Introduce FsPathFollow

Make sure all operations of FsPath do not follow symlinks, and provide
a way to explicitly switch over to a set of operations that DO follow
symlinks by FsPath::follow_link.

native/src/base/cstr.rs

@@ -501,6 +501,25 @@ impl DerefMut for FsPath {
     }
 }
 
+#[repr(transparent)]
+pub struct FsPathFollow(Utf8CStr);
+
+impl Deref for FsPathFollow {
+    type Target = Utf8CStr;
+
+    #[inline(always)]
+    fn deref(&self) -> &Utf8CStr {
+        &self.0
+    }
+}
+
+impl DerefMut for FsPathFollow {
+    #[inline(always)]
+    fn deref_mut(&mut self) -> &mut Utf8CStr {
+        &mut self.0
+    }
+}
+
 enum Utf8CStrBufOwned<const N: usize> {
     Dynamic(Utf8CString),
     Fixed(Utf8CStrBufArr<N>),
@@ -667,6 +686,7 @@ macro_rules! impl_str {
 impl_str!(
     (Utf8CStr,)
     (FsPath,)
+    (FsPathFollow,)
     (FsPathBuf<N>, const N: usize)
     (Utf8CStrBufRef<'_>,)
     (Utf8CStrBufArr<N>, const N: usize)

