library/std/src/os/wasi/fs.rs - rust - Git at Google

 //! WASIp1-specific extensions to primitives in the [`std::fs`] module.
 //!
 //! [`std::fs`]: crate::fs

 #![unstable(feature = "wasi_ext", issue = "71213")]

 // Used for `File::read` on intra-doc links
 #[allow(unused_imports)]
 use io::{Read, Write};

 #[cfg(target_env = "p1")]
 use crate::ffi::OsStr;
 use crate::fs::{self, File, OpenOptions};
 use crate::io::{self, BorrowedCursor, IoSlice, IoSliceMut};
 #[cfg(target_env = "p1")]
 use crate::os::fd::AsRawFd;
 use crate::path::Path;
 #[cfg(target_env = "p1")]
 use crate::sys::err2io;
 use crate::sys::{AsInner, AsInnerMut};

 /// WASI-specific extensions to [`File`].
 pub trait FileExt {
     /// Reads a number of bytes starting from a given offset.
     ///
     /// Returns the number of bytes read.
     ///
     /// The offset is relative to the start of the file and thus independent
     /// from the current cursor.
     ///
     /// The current file cursor is not affected by this function.
     ///
     /// Note that similar to [`File::read`], it is not an error to return with a
     /// short read.
     fn read_at(&self, buf: &mut [u8], offset: u64) -> io::Result<usize>;

     /// Reads a number of bytes starting from a given offset.
     ///
     /// Returns the number of bytes read.
     ///
     /// The offset is relative to the start of the file and thus independent
     /// from the current cursor.
     ///
     /// The current file cursor is not affected by this function.
     ///
     /// Note that similar to [`File::read_vectored`], it is not an error to
     /// return with a short read.
     fn read_vectored_at(&self, bufs: &mut [IoSliceMut<'_>], offset: u64) -> io::Result<usize>;

     /// Reads some bytes starting from a given offset into the buffer.
     ///
     /// This equivalent to the [`read_at`](FileExt::read_at) method, except that it is passed a
     /// [`BorrowedCursor`] rather than `&mut [u8]` to allow use with uninitialized buffers. The new
     /// data will be appended to any existing contents of `buf`.
     fn read_buf_at(&self, buf: BorrowedCursor<'_>, offset: u64) -> io::Result<()>;

     /// Reads the exact number of byte required to fill `buf` from the given offset.
     ///
     /// The offset is relative to the start of the file and thus independent
     /// from the current cursor.
     ///
     /// The current file cursor is not affected by this function.
     ///
     /// Similar to [`Read::read_exact`] but uses [`read_at`] instead of `read`.
     ///
     /// [`read_at`]: FileExt::read_at
     ///
     /// # Errors
     ///
     /// If this function encounters an error of the kind
     /// [`io::ErrorKind::Interrupted`] then the error is ignored and the operation
     /// will continue.
     ///
     /// If this function encounters an "end of file" before completely filling
     /// the buffer, it returns an error of the kind [`io::ErrorKind::UnexpectedEof`].
     /// The contents of `buf` are unspecified in this case.
     ///
     /// If any other read error is encountered then this function immediately
     /// returns. The contents of `buf` are unspecified in this case.
     ///
     /// If this function returns an error, it is unspecified how many bytes it
     /// has read, but it will never read more than would be necessary to
     /// completely fill the buffer.
     fn read_exact_at(&self, mut buf: &mut [u8], mut offset: u64) -> io::Result<()> {
         while !buf.is_empty() {
             match self.read_at(buf, offset) {
                 Ok(0) => break,
                 Ok(n) => {
                     let tmp = buf;
                     buf = &mut tmp[n..];
                     offset += n as u64;
                 }
                 Err(ref e) if e.is_interrupted() => {}
                 Err(e) => return Err(e),
             }
         }
         if !buf.is_empty() { Err(io::Error::READ_EXACT_EOF) } else { Ok(()) }
     }

     /// Writes a number of bytes starting from a given offset.
     ///
     /// Returns the number of bytes written.
     ///
     /// The offset is relative to the start of the file and thus independent
     /// from the current cursor.
     ///
     /// The current file cursor is not affected by this function.
     ///
     /// When writing beyond the end of the file, the file is appropriately
     /// extended and the intermediate bytes are initialized with the value 0.
     ///
     /// Note that similar to [`File::write`], it is not an error to return a
     /// short write.
     fn write_at(&self, buf: &[u8], offset: u64) -> io::Result<usize>;

