add a simple echo message at checking root access

app/src/main/kotlin/com/simplemobiletools/filemanager/activities/SettingsActivity.kt

@@ -8,6 +8,7 @@ import com.simplemobiletools.commons.extensions.updateTextColors
 import com.simplemobiletools.commons.helpers.SHOW_ALL_TABS
 import com.simplemobiletools.filemanager.R
 import com.simplemobiletools.filemanager.extensions.config
+import com.simplemobiletools.filemanager.helpers.RootHelpers
 import kotlinx.android.synthetic.main.activity_settings.*
 
 class SettingsActivity : SimpleActivity() {
@@ -74,8 +75,18 @@ class SettingsActivity : SimpleActivity() {
     private fun setupEnableRootAccess() {
         settings_enable_root_access.isChecked = config.enableRootAccess
         settings_enable_root_access_holder.setOnClickListener {
-            settings_enable_root_access.toggle()
-            config.enableRootAccess = settings_enable_root_access.isChecked
+            if (!config.enableRootAccess) {
+                RootHelpers().askRootIFNeeded(this) {
+                    toggleRootAccess(it)
+                }
+            } else {
+                toggleRootAccess(false)
+            }
         }
     }
+
+    private fun toggleRootAccess(enable: Boolean) {
+        settings_enable_root_access.isChecked = enable
+        config.enableRootAccess = enable
+    }
 }

app/src/main/kotlin/com/simplemobiletools/filemanager/helpers/RootHelpers.kt

@@ -1,10 +1,38 @@
 package com.simplemobiletools.filemanager.helpers
 
+import com.simplemobiletools.commons.extensions.showErrorToast
 import com.simplemobiletools.commons.models.FileDirItem
+import com.simplemobiletools.filemanager.activities.SimpleActivity
 import com.stericson.RootShell.execution.Command
 import com.stericson.RootTools.RootTools
 
 class RootHelpers {
+    fun askRootIFNeeded(activity: SimpleActivity, callback: (success: Boolean) -> Unit) {
+        val SIMPLE_MOBILE_TOOLS = "simple mobile tools"
+        val command = object : Command(0, "echo $SIMPLE_MOBILE_TOOLS") {
+            override fun commandOutput(id: Int, line: String) {
+                if (line == SIMPLE_MOBILE_TOOLS)
+                    callback(true)
+                super.commandOutput(id, line)
+            }
+
+            override fun commandTerminated(id: Int, reason: String?) {
+                super.commandTerminated(id, reason)
+            }
+
+            override fun commandCompleted(id: Int, exitcode: Int) {
+                super.commandCompleted(id, exitcode)
+            }
+        }
+
+        try {
+            RootTools.getShell(true).add(command)
+        } catch (exception: Exception) {
+            activity.showErrorToast(exception)
+            callback(false)
+        }
+    }
+
     fun getFiles(path: String, callback: (fileDirItems: ArrayList<FileDirItem>) -> Unit) {
         val command = object : Command(0, "ls -la $path | awk '{print \$1,\$NF}'") {
             override fun commandOutput(id: Int, line: String) {