OPFS Rust

Rust wrapper for the the Origin Private File System browser API. (This is an API that gives webapps limited access to the native file system.)

This library mostly exists because using the OPFS from Rust is very painful. As a bonus, it also gives you support for native platforms for free - when compiling to native platforms, it will use tokio::fs instead of browser APIs.

Overview

This crate provides an API for file system operations that automatically uses the appropriate implementation based on the target platform:

• Web (WASM): Uses the Origin Private File System (OPFS) API
• Native platforms: Uses tokio::fs

An in-memory filesystem is also provided for use in tests (or when persistence isn't necessary)

Features

• Write once, run anywhere: The same code works natively and on the web
• Async/await: All operations are asynchronous
• Type safety: The type-unsafe JsValue soup associated with working with browser APIs from Rust is hidden behind a type-safe API.

Installation

cargo add opfs

Usage

use opfs::persistent::{DirectoryHandle, FileHandle, WritableFileStream, app_specific_dir};
use opfs::{GetFileHandleOptions, CreateWritableOptions};
use opfs::persistent;

// you must import the traits to call methods on the types
use opfs::{DirectoryHandle as _, FileHandle as _, WritableFileStream as _};

// This code works on both native and web platforms
async fn example(dir: DirectoryHandle) -> persistent::Result<()> {
    let options = GetFileHandleOptions { create: true };
    let mut file = dir.get_file_handle_with_options("example.txt", &options).await?;
    
    let write_options = CreateWritableOptions { keep_existing_data: false };
    let mut writer = file.create_writable_with_options(&write_options).await?;
    
    writer.write_at_cursor_pos(b"Hello, world!".to_vec()).await?;
    writer.close().await?;
    
    let data = file.read().await?;
    println!("File contents: {:?}", String::from_utf8(data));
    
    Ok(())
}

async fn use_example() -> persistent::Result<()> {
    let directory: DirectoryHandle = app_specific_dir().await?;
    example(directory).await?;
    Ok(())
}