src/tools/fs.rs

   1 //! File system helper utilities.
   2
   3 use std::os::unix::io::RawFd;
   4
   5 use failure::Error;
   6 use nix::dir;
   7 use nix::dir::Dir;
   8
   9 use crate::tools::borrow::Tied;
  10
  11 // Since Tied<T, U> implements Deref to U, a Tied<Dir, Iterator> already implements Iterator.
  12 // This is simply a wrapper with a shorter type name mapping nix::Error to failure::Error.
  13 /// Wrapper over a pair of `nix::dir::Dir` and `nix::dir::Iter`, returned by `read_subdir()`.
  14 pub struct ReadDir {
  15     iter: Tied<Dir, Iterator<Item = nix::Result<dir::Entry>>>,
  16 }
  17
  18 impl Iterator for ReadDir {
  19     type Item = Result<dir::Entry, Error>;
  20
  21     fn next(&mut self) -> Option<Self::Item> {
  22         self.iter.next().map(|res| res.map_err(|e| Error::from(e)))
  23     }
  24 }
  25
  26 /// Create an iterator over sub directory entries.
  27 /// This uses `openat` on `dirfd`, so `path` can be relative to that or an absolute path.
  28 pub fn read_subdir<P: ?Sized + nix::NixPath>(dirfd: RawFd, path: &P) -> Result<ReadDir, Error> {
  29     use nix::fcntl::OFlag;
  30     use nix::sys::stat::Mode;
  31
  32     let dir = Dir::openat(dirfd, path, OFlag::O_RDONLY, Mode::empty())?;
  33     let iter = Tied::new(dir, |dir| {
  34         Box::new(unsafe { (*dir).iter() }) as Box<Iterator<Item = nix::Result<dir::Entry>>>
  35     });
  36     Ok(ReadDir { iter })
  37 }