way to prevent openDirStream from following symlinks

[joeyh]

haskell/directory#97 needs a way to list the content of a directory that avoids following a symlink. The unix way to do that is open with O_NOFOLLOW and then passing the fd to fdopendir. This library does not provide a way to do that; could it?

---

One way would be to add

openDirStreamFromFd :: Fd -> IO DirStream

But that is fairly low-level. The user needs to take care to avoid reusing the Fd after calling it. Also, while some of the OpenFileFlags may make sense for opening a directory, most of them probably don't. And the user would need to take care to set O_CLOEXEC to avoid a possible fd leak.

This interface would avoid those problems (pass O_CLOEXEC always):

data OpenDirFlags = OpenDirFlags { dir_nofollow :: Bool, ... }

openDirStream' :: OpenDirFlags -> IO DirStream

Assuming this is exported from the same module as OpenFileFlags, the fields in OpenDirFlags need to be qualified to avoid name conflicts. Or OpenFileFlags could be used for openDirStream', but a number of those flags don't make sense for opening a directory.

Also openDirStream could be changed to take such an OpenDirFlags, if an API bump appeals.

I'd be happy to implement whichever of these you prefer.

[hasufell]

Check https://hackage.haskell.org/package/hpath-io-0.10.0/docs/System-Posix-Directory-Traversals.html for inspiration, which has fdopendir.

https://github.com/hasufell/hpath/blob/3b6eb46dc9a95395afe06b8cf5ec507e264628fc/hpath-io/src/System/Posix/Directory/Traversals.hs#L226-L245

[hasufell]

Seems there already is a PR: #110

[Rufflewind]

Sorry, posted on the wrong thread. Moved to: haskell/directory#97 (comment)

[hs-viktor]

With #110 merged, can we close this?

[Rufflewind]

Are there plans to release #110 any time soon? directory is unable to use the new functionality to resolve haskell/directory#97 if the changes aren't released.

[Bodigrim]

Yes, we are likely to make a release soon (but not immediately).