Implementing `mkdir -p`

[willemneal]

I'm implementing Wasi for AssemblyScript and currently I'm confused with the API for creating a directory. Is it safe to assume that by default trying to create a directory, whose parent(s) don't exist that it would fail?

Also what is the best way to determine if a file or directory exists?

[sunfishcode]

Yes, __wasi_path_create_directory only creates one directory, similar to POSIX mkdir, and fails if the parent doesn't exist.

The typical way to test whether a file or directory exists is to just try to do whatever you would want to do, and handle errors in case it doesn't work. For mkdir -p, this means that you can just call __wasi_path_create_directory once for each path component. At each component, if you get __WASI_EEXIST, then it already exists and you can move the the next component. If it succeeds, then you just created it and you can move to the next component.

[willemneal]

Thanks! That makes a lot of sense.

[tschneidereit]

Closing this based on @sunfishcode's comment.