     /// Writes a number of bytes starting from a given offset.
     ///
     /// Returns the number of bytes written.
     ///
     /// The offset is relative to the start of the file and thus independent
     /// from the current cursor.
     ///
     /// The current file cursor is not affected by this function.
     ///
     /// When writing beyond the end of the file, the file is appropriately
     /// extended and the intermediate bytes are initialized with the value 0.
     ///
     /// Note that similar to [`File::write_vectored`], it is not an error to return a
     /// short write.
     fn write_vectored_at(&self, bufs: &[IoSlice<'_>], offset: u64) -> io::Result<usize>;

     /// Attempts to write an entire buffer starting from a given offset.
     ///
     /// The offset is relative to the start of the file and thus independent
     /// from the current cursor.
     ///
     /// The current file cursor is not affected by this function.
     ///
     /// This method will continuously call [`write_at`] until there is no more data
     /// to be written or an error of non-[`io::ErrorKind::Interrupted`] kind is
     /// returned. This method will not return until the entire buffer has been
     /// successfully written or such an error occurs. The first error that is
     /// not of [`io::ErrorKind::Interrupted`] kind generated from this method will be
     /// returned.
     ///
     /// # Errors
     ///
     /// This function will return the first error of
     /// non-[`io::ErrorKind::Interrupted`] kind that [`write_at`] returns.
     ///
     /// [`write_at`]: FileExt::write_at
     fn write_all_at(&self, mut buf: &[u8], mut offset: u64) -> io::Result<()> {
         while !buf.is_empty() {
             match self.write_at(buf, offset) {
                 Ok(0) => {
                     return Err(io::Error::WRITE_ALL_EOF);
                 }
                 Ok(n) => {
                     buf = &buf[n..];
                     offset += n as u64
                 }
                 Err(ref e) if e.is_interrupted() => {}
                 Err(e) => return Err(e),
             }
         }
         Ok(())
     }

     /// Adjusts the flags associated with this file.
     ///
     /// This corresponds to the `fd_fdstat_set_flags` syscall.
     #[doc(alias = "fd_fdstat_set_flags")]
     #[cfg(target_env = "p1")]
     fn fdstat_set_flags(&self, flags: u16) -> io::Result<()>;

     /// Adjusts the rights associated with this file.
     ///
     /// This corresponds to the `fd_fdstat_set_rights` syscall.
     #[doc(alias = "fd_fdstat_set_rights")]
     #[cfg(target_env = "p1")]
     fn fdstat_set_rights(&self, rights: u64, inheriting: u64) -> io::Result<()>;

     /// Provides file advisory information on a file descriptor.
     ///
     /// This corresponds to the `fd_advise` syscall.
     #[doc(alias = "fd_advise")]
     #[cfg(target_env = "p1")]
     fn advise(&self, offset: u64, len: u64, advice: u8) -> io::Result<()>;

     /// Forces the allocation of space in a file.
     ///
     /// This corresponds to the `fd_allocate` syscall.
     #[doc(alias = "fd_allocate")]
     #[cfg(target_env = "p1")]
     fn allocate(&self, offset: u64, len: u64) -> io::Result<()>;

     /// Creates a directory.
     ///
     /// This corresponds to the `path_create_directory` syscall.
     #[doc(alias = "path_create_directory")]
     #[cfg(target_env = "p1")]
     fn create_directory<P: AsRef<Path>>(&self, dir: P) -> io::Result<()>;

     /// Unlinks a file.
     ///
     /// This corresponds to the `path_unlink_file` syscall.
     #[doc(alias = "path_unlink_file")]
     #[cfg(target_env = "p1")]
     fn remove_file<P: AsRef<Path>>(&self, path: P) -> io::Result<()>;

     /// Removes a directory.
     ///
     /// This corresponds to the `path_remove_directory` syscall.
     #[doc(alias = "path_remove_directory")]
     #[cfg(target_env = "p1")]
     fn remove_directory<P: AsRef<Path>>(&self, path: P) -> io::Result<()>;
 }