native/src/base/dir.rs

@@ -0,0 +1,420 @@
+use crate::cxx_extern::readlinkat_for_cxx;
+use crate::{
+    cstr, cstr_buf, errno, fd_path, fd_set_attr, FileAttr, FsPath, LibcReturn, Utf8CStr,
+    Utf8CStrBuf,
+};
+use libc::{dirent, O_CLOEXEC, O_CREAT, O_RDONLY, O_TRUNC, O_WRONLY};
+use std::ffi::CStr;
+use std::fs::File;
+use std::ops::Deref;
+use std::os::fd::{AsFd, AsRawFd, BorrowedFd, FromRawFd, IntoRawFd, OwnedFd, RawFd};
+use std::{io, mem, slice};
+
+pub struct DirEntry<'a> {
+    dir: &'a Directory,
+    entry: &'a dirent,
+    d_name_len: usize,
+}
+
+impl DirEntry<'_> {
+    pub fn name(&self) -> &CStr {
+        unsafe {
+            CStr::from_bytes_with_nul_unchecked(slice::from_raw_parts(
+                self.d_name.as_ptr().cast(),
+                self.d_name_len,
+            ))
+        }
+    }
+
+    pub fn path(&self, buf: &mut dyn Utf8CStrBuf) -> io::Result<()> {
+        self.dir.path(buf)?;
+        buf.push_str("/");
+        buf.push_lossy(self.name().to_bytes());
+        Ok(())
+    }
+
+    pub fn is_dir(&self) -> bool {
+        self.d_type == libc::DT_DIR
+    }
+
+    pub fn is_file(&self) -> bool {
+        self.d_type == libc::DT_REG
+    }
+
+    pub fn is_symlink(&self) -> bool {
+        self.d_type == libc::DT_LNK
+    }
+
+    pub fn is_block_device(&self) -> bool {
+        self.d_type == libc::DT_BLK
+    }
+
+    pub fn is_char_device(&self) -> bool {
+        self.d_type == libc::DT_CHR
+    }
+
+    pub fn is_fifo(&self) -> bool {
+        self.d_type == libc::DT_FIFO
+    }
+
+    pub fn is_socket(&self) -> bool {
+        self.d_type == libc::DT_SOCK
+    }
+
+    pub fn unlink(&self) -> io::Result<()> {
+        let flag = if self.is_dir() { libc::AT_REMOVEDIR } else { 0 };
+        unsafe {
+            libc::unlinkat(self.dir.as_raw_fd(), self.d_name.as_ptr(), flag).check_os_err()?;
+        }
+        Ok(())
+    }
+
+    pub fn read_link(&self, buf: &mut dyn Utf8CStrBuf) -> io::Result<()> {
+        buf.clear();
+        unsafe {
+            let r = readlinkat_for_cxx(
+                self.dir.as_raw_fd(),
+                self.d_name.as_ptr(),
+                buf.as_mut_ptr().cast(),
+                buf.capacity(),
+            )
+            .check_os_err()? as usize;
+            buf.set_len(r);
+        }
+        Ok(())
+    }
+
+    unsafe fn open_fd(&self, flags: i32) -> io::Result<RawFd> {
+        unsafe { self.dir.open_raw_fd(self.name(), flags, 0) }
+    }
+
+    pub fn open_as_dir(&self) -> io::Result<Directory> {
+        if !self.is_dir() {
+            return Err(io::Error::from(io::ErrorKind::NotADirectory));
+        }
+        unsafe { Directory::try_from(OwnedFd::from_raw_fd(self.open_fd(O_RDONLY)?)) }
+    }
+
+    pub fn open_as_file(&self, flags: i32) -> io::Result<File> {
+        if self.is_dir() {
+            return Err(io::Error::from(io::ErrorKind::IsADirectory));
+        }
+        unsafe { Ok(File::from_raw_fd(self.open_fd(flags)?)) }
+    }
+
+    pub fn get_attr(&self) -> io::Result<FileAttr> {
+        let mut path = cstr_buf::default();
+        self.path(&mut path)?;
+        FsPath::from(&path).get_attr()
+    }
+
+    pub fn set_attr(&self, attr: &FileAttr) -> io::Result<()> {
+        let mut path = cstr_buf::default();
+        self.path(&mut path)?;
+        FsPath::from(&path).set_attr(attr)
+    }
+
+    pub fn get_secontext(&self, con: &mut dyn Utf8CStrBuf) -> io::Result<()> {
+        let mut path = cstr_buf::default();
+        self.path(&mut path)?;
+        FsPath::from(&path).get_secontext(con)
+    }
+
+    pub fn set_secontext(&self, con: &Utf8CStr) -> io::Result<()> {
+        let mut path = cstr_buf::default();
+        self.path(&mut path)?;
+        FsPath::from(&path).set_secontext(con)
+    }
+}
+
+impl Deref for DirEntry<'_> {
+    type Target = dirent;
+
+    fn deref(&self) -> &dirent {
+        self.entry
+    }
+}
+
+pub struct Directory {
+    dirp: *mut libc::DIR,
+}
+
+pub enum WalkResult {
+    Continue,
+    Abort,
+    Skip,
+}
+
+impl Directory {
+    pub fn open(path: &Utf8CStr) -> io::Result<Directory> {
+        let dirp = unsafe { libc::opendir(path.as_ptr()) }.check_os_err()?;
+        Ok(Directory { dirp })
+    }
+
+    pub fn read(&mut self) -> io::Result<Option<DirEntry<'_>>> {
+        *errno() = 0;
+        let e = unsafe { libc::readdir(self.dirp) };
+        if e.is_null() {
+            return if *errno() != 0 {
+                Err(io::Error::last_os_error())
+            } else {
+                Ok(None)
+            };
+        }
+        // Skip both "." and ".."
+        unsafe {
+            let entry = &*e;
+            let d_name = CStr::from_ptr(entry.d_name.as_ptr());
+            if d_name == cstr!(".") || d_name == cstr!("..") {
+                self.read()
+            } else {
+                let e = DirEntry {
+                    dir: self,
+                    entry,
+                    d_name_len: d_name.to_bytes_with_nul().len(),
+                };
+                Ok(Some(e))
+            }
+        }
+    }
+
+    pub fn rewind(&mut self) {
+        unsafe { libc::rewinddir(self.dirp) }
+    }
+
+    unsafe fn open_raw_fd(&self, name: &CStr, flags: i32, mode: i32) -> io::Result<RawFd> {
+        unsafe {
+            libc::openat(self.as_raw_fd(), name.as_ptr(), flags | O_CLOEXEC, mode).check_os_err()
+        }
+    }
+
+    pub fn open_fd(&self, name: &Utf8CStr, flags: i32, mode: i32) -> io::Result<OwnedFd> {
+        unsafe {
+            self.open_raw_fd(name.as_cstr(), flags, mode)
+                .map(|fd| OwnedFd::from_raw_fd(fd))
+        }
+    }
+
+    pub fn contains_path(&self, path: &CStr) -> bool {
+        // WARNING: Using faccessat is incorrect, because the raw linux kernel syscall
+        // does not support the flag AT_SYMLINK_NOFOLLOW until 5.8 with faccessat2.
+        // Use fstatat to check the existence of a file instead.
+        unsafe {
+            let mut st: libc::stat = mem::zeroed();
+            libc::fstatat(
+                self.as_raw_fd(),
+                path.as_ptr(),
+                &mut st,
+                libc::AT_SYMLINK_NOFOLLOW,
+            ) == 0
+        }
+    }
+
+    pub fn path(&self, buf: &mut dyn Utf8CStrBuf) -> io::Result<()> {
+        fd_path(self.as_raw_fd(), buf)
+    }
+
+    pub fn post_order_walk<F: FnMut(&DirEntry) -> io::Result<WalkResult>>(
+        &mut self,
+        mut f: F,
