Crate openat_ct 

Handling Files Relative to File Descriptor

Main concept here is a Dir which holds O_PATH file descriptor, you can create it with:

• Dir::open("/some/path") – open this directory as a file descriptor
• Dir::from_raw_fd(fd) – uses a file descriptor provided elsewhere

Note after opening file descriptors refer to same directory regardless of where it’s moved or mounted (with pivot_root or mount --move). It may also be unmounted or be out of chroot and you will still be able to access files relative to it.

Note2: The constructor Dir::cwd() is deprecated, and it’s recommended to use Dir::open(".") instead.

Note3: Some OS’s (e.g., macOS) do not provide O_PATH, in which case the file descriptor is of regular type.

Most other operations are done on Dir object and are executed relative to it:

• Dir::list_dir()
• Dir::sub_dir()
• Dir::read_link()
• Dir::open_file()
• Dir::create_file()
• Dir::update_file()
• Dir::create_dir()
• Dir::symlink()
• Dir::local_rename()

Functions that expect path relative to the directory accept both the traditional path-like objects, such as Path, PathBuf and &str, and Entry type returned from list_dir(). The latter is faster as underlying system call wants CString and we keep that in entry.

Note that if path supplied to any method of dir is absolute the Dir file descriptor is ignored.

Also while all methods of dir accept any path if you want to prevent certain symlink attacks and race condition you should only use a single-component path. I.e. open one part of a chain at a time.

Structs

Dir

A safe wrapper around directory file descriptor

DirFlags

‘Dir::new()’ creates a new DirFlags object with default (O_CLOEXEC) flags. One can then freely add/remove flags to the set. The final open calls will add O_DIRECTORY and O_PATH as applicable/supported but not verify or remove any defined flags. This allows passing flags the ‘openat’ implementation is not even aware about. Thus the open call may fail with some error when one constructed an invalid flag set.

DirIter

Iterator over directory entries

DirMethodFlags

‘Dir::with(&self)’/‘Dir::with(&self)’ creates a new DirMethodsFlags object with default (O_CLOEXEC|O_NOFOLLOW) flags. One can then freely add/remove flags to the set. Implements proxies for the Dir:: methods that open contained objects.

Entry

Entry returned by iterating over DirIter iterator

Metadata

A file metadata

Enums

SimpleType

This is a simplified file type enum that is easy to match

Constants

O_DIRECTORY

Value if the libc::O_DIRECTORY flag when supported by the system, otherwise 0

O_PATH

Value if the libc::O_PATH flag when supported by the system, otherwise 0

O_SEARCH

Value if the libc::O_SEARCH flag when supported by the system, otherwise 0

Traits

AsPath

The purpose of this is similar to AsRef<Path> but it’s optimized for things that can be directly used as CStr (which is type passed to the underlying system call).

Functions

hardlink

Create a hardlink to a file

rename

Rename (move) a file between directories