brush_core/sys/unix/
fd.rs

1//! File descriptor utilities.
2
3use std::os::fd::RawFd;
4
5use crate::{ShellFd, error, openfiles};
6
7cfg_if::cfg_if! {
8    if #[cfg(any(target_os = "linux", target_os = "android"))] {
9        const FD_DIR_PATH: &str = "/proc/self/fd";
10    } else if #[cfg(any(
11            target_os = "freebsd",
12            target_os = "macos",
13            target_os = "netbsd",
14            target_os = "openbsd"
15        ))] {
16        const FD_DIR_PATH: &str = "/dev/fd";
17    } else {
18        /// Returns an iterator over all open file descriptors for the shell.
19        pub fn iter_fds()
20        -> Result<impl Iterator<Item = (ShellFd, openfiles::OpenFile)>, error::Error> {
21            Ok(std::iter::empty())
22        }
23    }
24}
25
26/// Makes a best-effort attempt to iterate over all open file descriptors
27/// for the current process.
28///
29/// If the platform does not support enumerating file descriptors, an empty iterator
30/// is returned. This function will skip any file descriptors that cannot be opened.
31#[cfg(any(
32    target_os = "linux",
33    target_os = "android",
34    target_os = "freebsd",
35    target_os = "macos",
36    target_os = "netbsd",
37    target_os = "openbsd"
38))]
39pub fn try_iter_open_fds() -> impl Iterator<Item = (ShellFd, openfiles::OpenFile)> {
40    std::fs::read_dir(FD_DIR_PATH)
41        .into_iter()
42        .flatten()
43        .filter_map(Result::ok)
44        .filter_map(|entry| {
45            let fd: RawFd = entry.file_name().to_str()?.parse().ok()?;
46
47            // SAFETY:
48            // We are trying to open the file descriptor we found listed
49            // in the filesystem, but there's a risk that it's not the same one
50            // that we enumerated or that it's since been closed. For the purposes
51            // of this function, either of those outcomes are acceptable. We
52            // simply skip any fds that we can't open, and the function's purpose
53            // is to make a best-effort attempt to open all available fds.
54            let file = unsafe { open_file_by_fd(fd) }.ok()?;
55
56            Some((fd, file))
57        })
58}
59
60/// Attempts to retrieve an `OpenFile` representation for the given already-open file descriptor.
61///
62/// If the file descriptor cannot be opened, `None` is returned. Note that there is no guarantee
63/// that the returned file matches the original file descriptor, as the fd may have been closed
64/// and potentially re-used in the meantime.
65///
66/// # Arguments
67///
68/// * `fd` - The file descriptor to open.
69pub fn try_get_file_for_open_fd(fd: RawFd) -> Option<openfiles::OpenFile> {
70    // SAFETY:
71    // We are trying to open the file descriptor provided by the caller. There's a risk that the fd
72    // is invalid or has been closed since it was enumerated. For the purposes of this function,
73    // we simply return None if we can't open it. There's also a risk that the fd has been closed
74    // and re-used for a different file; again, for the purposes of this function, we accept that
75    // risk and document it as part of the function's contract.
76    unsafe { open_file_by_fd(fd).ok() }
77}
78
79unsafe fn open_file_by_fd(fd: RawFd) -> Result<openfiles::OpenFile, error::Error> {
80    // SAFETY: We are creating a BorrowedFd from a file descriptor. Callers typically
81    // enumerate available file descriptors from procfs, devfs, or similar, but there's
82    // still a risk that the fd has become invalid or closed since then -- or that this
83    // function gets used incorrectly.
84    let borrowed_fd = unsafe { std::os::fd::BorrowedFd::borrow_raw(fd) };
85    let owned_fd = borrowed_fd.try_clone_to_owned()?;
86    Ok(std::fs::File::from(owned_fd).into())
87}
brush_core/sys/unix/fd.rs

brush_core/sys/unix/
fd.rs