+    ) -> io::Result<WalkResult> {
+        self.post_order_walk_impl(&mut f)
+    }
+
+    pub fn pre_order_walk<F: FnMut(&DirEntry) -> io::Result<WalkResult>>(
+        &mut self,
+        mut f: F,
+    ) -> io::Result<WalkResult> {
+        self.pre_order_walk_impl(&mut f)
+    }
+
+    pub fn remove_all(&mut self) -> io::Result<()> {
+        self.post_order_walk(|e| {
+            e.unlink()?;
+            Ok(WalkResult::Continue)
+        })?;
+        Ok(())
+    }
+
+    pub fn copy_into(&mut self, dir: &Directory) -> io::Result<()> {
+        while let Some(ref e) = self.read()? {
+            let attr = e.get_attr()?;
+            let new_entry = DirEntry {
+                dir,
+                entry: e.entry,
+                d_name_len: e.d_name_len,
+            };
+            if e.is_dir() {
+                unsafe {
+                    libc::mkdirat(dir.as_raw_fd(), e.d_name.as_ptr(), 0o777).as_os_err()?;
+                }
+                let mut src = e.open_as_dir()?;
+                let dest = new_entry.open_as_dir()?;
+                src.copy_into(&dest)?;
+                fd_set_attr(dest.as_raw_fd(), &attr)?;
+            } else if e.is_file() {
+                let mut src = e.open_as_file(O_RDONLY)?;
+                let mut dest = unsafe {
+                    File::from_raw_fd(dir.open_raw_fd(
+                        e.name(),
+                        O_WRONLY | O_CREAT | O_TRUNC,
+                        0o777,
+                    )?)
+                };
+                std::io::copy(&mut src, &mut dest)?;
+                fd_set_attr(dest.as_raw_fd(), &attr)?;
+            } else if e.is_symlink() {
+                let mut path = cstr_buf::default();
+                e.read_link(&mut path)?;
+                unsafe {
+                    libc::symlinkat(path.as_ptr(), dir.as_raw_fd(), e.d_name.as_ptr())
+                        .as_os_err()?;
+                }
+                new_entry.set_attr(&attr)?;
+            }
+        }
+        Ok(())
+    }
+
+    pub fn move_into(&mut self, dir: &Directory) -> io::Result<()> {
+        let dir_fd = self.as_raw_fd();
+        while let Some(ref e) = self.read()? {
+            if e.is_dir() && dir.contains_path(e.name()) {
+                // Destination folder exists, needs recursive move
+                let mut src = e.open_as_dir()?;
+                let new_entry = DirEntry {
+                    dir,
+                    entry: e.entry,
+                    d_name_len: e.d_name_len,
+                };
+                let dest = new_entry.open_as_dir()?;
+                src.move_into(&dest)?;
+                return e.unlink();
+            }
+
+            unsafe {
+                libc::renameat(
+                    dir_fd,
+                    e.d_name.as_ptr(),
+                    dir.as_raw_fd(),
+                    e.d_name.as_ptr(),
+                )
+                .as_os_err()?;
+            }
+        }
+        Ok(())
+    }
+
+    pub fn link_into(&mut self, dir: &Directory) -> io::Result<()> {
+        let dir_fd = self.as_raw_fd();
+        while let Some(ref e) = self.read()? {
+            if e.is_dir() {
+                unsafe {
+                    libc::mkdirat(dir.as_raw_fd(), e.d_name.as_ptr(), 0o777).as_os_err()?;
+                }
+                let attr = e.get_attr()?;
+                let new_entry = DirEntry {
+                    dir,
+                    entry: e.entry,
+                    d_name_len: e.d_name_len,
+                };
+                let mut src = e.open_as_dir()?;
+                let dest = new_entry.open_as_dir()?;
+                src.link_into(&dest)?;
+                fd_set_attr(dest.as_raw_fd(), &attr)?;
+            } else {
+                unsafe {
+                    libc::linkat(
+                        dir_fd,
+                        e.d_name.as_ptr(),
+                        dir.as_raw_fd(),
+                        e.d_name.as_ptr(),
+                        0,
+                    )
+                    .as_os_err()?;
+                }
+            }
+        }
+        Ok(())
+    }
+}
+
+impl Directory {
+    fn post_order_walk_impl<F: FnMut(&DirEntry) -> io::Result<WalkResult>>(
+        &mut self,
+        f: &mut F,
+    ) -> io::Result<WalkResult> {
+        use WalkResult::*;
+        loop {
+            match self.read()? {
+                None => return Ok(Continue),
+                Some(ref e) => {
+                    if e.is_dir() {
+                        let mut dir = e.open_as_dir()?;
+                        if let Abort = dir.post_order_walk_impl(f)? {
+                            return Ok(Abort);
+                        }
+                    }
+                    match f(e)? {
+                        Abort => return Ok(Abort),
+                        Skip => return Ok(Continue),
+                        Continue => {}
+                    }
+                }
+            }
+        }
+    }
+
+    fn pre_order_walk_impl<F: FnMut(&DirEntry) -> io::Result<WalkResult>>(
+        &mut self,
+        f: &mut F,
+    ) -> io::Result<WalkResult> {
+        use WalkResult::*;
+        loop {
+            match self.read()? {
+                None => return Ok(Continue),
+                Some(ref e) => match f(e)? {
+                    Abort => return Ok(Abort),
+                    Skip => continue,
+                    Continue => {
+                        if e.is_dir() {
+                            let mut dir = e.open_as_dir()?;
+                            if let Abort = dir.pre_order_walk_impl(f)? {
+                                return Ok(Abort);
+                            }
+                        }
+                    }
+                },
+            }
+        }
+    }
+}
+
+impl TryFrom<OwnedFd> for Directory {
+    type Error = io::Error;
+
+    fn try_from(fd: OwnedFd) -> io::Result<Self> {
+        let dirp = unsafe { libc::fdopendir(fd.into_raw_fd()) }.check_os_err()?;
+        Ok(Directory { dirp })
+    }
+}
+
+impl AsRawFd for Directory {
+    fn as_raw_fd(&self) -> RawFd {
+        unsafe { libc::dirfd(self.dirp) }
+    }
+}
+
+impl AsFd for Directory {
+    fn as_fd(&self) -> BorrowedFd {
+        unsafe { BorrowedFd::borrow_raw(self.as_raw_fd()) }
+    }
+}
+
+impl Drop for Directory {
+    fn drop(&mut self) {
+        unsafe {
+            libc::closedir(self.dirp);
+        }
+    }
+}

