Add C Language Plugin Support

.env.original

@@ -0,0 +1,5 @@
+# see https://github.com/WebAssembly/wasi-sdk/releases for exact possibilities
+WASI_OS=macos # 'macos' | 'linux' | ''windows'
+WASI_ARCH=x86_64 # 'x86_64' | 'arm64'
+WASI_VERSION=25
+WASI_VERSION_FULL=${WASI_VERSION}.0

.github/workflows/rust-host.yml

@@ -5,6 +5,20 @@ jobs:
   build-and-test:
     runs-on: ubuntu-latest
     steps:
+      - name: Set variables based on OS and architecture for just dl-wasi-sdk
+        run: |
+          if [ "${{ runner.arch }}" = "X64" ]; then
+            echo "WASI_ARCH=x86_64" >> $GITHUB_ENV
+          else
+            echo "WASI_ARCH=arm64" >> $GITHUB_ENV
+          fi
+          if [ "${{ runner.os }}" = "Windows" ]; then
+            echo "WASI_OS=windows" >> $GITHUB_ENV
+          else
+            echo "WASI_OS=linux" >> $GITHUB_ENV
+          fi
+          echo "WASI_VERSION_FULL=25.0" >> $GITHUB_ENV
+          echo "WASI_VERSION=25" >> $GITHUB_ENV
       - uses: actions/checkout@v4
       - uses: actions-rs/toolchain@v1
         with:
@@ -15,6 +29,14 @@ jobs:
       - uses: extractions/setup-just@v3
       - name: Install cargo-component
         run: cargo binstall cargo-component@0.21.1
+      - name: Install wasm-tools
+        run: cargo binstall wasm-tools@1.235.0
+      - name: Install wit-bindgen
+        run: cargo install wit-bindgen-cli@0.43.0
+      - name: Install wasi-sdk
+        run: |
+          mkdir c_deps
+          just dl-wasi-sdk
       - name: Build
         run: just build
       - name: Test

.github/workflows/web-host.yml

@@ -5,6 +5,20 @@ jobs:
   build:
     runs-on: ubuntu-latest
     steps:
+      - name: Set variables based on OS and architecture for just dl-wasi-sdk
+        run: |
+          if [ "${{ runner.arch }}" = "X64" ]; then
+            echo "WASI_ARCH=x86_64" >> $GITHUB_ENV
+          else
+            echo "WASI_ARCH=arm64" >> $GITHUB_ENV
+          fi
+          if [ "${{ runner.os }}" = "Windows" ]; then
+            echo "WASI_OS=windows" >> $GITHUB_ENV
+          else
+            echo "WASI_OS=linux" >> $GITHUB_ENV
+          fi
+          echo "WASI_VERSION_FULL=25.0" >> $GITHUB_ENV
+          echo "WASI_VERSION=25" >> $GITHUB_ENV
       - uses: actions/checkout@v4
       - uses: actions-rs/toolchain@v1
         with:
@@ -18,6 +32,14 @@ jobs:
       - uses: extractions/setup-just@v3
       - name: Install cargo-component
         run: cargo binstall cargo-component@0.21.1
+      - name: Install wasm-tools
+        run: cargo binstall wasm-tools@1.235.0
+      - name: Install wit-bindgen
+        run: cargo install wit-bindgen-cli@0.43.0
+      - name: Install wasi-sdk
+        run: |
+          mkdir c_deps
+          just dl-wasi-sdk
       - name: Install JavaScript dependencies
         run: npm ci
       - name: Build

.gitignore

@@ -17,3 +17,7 @@ target/
 ### JavaScript ###
 node_modules/
 dist/
+
+# C
+.env
+c_deps/

.vscode/extensions.json

@@ -5,6 +5,7 @@
     "skellock.just",
     "biomejs.biome",
     "bradlc.vscode-tailwindcss",
-    "ms-playwright.playwright"
+    "ms-playwright.playwright",
+    "ms-vscode.cpptools"
   ]
 }

README.md

@@ -23,7 +23,7 @@ There are two kinds of hosts:
 Those hosts then run the same codebase which is compiled to WebAssembly:
 
 - the REPL logic
-- the plugins
+- the plugins (made a few in rust, C and TypeScript)
 
