5c51940100
* Refactor use of Refs and RefMuts in wasi-common This commit refactors the use of `Ref`s and `RefMut`s in `wasi-common`. Now, `Entry` is stored behind an `Rc` inside the `EntryTable`. The `Entry` itself on the other hand now stores rights behind a `RefCell` and the descriptor as `Rc<RefCell<..>>` combo to enable easy reference tracking and interior mutability which is required down the line in a couple of syscalls. In essence, this implies that we no longer have need for mutable accessor to `Entry` from `WasiCtx`, and so all related methods go away (`get_entry_mut`, etc.). While here, I've also simplified handling and aggregating of rights on the `Entry` object. Instead of storing base and inheriting rights as separate fields, they are now aggregated into one struct `EntryRights` which features convenient constructors for each possible combination; i.e., when only base rights are set, or both base and inheriting are set, or both are left as empty. Since we do need to be able to mutate those rights down the line in `fdstat_set_rights` syscall, this object is kept behind a `RefCell` (note no `Rc` since we don't need to pass it around anywhere). The descriptor field in `Entry` is now kept behind `Rc<RefCell<..>>` combo since we not only need to mutate it down the line, but we also need to be able to pass it around (as part of the machinery making `poll_oneoff` work). I've also removed `as_file` and `try_clone` methods on `Descriptor` struct since they were adding more noise than necessary, and making them work with `Rc` was unnecessarily complicated. Finally, I've converted the `get_dir_from_os_handle` function into a method attached to the `OsHandle` itself, called `dir_stream`. IMHO, it makes more sense to have it there directly as a method than as a separate function. * Use Cell for types that are Copy
66 lines
2.1 KiB
Rust
66 lines
2.1 KiB
Rust
use crate::wasi::Result;
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use std::cell::{RefCell, RefMut};
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use std::fs;
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use std::ops::Deref;
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use std::os::unix::prelude::{AsRawFd, RawFd};
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use yanix::dir::Dir;
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#[derive(Debug)]
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pub(crate) struct OsHandle {
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file: fs::File,
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// In case that this `OsHandle` actually refers to a directory,
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// when the client makes a `fd_readdir` syscall on this descriptor,
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// we will need to cache the `libc::DIR` pointer manually in order
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// to be able to seek on it later. While on Linux, this is handled
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// by the OS, BSD Unixes require the client to do this caching.
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//
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// This comes directly from the BSD man pages on `readdir`:
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// > Values returned by telldir() are good only for the lifetime
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// > of the DIR pointer, dirp, from which they are derived.
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// > If the directory is closed and then reopened, prior values
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// > returned by telldir() will no longer be valid.
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dir: RefCell<Option<Dir>>,
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}
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impl OsHandle {
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pub(crate) fn dir_stream(&self) -> Result<RefMut<Dir>> {
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if self.dir.borrow().is_none() {
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// We need to duplicate the fd, because `opendir(3)`:
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// Upon successful return from fdopendir(), the file descriptor is under
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// control of the system, and if any attempt is made to close the file
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// descriptor, or to modify the state of the associated description other
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// than by means of closedir(), readdir(), readdir_r(), or rewinddir(),
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// the behaviour is undefined.
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let fd = self.file.try_clone()?;
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let d = Dir::from(fd)?;
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*self.dir.borrow_mut() = Some(d);
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}
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Ok(RefMut::map(self.dir.borrow_mut(), |dir| {
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dir.as_mut().unwrap()
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}))
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}
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}
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impl From<fs::File> for OsHandle {
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fn from(file: fs::File) -> Self {
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Self {
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file,
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dir: RefCell::new(None),
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}
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}
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}
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impl AsRawFd for OsHandle {
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fn as_raw_fd(&self) -> RawFd {
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self.file.as_raw_fd()
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}
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}
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impl Deref for OsHandle {
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type Target = fs::File;
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fn deref(&self) -> &Self::Target {
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&self.file
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}
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}
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