 // FIXME: bind fd_fdstat_get - need to define a custom return type
 // FIXME: bind fd_readdir - can't return `ReadDir` since we only have entry name
 // FIXME: bind fd_filestat_set_times maybe? - on crates.io for unix
 // FIXME: bind path_filestat_set_times maybe? - on crates.io for unix
 // FIXME: bind poll_oneoff maybe? - probably should wait for I/O to settle
 // FIXME: bind random_get maybe? - on crates.io for unix

 impl FileExt for File {
     fn read_at(&self, buf: &mut [u8], offset: u64) -> io::Result<usize> {
         self.as_inner().read_at(buf, offset)
     }

     fn read_buf_at(&self, buf: BorrowedCursor<'_>, offset: u64) -> io::Result<()> {
         self.as_inner().read_buf_at(buf, offset)
     }

     fn read_vectored_at(&self, bufs: &mut [IoSliceMut<'_>], offset: u64) -> io::Result<usize> {
         self.as_inner().read_vectored_at(bufs, offset)
     }

     fn write_at(&self, buf: &[u8], offset: u64) -> io::Result<usize> {
         self.as_inner().write_at(buf, offset)
     }

     fn write_vectored_at(&self, bufs: &[IoSlice<'_>], offset: u64) -> io::Result<usize> {
         self.as_inner().write_vectored_at(bufs, offset)
     }

     #[cfg(target_env = "p1")]
     fn fdstat_set_flags(&self, flags: u16) -> io::Result<()> {
         unsafe { wasi::fd_fdstat_set_flags(self.as_raw_fd() as wasi::Fd, flags).map_err(err2io) }
     }

     #[cfg(target_env = "p1")]
     fn fdstat_set_rights(&self, rights: u64, inheriting: u64) -> io::Result<()> {
         unsafe {
             wasi::fd_fdstat_set_rights(self.as_raw_fd() as wasi::Fd, rights, inheriting)
                 .map_err(err2io)
         }
     }

     #[cfg(target_env = "p1")]
     fn advise(&self, offset: u64, len: u64, advice: u8) -> io::Result<()> {
         let advice = match advice {
             a if a == wasi::ADVICE_NORMAL.raw() => wasi::ADVICE_NORMAL,
             a if a == wasi::ADVICE_SEQUENTIAL.raw() => wasi::ADVICE_SEQUENTIAL,
             a if a == wasi::ADVICE_RANDOM.raw() => wasi::ADVICE_RANDOM,
             a if a == wasi::ADVICE_WILLNEED.raw() => wasi::ADVICE_WILLNEED,
             a if a == wasi::ADVICE_DONTNEED.raw() => wasi::ADVICE_DONTNEED,
             a if a == wasi::ADVICE_NOREUSE.raw() => wasi::ADVICE_NOREUSE,
             _ => {
                 return Err(io::const_error!(
                     io::ErrorKind::InvalidInput,
                     "invalid parameter 'advice'",
                 ));
             }
         };

         unsafe {
             wasi::fd_advise(self.as_raw_fd() as wasi::Fd, offset, len, advice).map_err(err2io)
         }
     }

     #[cfg(target_env = "p1")]
     fn allocate(&self, offset: u64, len: u64) -> io::Result<()> {
         unsafe { wasi::fd_allocate(self.as_raw_fd() as wasi::Fd, offset, len).map_err(err2io) }
     }

     #[cfg(target_env = "p1")]
     fn create_directory<P: AsRef<Path>>(&self, dir: P) -> io::Result<()> {
         let path = osstr2str(dir.as_ref().as_ref())?;
         unsafe { wasi::path_create_directory(self.as_raw_fd() as wasi::Fd, path).map_err(err2io) }
     }

     #[cfg(target_env = "p1")]
     fn remove_file<P: AsRef<Path>>(&self, path: P) -> io::Result<()> {
         let path = osstr2str(path.as_ref().as_ref())?;
         unsafe { wasi::path_unlink_file(self.as_raw_fd() as wasi::Fd, path).map_err(err2io) }
     }

     #[cfg(target_env = "p1")]
     fn remove_directory<P: AsRef<Path>>(&self, path: P) -> io::Result<()> {
         let path = osstr2str(path.as_ref().as_ref())?;
         unsafe { wasi::path_remove_directory(self.as_raw_fd() as wasi::Fd, path).map_err(err2io) }
     }
 }

 /// WASI-specific extensions to [`OpenOptions`].
 pub trait OpenOptionsExt {
     /// Pass custom flags to the `flags` argument of `open`.
     fn custom_flags(&mut self, flags: i32) -> &mut Self;
 }

 impl OpenOptionsExt for OpenOptions {
     fn custom_flags(&mut self, flags: i32) -> &mut OpenOptions {
         self.as_inner_mut().custom_flags(flags);
         self
     }
 }

