1 files changed, 315 insertions, 0 deletions
diff --git a/vendor/rustix/src/backend/linux_raw/fs/dir.rs b/vendor/rustix/src/backend/linux_raw/fs/dir.rs
new file mode 100644
index 0000000..dbddd58
--- /dev/null
+++ b/vendor/rustix/src/backend/linux_raw/fs/dir.rs
@@ -0,0 +1,315 @@
+use crate::fd::{AsFd, BorrowedFd, OwnedFd};
+use crate::ffi::{CStr, CString};
+use crate::fs::{
+    fcntl_getfl, fstat, fstatfs, fstatvfs, openat, FileType, Mode, OFlags, Stat, StatFs, StatVfs,
+};
+use crate::io;
+#[cfg(feature = "process")]
+use crate::process::fchdir;
+use crate::utils::as_ptr;
+use alloc::borrow::ToOwned;
+use alloc::vec::Vec;
+use core::fmt;
+use core::mem::size_of;
+use linux_raw_sys::general::{linux_dirent64, SEEK_SET};
+
+/// `DIR*`
+pub struct Dir {
+    /// The `OwnedFd` that we read directory entries from.
+    fd: OwnedFd,
+
+    /// Have we seen any errors in this iteration?
+    any_errors: bool,
+
+    /// Should we rewind the stream on the next iteration?
+    rewind: bool,
+
+    /// The buffer for `linux_dirent64` entries.
+    buf: Vec<u8>,
+
+    /// Where we are in the buffer.
+    pos: usize,
+}
+
+impl Dir {
+    /// Take ownership of `fd` and construct a `Dir` that reads entries from
+    /// the given directory file descriptor.
+    #[inline]
+    pub fn new<Fd: Into<OwnedFd>>(fd: Fd) -> io::Result<Self> {
+        Self::_new(fd.into())
+    }
+
+    #[inline]
+    fn _new(fd: OwnedFd) -> io::Result<Self> {
+        Ok(Self {
+            fd,
+            any_errors: false,
+            rewind: false,
+            buf: Vec::new(),
+            pos: 0,
+        })
+    }
+
+    /// Borrow `fd` and construct a `Dir` that reads entries from the given
+    /// directory file descriptor.
+    #[inline]
+    pub fn read_from<Fd: AsFd>(fd: Fd) -> io::Result<Self> {
+        Self::_read_from(fd.as_fd())
+    }
+
+    #[inline]
+    fn _read_from(fd: BorrowedFd<'_>) -> io::Result<Self> {
+        let flags = fcntl_getfl(fd)?;
+        let fd_for_dir = openat(fd, cstr!("."), flags | OFlags::CLOEXEC, Mode::empty())?;
+
+        Ok(Self {
+            fd: fd_for_dir,
+            any_errors: false,
+            rewind: false,
+            buf: Vec::new(),
+            pos: 0,
+        })
+    }
+
+    /// `rewinddir(self)`
+    #[inline]
+    pub fn rewind(&mut self) {
+        self.any_errors = false;
+        self.rewind = true;
+        self.pos = self.buf.len();
+    }
+
+    /// `readdir(self)`, where `None` means the end of the directory.
+    pub fn read(&mut self) -> Option<io::Result<DirEntry>> {
+        // If we've seen errors, don't continue to try to read anyting further.
+        if self.any_errors {
+            return None;
+        }
+
+        // If a rewind was requested, seek to the beginning.
+        if self.rewind {
+            self.rewind = false;
+            match io::retry_on_intr(|| {
+                crate::backend::fs::syscalls::_seek(self.fd.as_fd(), 0, SEEK_SET)
+            }) {
+                Ok(_) => (),
+                Err(err) => {
+                    self.any_errors = true;
+                    return Some(Err(err));
+                }
+            }
+        }
+
+        // Compute linux_dirent64 field offsets.
+        let z = linux_dirent64 {
+            d_ino: 0_u64,
+            d_off: 0_i64,
+            d_type: 0_u8,
+            d_reclen: 0_u16,
+            d_name: Default::default(),
+        };
+        let base = as_ptr(&z) as usize;
+        let offsetof_d_reclen = (as_ptr(&z.d_reclen) as usize) - base;
+        let offsetof_d_name = (as_ptr(&z.d_name) as usize) - base;
+        let offsetof_d_ino = (as_ptr(&z.d_ino) as usize) - base;
+        let offsetof_d_type = (as_ptr(&z.d_type) as usize) - base;
+
+        // Test if we need more entries, and if so, read more.
+        if self.buf.len() - self.pos < size_of::<linux_dirent64>() {
+            match self.read_more()? {
+                Ok(()) => (),
+                Err(err) => return Some(Err(err)),
+            }
+        }
+
+        // We successfully read an entry. Extract the fields.
+        let pos = self.pos;
+
+        // Do an unaligned u16 load.
+        let d_reclen = u16::from_ne_bytes([
+            self.buf[pos + offsetof_d_reclen],
+            self.buf[pos + offsetof_d_reclen + 1],
+        ]);
+        assert!(self.buf.len() - pos >= d_reclen as usize);
+        self.pos += d_reclen as usize;
+
+        // Read the NUL-terminated name from the `d_name` field. Without
+        // `unsafe`, we need to scan for the NUL twice: once to obtain a size
+        // for the slice, and then once within `CStr::from_bytes_with_nul`.
+        let name_start = pos + offsetof_d_name;
+        let name_len = self.buf[name_start..]
