Max BrunsfeldandJakub Konka
c4d75ea6d5
### Background Zed extensions use WASI to access the file-system. They only have read-write access to one specific folder called their work dir. But extensions do need to be able to *refer* to other arbitrary files on the user's machine. For instance, extensions need to be able to look up existing binaries on the user's `PATH`, and request that Zed invoke them as language servers. Similarly, extensions can create paths to files in the user's project, and use them as arguments in commands that Zed should run. For these reasons, we pass *real* paths back and forth between the host and extensions; we don't try to abstract over the file-system with some virtualization scheme. On Windows, this results in a bit of mismatch, because `wasi-libc` uses *unix-like* path conventions (and thus, so does the Rust standard library when compiling to WASI). ### Change 1 - Fixing `current_dir` In order to keep the extension API minimal, extensions use the standard library function`env::current_dir()` to query the location of their "work" directory. Previously, when initializing extensions, we used the `env::set_current_dir` function to set their work directory, but on Windows, where absolute paths typically begin with a drive letter, like `C:`, the [`wasi-libc` implementation of `chdir`](https://github.com/WebAssembly/wasi-libc/blob/d1793637d8afcdc730408e7b6a19a050c3336ce7/libc-bottom-half/sources/chdir.c#L21) was prepending an extra forward slash to the path, which caused `current_dir()` to return an invalid path. See https://github.com/bytecodealliance/wasmtime/issues/10415 In this PR, I've switched our extension initialization function to *bypass* wasi-libc's `chdir` function, and instead write directly to wasi-libc's private, internal state. This is a bit of a hack, but it causes the `current_dir()` function to do what we want on Windows without any changes to extensions' source code. ### Change 2 - Working around WASI's relative path handling Once `current_dir` was fixed (giving us correct absolute paths on Windows), @kubkon and I discovered that without the spurious leading `/` character, windows absolute paths were no longer accepted by Rust's `std::fs` APIs, because they were now recognized as relative paths, and were being appended to the working directory. We first tried to override the `__wasilibc_find_abspath` function in `wasi-libc` to make it recognize windows absolute paths as being absolute, but that functionality is difficult to override. Eventually @kubkon realized that we could prevent WASI-libc's CWD handling from being linked into the WASM file by overriding the `chdir` function. wasi-libc is designed so that if you don't use their `chdir` function, then all paths will be interpreted as relative to `/`. This makes absolute paths behave correctly. Then, in order to make *relative* paths work again, we simply add a preopen for `.`. Relative paths will match that. ### Next Steps This is a change to `zed-extension-api`, so we do need to update every Zed extension to use the new version, in order for them to work on windows. Release Notes: - N/A --------- Co-authored-by: Jakub Konka <kubkon@jakubkonka.com>
The Zed Rust Extension API
This crate lets you write extensions for Zed in Rust.
Extension Manifest
You'll need an extension.toml file at the root of your extension directory, with the following structure:
id = "my-extension"
name = "My Extension"
description = "..."
version = "0.0.1"
schema_version = 1
authors = ["Your Name <you@example.com>"]
repository = "https://github.com/your/extension-repository"
Cargo metadata
Zed extensions are packaged as WebAssembly files. In your Cargo.toml, you'll
need to set your crate-type accordingly:
[dependencies]
zed_extension_api = "0.6.0"
[lib]
crate-type = ["cdylib"]
Implementing an Extension
To define your extension, create a type that implements the Extension trait, and register it.
use zed_extension_api as zed;
struct MyExtension {
// ... state
}
impl zed::Extension for MyExtension {
// ...
}
zed::register_extension!(MyExtension);
Testing your extension
To run your extension in Zed as you're developing it:
- Make sure you have Rust installed
- Have the
wasm32-wasip2target installed (rustup target add wasm32-wasip2) - Open the extensions view using the
zed: extensionsaction in the command palette. - Click the
Install Dev Extensionbutton in the top right - Choose the path to your extension directory.
Compatible Zed versions
Extensions created using newer versions of the Zed extension API won't be compatible with older versions of Zed.
Here is the compatibility of the zed_extension_api with versions of Zed:
| Zed version | zed_extension_api version |
|---|---|
0.192.x |
0.0.1 - 0.6.0 |
0.186.x |
0.0.1 - 0.5.0 |
0.184.x |
0.0.1 - 0.4.0 |
0.178.x |
0.0.1 - 0.3.0 |
0.162.x |
0.0.1 - 0.2.0 |
0.149.x |
0.0.1 - 0.1.0 |
0.131.x |
0.0.1 - 0.0.6 |
0.130.x |
0.0.1 - 0.0.5 |
0.129.x |
0.0.1 - 0.0.4 |
0.128.x |
0.0.1 |