 /// WASI-specific extensions to [`fs::Metadata`].
 pub trait MetadataExt {
     /// Returns the `st_dev` field of the internal `filestat_t`
     fn dev(&self) -> u64;
     /// Returns the `st_ino` field of the internal `filestat_t`
     fn ino(&self) -> u64;
     /// Returns the `st_nlink` field of the internal `filestat_t`
     fn nlink(&self) -> u64;
 }

 impl MetadataExt for fs::Metadata {
     fn dev(&self) -> u64 {
         self.as_inner().as_inner().st_dev
     }
     fn ino(&self) -> u64 {
         self.as_inner().as_inner().st_ino
     }
     fn nlink(&self) -> u64 {
         self.as_inner().as_inner().st_nlink
     }
 }

 /// WASI-specific extensions for [`fs::FileType`].
 ///
 /// Adds support for special WASI file types such as block/character devices,
 /// pipes, and sockets.
 pub trait FileTypeExt {
     /// Returns `true` if this file type is a block device.
     fn is_block_device(&self) -> bool;
     /// Returns `true` if this file type is a character device.
     fn is_char_device(&self) -> bool;
     /// Returns `true` if this file type is any type of socket.
     fn is_socket(&self) -> bool;
 }

 impl FileTypeExt for fs::FileType {
     fn is_block_device(&self) -> bool {
         self.as_inner().is(libc::S_IFBLK)
     }
     fn is_char_device(&self) -> bool {
         self.as_inner().is(libc::S_IFCHR)
     }
     fn is_socket(&self) -> bool {
         self.as_inner().is(libc::S_IFSOCK)
     }
 }

 /// WASI-specific extension methods for [`fs::DirEntry`].
 pub trait DirEntryExt {
     /// Returns the underlying `d_ino` field of the `dirent_t`
     fn ino(&self) -> u64;
 }

 impl DirEntryExt for fs::DirEntry {
     fn ino(&self) -> u64 {
         self.as_inner().ino()
     }
 }

 /// Creates a hard link.
 ///
 /// This corresponds to the `path_link` syscall.
 #[doc(alias = "path_link")]
 #[cfg(target_env = "p1")]
 pub fn link<P: AsRef<Path>, U: AsRef<Path>>(
     old_fd: &File,
     old_flags: u32,
     old_path: P,
     new_fd: &File,
     new_path: U,
 ) -> io::Result<()> {
     unsafe {
         wasi::path_link(
             old_fd.as_raw_fd() as wasi::Fd,
             old_flags,
             osstr2str(old_path.as_ref().as_ref())?,
             new_fd.as_raw_fd() as wasi::Fd,
             osstr2str(new_path.as_ref().as_ref())?,
         )
         .map_err(err2io)
     }
 }

 /// Renames a file or directory.
 ///
 /// This corresponds to the `path_rename` syscall.
 #[doc(alias = "path_rename")]
 #[cfg(target_env = "p1")]
 pub fn rename<P: AsRef<Path>, U: AsRef<Path>>(
     old_fd: &File,
     old_path: P,
     new_fd: &File,
     new_path: U,
 ) -> io::Result<()> {
     unsafe {
         wasi::path_rename(
             old_fd.as_raw_fd() as wasi::Fd,
             osstr2str(old_path.as_ref().as_ref())?,
             new_fd.as_raw_fd() as wasi::Fd,
             osstr2str(new_path.as_ref().as_ref())?,
         )
         .map_err(err2io)
     }
 }

 /// Creates a symbolic link.
 ///
 /// This corresponds to the `path_symlink` syscall.
 #[doc(alias = "path_symlink")]
 #[cfg(target_env = "p1")]
 pub fn symlink<P: AsRef<Path>, U: AsRef<Path>>(
     old_path: P,
     fd: &File,
     new_path: U,
 ) -> io::Result<()> {
     unsafe {
         wasi::path_symlink(
             osstr2str(old_path.as_ref().as_ref())?,
             fd.as_raw_fd() as wasi::Fd,
             osstr2str(new_path.as_ref().as_ref())?,
         )
         .map_err(err2io)
     }
 }

 /// Creates a symbolic link.
 ///
 /// This is a convenience API similar to `std::os::unix::fs::symlink` and
 /// `std::os::windows::fs::symlink_file` and `std::os::windows::fs::symlink_dir`.
 pub fn symlink_path<P: AsRef<Path>, U: AsRef<Path>>(old_path: P, new_path: U) -> io::Result<()> {
     crate::sys::fs::symlink(old_path.as_ref(), new_path.as_ref())
 }

