cbf7cbfa39
* Introduce strongly-typed system primitives This commit does a lot of reshuffling and even some more. It introduces strongly-typed system primitives which are: `OsFile`, `OsDir`, `Stdio`, and `OsOther`. Those primitives are separate structs now, each implementing a subset of `Handle` methods, rather than all being an enumeration of some supertype such as `OsHandle`. To summarise the structs: * `OsFile` represents a regular file, and implements fd-ops of `Handle` trait * `OsDir` represents a directory, and primarily implements path-ops, plus `readdir` and some common fd-ops such as `fdstat`, etc. * `Stdio` represents a stdio handle, and implements a subset of fd-ops such as `fdstat` _and_ `read_` and `write_vectored` calls * `OsOther` currently represents anything else and implements a set similar to that implemented by `Stdio` This commit is effectively an experiment and an excercise into better understanding what's going on for each OS resource/type under-the-hood. It's meant to give us some intuition in order to move on with the idea of having strongly-typed handles in WASI both in the syscall impl as well as at the libc level. Some more minor changes include making `OsHandle` represent an OS-specific wrapper for a raw OS handle (Unix fd or Windows handle). Also, since `OsDir` is tricky across OSes, we also have a supertype of `OsHandle` called `OsDirHandle` which may store a `DIR*` stream pointer (mainly BSD). Last but not least, the `Filetype` and `Rights` are now computed when the resource is created, rather than every time we call `Handle::get_file_type` and `Handle::get_rights`. Finally, in order to facilitate the latter, I've converted `EntryRights` into `HandleRights` and pushed them into each `Handle` implementor. * Do not adjust rights on Stdio * Clean up testing for TTY and escaping writes * Implement AsFile for dyn Handle This cleans up a lot of repeating boilerplate code todo with dynamic dispatch. * Delegate definition of OsDir to OS-specific modules Delegates defining `OsDir` struct to OS-specific modules (BSD, Linux, Emscripten, Windows). This way, `OsDir` can safely re-use `OsHandle` for raw OS handle storage, and can store some aux data such as an initialized stream ptr in case of BSD. As a result, we can safely get rid of `OsDirHandle` which IMHO was causing unnecessary noise and overcomplicating the design. On the other hand, delegating definition of `OsDir` to OS-specific modules isn't super clean in and of itself either. Perhaps there's a better way of handling this? * Check if filetype of OS handle matches WASI filetype when creating It seems prudent to check if the passed in `File` instance is of type matching that of the requested WASI filetype. In other words, we'd like to avoid situations where `OsFile` is created from a pipe. * Make AsFile fallible Return `EBADF` in `AsFile` in case a `Handle` cannot be made into a `std::fs::File`. * Remove unnecessary as_file conversion * Remove unnecessary check for TTY for Stdio handle type * Fix incorrect stdio ctors on Unix * Split Stdio into three separate types: Stdin, Stdout, Stderr * Rename PendingEntry::File to PendingEntry::OsHandle to avoid confusion * Rename OsHandle to RawOsHandle Also, since `RawOsHandle` on *nix doesn't need interior mutability wrt the inner raw file descriptor, we can safely swap the `RawFd` for `File` instance. * Add docs explaining what OsOther is * Allow for stdio to be non-character-device (e.g., piped) * Return error on bad preopen rather than panic
wasi-common
A Bytecode Alliance project
A library providing a common implementation of WASI hostcalls for re-use in any WASI-enabled runtime.
The wasi-common crate will ultimately serve as a library providing a common implementation of
WASI hostcalls for re-use in any WASI (and potentially non-WASI) runtimes
such as Wasmtime and Lucet.
The library is an adaption of lucet-wasi crate from the Lucet project, and it is currently based on 40ae1df git revision.
Please note that the library requires Rust compiler version at least 1.37.0.
Supported syscalls
*nix
In our *nix implementation, we currently support the entire WASI API with the exception of socket hostcalls:
sock_recvsock_sendsock_shutdown
We expect these to be implemented when network access is standardised.
We also currently do not support the proc_raise hostcall, as it is expected to
be dropped entirely from WASI.
Windows
In our Windows implementation, we currently support the minimal subset of WASI API which allows for running the very basic "Hello world!" style WASM apps. More coming shortly, so stay tuned!
Development hints
When testing the crate, you may want to enable and run full wasm32 integration testsuite. This
requires wasm32-wasi target installed which can be done as follows using rustup
rustup target add wasm32-wasi
Now, you should be able to run the integration testsuite by running cargo test on the
test-programs package with test-programs/test_programs feature enabled:
cargo test --features test-programs/test_programs --package test-programs
Third-Party Code
Significant parts of our hostcall implementations are derived from the C implementations in
cloudabi-utils. See LICENSE.cloudabi-utils for license information.