du -X with a nonexistent file panics

[ajanicij]

Running

du -X nonexistent-file

causes panic:

thread 'main' (1402696) panicked at src/uu/du/src/du.rs:759:37:
no such file: Os { code: 2, kind: NotFound, message: "No such file or directory" }
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
Aborted (core dumped)

But GNU's du just prints this:

du: nonexistent-file: No such file or directory
Try 'du --help' for more information.

[oech3]

Oh... We would achieve a bunch of Result<> again...

coreutils/src/uu/du/src/du.rs

Line 758 in 0366d3c

fn file_as_vec(filename: impl AsRef<Path>) -> Vec<String> {

[ajanicij]

Sorry, can you please explain? I am quite new here (last time I was active at coreutils - briefly - was about 5 years ago), does this issue have a history?

[oech3]

Oh sorry. I don't know about history. But this is caused by except() at

coreutils/src/uu/du/src/du.rs

Line 759 in 0366d3c

let file = File::open(filename).expect("no such file");

. We should return error to uumain to avoid panic.

[ajanicij]

That is one way. How about an alternative: if File::open fails, return an empty vector:

fn file_as_vec(filename: impl AsRef<Path>) -> Vec<String> {
    if let Ok(file) = File::open(filename) {
        let buf = BufReader::new(file);

        buf.lines()
            .map(|l| l.expect("Could not parse line"))
            .collect()
    } else {
        Vec::new()
    }
}

[oech3]

It is possible, but mismatches with corrent codebase.

[oech3]

No. because we need to extract ErrorKind:

> du -X /proc/self/mem

thread 'main' (653) panicked at src/uu/du/src/du.rs:763:20:
Could not parse line: Os { code: 5, kind: Uncategorized, message: "Input/output error" }
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
fish: Job 1, 'du -X /proc/self/mem' terminated by signal SIGABRT (Abort)

[oech3]

 du -X /tmp

thread 'main' (1390) panicked at src/uu/du/src/du.rs:763:20:
Could not parse line: Os { code: 21, kind: IsADirectory, message: "Is a directory" }

[ajanicij]

You are right, we need to exit the program if the file doesn't exist. I tried with GNU's du:

$ du -X nofile -X somefile dir/*
du: nofile: No such file or directory
Try 'du --help' for more information.

(Here, somefile exists, but nofile doesn't. So du exits with error.)