 #[cfg(target_env = "p1")]
 fn osstr2str(f: &OsStr) -> io::Result<&str> {
     f.to_str().ok_or_else(|| io::const_error!(io::ErrorKind::Uncategorized, "input must be utf-8"))
 }
	//! WASIp1-specific extensions to primitives in the [`std::fs`] module.
	//!
	//! [`std::fs`]: crate::fs

	#![unstable(feature = "wasi_ext", issue = "71213")]

	// Used for `File::read` on intra-doc links
	#[allow(unused_imports)]
	use io::{Read, Write};

	#[cfg(target_env = "p1")]
	use crate::ffi::OsStr;
	use crate::fs::{self, File, OpenOptions};
	use crate::io::{self, BorrowedCursor, IoSlice, IoSliceMut};
	#[cfg(target_env = "p1")]
	use crate::os::fd::AsRawFd;
	use crate::path::Path;
	#[cfg(target_env = "p1")]
	use crate::sys::err2io;
	use crate::sys::{AsInner, AsInnerMut};

	/// WASI-specific extensions to [`File`].
	pub trait FileExt {
	/// Reads a number of bytes starting from a given offset.
	///
	/// Returns the number of bytes read.
	///
	/// The offset is relative to the start of the file and thus independent
	/// from the current cursor.
	///
	/// The current file cursor is not affected by this function.
	///
	/// Note that similar to [`File::read`], it is not an error to return with a
	/// short read.
	fn read_at(&self, buf: &mut [u8], offset: u64) -> io::Result<usize>;

	/// Reads a number of bytes starting from a given offset.
	///
	/// Returns the number of bytes read.
	///
	/// The offset is relative to the start of the file and thus independent
	/// from the current cursor.
	///
	/// The current file cursor is not affected by this function.
	///
	/// Note that similar to [`File::read_vectored`], it is not an error to
	/// return with a short read.
	fn read_vectored_at(&self, bufs: &mut [IoSliceMut<'_>], offset: u64) -> io::Result<usize>;

	/// Reads some bytes starting from a given offset into the buffer.
	///
	/// This equivalent to the [`read_at`](FileExt::read_at) method, except that it is passed a
	/// [`BorrowedCursor`] rather than `&mut [u8]` to allow use with uninitialized buffers. The new
	/// data will be appended to any existing contents of `buf`.
	fn read_buf_at(&self, buf: BorrowedCursor<'_>, offset: u64) -> io::Result<()>;

	/// Reads the exact number of byte required to fill `buf` from the given offset.
	///
	/// The offset is relative to the start of the file and thus independent
	/// from the current cursor.
	///
	/// The current file cursor is not affected by this function.
	///
	/// Similar to [`Read::read_exact`] but uses [`read_at`] instead of `read`.
	///
	/// [`read_at`]: FileExt::read_at
	///
	/// # Errors
	///
	/// If this function encounters an error of the kind
	/// [`io::ErrorKind::Interrupted`] then the error is ignored and the operation
	/// will continue.
	///
	/// If this function encounters an "end of file" before completely filling
	/// the buffer, it returns an error of the kind [`io::ErrorKind::UnexpectedEof`].
	/// The contents of `buf` are unspecified in this case.
	///
	/// If any other read error is encountered then this function immediately
	/// returns. The contents of `buf` are unspecified in this case.
	///
	/// If this function returns an error, it is unspecified how many bytes it
	/// has read, but it will never read more than would be necessary to
	/// completely fill the buffer.
	fn read_exact_at(&self, mut buf: &mut [u8], mut offset: u64) -> io::Result<()> {
	while !buf.is_empty() {
	match self.read_at(buf, offset) {
	Ok(0) => break,
	Ok(n) => {
	let tmp = buf;
	buf = &mut tmp[n..];
	offset += n as u64;
	}
	Err(ref e) if e.is_interrupted() => {}
	Err(e) => return Err(e),
	}
	}
	if !buf.is_empty() { Err(io::Error::READ_EXACT_EOF) } else { Ok(()) }
	}

	/// Writes a number of bytes starting from a given offset.
	///
	/// Returns the number of bytes written.
	///
	/// The offset is relative to the start of the file and thus independent
	/// from the current cursor.
	///
	/// The current file cursor is not affected by this function.
	///
	/// When writing beyond the end of the file, the file is appropriately
	/// extended and the intermediate bytes are initialized with the value 0.
	///
	/// Note that similar to [`File::write`], it is not an error to return a
	/// short write.
	fn write_at(&self, buf: &[u8], offset: u64) -> io::Result<usize>;

