Remove dependency on librootjava

2020-08-08 07:18:28 +08:00
parent 9599378c39
commit 6b10334919
4 changed files with 76 additions and 63 deletions
--- a/mobile/src/main/java/be/mygod/librootkotlinx/AppProcess.kt
+++ b/mobile/src/main/java/be/mygod/librootkotlinx/AppProcess.kt
@@ -0,0 +1,72 @@
+package be.mygod.librootkotlinx
+
+import android.os.Build
+import android.os.Debug
+import android.os.Process
+import androidx.annotation.RequiresApi
+import java.io.File
+
+object AppProcess {
+    /**
+     * Based on: https://android.googlesource.com/platform/bionic/+/aff9a34/linker/linker.cpp#3397
+     */
+    @get:RequiresApi(29)
+    val genericLdConfigFilePath: String get() {
+        "/system/etc/ld.config.${Build.VERSION.SDK_INT}.txt".let { if (File(it).isFile) return it }
+        if (Build.VERSION.SDK_INT >= 30) "/linkerconfig/ld.config.txt".let {
+            check(File(it).isFile) { "failed to find generated linker configuration from \"$it\"" }
+            return it
+        }
+        val prop = Class.forName("android.os.SystemProperties")
+        if (prop.getDeclaredMethod("getBoolean", String::class.java, Boolean::class.java).invoke(null,
+                        "ro.vndk.lite", false) as Boolean) return "/system/etc/ld.config.vndk_lite.txt"
+        when (val version = prop.getDeclaredMethod("get", String::class.java, String::class.java).invoke(null,
+                "ro.vndk.version", "") as String) {
+            "", "current" -> { }
+            else -> "/system/etc/ld.config.$version.txt".let { if (File(it).isFile) return it }
+        }
+        return "/system/etc/ld.config.txt"
+    }
+
+    val myExe get() = "/proc/${Process.myPid()}/exe"
+
+    /**
+     * To workaround Samsung's stupid kernel patch that prevents exec, we need to relocate exe outside of /data.
+     * See also: https://github.com/Chainfire/librootjava/issues/19
+     *
+     * @return The script to be executed to perform relocation and the relocated binary path.
+     */
+    fun relocateScript(token: String): Pair<StringBuilder, String> {
+        val script = StringBuilder()
+        val (baseDir, relocated) = if (Build.VERSION.SDK_INT < 29) "/dev" to "/dev/app_process_$token" else {
+            val apexPath = "/apex/$token"
+            script.appendln("[ -d $apexPath ] || " +
+                    "mkdir $apexPath && " +
+                    // we need to mount a new tmpfs to override noexec flag
+                    "mount -t tmpfs -o size=1M tmpfs $apexPath || exit 1")
+            // unfortunately native ld.config.txt only recognizes /data,/system,/system_ext as system directories;
+            // to link correctly, we need to add our path to the linker config too
+            val ldConfig = "$apexPath/etc/ld.config.txt"
+            script.appendln("[ -f $ldConfig ] || " +
+                    "mkdir -p $apexPath/etc && " +
+                    "echo dir.system = $apexPath >$ldConfig && " +
+                    "cat $genericLdConfigFilePath >>$ldConfig || exit 1")
+            "$apexPath/bin" to "$apexPath/bin/app_process"
+        }
+        script.appendln("[ -f $relocated ] || " +
+                "mkdir -p $baseDir && " +
+                "cp $myExe $relocated && " +
+                "chmod 700 $relocated || exit 1")
+        return script to relocated
+    }
+
+    fun launchString(packageCodePath: String, clazz: String, appProcess: String, niceName: String?): String {
+        val debugParams = if (Debug.isDebuggerConnected()) when (Build.VERSION.SDK_INT) {
+            in 29..Int.MAX_VALUE -> "-XjdwpProvider:adbconnection"
+            28 -> "-XjdwpProvider:adbconnection -XjdwpOptions:suspend=n,server=y -Xcompiler-option --debuggable"
+            else -> "-Xrunjdwp:transport=dt_android_adb,suspend=n,server=y -Xcompiler-option --debuggable"
+        } else ""
+        val extraParams = if (niceName != null) " --nice-name=$niceName" else ""
+        return "CLASSPATH=$packageCodePath exec $appProcess $debugParams /system/bin$extraParams $clazz"
+    }
+}