Base: Allow default settings to be provided in meta-data

This is useful for apps that include microG as a library, so they can easily
modify the default configuration of their embedded microG.

play-services-base/core/src/main/kotlin/org/microg/gms/settings/MetaDataPreferences.kt

@@ -0,0 +1,45 @@
+/*
+ * SPDX-FileCopyrightText: 2023 microG Project Team
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package org.microg.gms.settings
+
+import android.content.Context
+import android.content.SharedPreferences
+import android.content.pm.PackageManager.GET_META_DATA
+import android.os.Bundle
+
+class MetaDataPreferences(private val context: Context, private val prefix: String = "") : SharedPreferences {
+    private val metaData by lazy {
+        runCatching { context.packageManager.getApplicationInfo(context.packageName, GET_META_DATA) }.getOrNull()?.metaData ?: Bundle.EMPTY
+    }
+
+    override fun getAll(): Map<String, *> = metaData.keySet().filter { it.startsWith(prefix) }.associate { it.substring(prefix.length) to metaData.get(it) }
+
+    override fun getString(key: String, defValue: String?): String? = metaData.getString(prefix + key, defValue)
+
+    override fun getStringSet(key: String, defValues: Set<String>?): Set<String>? = metaData.getStringArray(prefix + key)?.toSet() ?: defValues
+
+    override fun getInt(key: String?, defValue: Int): Int = metaData.getInt(prefix + key, defValue)
+
+    override fun getLong(key: String?, defValue: Long): Long = metaData.getLong(prefix + key, defValue)
+
+    override fun getFloat(key: String?, defValue: Float): Float = metaData.getFloat(prefix + key, defValue)
+
+    override fun getBoolean(key: String?, defValue: Boolean): Boolean = metaData.getBoolean(prefix + key, defValue)
+
+    override fun contains(key: String?): Boolean = metaData.containsKey(prefix + key)
+
+    override fun edit(): SharedPreferences.Editor {
+        throw UnsupportedOperationException()
+    }
+
+    override fun registerOnSharedPreferenceChangeListener(listener: SharedPreferences.OnSharedPreferenceChangeListener?) {
+        throw UnsupportedOperationException()
+    }
+
+    override fun unregisterOnSharedPreferenceChangeListener(listener: SharedPreferences.OnSharedPreferenceChangeListener?) {
+        throw UnsupportedOperationException()
+    }
+}

play-services-base/core/src/main/kotlin/org/microg/gms/settings/SettingsProvider.kt

@@ -27,6 +27,8 @@ import org.microg.gms.settings.SettingsContract.SafetyNet
 import org.microg.gms.settings.SettingsContract.getAuthority
 import java.io.File
 
+private const val SETTINGS_PREFIX = "org.microg.gms.settings."
+
 /**
  * All settings access should go through this [ContentProvider],
  * because it provides safe access from different processes which normal [SharedPreferences] don't.
@@ -53,6 +55,9 @@ class SettingsProvider : ContentProvider() {
             null
         }
     }
+    private val metaDataPreferences: SharedPreferences by lazy {
+        MetaDataPreferences(context!!, SETTINGS_PREFIX)
+    }
 
     override fun onCreate(): Boolean {
         return true
@@ -355,12 +360,12 @@ class SettingsProvider : ContentProvider() {
      * @return the current setting as [Int], because [ContentProvider] does not support [Boolean].
      */
     private fun getSettingsBoolean(key: String, def: Boolean): Int {
-        return listOf(preferences, systemDefaultPreferences).getBooleanAsInt(key, def)
+        return listOf(preferences, systemDefaultPreferences, metaDataPreferences).getBooleanAsInt(key, def)
     }
 
-    private fun getSettingsString(key: String, def: String? = null): String? = listOf(preferences, systemDefaultPreferences).getString(key, def)
-    private fun getSettingsInt(key: String, def: Int): Int = listOf(preferences, systemDefaultPreferences).getInt(key, def)
-    private fun getSettingsLong(key: String, def: Long): Long = listOf(preferences, systemDefaultPreferences).getLong(key, def)
+    private fun getSettingsString(key: String, def: String? = null): String? = listOf(preferences, systemDefaultPreferences, metaDataPreferences).getString(key, def)
+    private fun getSettingsInt(key: String, def: Int): Int = listOf(preferences, systemDefaultPreferences, metaDataPreferences).getInt(key, def)
+    private fun getSettingsLong(key: String, def: Long): Long = listOf(preferences, systemDefaultPreferences, metaDataPreferences).getLong(key, def)
     private fun getUnifiedNlpSettingsStringSetCompat(key: String, def: Set<String>): Set<String> = listOf(unifiedNlpPreferences, preferences, systemDefaultPreferences).getStringSetCompat(key, def)
 
     private fun SharedPreferences.getStringSetCompat(key: String, def: Set<String>): Set<String> {