wip

See https://github.com/bytecodealliance/wasmtime/issues/8799

I will make a 1.4.1 release after this is merged

.github/workflows/kernel.yml

@@ -21,6 +21,9 @@ jobs:
           target: wasm32-unknown-unknown
       - uses: Swatinem/rust-cache@v2
 
+      - name: install wasm-tools
+        uses: bytecodealliance/actions/wasm-tools/setup@v1
+
       - name: Install deps
         run: |
           sudo apt install wabt --yes

Makefile

@@ -4,10 +4,12 @@ AEXT=a
 FEATURES?=default
 DEFAULT_FEATURES?=yes
 RUST_TARGET?=
+EXTRA_LIBS=
 
 UNAME := $(shell uname -s)
 ifeq ($(UNAME),Darwin)
 	SOEXT=dylib
+	EXTRA_LIBS=-framework Security
 endif
 
 ifeq ($(DEFAULT_FEATURES),no)
@@ -29,7 +31,8 @@ endif
 build:
 	cargo build --release $(FEATURE_FLAGS) --manifest-path libextism/Cargo.toml $(TARGET_FLAGS)
 	sed -e "s%@CMAKE_INSTALL_PREFIX@%$(DEST)%" libextism/extism.pc.in > libextism/extism.pc
-	sed -e "s%@CMAKE_INSTALL_PREFIX@%$(DEST)%" libextism/extism-static.pc.in > libextism/extism-static.pc
+	sed -e "s%@CMAKE_INSTALL_PREFIX@%$(DEST)%" \
+	    -e "s%Libs: %Libs: $(EXTRA_LIBS) %" libextism/extism-static.pc.in > libextism/extism-static.pc
 
 bench:
 	@(cargo criterion $(TARGET_FLAGS) || echo 'For nicer output use cargo-criterion: `cargo install cargo-criterion` - using `cargo bench`') && cargo bench $(TARGET_FLAGS)

README.md

@@ -8,7 +8,7 @@
 
 [![Discord](https://img.shields.io/discord/1011124058408112148?color=%23404eed&label=Community%20Chat&logo=Discord&logoColor=%23404eed)](https://extism.org/discord)
 ![GitHub Org's stars](https://img.shields.io/github/stars/extism)
-![GitHub all releases](https://img.shields.io/github/downloads/extism/extism/total)
+![Downloads](https://img.shields.io/crates/d/extism)
 ![GitHub License](https://img.shields.io/github/license/extism/extism)
 ![GitHub release (with filter)](https://img.shields.io/github/v/release/extism/extism)
 
@@ -51,6 +51,7 @@ started:
 | Java SDK    | <img alt="Java SDK" src="https://extism.org/img/sdk-languages/java-android.svg" width="50px"/> | https://github.com/extism/java-sdk                                      | [Sonatype](https://central.sonatype.com/artifact/org.extism.sdk/extism) |
 | .NET SDK    | <img alt=".NET SDK" src="https://extism.org/img/sdk-languages/dotnet.svg" width="50px"/>       | https://github.com/extism/dotnet-sdk <br/>(supports C# & F#!)           | [Nuget](https://www.nuget.org/packages/Extism.Sdk)                      |
 | OCaml SDK   | <img alt="OCaml SDK" src="https://extism.org/img/sdk-languages/ocaml.svg" width="50px"/>       | https://github.com/extism/ocaml-sdk                                     | [opam](https://opam.ocaml.org/packages/extism/)                         |
+| Perl SDK    | <img alt="Perl SDK" src="https://extism.org/img/sdk-languages/perl.svg" width="50px"/>         | https://github.com/extism/perl-sdk                                      | [CPAN](https://metacpan.org/pod/Extism)                                 |
 | PHP SDK     | <img alt="PHP SDK" src="https://extism.org/img/sdk-languages/php.svg" width="50px"/>           | https://github.com/extism/php-sdk                                       | [Packagist](https://packagist.org/packages/extism/extism)               |
 | Python SDK  | <img alt="Python SDK" src="https://extism.org/img/sdk-languages/python.svg" width="50px"/>     | https://github.com/extism/python-sdk                                    | [PyPi](https://pypi.org/project/extism/)                                |
 | Ruby SDK    | <img alt="Ruby SDK" src="https://extism.org/img/sdk-languages/ruby.svg" width="50px"/>         | https://github.com/extism/ruby-sdk                                      | [RubyGems](https://rubygems.org/gems/extism)                            |