native/src/base/files.rs

@@ -1,8 +1,10 @@
-use crate::cxx_extern::readlinkat_for_cxx;
-use crate::{cstr, cstr_buf, errno, error, FsPath, FsPathBuf, LibcReturn, Utf8CStr, Utf8CStrBuf};
+use crate::{
+    cstr_buf, errno, error, Directory, FsPath, FsPathBuf, FsPathFollow, LibcReturn, Utf8CStr,
+    Utf8CStrBuf,
+};
 use bytemuck::{bytes_of, bytes_of_mut, Pod};
 use libc::{
-    c_uint, dirent, makedev, mode_t, EEXIST, ENOENT, F_OK, O_CLOEXEC, O_CREAT, O_PATH, O_RDONLY,
+    c_uint, makedev, mode_t, stat, EEXIST, ENOENT, F_OK, O_CLOEXEC, O_CREAT, O_PATH, O_RDONLY,
     O_RDWR, O_TRUNC, O_WRONLY,
 };
 use mem::MaybeUninit;
@@ -11,8 +13,7 @@ use std::cmp::min;
 use std::ffi::CStr;
 use std::fs::File;
 use std::io::{BufRead, BufReader, Read, Seek, SeekFrom, Write};
-use std::ops::Deref;
-use std::os::fd::{AsFd, BorrowedFd, IntoRawFd};
+use std::os::fd::{AsFd, BorrowedFd};
 use std::os::unix::ffi::OsStrExt;
 use std::os::unix::io::{AsRawFd, FromRawFd, OwnedFd, RawFd};
 use std::path::Path;
@@ -186,418 +187,13 @@ impl FileAttr {
     }
 }
 