 Security model: the REPL cli implements a security model inspired by [deno](https://docs.deno.com/runtime/fundamentals/security/#permissions):
 
@@ -63,7 +63,7 @@ In the last seven years I've done a few projects involving rust and WebAssembly:
 
 ## Usage
 
-### pluginlab (rust)
+### pluginlab (rust) - REPL cli host
 
 #### Install
 
@@ -82,6 +82,7 @@ pluginlab\
   --plugins https://topheman.github.io/webassembly-component-model-experiments/plugins/plugin_echo.wasm\
   --plugins https://topheman.github.io/webassembly-component-model-experiments/plugins/plugin_weather.wasm\
   --plugins https://topheman.github.io/webassembly-component-model-experiments/plugins/plugin_cat.wasm\
+  --plugins https://topheman.github.io/webassembly-component-model-experiments/plugins/plugin-echo-c.wasm\
   --allow-all
 ```
 
@@ -105,6 +106,7 @@ pluginlab\
   --plugins https://topheman.github.io/webassembly-component-model-experiments/plugins/plugin_echo.wasm\
   --plugins https://topheman.github.io/webassembly-component-model-experiments/plugins/plugin_weather.wasm\
   --plugins https://topheman.github.io/webassembly-component-model-experiments/plugins/plugin_cat.wasm\
+  --plugins https://topheman.github.io/webassembly-component-model-experiments/plugins/plugin-echo-c.wasm\
   --allow-all
 [Host] Starting REPL host...
 [Host] Loading REPL logic from: https://topheman.github.io/webassembly-component-model-experiments/plugins/repl_logic_guest.wasm
@@ -169,7 +171,31 @@ npm install
 npx playwright install
 ```
 
-### pluginlab (rust)
+#### C tooling
+
+[From the WebAssembly Component Model section for C tooling](https://component-model.bytecodealliance.org/language-support/c.html)
+
+```bash
+# Initialize the .env file tracking the WASI SDK version for C development
+# You will be asked to update the WASI_OS and WASI_ARCH variables if needed
+just init-env-file
+```
+
+```bash
+cargo install wit-bindgen-cli@0.43.0
+```
+
+```bash
+# Install the wasm-tools tool - you can also use cargo install wasm-tools@1.235.0 if you don't have cargo-binstall
+cargo binstall wasm-tools@1.235.0
+```
+
+```bash
+# Download the WASI SDK into ./c_deps/wasi-sdk folder
+just dl-wasi-sdk
+```
+
+### pluginlab (rust) - REPL cli host
 
 #### Build
 
@@ -182,6 +208,7 @@ This will (see [justfile](./justfile)):
 - compile the pluginlab crate from rust to a binary file
 - compile the repl-logic-guest crate from rust to wasm
 - compile the plugin-* crates from rust to wasm
+- compile the c_modules/plugin-* C plugins to wasm
 
