What is the Best Practice for Reading/Writing Files and Directories to Android Internal Storage with Rust Backend

[tyrsday29]

Hi!

Forgive me if this is a noob question, but recompiles have been pretty taxing, and I'm relatively new to mobile development. I found a similar 'unanswered' question from a year ago that referenced some things from v1. Some of what was referenced appears deprecated, and I'm running into some road blocks in development- so wanted to reach out before I pour too much time into this.

My app is going to be reading some files on start-up/actively (likely bincode) which will need to be deserialized in the backend- data will be queried occasionally from the front. I see that plugin allows you to read from the front end, but it seems like I'm running into some permissions issues- I cant create files anywhere or read files from anywhere in rust. Whenever I try to create a directory relative to the current directory I receive
... I RustStdoutStderr: ...: Read-only file system (os error 30)
I've tried the dirs crate and checking std::env for paths to check the correct directory, even absolute paths of what I think the application folder should be- all to no avail.

I'm hoping this is a permissions thing, but haven't had any luck with that line either. I was trying to avoid looking up directories on the front end and sending messages to the backend since that seems a bit unsafe- anyone have any advice?

[aiueo13]

What does internal storage mean? Is it private storage for the app only, or the device’s built-in storage (as opposed to an SD card)?

[aiueo13]

If it is the former, you can get an app-specific directory path as follows.

fn example(app: &tauri::AppHandle) -> tauri::Result<()> {
    use tauri::Manager as _;

    // Apps can fully manage entries within this directory with std::fs.
    let private_dir_path: std::path::PathBuf = app.path().app_data_dir()?;

    Ok(())
}

In the latter case, it is a bit of a hassle.

It must be read and written using tauri_plugin_fs and tauri_plugin_dialog. This article is helpful, This is done on the frontend, but can also be done on the backend, since a similar function exists there.

There is also an Android file system plugin, although it is not compatible with other platforms.

[tyrsday29]

Hey yes I meant application storage- thanks for the information, that definitely cleared things up for me. Thanks for all of the info