-const XATTR_NAME_SELINUX: &[u8] = b"security.selinux\0";
-
-pub struct DirEntry<'a> {
-    dir: &'a Directory,
-    entry: &'a dirent,
-    d_name_len: usize,
-}
-
-impl DirEntry<'_> {
-    pub fn name(&self) -> &CStr {
-        unsafe {
-            CStr::from_bytes_with_nul_unchecked(slice::from_raw_parts(
-                self.d_name.as_ptr().cast(),
-                self.d_name_len,
-            ))
-        }
-    }
-
-    pub fn path(&self, buf: &mut dyn Utf8CStrBuf) -> io::Result<()> {
-        self.dir.path(buf)?;
-        buf.push_str("/");
-        buf.push_lossy(self.name().to_bytes());
-        Ok(())
-    }
-
-    pub fn is_dir(&self) -> bool {
-        self.d_type == libc::DT_DIR
-    }
-
-    pub fn is_file(&self) -> bool {
-        self.d_type == libc::DT_REG
-    }
-
-    pub fn is_symlink(&self) -> bool {
-        self.d_type == libc::DT_LNK
-    }
-
-    pub fn is_block_device(&self) -> bool {
-        self.d_type == libc::DT_BLK
-    }
-
-    pub fn is_char_device(&self) -> bool {
-        self.d_type == libc::DT_CHR
-    }
-
-    pub fn is_fifo(&self) -> bool {
-        self.d_type == libc::DT_FIFO
-    }
-
-    pub fn is_socket(&self) -> bool {
-        self.d_type == libc::DT_SOCK
-    }
-
-    pub fn unlink(&self) -> io::Result<()> {
-        let flag = if self.is_dir() { libc::AT_REMOVEDIR } else { 0 };
-        unsafe {
-            libc::unlinkat(self.dir.as_raw_fd(), self.d_name.as_ptr(), flag).check_os_err()?;
-        }
-        Ok(())
-    }
-
-    pub fn read_link(&self, buf: &mut dyn Utf8CStrBuf) -> io::Result<()> {
-        buf.clear();
-        unsafe {
-            let r = readlinkat_for_cxx(
-                self.dir.as_raw_fd(),
-                self.d_name.as_ptr(),
-                buf.as_mut_ptr().cast(),
-                buf.capacity(),
-            )
-            .check_os_err()? as usize;
-            buf.set_len(r);
-        }
-        Ok(())
-    }
-
-    unsafe fn open_fd(&self, flags: i32) -> io::Result<RawFd> {
-        unsafe { self.dir.open_raw_fd(self.name(), flags, 0) }
-    }
-
-    pub fn open_as_dir(&self) -> io::Result<Directory> {
-        if !self.is_dir() {
-            return Err(io::Error::from(io::ErrorKind::NotADirectory));
-        }
-        unsafe { Directory::try_from(OwnedFd::from_raw_fd(self.open_fd(O_RDONLY)?)) }
-    }
-
-    pub fn open_as_file(&self, flags: i32) -> io::Result<File> {
-        if self.is_dir() {
-            return Err(io::Error::from(io::ErrorKind::IsADirectory));
-        }
-        unsafe { Ok(File::from_raw_fd(self.open_fd(flags)?)) }
-    }
-
-    pub fn get_attr(&self) -> io::Result<FileAttr> {
-        let mut path = cstr_buf::default();
-        self.path(&mut path)?;
-        FsPath::from(&path).get_attr()
-    }
-
-    pub fn set_attr(&self, attr: &FileAttr) -> io::Result<()> {
-        let mut path = cstr_buf::default();
-        self.path(&mut path)?;
-        FsPath::from(&path).set_attr(attr)
-    }
-
-    pub fn get_secontext(&self, con: &mut dyn Utf8CStrBuf) -> io::Result<()> {
-        let mut path = cstr_buf::default();
-        self.path(&mut path)?;
-        FsPath::from(&path).get_secontext(con)
-    }
-
-    pub fn set_secontext(&self, con: &Utf8CStr) -> io::Result<()> {
-        let mut path = cstr_buf::default();
-        self.path(&mut path)?;
-        FsPath::from(&path).set_secontext(con)
-    }
-}
-
-impl Deref for DirEntry<'_> {
-    type Target = dirent;
-
-    fn deref(&self) -> &dirent {
-        self.entry
-    }
-}
-
-pub struct Directory {
-    dirp: *mut libc::DIR,
-}
-
-pub enum WalkResult {
-    Continue,
-    Abort,
-    Skip,
-}
-
-impl Directory {
-    pub fn open(path: &Utf8CStr) -> io::Result<Directory> {
-        let dirp = unsafe { libc::opendir(path.as_ptr()) }.check_os_err()?;
-        Ok(Directory { dirp })
-    }
-
-    pub fn read(&mut self) -> io::Result<Option<DirEntry<'_>>> {
-        *errno() = 0;
-        let e = unsafe { libc::readdir(self.dirp) };
-        if e.is_null() {
-            return if *errno() != 0 {
-                Err(io::Error::last_os_error())
-            } else {
-                Ok(None)
-            };
-        }
-        // Skip both "." and ".."
-        unsafe {
-            let entry = &*e;
-            let d_name = CStr::from_ptr(entry.d_name.as_ptr());
-            if d_name == cstr!(".") || d_name == cstr!("..") {
-                self.read()
-            } else {
-                let e = DirEntry {
-                    dir: self,
-                    entry,
-                    d_name_len: d_name.to_bytes_with_nul().len(),
-                };
-                Ok(Some(e))
-            }
-        }
-    }
-
-    pub fn rewind(&mut self) {
-        unsafe { libc::rewinddir(self.dirp) }
-    }
-
-    unsafe fn open_raw_fd(&self, name: &CStr, flags: i32, mode: i32) -> io::Result<RawFd> {
-        unsafe {
-            libc::openat(self.as_raw_fd(), name.as_ptr(), flags | O_CLOEXEC, mode).check_os_err()
-        }
-    }
-
-    pub fn open_fd(&self, name: &Utf8CStr, flags: i32, mode: i32) -> io::Result<OwnedFd> {
-        unsafe {
-            self.open_raw_fd(name.as_cstr(), flags, mode)
-                .map(|fd| OwnedFd::from_raw_fd(fd))
-        }
-    }
-
-    pub fn contains_path(&self, path: &CStr) -> bool {
-        // WARNING: Using faccessat is incorrect, because the raw linux kernel syscall
-        // does not support the flag AT_SYMLINK_NOFOLLOW until 5.8 with faccessat2.
-        // Use fstatat to check the existence of a file instead.
-        unsafe {
-            let mut st: libc::stat = mem::zeroed();
-            libc::fstatat(
-                self.as_raw_fd(),
-                path.as_ptr(),
-                &mut st,
-                libc::AT_SYMLINK_NOFOLLOW,
-            ) == 0
-        }
-    }
-
-    pub fn path(&self, buf: &mut dyn Utf8CStrBuf) -> io::Result<()> {
-        fd_path(self.as_raw_fd(), buf)
-    }
-
-    pub fn post_order_walk<F: FnMut(&DirEntry) -> io::Result<WalkResult>>(
-        &mut self,
-        mut f: F,
-    ) -> io::Result<WalkResult> {
-        self.post_order_walk_impl(&mut f)
-    }
-
-    pub fn pre_order_walk<F: FnMut(&DirEntry) -> io::Result<WalkResult>>(
-        &mut self,
-        mut f: F,
-    ) -> io::Result<WalkResult> {
