diff options
Diffstat (limited to 'vendor/rustix/src/imp/linux_raw/fs/dir.rs')
| -rw-r--r-- | vendor/rustix/src/imp/linux_raw/fs/dir.rs | 213 |
1 files changed, 213 insertions, 0 deletions
diff --git a/vendor/rustix/src/imp/linux_raw/fs/dir.rs b/vendor/rustix/src/imp/linux_raw/fs/dir.rs new file mode 100644 index 000000000..64f5aa652 --- /dev/null +++ b/vendor/rustix/src/imp/linux_raw/fs/dir.rs @@ -0,0 +1,213 @@ +use crate::fd::{AsFd, BorrowedFd}; +use crate::ffi::{CStr, CString}; +use crate::fs::{fcntl_getfl, fstat, fstatfs, openat, FileType, Mode, OFlags, Stat, StatFs}; +use crate::io::{self, OwnedFd}; +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, + + buf: Vec<u8>, + pos: usize, + next: Option<u64>, +} + +impl Dir { + /// 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, + buf: Vec::new(), + pos: 0, + next: None, + }) + } + + /// `rewinddir(self)` + #[inline] + pub fn rewind(&mut self) { + self.pos = self.buf.len(); + self.next = Some(0); + } + + /// `readdir(self)`, where `None` means the end of the directory. + pub fn read(&mut self) -> Option<io::Result<DirEntry>> { + if let Some(next) = self.next.take() { + match crate::imp::fs::syscalls::_seek(self.fd.as_fd(), next as i64, SEEK_SET) { + Ok(_) => (), + Err(err) => 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(e) => return Some(Err(e)), + } + } + + // 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_start + name_len + 1]).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, + })) + } + + fn read_more(&mut self) -> Option<io::Result<()>> { + // Capacity increment currently chosen by wild guess. + self.buf + .resize(self.buf.capacity() + 32 * size_of::<linux_dirent64>(), 0); + self.pos = 0; + let nread = match crate::imp::fs::syscalls::getdents(self.fd.as_fd(), &mut self.buf) { + Ok(nread) => nread, + Err(err) => return Some(Err(err)), + }; + self.buf.resize(nread, 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) + } + + /// `fchdir(self)` + #[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 + } +} |