convert/Cargo.toml

@@ -11,7 +11,7 @@ description = "Traits to make Rust types usable with Extism"
 
 [dependencies]
 anyhow = "1.0.75"
-base64 = "~0.21"
+base64 = "~0.22"
 bytemuck = {version = "1.14.0", optional = true }
 prost = { version = "0.12.0", optional = true }
 protobuf = { version = "3.2.0", optional = true }

kernel/.gitignore

@@ -0,0 +1,3 @@
+owi-out
+*.wat
+proofs

kernel/Cargo.toml

@@ -7,6 +7,7 @@ edition = "2021"
 
 [dev-dependencies]
 wasm-bindgen-test = "0.3.39"
+owi = {git = "https://github.com/dylibso/owi-rs"}
 
 [features]
 default = ["bounds-checking"]
@@ -15,4 +16,4 @@ bounds-checking = []
 [workspace]
 members = [
   "."
-]
+]

kernel/build.sh

@@ -1,5 +1,7 @@
 #!/usr/bin/env bash
 
+set -e
+
 export CARGO_FLAGS=""
 
 while getopts d flag
@@ -17,6 +19,9 @@ done
 
 cargo build --package extism-runtime-kernel --bin extism-runtime --release --target wasm32-unknown-unknown $CARGO_FLAGS
 cp target/wasm32-unknown-unknown/release/extism-runtime.wasm .
-wasm-strip extism-runtime.wasm
-mv extism-runtime.wasm ../runtime/src/extism-runtime.wasm
 
+wasm-tools parse extism-context.wat -o extism-context.wasm
+wasm-merge --enable-reference-types ./extism-runtime.wasm runtime extism-context.wasm context -o ../runtime/src/extism-runtime.wasm
+rm extism-context.wasm
+rm extism-runtime.wasm
+wasm-strip ../runtime/src/extism-runtime.wasm

kernel/examples/alloc_length.rs

@@ -0,0 +1,21 @@
+#![no_main]
+#![no_std]
+use extism_runtime_kernel::*;
+use owi::*;
+
+main!({
+    let n = alloc(1024);
+
+    let x = u64();
+    assume(x > 0);
+
+    let m = alloc(x);
+
+    // 1. Length should equal `x` while active
+    assert(length(m) == x);
+
+    // 2. Length should equal `0` after free
+    free(m); // Free the block
+    assert(length(m) == 0);
+    free(n);
+});

kernel/examples/error.rs

@@ -0,0 +1,24 @@
+#![no_main]
+#![no_std]
+use extism_runtime_kernel::*;
+use owi::*;
+
+main!({
+    let x = u64();
+    let n = u64();
+    let m = u64();
+    assume(x > 0);
+    assume(n > 0);
+    assume(m > 0);
+
+    alloc(n);
+    alloc(m);
+    let n = alloc(x);
+    assert(error_get() == 0);
+
+    error_set(n);
+    assert(error_get() == n);
+    alloc(m);
+    error_set(0);
+    assert(error_get() == 0);
+});

kernel/examples/load_store.rs

@@ -0,0 +1,17 @@
+#![no_main]
+#![no_std]
+use extism_runtime_kernel::*;
+use owi::*;
+
+main!({
+    let x = u64();
+    assume(x > 0);
+
+    let m = alloc(x);
+    assert(length(m) == x);
+    for i in 0..x {
+        store_u8(m + i, i as u8);
+        assert(load_u8(m + i) == i as u8);
+    }
+    free(m);
+});