-        self.pre_order_walk_impl(&mut f)
-    }
-
-    pub fn remove_all(&mut self) -> io::Result<()> {
-        self.post_order_walk(|e| {
-            e.unlink()?;
-            Ok(WalkResult::Continue)
-        })?;
-        Ok(())
-    }
-
-    pub fn copy_into(&mut self, dir: &Directory) -> io::Result<()> {
-        while let Some(ref e) = self.read()? {
-            let attr = e.get_attr()?;
-            let new_entry = DirEntry {
-                dir,
-                entry: e.entry,
-                d_name_len: e.d_name_len,
-            };
-            if e.is_dir() {
-                unsafe {
-                    libc::mkdirat(dir.as_raw_fd(), e.d_name.as_ptr(), 0o777).as_os_err()?;
-                }
-                let mut src = e.open_as_dir()?;
-                let dest = new_entry.open_as_dir()?;
-                src.copy_into(&dest)?;
-                fd_set_attr(dest.as_raw_fd(), &attr)?;
-            } else if e.is_file() {
-                let mut src = e.open_as_file(O_RDONLY)?;
-                let mut dest = unsafe {
-                    File::from_raw_fd(dir.open_raw_fd(
-                        e.name(),
-                        O_WRONLY | O_CREAT | O_TRUNC,
-                        0o777,
-                    )?)
-                };
-                std::io::copy(&mut src, &mut dest)?;
-                fd_set_attr(dest.as_raw_fd(), &attr)?;
-            } else if e.is_symlink() {
-                let mut path = cstr_buf::default();
-                e.read_link(&mut path)?;
-                unsafe {
-                    libc::symlinkat(path.as_ptr(), dir.as_raw_fd(), e.d_name.as_ptr())
-                        .as_os_err()?;
-                }
-                new_entry.set_attr(&attr)?;
-            }
-        }
-        Ok(())
-    }
-
-    pub fn move_into(&mut self, dir: &Directory) -> io::Result<()> {
-        let dir_fd = self.as_raw_fd();
-        while let Some(ref e) = self.read()? {
-            if e.is_dir() && dir.contains_path(e.name()) {
-                // Destination folder exists, needs recursive move
-                let mut src = e.open_as_dir()?;
-                let new_entry = DirEntry {
-                    dir,
-                    entry: e.entry,
-                    d_name_len: e.d_name_len,
-                };
-                let dest = new_entry.open_as_dir()?;
-                src.move_into(&dest)?;
-                return e.unlink();
-            }
-
-            unsafe {
-                libc::renameat(
-                    dir_fd,
-                    e.d_name.as_ptr(),
-                    dir.as_raw_fd(),
-                    e.d_name.as_ptr(),
-                )
-                .as_os_err()?;
-            }
-        }
-        Ok(())
-    }
-
-    pub fn link_into(&mut self, dir: &Directory) -> io::Result<()> {
-        let dir_fd = self.as_raw_fd();
-        while let Some(ref e) = self.read()? {
-            if e.is_dir() {
-                unsafe {
-                    libc::mkdirat(dir.as_raw_fd(), e.d_name.as_ptr(), 0o777).as_os_err()?;
-                }
-                let attr = e.get_attr()?;
-                let new_entry = DirEntry {
-                    dir,
-                    entry: e.entry,
-                    d_name_len: e.d_name_len,
-                };
-                let mut src = e.open_as_dir()?;
-                let dest = new_entry.open_as_dir()?;
-                src.link_into(&dest)?;
-                fd_set_attr(dest.as_raw_fd(), &attr)?;
-            } else {
-                unsafe {
-                    libc::linkat(
-                        dir_fd,
-                        e.d_name.as_ptr(),
-                        dir.as_raw_fd(),
-                        e.d_name.as_ptr(),
-                        0,
-                    )
-                    .as_os_err()?;
-                }
-            }
-        }
-        Ok(())
-    }
-}
-
-impl Directory {
-    fn post_order_walk_impl<F: FnMut(&DirEntry) -> io::Result<WalkResult>>(
-        &mut self,
-        f: &mut F,
-    ) -> io::Result<WalkResult> {
-        use WalkResult::*;
-        loop {
-            match self.read()? {
-                None => return Ok(Continue),
-                Some(ref e) => {
-                    if e.is_dir() {
-                        let mut dir = e.open_as_dir()?;
-                        if let Abort = dir.post_order_walk_impl(f)? {
-                            return Ok(Abort);
-                        }
-                    }
-                    match f(e)? {
-                        Abort => return Ok(Abort),
-                        Skip => return Ok(Continue),
-                        Continue => {}
-                    }
-                }
-            }
-        }
-    }
-
-    fn pre_order_walk_impl<F: FnMut(&DirEntry) -> io::Result<WalkResult>>(
-        &mut self,
-        f: &mut F,
-    ) -> io::Result<WalkResult> {
-        use WalkResult::*;
-        loop {
-            match self.read()? {
-                None => return Ok(Continue),
-                Some(ref e) => match f(e)? {
-                    Abort => return Ok(Abort),
-                    Skip => continue,
-                    Continue => {
-                        if e.is_dir() {
-                            let mut dir = e.open_as_dir()?;
-                            if let Abort = dir.pre_order_walk_impl(f)? {
-                                return Ok(Abort);
-                            }
-                        }
-                    }
-                },
-            }
-        }
-    }
-}
-
-impl TryFrom<OwnedFd> for Directory {
-    type Error = io::Error;
-
-    fn try_from(fd: OwnedFd) -> io::Result<Self> {
-        let dirp = unsafe { libc::fdopendir(fd.into_raw_fd()) }.check_os_err()?;
-        Ok(Directory { dirp })
-    }
-}
-
-impl AsRawFd for Directory {
-    fn as_raw_fd(&self) -> RawFd {
-        unsafe { libc::dirfd(self.dirp) }
-    }
-}
-
-impl AsFd for Directory {
-    fn as_fd(&self) -> BorrowedFd {
-        unsafe { BorrowedFd::borrow_raw(self.as_raw_fd()) }
-    }
-}
-
-impl Drop for Directory {
-    fn drop(&mut self) {
-        unsafe {
-            libc::closedir(self.dirp);
-        }
-    }
-}
+const XATTR_NAME_SELINUX: &CStr = c"security.selinux";
 
