* 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
* Clean up the use of mutable Entry
Until now, several syscalls including `fd_pwrite` etc. were relying on
mutating `&mut Entry` by mutating its inner file handle. This is
unnecessary in almost all cases since all methods mutating `std::fs::File`
in Rust's libstd are also implemented for `&std::fs::File`.
While here, I've also modified `OsHandle` in BSD to include `RefCell<Option<Dir>>`
rather than `Option<Mutex<Dir>>` as was until now. While `RefCell`
could easily be replaced with `RefCell`, since going multithreading
will require a lot of (probably even) conceptual changes to `wasi-common`,
I thought it'd be best not to mix single- with multithreading contexts
and swap all places at once when it comes to it.
I've also had to make some modifications to virtual FS which mainly
swapped mutability for interior mutability in places.
* Use one-liners wherever convenient
* Add yanix crate
This commit adds `yanix` crate as a Unix dependency for `wasi-common`.
`yanix` stands for Yet Another Nix crate and is exactly what the name
suggests: a crate in the spirit of the `nix` crate, but which takes a different
approach, using lower-level interfaces with less abstraction, so that it fits
better with its main use case, implementation of WASI syscalls.
* Replace nix with yanix crate
Having introduced `yanix` crate as an in-house replacement for the
`nix` crate, this commit makes the necessary changes to `wasi-common`
to depend _only_ on `yanix` crate.
* Address review comments
* make `fd_dup` unsafe
* rename `get_fd` to `get_fd_flags`, etc.
* reuse `io::Error::last_os_error()` to get the last errno value
* Address more comments
* make all `fcntl` fns unsafe
* adjust `wasi-common` impl appropriately
* Make all fns operating on RawFd unsafe
* Fix linux build
* Address more comments
* Support fd_fdstat_get on stdin/stdout/stderr.
Add a routine for obtaining an `OsFile` containing a file descriptor for
stdin/stdout/stderr so that we can do fd_fdstat_get on them.
* Add a testcase for fd_fdstat_get etc. on stdin etc.
* Don't dup file descriptors in fd_renumber.
* Fix compilation on macOS
* Rename OsFile to OsHandle
This commits renames `OsFile` to `OsHandle` which seems to make
more sense semantically as it is permitted to hold a valid OS handle
to OS entities other than simply file/dir (e.g., socket, stream, etc.).
As such, this commit also renames methods on `Descriptor` struct
from `as_actual_file` to `as_file` as this in reality does pertain
ops on FS entities such as files/dirs, and `as_file` to `as_os_handle`
as in this case it can be anything, from file, through a socket, to
a stream.
* Fix compilation on Linux
* Introduce `OsHandleRef` for borrowing OS resources.
To prevent a `ManuallyDrop<OsHandleRef>` from outliving the resource it
holds on to, create an `OsHandleRef` class parameterized on the lifetime
of the `Descriptor`.
* Fix scoping to pub-priv and backport to snapshot_0