kernel/examples/reuse.rs

@@ -0,0 +1,39 @@
+#![no_main]
+#![no_std]
+use extism_runtime_kernel::*;
+use owi::*;
+
+main!({
+    let x = u64();
+    assume(x > 0);
+
+    let y = u64();
+    assume(y > 0);
+
+    let mut tmp = 0;
+
+    for _ in 0..y {
+        let m = alloc(x);
+        if tmp == 0 {
+            tmp = m;
+        } else {
+            // Check that the existing block is being re-used
+            assert(m == tmp);
+        }
+
+        assert(length(m) == x);
+        free(m); // Free the block
+    }
+
+    let y = u64();
+    assume(y == x + 1);
+    let n = alloc(y);
+    assert(n > tmp);
+
+    let z = u64();
+    assume(z <= x);
+    assume(x - z < 32);
+    assume(z > 0);
+    let p = alloc(z);
+    assert(p == tmp);
+});

kernel/extism-context.wat

@@ -0,0 +1,3 @@
+(module
+  (global (export "extism_context") (mut externref) (ref.null extern))
+)

kernel/src/bin/extism-runtime.rs

@@ -1,5 +1,5 @@
-#![no_main]
 #![no_std]
+#![no_main]
 
 pub use extism_runtime_kernel::*;
 

kernel/src/lib.rs

@@ -175,7 +175,7 @@ impl MemoryRoot {
         core::ptr::write_bytes(
             self.blocks.as_mut_ptr() as *mut u8,
             MemoryStatus::Unused as u8,
-            self_position as usize,
+            self_position as usize - core::mem::size_of::<MemoryRoot>(),
         );
 
         // Clear extism runtime metadata
@@ -638,4 +638,15 @@ mod test {
 
         assert_eq!(last, 0);
     }
+
+    #[wasm_bindgen_test]
+    fn test_sym() {
+        unsafe {
+            reset();
+            let a = alloc(47);
+            let b = alloc(20);
+            assert_eq!(length(a), 47);
+            assert_eq!(length(b), 20);
+        }
+    }
 }

kernel/verify.sh

@@ -0,0 +1,23 @@
+#!/usr/bin/env bash
+
+set -e
+
+OUT_DIR=./target/wasm32-unknown-unknown/release/examples/
+get_proof() {
+   cp "$OUT_DIR/$1.wasm" "./proofs/$1.wasm"
+}
+
+cargo build --examples --release --target wasm32-unknown-unknown --no-default-features
+
+mkdir -p proofs
+get_proof alloc_length
+get_proof load_store
+get_proof reuse
+get_proof error
+
+for proof in $(ls proofs/*.wasm); do
+  echo "Checking $proof"
+  owi  conc "$proof" $@
+  echo
+  echo "---"
+done

libextism/.clang-format

@@ -0,0 +1,2 @@
+BasedOnStyle: LLVM
+IndentWidth: 2

libextism/API.md

@@ -14,7 +14,9 @@ Create a new plugin.
 - `functions`: is an array of `ExtismFunction*`
 - `n_functions`: is the number of functions
 - `with_wasi`: enables/disables WASI
-- `errmsg`: error message during plugin creation
+- `errmsg`: error message during plugin creation, this should be freed with
+  `extism_plugin_new_error_free`
+
 
 ```c
 ExtismPlugin extism_plugin_new(const uint8_t *wasm,
@@ -24,6 +26,17 @@ ExtismPlugin extism_plugin_new(const uint8_t *wasm,
                                bool with_wasi,
                                char **errmsg);
 ```
+---
+
+### `extism_plugin_new_error_free`
+
+Frees the error message returned when creating a plugin
+
+```c
+void extism_plugin_new_error_free(char *err);
+```
+
+---
 