 impl FsPath {
+    pub fn follow_link(&self) -> &FsPathFollow {
+        unsafe { mem::transmute(self) }
+    }
+
     pub fn open(&self, flags: i32) -> io::Result<File> {
         Ok(File::from(open_fd!(self, flags)?))
     }
@@ -607,7 +203,10 @@ impl FsPath {
     }
 
     pub fn exists(&self) -> bool {
-        unsafe { libc::access(self.as_ptr(), F_OK) == 0 }
+        unsafe {
+            let mut st: stat = mem::zeroed();
+            libc::lstat(self.as_ptr(), &mut st) == 0
+        }
     }
 
     pub fn rename_to<T: AsRef<Utf8CStr>>(&self, name: T) -> io::Result<()> {
@@ -732,7 +331,7 @@ impl FsPath {
         unsafe {
             let sz = libc::lgetxattr(
                 self.as_ptr(),
-                XATTR_NAME_SELINUX.as_ptr().cast(),
+                XATTR_NAME_SELINUX.as_ptr(),
                 con.as_mut_ptr().cast(),
                 con.capacity(),
             );
@@ -752,7 +351,7 @@ impl FsPath {
         unsafe {
             libc::lsetxattr(
                 self.as_ptr(),
-                XATTR_NAME_SELINUX.as_ptr().cast(),
+                XATTR_NAME_SELINUX.as_ptr(),
                 con.as_ptr().cast(),
                 con.len() + 1,
                 0,
@@ -832,6 +431,69 @@ impl FsPath {
     }
 }
 