+            .iter()
+            .position(|x| *x == b'\0')
+            .unwrap();
+        let name = CStr::from_bytes_with_nul(&self.buf[name_start..][..=name_len]).unwrap();
+        let name = name.to_owned();
+        assert!(name.as_bytes().len() <= self.buf.len() - name_start);
+
+        // Do an unaligned u64 load.
+        let d_ino = u64::from_ne_bytes([
+            self.buf[pos + offsetof_d_ino],
+            self.buf[pos + offsetof_d_ino + 1],
+            self.buf[pos + offsetof_d_ino + 2],
+            self.buf[pos + offsetof_d_ino + 3],
+            self.buf[pos + offsetof_d_ino + 4],
+            self.buf[pos + offsetof_d_ino + 5],
+            self.buf[pos + offsetof_d_ino + 6],
+            self.buf[pos + offsetof_d_ino + 7],
+        ]);
+
+        let d_type = self.buf[pos + offsetof_d_type];
+
+        // Check that our types correspond to the `linux_dirent64` types.
+        let _ = linux_dirent64 {
+            d_ino,
+            d_off: 0,
+            d_type,
+            d_reclen,
+            d_name: Default::default(),
+        };
+
+        Some(Ok(DirEntry {
+            d_ino,
+            d_type,
+            name,
+        }))
+    }
+
+    #[must_use]
+    fn read_more(&mut self) -> Option<io::Result<()>> {
+        // The first few times we're called, we allocate a relatively small
+        // buffer, because many directories are small. If we're called more,
+        // use progressively larger allocations, up to a fixed maximum.
+        //
+        // The specific sizes and policy here have not been tuned in detail yet
+        // and may need to be adjusted. In doing so, we should be careful to
+        // avoid unbounded buffer growth. This buffer only exists to share the
+        // cost of a `getdents` call over many entries, so if it gets too big,
+        // cache and heap usage will outweigh the benefit. And ultimately,
+        // directories can contain more entries than we can allocate contiguous
+        // memory for, so we'll always need to cap the size at some point.
+        if self.buf.len() < 1024 * size_of::<linux_dirent64>() {
+            self.buf.reserve(32 * size_of::<linux_dirent64>());
+        }
+        self.buf.resize(self.buf.capacity(), 0);
+        let nread = match io::retry_on_intr(|| {
+            crate::backend::fs::syscalls::getdents(self.fd.as_fd(), &mut self.buf)
+        }) {
+            Ok(nread) => nread,
+            Err(io::Errno::NOENT) => {
+                self.any_errors = true;
+                return None;
+            }
+            Err(err) => {
+                self.any_errors = true;
+                return Some(Err(err));
+            }
+        };
+        self.buf.resize(nread, 0);
+        self.pos = 0;
+        if nread == 0 {
+            None
+        } else {
+            Some(Ok(()))
+        }
+    }
+
+    /// `fstat(self)`
+    #[inline]
+    pub fn stat(&self) -> io::Result<Stat> {
+        fstat(&self.fd)
+    }
+
+    /// `fstatfs(self)`
+    #[inline]
+    pub fn statfs(&self) -> io::Result<StatFs> {
+        fstatfs(&self.fd)
+    }
+
+    /// `fstatvfs(self)`
+    #[inline]
+    pub fn statvfs(&self) -> io::Result<StatVfs> {
+        fstatvfs(&self.fd)
+    }
+
+    /// `fchdir(self)`
+    #[cfg(feature = "process")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "process")))]
+    #[inline]
+    pub fn chdir(&self) -> io::Result<()> {
+        fchdir(&self.fd)
+    }
+}
+
+impl Iterator for Dir {
+    type Item = io::Result<DirEntry>;
+
+    #[inline]
+    fn next(&mut self) -> Option<Self::Item> {
+        Self::read(self)
+    }
+}
+
+impl fmt::Debug for Dir {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("Dir").field("fd", &self.fd).finish()
+    }
+}
+
+/// `struct dirent`
+#[derive(Debug)]
+pub struct DirEntry {
+    d_ino: u64,
+    d_type: u8,
+    name: CString,
+}
+
+impl DirEntry {
+    /// Returns the file name of this directory entry.
+    #[inline]
+    pub fn file_name(&self) -> &CStr {
+        &self.name
+    }
+
+    /// Returns the type of this directory entry.
+    #[inline]
+    pub fn file_type(&self) -> FileType {
+        FileType::from_dirent_d_type(self.d_type)
+    }
+
+    /// Return the inode number of this directory entry.
+    #[inline]
+    pub fn ino(&self) -> u64 {
+        self.d_ino
+    }
+}
+
+#[test]
+fn dir_iterator_handles_io_errors() {
+    // create a dir, keep the FD, then delete the dir
+    let tmp = tempfile::tempdir().unwrap();
+    let fd = crate::fs::openat(
+        crate::fs::CWD,
+        tmp.path(),
+        crate::fs::OFlags::RDONLY | crate::fs::OFlags::CLOEXEC,
+        crate::fs::Mode::empty(),
+    )
+    .unwrap();
+
+    let file_fd = crate::fs::openat(
+        &fd,
+        tmp.path().join("test.txt"),
+        crate::fs::OFlags::WRONLY | crate::fs::OFlags::CREATE,
+        crate::fs::Mode::RWXU,
+    )
+    .unwrap();
+
+    let mut dir = Dir::read_from(&fd).unwrap();
+
+    // Reach inside the `Dir` and replace its directory with a file, which
+    // will cause the subsequent `getdents64` to fail.
+    crate::io::dup2(&file_fd, &mut dir.fd).unwrap();
+
+    assert!(matches!(dir.next(), Some(Err(_))));
+    assert!(dir.next().is_none());
+}