properties set which
is initialized as an empty set and then added with the properties which
had the next_boot prefix.

As a result...

Before the boot:
* persist.a = 1
* next_boot.b = 2
* next_boot.persist.c = 3

After the reboot:
* b = 2
* persist.c = 3

persist.a gets lost.

This change fixes the issue by populating properties set from the memory
and then save it to the file.

Bug: 306062513
Bug: 300111812
Test: do the following.
$ adb root
$ adb shell setprop persist.a 1
$ adb shell setprop next_boot.b 1
$ adb shell setprop next_boot.persist.c 1

$ adb reboot
$ adb shell getprop persist.a
1    // was (none) before this change
$ adb shell getprop b
1
$ adb shell getprop persist.c
1

$ adb reboot
$ adb shell getprop persist.a
1    // was (none) before this change
$ adb shell getprop b
     // (none) because b isn't persisted. WAI.
$ adb shell getprop persist.c
1

Change-Id: I85d3777f9b32523b010e49b8ca53f4319dd2ce05

init/persistent_properties.cpp

@@ -115,24 +115,6 @@ void RemoveLegacyPersistentPropertyFiles() {
     }
 }
 
-PersistentProperties LoadPersistentPropertiesFromMemory() {
-    PersistentProperties persistent_properties;
-    __system_property_foreach(
-        [](const prop_info* pi, void* cookie) {
-            __system_property_read_callback(
-                pi,
-                [](void* cookie, const char* name, const char* value, unsigned serial) {
-                    if (StartsWith(name, "persist.")) {
-                        auto properties = reinterpret_cast<PersistentProperties*>(cookie);
-                        AddPersistentProperty(name, value, properties);
-                    }
-                },
-                cookie);
-        },
-        &persistent_properties);
-    return persistent_properties;
-}
-
 Result<std::string> ReadPersistentPropertyFile() {
     const std::string temp_filename = persistent_property_filename + ".tmp";
     if (access(temp_filename.c_str(), F_OK) == 0) {
@@ -221,6 +203,24 @@ Result<void> WritePersistentPropertyFile(const PersistentProperties& persistent_
     return {};
 }
 
+PersistentProperties LoadPersistentPropertiesFromMemory() {
+    PersistentProperties persistent_properties;
+    __system_property_foreach(
+            [](const prop_info* pi, void* cookie) {
+                __system_property_read_callback(
+                        pi,
+                        [](void* cookie, const char* name, const char* value, unsigned serial) {
+                            if (StartsWith(name, "persist.")) {
+                                auto properties = reinterpret_cast<PersistentProperties*>(cookie);
+                                AddPersistentProperty(name, value, properties);
+                            }
+                        },
+                        cookie);
+            },
+            &persistent_properties);
+    return persistent_properties;
+}
+
 // Persistent properties are not written often, so we rather not keep any data in memory and read
 // then rewrite the persistent property file for each update.
 void WritePersistentProperty(const std::string& name, const std::string& value) {

init/persistent_properties.h

@@ -29,6 +29,7 @@ void AddPersistentProperty(const std::string& name, const std::string& value,
                            PersistentProperties* persistent_properties);
 PersistentProperties LoadPersistentProperties();
 void WritePersistentProperty(const std::string& name, const std::string& value);
+PersistentProperties LoadPersistentPropertiesFromMemory();
 
 // Exposed only for testing
 Result<PersistentProperties> LoadPersistentPropertyFile();

init/property_service.cpp

@@ -1400,8 +1400,6 @@ static void HandleInitSocket() {
             // Apply staged and persistent properties
             bool has_staged_prop = false;
             auto const staged_prefix = std::string_view("next_boot.");
-            auto const staged_persist_prefix = std::string_view("next_boot.persist.");
-            auto persist_props_map = std::unordered_map<std::string, std::string>();
 
             auto persistent_properties = LoadPersistentProperties();
             for (const auto& property_record : persistent_properties.properties()) {
@@ -1412,23 +1410,16 @@ static void HandleInitSocket() {
                   has_staged_prop = true;
                   auto actual_prop_name = prop_name.substr(staged_prefix.size());
                   InitPropertySet(actual_prop_name, prop_value);
-                  if (StartsWith(prop_name, staged_persist_prefix)) {
-                    persist_props_map[actual_prop_name] = prop_value;
-                  }
-                } else if (!persist_props_map.count(prop_name)) {
+                } else {
                   InitPropertySet(prop_name, prop_value);
                 }
             }
 
             // Update persist prop file if there are staged props
             if (has_staged_prop) {
-                PersistentProperties updated_persist_props;
-                for (auto const& [prop_name, prop_value] : persist_props_map) {
-                    AddPersistentProperty(prop_name, prop_value, &updated_persist_props);
-                }
-
+                PersistentProperties props = LoadPersistentPropertiesFromMemory();
                 // write current updated persist prop file
-                auto result = WritePersistentPropertyFile(updated_persist_props);
+                auto result = WritePersistentPropertyFile(props);
                 if (!result.ok()) {
                     LOG(ERROR) << "Could not store persistent property: " << result.error();
                 }