+impl FsPathFollow {
+    pub fn exists(&self) -> bool {
+        unsafe { libc::access(self.as_ptr(), F_OK) == 0 }
+    }
+
+    pub fn get_attr(&self) -> io::Result<FileAttr> {
+        let mut attr = FileAttr::new();
+        unsafe {
+            libc::stat(self.as_ptr(), &mut attr.st).as_os_err()?;
+
+            #[cfg(feature = "selinux")]
+            self.get_secontext(&mut attr.con)?;
+        }
+        Ok(attr)
+    }
+
+    pub fn set_attr(&self, attr: &FileAttr) -> io::Result<()> {
+        unsafe {
+            libc::chmod(self.as_ptr(), (attr.st.st_mode & 0o777).as_()).as_os_err()?;
+            libc::chown(self.as_ptr(), attr.st.st_uid, attr.st.st_gid).as_os_err()?;
+
+            #[cfg(feature = "selinux")]
+            if !attr.con.is_empty() {
+                self.set_secontext(&attr.con)?;
+            }
+        }
+        Ok(())
+    }
+
+    pub fn get_secontext(&self, con: &mut dyn Utf8CStrBuf) -> io::Result<()> {
+        unsafe {
+            let sz = libc::getxattr(
+                self.as_ptr(),
+                XATTR_NAME_SELINUX.as_ptr(),
+                con.as_mut_ptr().cast(),
+                con.capacity(),
+            );
+            if sz < 1 {
+                con.clear();
+                if *errno() != libc::ENODATA {
+                    return Err(io::Error::last_os_error());
+                }
+            } else {
+                con.set_len((sz - 1) as usize);
+            }
+        }
+        Ok(())
+    }
+
+    pub fn set_secontext(&self, con: &Utf8CStr) -> io::Result<()> {
+        unsafe {
+            libc::setxattr(
+                self.as_ptr(),
+                XATTR_NAME_SELINUX.as_ptr(),
+                con.as_ptr().cast(),
+                con.len() + 1,
+                0,
+            )
+            .as_os_err()
+        }
+    }
+}
+
 pub fn fd_get_attr(fd: RawFd) -> io::Result<FileAttr> {
     let mut attr = FileAttr::new();
     unsafe {
@@ -841,7 +503,7 @@ pub fn fd_get_attr(fd: RawFd) -> io::Result<FileAttr> {
         {
             let sz = libc::fgetxattr(
                 fd,
-                XATTR_NAME_SELINUX.as_ptr().cast(),
+                XATTR_NAME_SELINUX.as_ptr(),
                 attr.con.as_mut_ptr().cast(),
                 attr.con.capacity(),
             );
@@ -866,7 +528,7 @@ pub fn fd_set_attr(fd: RawFd, attr: &FileAttr) -> io::Result<()> {
         if !attr.con.is_empty() {
             libc::fsetxattr(
                 fd,
-                XATTR_NAME_SELINUX.as_ptr().cast(),
+                XATTR_NAME_SELINUX.as_ptr(),
                 attr.con.as_ptr().cast(),
                 attr.con.len() + 1,
                 0,

native/src/base/lib.rs

@@ -8,6 +8,7 @@ use num_traits::FromPrimitive;
 
 pub use cstr::*;
 use cxx_extern::*;
+pub use dir::*;
 pub use ffi::fork_dont_care;
 pub use files::*;
 pub use logging::*;
@@ -16,6 +17,7 @@ pub use result::*;
 
 mod cstr;
 mod cxx_extern;
+mod dir;
 mod files;
 mod logging;
 mod misc;

native/src/init/twostage.rs

@@ -2,7 +2,7 @@ use crate::ffi::MagiskInit;
 use base::{
     clone_attr, cstr, debug, error, info,
     libc::{
-        fstatat, mount, stat, statfs, umount2, AT_SYMLINK_NOFOLLOW, MNT_DETACH, MS_BIND, O_CLOEXEC,
+        mount, statfs, umount2, MNT_DETACH, MS_BIND, O_CLOEXEC,
         O_CREAT, O_RDONLY, O_WRONLY, TMPFS_MAGIC,
     },
     path, raw_cstr, LibcReturn, MappedFile, MutBytesExt, ResultExt,
@@ -14,16 +14,7 @@ impl MagiskInit {
         info!("First Stage Init");
         self.prepare_data();
 
-        if unsafe {
-            let mut st: stat = std::mem::zeroed();
-            fstatat(-1, raw_cstr!("/sdcard"), &mut st, AT_SYMLINK_NOFOLLOW) != 0
-                && fstatat(
-                    -1,
-                    raw_cstr!("/first_stage_ramdisk/sdcard"),
-                    &mut st,
-                    AT_SYMLINK_NOFOLLOW,
-                ) != 0
-        } {
+        if !path!("/sdcard").exists() && !path!("/first_stage_ramdisk/sdcard").exists() {
             if self.config.force_normal_boot {
                 path!("/first_stage_ramdisk/storage/self")
                     .mkdirs(0o755)