From 1b6a04ca5504955c571d1c97504fb45ea0befee4 Mon Sep 17 00:00:00 2001 From: Valentin Popov Date: Mon, 8 Jan 2024 01:21:28 +0400 Subject: Initial vendor packages Signed-off-by: Valentin Popov --- vendor/rustix/src/backend/linux_raw/fs/dir.rs | 315 ++++++++++++++++++++++++++ 1 file changed, 315 insertions(+) create mode 100644 vendor/rustix/src/backend/linux_raw/fs/dir.rs (limited to 'vendor/rustix/src/backend/linux_raw/fs/dir.rs') 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, + + /// 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: Fd) -> io::Result { + Self::_new(fd.into()) + } + + #[inline] + fn _new(fd: OwnedFd) -> io::Result { + 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: Fd) -> io::Result { + Self::_read_from(fd.as_fd()) + } + + #[inline] + fn _read_from(fd: BorrowedFd<'_>) -> io::Result { + 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> { + // 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::() { + 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> { + // 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::() { + self.buf.reserve(32 * size_of::()); + } + 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 { + fstat(&self.fd) + } + + /// `fstatfs(self)` + #[inline] + pub fn statfs(&self) -> io::Result { + fstatfs(&self.fd) + } + + /// `fstatvfs(self)` + #[inline] + pub fn statvfs(&self) -> io::Result { + 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; + + #[inline] + fn next(&mut self) -> Option { + 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()); +} -- cgit v1.2.3