	/// Writes a number of bytes starting from a given offset.
	///
	/// Returns the number of bytes written.
	///
	/// The offset is relative to the start of the file and thus independent
	/// from the current cursor.
	///
	/// The current file cursor is not affected by this function.
	///
	/// When writing beyond the end of the file, the file is appropriately
	/// extended and the intermediate bytes are initialized with the value 0.
	///
	/// Note that similar to [`File::write_vectored`], it is not an error to return a
	/// short write.
	fn write_vectored_at(&self, bufs: &[IoSlice<'_>], offset: u64) -> io::Result<usize>;

	/// Attempts to write an entire buffer starting from a given offset.
	///
	/// The offset is relative to the start of the file and thus independent
	/// from the current cursor.
	///
	/// The current file cursor is not affected by this function.
	///
	/// This method will continuously call [`write_at`] until there is no more data
	/// to be written or an error of non-[`io::ErrorKind::Interrupted`] kind is
	/// returned. This method will not return until the entire buffer has been
	/// successfully written or such an error occurs. The first error that is
	/// not of [`io::ErrorKind::Interrupted`] kind generated from this method will be
	/// returned.
	///
	/// # Errors
	///
	/// This function will return the first error of
	/// non-[`io::ErrorKind::Interrupted`] kind that [`write_at`] returns.
	///
	/// [`write_at`]: FileExt::write_at
	fn write_all_at(&self, mut buf: &[u8], mut offset: u64) -> io::Result<()> {
	while !buf.is_empty() {
	match self.write_at(buf, offset) {
	Ok(0) => {
	return Err(io::Error::WRITE_ALL_EOF);
	}
	Ok(n) => {
	buf = &buf[n..];
	offset += n as u64
	}
	Err(ref e) if e.is_interrupted() => {}
	Err(e) => return Err(e),
	}
	}
	Ok(())
	}

	/// Adjusts the flags associated with this file.
	///
	/// This corresponds to the `fd_fdstat_set_flags` syscall.
	#[doc(alias = "fd_fdstat_set_flags")]
	#[cfg(target_env = "p1")]
	fn fdstat_set_flags(&self, flags: u16) -> io::Result<()>;

	/// Adjusts the rights associated with this file.
	///
	/// This corresponds to the `fd_fdstat_set_rights` syscall.
	#[doc(alias = "fd_fdstat_set_rights")]
	#[cfg(target_env = "p1")]
	fn fdstat_set_rights(&self, rights: u64, inheriting: u64) -> io::Result<()>;

	/// Provides file advisory information on a file descriptor.
	///
	/// This corresponds to the `fd_advise` syscall.
	#[doc(alias = "fd_advise")]
	#[cfg(target_env = "p1")]
	fn advise(&self, offset: u64, len: u64, advice: u8) -> io::Result<()>;

	/// Forces the allocation of space in a file.
	///
	/// This corresponds to the `fd_allocate` syscall.
	#[doc(alias = "fd_allocate")]
	#[cfg(target_env = "p1")]
	fn allocate(&self, offset: u64, len: u64) -> io::Result<()>;

	/// Creates a directory.
	///
	/// This corresponds to the `path_create_directory` syscall.
	#[doc(alias = "path_create_directory")]
	#[cfg(target_env = "p1")]
	fn create_directory<P: AsRef<Path>>(&self, dir: P) -> io::Result<()>;

	/// Unlinks a file.
	///
	/// This corresponds to the `path_unlink_file` syscall.
	#[doc(alias = "path_unlink_file")]
	#[cfg(target_env = "p1")]
	fn remove_file<P: AsRef<Path>>(&self, path: P) -> io::Result<()>;

	/// Removes a directory.
	///
	/// This corresponds to the `path_remove_directory` syscall.
	#[doc(alias = "path_remove_directory")]
	#[cfg(target_env = "p1")]
	fn remove_directory<P: AsRef<Path>>(&self, path: P) -> io::Result<()>;
	}

