App Logs logcat listener

[john-peterson]

How does it work?

Sometimes App Logs is empty nothing is picked up

How is it able to listen to another app without READ_LOGS permission

[itsaky]

Sometimes App Logs is empty nothing is picked up

Can't say what actually causes this issue without more information, but you can try the following things :

• Make sure that you install the debug variant of your application that has been built with AndroidIDE.
• Enable USB debugging.
• Increase the log buffer size in Android's developer options.

If it still doens't work, file a bug report with more details about the issue.

How is it able to listen to another app without READ_LOGS permission

This is achieved using AndroidIDE's logsender module.

When you build an application in AndroidIDE, the LogSender Gradle plugin is applied to the Android application modules (com.android.application). This plugin adds the logsender dependency to the debuggable variants of your project (source). This means that every debuggable variant of your application module(s) (not libraries) in your whole project has this dependency.

ContentProviders in Android are started automatically when you open an application. So, the logsender dependency has a non-exported (private) content provider (LogSenderInstaller), which, when started, spawns a new background service to read the logs of your application. When this background service starts (in your application), it binds with the log receiver service in AndroidIDE. When the communication has been established, your application (the service) reads every line from logcat and sends these lines to AndroidIDE's log receiver over a local socket connection which are then shown in AndroidIDE's UI.

This works because the READ_LOGS permissions is not needed for an application to read its own logs.

Here is a flowchart of the whole process (view on web):

flowchart TD
    A[Build Application in AndroidIDE] --> B[Launch Application]
    B --> C[Start non-exported ContentProvider: LogSenderInstaller]
    C --> D[Spawn Background Service: LogSenderService]
    D --> E[Bind LogSenderService with AndroidIDE's LogReceiverService]
    E --> F[Establish Socket Communication between Application and AndroidIDE]
    F --> G[Read logcat lines in Application Service]
    G --> H[Send logcat lines to AndroidIDE over Local Socket]
    H --> I[Display logs in AndroidIDE's UI]

    subgraph Notes
        note1[READ_LOGS permission is not needed for an application to read its own logs.]
    end

    I -.-> note1

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I hope this helps.