[BUG] Full-path search and globbing leads to fd not exit on pipeline closing

[postsolar]

Checks

• I have read the troubleshooting section and still think this is a bug.

Describe the bug you encountered:

The shortest example I came up with is this:

> (fd . -p / | (exit))
# closes immediately, as expected
> (fd -g '*' -p / | (exit))
# hangs until the search is complete

I noticed it sometimes doesn't seem to happen when a ** pattern is used, only with single * or with both * and **, but it's hard to establish a clear pattern.

Where it matters practically though is when piping into fzf. It will not abort the search even when fzf has exited.

One workaround I found for my use-case specifically is to make fzf invoke fd itself, i.e. FZF_DEFAULT_COMMAND='fd -gp "*" /' fzf. Alternatively, something like fd -gp "*" / | { (fzf; exit) } can also work.

Describe what you expected to happen:

fd should exit the same way it does with regex search.

What version of fd are you using?

9.0.0

Which operating system / distribution are you on?

Linux 6.1.72 x86_64

No LSB modules are available.
Distributor ID:	NixOS
Description:	NixOS 24.05 (Uakari)
Release:	24.05
Codename:	uakari

[tavianator]

Well, the deeper issue is that fd -p -g '*' doesn't print anything. That's why it never quits, it never even writes anything to the pipe.

[tavianator]

Oh wait, I guess that's on purpose. * is only matching a single path component. It works with **. See #404 (comment) and 47974b6

[postsolar]

> (fd -gp '**' / | exit)
# exits normally
> (fd -gp '**' / | fzf)
# exits normally
> fd -gp '**' / | fzf
# exits normally
> (fd -gp '/home/me/**' / | exit)
# exits normally
> (fd -gp '/home/me/**' / | fzf)
# blocks
> fd -gp '/home/me/**' / | fzf
# blocks
> (fd -gpHL '/home/me/**' / | exit)
# forks??
> (fd -gpHL '/home/me/**' / | fzf)
# also forks
> fd -gpHL '/home/me/**' / | fzf
# blocks

[tavianator]

Hmm I'm not sure what you mean by "forks". But as far as I can tell the behaviour of all those commands is within the expected range. fd will only exit on a closed pipe if it actually tries to write while the pipeline is closed. For something like

> (fd -gp '/home/me/**' / | fzf)

it's quite possible that fd prints all the matching paths while fzf is still running, meaning the pipe is open. When you quit fzf, fd might still be searching the rest of /, but it will never print anything again so it will never learn that the pipe is closed.

See #472 for some related discussion about detecting closed pipes.

[postsolar]

Thank you, I now undestand the problem. I didn't know how terminating the pipe works, my assumption was that a signal is sent when the receiving process exits, not when the sending process tries to write data.

By "forks" I mean fd starts to consume a lot of CPU and the process becomes independent of where I launched it from. I can even close the terminal and it's still running, as can be inspected in a process monitor utility.