 #### Run
 
@@ -193,6 +220,7 @@ This will (see [justfile](./justfile)):
   --plugins ./target/wasm32-wasip1/debug/plugin_echo.wasm\
   --plugins ./target/wasm32-wasip1/debug/plugin_weather.wasm\
   --plugins ./target/wasm32-wasip1/debug/plugin_cat.wasm\
+  --plugins ./c_modules/plugin-echo/plugin-echo-c.wasm\
   --allow-all
 ```
 
@@ -300,14 +328,23 @@ In [`.github/workflows/web-host.yml`](./.github/workflows/web-host.yml), after t
 
 To be sure that the preview server is up and running before running the tests, we use the [`webServer.command` option](https://playwright.dev/docs/test-webserver) of [playwright.config.ts](./packages/web-host/playwright.config.ts) to run `WAIT_FOR_SERVER_AT_URL=http://localhost:4173/webassembly-component-model-experiments/ npm run test:e2e:all:preview`
 
+### plugins
+
+There are currently plugins implemented in 3 languages (most of them are in rust):
+
+#### Rust
 
-### plugins (TypeScript)
+You can write plugins in rust in [`crates/plugin-*`](./crates).
 
-You can write plugins in rust in [`crates/plugin-*`](./crates), you can also write plugins in TypeScript in [`packages/plugin-*`](./packages), thanks to `jco componentize` (based on [componentize-js](https://github.com/bytecodealliance/componentize-js)).
+#### C
 
-There is a [`packages/plugin-echo`](./packages/plugin-echo/) example plugin in TypeScript.
+You can write plugins in C in [`c_modules/plugin-*`](./c_modules), thanks to `wit-bindgen` (based on [wit-bindgen](https://github.com/bytecodealliance/wit-bindgen)).
 
-The downsides of writing plugins in TypeScript is mostly that your `.wasm` file will be **much larger** than the one compiled from rust:
+#### TypeScript
+
+You can also write plugins in TypeScript in [`packages/plugin-*`](./packages), thanks to `jco componentize` (based on [componentize-js](https://github.com/bytecodealliance/componentize-js)).
+
+The downsides of writing plugins in TypeScript is mostly that your `.wasm` file will be **much larger** than the one compiled from rust or C:
 
 - ~100KB of wasm for the rust plugin
 - 11MB of wasm for the TypeScript plugin
@@ -316,9 +353,10 @@ The reason is that a JavaScript runtime needs to be embedded in the `.wasm` file
 
 More about the [SpiderMonkey runtime embedding](https://github.com/bytecodealliance/ComponentizeJS?tab=readme-ov-file#explainer).
 
-### plugins (Other languages)
+#### Other languages
+
+Coming.
 
-Coming soon.
 
 ## Developer experience
 
@@ -346,6 +384,7 @@ Those are **optional** tools that are handy for WebAssembly development:
 - [cargo component 0.21.1+](https://github.com/bytecodealliance/cargo-component?tab=readme-ov-file#installation)
 - [wasm-tools 1.235.0](https://github.com/bytecodealliance/wasm-tools?tab=readme-ov-file#installation)
 - [wasm-opt 116](https://github.com/WebAssembly/binaryen?tab=readme-ov-file#installation)
+- [wit-bindgen-cli 0.43.0](https://github.com/bytecodealliance/wit-bindgen)
 
