tauri-plugins-workspace/plugins/persisted-scope/src/lib.rs

// Copyright 2021 Tauri Programme within The Commons Conservancy
// SPDX-License-Identifier: Apache-2.0
// SPDX-License-Identifier: MIT

use aho_corasick::AhoCorasick;
use serde::{Deserialize, Serialize};
use tauri::{
    plugin::{Builder, TauriPlugin},
    AppHandle, FsScopeEvent, Manager, Runtime,
};

use std::{
    fs::{create_dir_all, File},
    io::Write,
    path::Path,
};

const SCOPE_STATE_FILENAME: &str = ".persisted-scope";

// Most of these patterns are just added to try to fix broken files in the wild.
// After a while we can hopefully reduce it to something like [r"[?]", r"[*]", r"\\?\\\?\"]
const PATTERNS: &[&str] = &[
    r"[[]",
    r"[]]",
    r"[?]",
    r"[*]",
    r"\?\?",
    r"\\?\\?\",
    r"\\?\\\?\",
];
const REPLACE_WITH: &[&str] = &[r"[", r"]", r"?", r"*", r"\?", r"\\?\", r"\\?\"];

#[derive(Debug, thiserror::Error)]
enum Error {
    #[error(transparent)]
    Io(#[from] std::io::Error),
    #[error(transparent)]
    Tauri(#[from] tauri::Error),
    #[error(transparent)]
    TauriApi(#[from] tauri::api::Error),
    #[error(transparent)]
    Bincode(#[from] Box<bincode::ErrorKind>),
}

#[derive(Debug, Default, Deserialize, Serialize)]
struct Scope {
    allowed_paths: Vec<String>,
    forbidden_patterns: Vec<String>,
}

fn fix_pattern(ac: &AhoCorasick, s: &str) -> String {
    let s = ac.replace_all(s, REPLACE_WITH);

    if ac.find(&s).is_some() {
        return fix_pattern(ac, &s);
    }

    s
}

fn save_scopes<R: Runtime>(app: &AppHandle<R>, app_dir: &Path, scope_state_path: &Path) {
    let fs_scope = app.fs_scope();

    let scope = Scope {
        allowed_paths: fs_scope
            .allowed_patterns()
            .into_iter()
            .map(|p| p.to_string())
            .collect(),
        forbidden_patterns: fs_scope
            .forbidden_patterns()
            .into_iter()
            .map(|p| p.to_string())
            .collect(),
    };

    let _ = create_dir_all(app_dir)
        .and_then(|_| File::create(scope_state_path))
        .map_err(Error::Io)
        .and_then(|mut f| {
            f.write_all(&bincode::serialize(&scope).map_err(Error::from)?)
                .map_err(Into::into)
        });
}

pub fn init<R: Runtime>() -> TauriPlugin<R> {
    Builder::new("persisted-scope")
        .setup(|app, _api| {
            let fs_scope = app.fs_scope();
            #[cfg(feature = "protocol-asset")]
            let asset_protocol_scope = app.asset_protocol_scope();
            let app = app.clone();
            let app_dir = app.path().app_data_dir();

            if let Ok(app_dir) = app_dir {
                let scope_state_path = app_dir.join(SCOPE_STATE_FILENAME);

                let _ = fs_scope.forbid_file(&scope_state_path);
                #[cfg(feature = "protocol-asset")]
                let _ = asset_protocol_scope.forbid_file(&scope_state_path);

                // We're trying to fix broken .persisted-scope files seamlessly, so we'll be running this on the values read on the saved file.
                // We will still save some semi-broken values because the scope events are quite spammy and we don't want to reduce runtime performance any further.
                let ac = AhoCorasick::new(PATTERNS).unwrap(/* This should be impossible to fail since we're using a small static input */);

                if scope_state_path.exists() {
                    let scope: Scope = tauri::api::file::read_binary(&scope_state_path)
                        .map_err(Error::from)
                        .and_then(|scope| bincode::deserialize(&scope).map_err(Into::into))
                        .unwrap_or_default();
                    for allowed in &scope.allowed_paths {
                        let allowed = fix_pattern(&ac, allowed);

                        let _ = fs_scope.allow_file(&allowed);
                        #[cfg(feature = "protocol-asset")]
                        let _ = asset_protocol_scope.allow_file(&allowed);
                    }
                    for forbidden in &scope.forbidden_patterns {
                        let forbidden = fix_pattern(&ac, forbidden);

                        let _ = fs_scope.forbid_file(&forbidden);
                        #[cfg(feature = "protocol-asset")]
                        let _ = asset_protocol_scope.forbid_file(&forbidden);
                    }

                    // Manually save the fixed scopes to disk once.
                    // This is needed to fix broken .peristed-scope files in case the app doesn't update the scope itself.
                    save_scopes(&app, &app_dir, &scope_state_path);
                }

                fs_scope.listen(move |event| {
                    if let FsScopeEvent::PathAllowed(_) = event {
                        save_scopes(&app, &app_dir, &scope_state_path);
                    }
                });
            }
            Ok(())
        })
        .build()
}