feat: uid and gid utils

app/src/main/java/me/hexile/odexpatcher/ktx/AndroidExt.kt

@@ -1,11 +1,39 @@
 package me.hexile.odexpatcher.ktx
 
 import android.annotation.SuppressLint
+import me.hexile.odexpatcher.core.App
 
 // https://android.googlesource.com/platform/frameworks/base/+/master/core/java/android/os/SystemProperties.java
 @SuppressLint("PrivateApi")
 fun getProperty(key: String, def: String): String {
     val c = Class.forName("android.os.SystemProperties")
     val method = c.getMethod("get", String::class.java, String::class.java)
     return method.invoke(c, key, def) as String
+}
+
+fun appUid(packageName: String): Int {
+    return App.getContext().packageManager.getApplicationInfo(packageName, 0).uid
+}
+
+fun selfAppUid(): Int {
+    return appUid(App.getContext().packageName)
+}
+
+fun multiuserSharedAppGid(packageName: String): Int {
+    return multiuserSharedAppGid(appUid(packageName))
+}
+
+fun multiuserSharedAppGid(appUid: Int): Int {
+    // Definition: https://android.googlesource.com/platform/system/core/+/refs/tags/android-12.0.0_r1/libcutils/include/private/android_filesystem_config.h#198
+    // Used by: https://android.googlesource.com/platform/system/core/+/refs/tags/android-12.0.0_r1/libcutils/multiuser.cpp#56
+    //  -> https://android.googlesource.com/platform/frameworks/native/+/refs/tags/android-12.0.0_r1/cmds/installd/InstalldNativeService.cpp#380
+    return (appUid % 100000) - 10000 + 50000
+}
+
+fun cacheAppGid(packageName: String): Int {
+    return cacheAppGid(appUid(packageName))
+}
+
+fun cacheAppGid(appUid: Int): Int {
+    return appUid - 10000 + 20000
 }