| 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, |
| |
| 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::backend::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_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, |
| })) |
| } |
| |
| fn read_more(&mut self) -> Option<io::Result<()>> { |
| let og_len = self.buf.len(); |
| // Capacity increment currently chosen by wild guess. |
| self.buf |
| .resize(self.buf.capacity() + 32 * size_of::<linux_dirent64>(), 0); |
| let nread = match crate::backend::fs::syscalls::getdents(self.fd.as_fd(), &mut self.buf) { |
| Ok(nread) => nread, |
| Err(err) => { |
| self.buf.resize(og_len, 0); |
| 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 |
| } |
| } |