 ```bash
 # latest versions
@@ -356,3 +395,9 @@ cargo binstall cargo-component wasm-tools wasm-opt
 # specific versions I used for this project
 cargo binstall cargo-component@0.21.1 wasm-tools@1.235.0 wasm-opt@116
 ```
+
+### C tooling
+
+- [From the WebAssembly Component Model section for C tooling](https://component-model.bytecodealliance.org/language-support/c.html)
+- [WASI SDK](https://github.com/WebAssembly/wasi-sdk)
+- [WIT Bindgen](https://github.com/bytecodealliance/wit-bindgen)

c_modules/README.md

@@ -0,0 +1,9 @@
+# Plugins written in C
+
+You can find here plugins written in C, some are re-implementations of the plugins written in Rust.
+
+The `plugin_api.c`, `plugin_api.h` and `plugin_api.component_type.o` are generated with [`wit-bindgen`](https://github.com/bytecodealliance/wit-bindgen), based on the [wit files](../crates/pluginlab/wit) of the project.
+
+The wasm files are compiled with the [wasi-sdk](https://github.com/WebAssembly/wasi-sdk) you downloaded with `just dl-wasi-sdk`, which contain the `clang` compiler.
+
+All you have to do is run `just build` to build everything (including the C plugins) and `just test` to run the tests (including the C plugins).

c_modules/plugin-echo/.gitignore

@@ -0,0 +1,4 @@
+*.wasm
+plugin_api.h
+plugin_api.c
+plugin_api_component_type.o

c_modules/plugin-echo/component.c

@@ -0,0 +1,85 @@
+#include "plugin_api.h"
+#include <string.h>
+#include <stdlib.h>
+
+/*
+ * C implementation of the echo plugin
+ *
+ * IMPLEMENTATION SOURCE:
+ * This implements the same interface as the Rust version in crates/plugin-echo/src/lib.rs
+ * The function signatures are generated from the WIT interface by wit-bindgen:
+ * - exports_repl_api_plugin_name() corresponds to fn name() -> String
+ * - exports_repl_api_plugin_man() corresponds to fn man() -> String
+ * - exports_repl_api_plugin_run() corresponds to fn run(payload: String) -> Result<PluginResponse, ()>
+ *
+ * MEMORY MANAGEMENT:
+ * - Input parameters (like payload) are owned by the runtime - DO NOT free them
+ * - Output parameters (like ret) are populated by us, freed by the runtime
+ * - plugin_api_string_dup() allocates new memory for string copies
+ * - The generated _free functions handle cleanup automatically
+ * - No explicit free() calls needed in plugin code
+ */
+
+void exports_repl_api_plugin_name(plugin_api_string_t *ret)
+{
+    // Populate ret with "echo" as the plugin name
+    // plugin_api_string_dup() allocates new memory and copies the string
+    plugin_api_string_dup(ret, "echoc");
+}
+
+void exports_repl_api_plugin_man(plugin_api_string_t *ret)
+{
+    // Populate ret with the manual text for the echo command
+    // plugin_api_string_dup() allocates new memory and copies the string
+    const char *man_text =
+        "\n"
+        "NAME\n"
+        "    echoc - Echo a message (built with C)\n"
+        "\n"
+        "USAGE\n"
+        "    echoc <message>\n"
+        "\n"
+        "DESCRIPTION\n"
+        "    Echo a message.\n"
+        "\n"
+        "        ";
+    plugin_api_string_dup(ret, man_text);
+}
+
+bool exports_repl_api_plugin_run(plugin_api_string_t *payload, exports_repl_api_plugin_plugin_response_t *ret)
+{
+    // Set status to success (0 = success, 1 = error)
+    ret->status = REPL_API_TRANSPORT_REPL_STATUS_SUCCESS;
+
+    // Set stdout to contain the payload
+    // is_some = true means the optional string has a value
+    ret->stdout.is_some = true;
+
+    // Create a properly null-terminated string from the payload
+    // The payload has ptr and len, we need to ensure it's null-terminated
+    char *temp_str = malloc(payload->len + 1);
+    if (temp_str == NULL)
+    {
+        // Handle allocation failure
+        ret->stdout.is_some = false;
+        ret->stderr.is_some = false;
+        return false;
+    }
+
+    // Copy the payload data and null-terminate it
+    memcpy(temp_str, payload->ptr, payload->len);
+    temp_str[payload->len] = '\0';
+
+    // Use plugin_api_string_dup to create the output string
+    plugin_api_string_dup(&ret->stdout.val, temp_str);
+
+    // Free our temporary string
+    free(temp_str);
+
+    // Set stderr to none (no error output)
+    ret->stderr.is_some = false;
+
+    // Return true for success (false would indicate an error)
+    // This corresponds to Ok(response) in the Rust Result<T, ()> pattern
+    return true;
+}

crates/pluginlab/README.md

@@ -18,7 +18,7 @@ There are two kinds of hosts:
 Those hosts then run the same codebase which is compiled to WebAssembly:
 
 - the REPL logic
-- the plugins
+- the plugins (made a few in rust, C and TypeScript)
 
 Security model: the REPL cli implements a security model inspired by [deno](https://docs.deno.com/runtime/fundamentals/security/#permissions):
 
@@ -61,6 +61,7 @@ pluginlab\
   --plugins https://topheman.github.io/webassembly-component-model-experiments/plugins/plugin_echo.wasm\
   --plugins https://topheman.github.io/webassembly-component-model-experiments/plugins/plugin_weather.wasm\
   --plugins https://topheman.github.io/webassembly-component-model-experiments/plugins/plugin_cat.wasm\
+  --plugins https://topheman.github.io/webassembly-component-model-experiments/plugins/plugin-echo-c.wasm\
   --allow-all
 ```
 
@@ -85,6 +86,7 @@ pluginlab\
   --plugins https://topheman.github.io/webassembly-component-model-experiments/plugins/plugin_echo.wasm\
   --plugins https://topheman.github.io/webassembly-component-model-experiments/plugins/plugin_weather.wasm\
   --plugins https://topheman.github.io/webassembly-component-model-experiments/plugins/plugin_cat.wasm\
+  --plugins https://topheman.github.io/webassembly-component-model-experiments/plugins/plugin-echo-c.wasm\
   --allow-all
 [Host] Starting REPL host...
 [Host] Loading REPL logic from: https://topheman.github.io/webassembly-component-model-experiments/plugins/repl_logic_guest.wasm