	// FIXME: bind fd_fdstat_get - need to define a custom return type
	// FIXME: bind fd_readdir - can't return `ReadDir` since we only have entry name
	// FIXME: bind fd_filestat_set_times maybe? - on crates.io for unix
	// FIXME: bind path_filestat_set_times maybe? - on crates.io for unix
	// FIXME: bind poll_oneoff maybe? - probably should wait for I/O to settle
	// FIXME: bind random_get maybe? - on crates.io for unix

	impl FileExt for File {
	fn read_at(&self, buf: &mut [u8], offset: u64) -> io::Result<usize> {
	self.as_inner().read_at(buf, offset)
	}

	fn read_buf_at(&self, buf: BorrowedCursor<'_>, offset: u64) -> io::Result<()> {
	self.as_inner().read_buf_at(buf, offset)
	}

	fn read_vectored_at(&self, bufs: &mut [IoSliceMut<'_>], offset: u64) -> io::Result<usize> {
	self.as_inner().read_vectored_at(bufs, offset)
	}

	fn write_at(&self, buf: &[u8], offset: u64) -> io::Result<usize> {
	self.as_inner().write_at(buf, offset)
	}

	fn write_vectored_at(&self, bufs: &[IoSlice<'_>], offset: u64) -> io::Result<usize> {
	self.as_inner().write_vectored_at(bufs, offset)
	}

	#[cfg(target_env = "p1")]
	fn fdstat_set_flags(&self, flags: u16) -> io::Result<()> {
	unsafe { wasi::fd_fdstat_set_flags(self.as_raw_fd() as wasi::Fd, flags).map_err(err2io) }
	}

	#[cfg(target_env = "p1")]
	fn fdstat_set_rights(&self, rights: u64, inheriting: u64) -> io::Result<()> {
	unsafe {
	wasi::fd_fdstat_set_rights(self.as_raw_fd() as wasi::Fd, rights, inheriting)
	.map_err(err2io)
	}
	}

	#[cfg(target_env = "p1")]
	fn advise(&self, offset: u64, len: u64, advice: u8) -> io::Result<()> {
	let advice = match advice {
	a if a == wasi::ADVICE_NORMAL.raw() => wasi::ADVICE_NORMAL,
	a if a == wasi::ADVICE_SEQUENTIAL.raw() => wasi::ADVICE_SEQUENTIAL,
	a if a == wasi::ADVICE_RANDOM.raw() => wasi::ADVICE_RANDOM,
	a if a == wasi::ADVICE_WILLNEED.raw() => wasi::ADVICE_WILLNEED,
	a if a == wasi::ADVICE_DONTNEED.raw() => wasi::ADVICE_DONTNEED,
	a if a == wasi::ADVICE_NOREUSE.raw() => wasi::ADVICE_NOREUSE,
	_ => {
	return Err(io::const_error!(
	io::ErrorKind::InvalidInput,
	"invalid parameter 'advice'",
	));
	}
	};

	unsafe {
	wasi::fd_advise(self.as_raw_fd() as wasi::Fd, offset, len, advice).map_err(err2io)
	}
	}

	#[cfg(target_env = "p1")]
	fn allocate(&self, offset: u64, len: u64) -> io::Result<()> {
	unsafe { wasi::fd_allocate(self.as_raw_fd() as wasi::Fd, offset, len).map_err(err2io) }
	}

	#[cfg(target_env = "p1")]
	fn create_directory<P: AsRef<Path>>(&self, dir: P) -> io::Result<()> {
	let path = osstr2str(dir.as_ref().as_ref())?;
	unsafe { wasi::path_create_directory(self.as_raw_fd() as wasi::Fd, path).map_err(err2io) }
	}

	#[cfg(target_env = "p1")]
	fn remove_file<P: AsRef<Path>>(&self, path: P) -> io::Result<()> {
	let path = osstr2str(path.as_ref().as_ref())?;
	unsafe { wasi::path_unlink_file(self.as_raw_fd() as wasi::Fd, path).map_err(err2io) }
	}

	#[cfg(target_env = "p1")]
	fn remove_directory<P: AsRef<Path>>(&self, path: P) -> io::Result<()> {
	let path = osstr2str(path.as_ref().as_ref())?;
	unsafe { wasi::path_remove_directory(self.as_raw_fd() as wasi::Fd, path).map_err(err2io) }
	}
	}

	/// WASI-specific extensions to [`OpenOptions`].
	pub trait OpenOptionsExt {
	/// Pass custom flags to the `flags` argument of `open`.
	fn custom_flags(&mut self, flags: i32) -> &mut Self;
	}

	impl OpenOptionsExt for OpenOptions {
	fn custom_flags(&mut self, flags: i32) -> &mut OpenOptions {
	self.as_inner_mut().custom_flags(flags);
	self
	}
	}

