bug: Recursive lister stops iteration after encountering PermissionDenied error

[cjlee38]

Describe the bug

When using a recursive lister, if a PermissionDenied error occurs while iterating (e.g., accessing a protected directory), the lister immediately returns None on the next .next() call, terminating the entire iteration.

This causes the listing to stop prematurely, even when there are many more accessible files/directories remaining at the same level or in sibling directories.

Steps to Reproduce

use futures::StreamExt as _;
use opendal::Operator;
use opendal::ErrorKind;

#[tokio::main]
async fn main() {
    opendal_reproduce().await;
}

async fn opendal_reproduce() -> Result<(), opendal::Error> {
    let builder = opendal::services::Fs::default().root("/foo/bar/");
    let op = Operator::new(builder)?.finish();

    println!("Listing directory...");

    let mut lister = op.lister_with("/").recursive(true).await.unwrap();

    while let Some(entry_res) = lister.next().await {
        match entry_res {
            Ok(entry) => { 
                println!("Process entry: {}", entry.path());
             }
            Err(e) if e.kind() == ErrorKind::PermissionDenied => {
                // I want to skip and continue
                println!("Permission denied: {}", e);
                continue;
            }
            Err(e) => {
                println!("Error: {}", e);
                return Err(e);
            },
        }
    }
    println!("Done listing directory.");
    Ok(())
}

For example, if there are several files or folders(e.g. A, B, C) with MyForbiddenPath, then the log output should be like below.

Listing directory...
Process entry: A
Process entry: B
Permission denied: PermissionDenied (permanent) at list, context: { service: fs, path: MyForbiddenPath/ } => permission denied, source: Operation not permitted (os error 1)
Done listing directory.

which skips the C

Expected Behavior

After encountering a PermissionDenied error, the lister should skip the inaccessible directory and continue returning the remaining entries from other accessible directories.

The iteration should only return None when all accessible entries have been exhausted.

Additional Context

I encountered this issue with the fs service on macOS (hitting Photos Library.photoslibrary), but I suspect this behavior applies to other services as well since the recursive lister logic may be shared.

Also, I haven't verified this, but it's worth checking whether other error types (not just PermissionDenied) also cause the lister to terminate prematurely in the same way.

Are you willing to submit a PR to fix this bug?

• Yes, I would like to submit a PR.