T0b1/wasmtime
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Refactor use of Refs and RefMuts in wasi-common (#1412)

Browse Source 
* 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
This commit is contained in:
Jakub Konka
2020-03-27 09:34:52 +01:00
committed by GitHub
parent 092538cc54
commit 5c51940100
20 changed files with 446 additions and 550 deletions
Download Patch File Download Diff File Expand all files Collapse all files

15
crates/wasi-common/src/path.rs
View File

@@ -1,7 +1,7 @@
use crate::entry::{Descriptor, Entry, EntryRights};
use crate::sys;
use crate::sys::entry::OsHandle;
use crate::wasi::{types, Errno, Result};
use crate::{entry::Descriptor, entry::Entry};
use std::path::{Component, Path};
use std::str;
use wiggle::{GuestBorrows, GuestPtr};
@@ -102,8 +102,7 @@ impl<'a, 'b> PathRef<'a, 'b> {
/// This is a workaround for not having Capsicum support in the OS.
pub(crate) fn get(
fe: &Entry,
rights_base: types::Rights,
rights_inheriting: types::Rights,
required_rights: &EntryRights,
dirflags: types::Lookupflags,
path: &GuestPtr<'_, str>,
needs_final_component: bool,
@@ -129,10 +128,12 @@ pub(crate) fn get(
return Err(Errno::Notdir);
}
let dirfd = fe
.as_descriptor(rights_base, rights_inheriting)?
.as_file()?
.try_clone()?;
let desc = fe.as_descriptor(required_rights)?;
let dirfd = match &*desc.borrow() {
Descriptor::OsHandle(file) => file.try_clone().map(|f| OsHandle::from(f).into())?,
Descriptor::VirtualFile(virt) => virt.try_clone().map(Descriptor::VirtualFile)?,
_ => return Err(Errno::Badf),
};
// Stack of directory file descriptors. Index 0 always corresponds with the directory provided
// to this function. Entering a directory causes a file descriptor to be pushed, while handling