cap-primitives 0.16.1

Capability-based primitives
Documentation 
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use crate::fs::{
    open_dir_for_reading, open_dir_for_reading_unchecked, open_entry_impl, read_dir_unchecked,
    remove_dir_unchecked, remove_file_unchecked, stat_unchecked, DirEntryInner, FollowSymlinks,
    Metadata, OpenOptions, ReadDir,
};
use io_lifetimes::AsFd;
use posish::fs::Dir;
#[cfg(unix)]
use std::os::unix::ffi::OsStrExt;
#[cfg(target_os = "wasi")]
use std::os::wasi::ffi::OsStrExt;
use std::{
    ffi::OsStr,
    fmt, fs, io,
    mem::ManuallyDrop,
    path::{Component, Path},
    sync::{Arc, Mutex},
};
use unsafe_io::os::posish::{AsRawFd, FromRawFd, RawFd};

pub(crate) struct ReadDirInner {
    raw_fd: RawFd,
    posish: Arc<Mutex<Dir>>,
}

impl ReadDirInner {
    pub(crate) fn new(start: &fs::File, path: &Path) -> io::Result<Self> {
        let dir = Dir::from(open_dir_for_reading(start, path)?)?;
        Ok(Self {
            raw_fd: dir.as_fd().as_raw_fd(),
            posish: Arc::new(Mutex::new(dir)),
        })
    }

    pub(crate) fn read_base_dir(start: &fs::File) -> io::Result<Self> {
        // Open ".", to obtain a new independent file descriptor. Don't use
        // `dup` since in that case the resulting file descriptor would share
        // a current position with the original, and `read_dir` calls after
        // the first `read_dir` call wouldn't start from the beginning.
        let dir = Dir::from(open_dir_for_reading_unchecked(
            start,
            Component::CurDir.as_ref(),
        )?)?;
        Ok(Self {
            raw_fd: dir.as_fd().as_raw_fd(),
            posish: Arc::new(Mutex::new(dir)),
        })
    }

    pub(crate) fn new_unchecked(start: &fs::File, path: &Path) -> io::Result<Self> {
        let dir = open_dir_for_reading_unchecked(start, path)?;
        Ok(Self {
            raw_fd: dir.as_fd().as_raw_fd(),
            posish: Arc::new(Mutex::new(Dir::from(dir)?)),
        })
    }

    pub(super) fn open(&self, file_name: &OsStr, options: &OpenOptions) -> io::Result<fs::File> {
        open_entry_impl(&self.as_file_view(), file_name, options)
    }

    pub(super) fn metadata(&self, file_name: &OsStr) -> io::Result<Metadata> {
        stat_unchecked(&self.as_file_view(), file_name.as_ref(), FollowSymlinks::No)
    }

    pub(super) fn remove_file(&self, file_name: &OsStr) -> io::Result<()> {
        remove_file_unchecked(&self.as_file_view(), file_name.as_ref())
    }

    pub(super) fn remove_dir(&self, file_name: &OsStr) -> io::Result<()> {
        remove_dir_unchecked(&self.as_file_view(), file_name.as_ref())
    }

    pub(super) fn self_metadata(&self) -> io::Result<Metadata> {
        Metadata::from_file(&self.as_file_view())
    }

    pub(super) fn read_dir(&self, file_name: &OsStr) -> io::Result<ReadDir> {
        read_dir_unchecked(&self.as_file_view(), file_name.as_ref())
    }

    #[allow(unsafe_code)]
    fn as_file_view(&self) -> ManuallyDrop<fs::File> {
        // Safety: `self.posish` owns the file desctiptor. We just hold a
        // copy outside so that we can read it without taking a lock.
        ManuallyDrop::new(unsafe { fs::File::from_raw_fd(self.raw_fd) })
    }
}

impl Iterator for ReadDirInner {
    type Item = io::Result<DirEntryInner>;

    fn next(&mut self) -> Option<Self::Item> {
        loop {
            let entry = match self.posish.lock().unwrap().read()? {
                Ok(entry) => entry,
                Err(e) => return Some(Err(e.into())),
            };
            let file_name = entry.file_name().to_bytes();
            if file_name != Component::CurDir.as_os_str().as_bytes()
                && file_name != Component::ParentDir.as_os_str().as_bytes()
            {
                let clone = Arc::clone(&self.posish);
                return Some(Ok(DirEntryInner {
                    posish: entry,
                    read_dir: Self {
                        raw_fd: self.raw_fd,
                        posish: clone,
                    },
                }));
            }
        }
    }
}

impl fmt::Debug for ReadDirInner {
    // Like libstd's version, but doesn't print the path.
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        let mut b = f.debug_struct("ReadDir");
        b.field("raw_fd", &self.raw_fd);
        b.finish()
    }
}