	/// WASI-specific extensions to [`fs::Metadata`].
	pub trait MetadataExt {
	/// Returns the `st_dev` field of the internal `filestat_t`
	fn dev(&self) -> u64;
	/// Returns the `st_ino` field of the internal `filestat_t`
	fn ino(&self) -> u64;
	/// Returns the `st_nlink` field of the internal `filestat_t`
	fn nlink(&self) -> u64;
	}

	impl MetadataExt for fs::Metadata {
	fn dev(&self) -> u64 {
	self.as_inner().as_inner().st_dev
	}
	fn ino(&self) -> u64 {
	self.as_inner().as_inner().st_ino
	}
	fn nlink(&self) -> u64 {
	self.as_inner().as_inner().st_nlink
	}
	}

	/// WASI-specific extensions for [`fs::FileType`].
	///
	/// Adds support for special WASI file types such as block/character devices,
	/// pipes, and sockets.
	pub trait FileTypeExt {
	/// Returns `true` if this file type is a block device.
	fn is_block_device(&self) -> bool;
	/// Returns `true` if this file type is a character device.
	fn is_char_device(&self) -> bool;
	/// Returns `true` if this file type is any type of socket.
	fn is_socket(&self) -> bool;
	}

	impl FileTypeExt for fs::FileType {
	fn is_block_device(&self) -> bool {
	self.as_inner().is(libc::S_IFBLK)
	}
	fn is_char_device(&self) -> bool {
	self.as_inner().is(libc::S_IFCHR)
	}
	fn is_socket(&self) -> bool {
	self.as_inner().is(libc::S_IFSOCK)
	}
	}

	/// WASI-specific extension methods for [`fs::DirEntry`].
	pub trait DirEntryExt {
	/// Returns the underlying `d_ino` field of the `dirent_t`
	fn ino(&self) -> u64;
	}

	impl DirEntryExt for fs::DirEntry {
	fn ino(&self) -> u64 {
	self.as_inner().ino()
	}
	}

	/// Creates a hard link.
	///
	/// This corresponds to the `path_link` syscall.
	#[doc(alias = "path_link")]
	#[cfg(target_env = "p1")]
	pub fn link<P: AsRef<Path>, U: AsRef<Path>>(
	old_fd: &File,
	old_flags: u32,
	old_path: P,
	new_fd: &File,
	new_path: U,
	) -> io::Result<()> {
	unsafe {
	wasi::path_link(
	old_fd.as_raw_fd() as wasi::Fd,
	old_flags,
	osstr2str(old_path.as_ref().as_ref())?,
	new_fd.as_raw_fd() as wasi::Fd,
	osstr2str(new_path.as_ref().as_ref())?,
	)
	.map_err(err2io)
	}
	}

	/// Renames a file or directory.
	///
	/// This corresponds to the `path_rename` syscall.
	#[doc(alias = "path_rename")]
	#[cfg(target_env = "p1")]
	pub fn rename<P: AsRef<Path>, U: AsRef<Path>>(
	old_fd: &File,
	old_path: P,
	new_fd: &File,
	new_path: U,
	) -> io::Result<()> {
	unsafe {
	wasi::path_rename(
	old_fd.as_raw_fd() as wasi::Fd,
	osstr2str(old_path.as_ref().as_ref())?,
	new_fd.as_raw_fd() as wasi::Fd,
	osstr2str(new_path.as_ref().as_ref())?,
	)
	.map_err(err2io)
	}
	}

	/// Creates a symbolic link.
	///
	/// This corresponds to the `path_symlink` syscall.
	#[doc(alias = "path_symlink")]
	#[cfg(target_env = "p1")]
	pub fn symlink<P: AsRef<Path>, U: AsRef<Path>>(
	old_path: P,
	fd: &File,
	new_path: U,
	) -> io::Result<()> {
	unsafe {
	wasi::path_symlink(
	osstr2str(old_path.as_ref().as_ref())?,
	fd.as_raw_fd() as wasi::Fd,
	osstr2str(new_path.as_ref().as_ref())?,
	)
	.map_err(err2io)
	}
	}

	/// Creates a symbolic link.
	///
	/// This is a convenience API similar to `std::os::unix::fs::symlink` and
	/// `std::os::windows::fs::symlink_file` and `std::os::windows::fs::symlink_dir`.
	pub fn symlink_path<P: AsRef<Path>, U: AsRef<Path>>(old_path: P, new_path: U) -> io::Result<()> {
	crate::sys::fs::symlink(old_path.as_ref(), new_path.as_ref())
	}

	#[cfg(target_env = "p1")]
	fn osstr2str(f: &OsStr) -> io::Result<&str> {
	f.to_str().ok_or_else(\|\| io::const_error!(io::ErrorKind::Uncategorized, "input must be utf-8"))
	}