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Commit c7230a1e authored by Jiyong Park's avatar Jiyong Park
Browse files

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
parent 3ef4da2f

init/persistent_properties.cpp

+18 −18
Original line number Diff line number Diff line
@@ -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

+1 −0
Original line number Diff line number Diff line
@@ -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

+3 −12
Original line number Diff line number Diff line
@@ -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();

                }