 ### `extism_plugin_free`
 
@@ -33,6 +46,8 @@ Remove a plugin from the registry and free associated memory.
 void extism_plugin_free(ExtismPlugin *plugin);
 ```
 
+---
+
 ### `extism_plugin_config`
 
 Update plugin config values, this will merge with the existing values.
@@ -43,6 +58,8 @@ bool extism_plugin_config(ExtismPlugin *plugin,
                           ExtismSize json_size);
 ```
 
+---
+
 ### `extism_plugin_function_exists`
 
 Returns true if `func_name` exists.
@@ -52,6 +69,8 @@ bool extism_plugin_function_exists(ExtismPlugin *plugin,
                                    const char *func_name);
 ```
 
+---
+
 ### `extism_plugin_call`
 
 Call a function.
@@ -59,6 +78,8 @@ Call a function.
 - `data`: is the input data
 - `data_len`: is the length of `data`
 
+Returns `0` when the call is successful.
+
 ```c
 int32_t extism_plugin_call(ExtismPlugin *plugin,
                            const char *func_name,
@@ -66,6 +87,28 @@ int32_t extism_plugin_call(ExtismPlugin *plugin,
                            ExtismSize data_len);
 ```
 
+---
+
+### `extism_plugin_call_with_host_context`
+
+Call a function with additional host context that can be accessed from inside host functions.
+- `func_name`: is the function to call
+- `data`: is the input data
+- `data_len`: is the length of `data`
+- `host_ctx`: an opaque pointer that can be accessed in host functions
+
+Returns `0` when the call is successful.
+
+```c
+int32_t extism_plugin_call_with_host_context(ExtismPlugin *plugin,
+                           const char *func_name,
+                           const uint8_t *data,
+                           ExtismSize data_len,
+                           void *host_ctx);
+```
+
+---
+
 ### `extism_plugin_error`
 
 Get the error associated with a `Plugin`
@@ -74,6 +117,8 @@ Get the error associated with a `Plugin`
 const char *extism_plugin_error(ExtismPlugin *plugin);
 ```
 
+---
+
 ### `extism_plugin_output_length`
 
 Get the length of a plugin's output data.
@@ -82,6 +127,8 @@ Get the length of a plugin's output data.
 ExtismSize extism_plugin_output_length(ExtismPlugin *plugin);
 ```
 
+---
+
 ### `extism_plugin_output_data`
 
 Get the plugin's output data.
@@ -90,6 +137,8 @@ Get the plugin's output data.
 const uint8_t *extism_plugin_output_data(ExtismPlugin *plugin);
 ```
 
+---
+
 ### `extism_plugin_reset`
 
 Reset the Extism runtime, this will invalidate all allocated memory.
@@ -98,6 +147,8 @@ Reset the Extism runtime, this will invalidate all allocated memory.
 bool extism_plugin_reset(ExtismPlugin *plugin);
 ```
 
+---
+
 ### `extism_log_file`
 
 Set log file and level.
@@ -106,6 +157,8 @@ Set log file and level.
 bool extism_log_file(const char *filename, const char *log_level);
 ```
 
+---
+
 ### `extism_log_custom`
 
 Enable a custom log handler, this will buffer logs until `extism_log_drain`
@@ -115,6 +168,8 @@ is called Log level should be one of: info, error, trace, debug, warn
 bool extism_log_custom(const char *log_level);
 ```
 
+---
+
 ### `extism_log_drain`
 
 Calls the provided callback function for each buffered log line.
@@ -124,6 +179,8 @@ This is only needed when `extism_log_custom` is used.
 void extism_log_drain(void (*handler)(const char *, uintptr_t));
 ```
 
+---
+
 ### `extism_version`
 
 Get the Extism version string.
@@ -132,6 +189,8 @@ Get the Extism version string.
 const char *extism_version(void);
 ```
 
+---
+
 ### `extism_current_plugin_memory`
 
 Returns a pointer to the memory of the currently running plugin
@@ -140,6 +199,19 @@ Returns a pointer to the memory of the currently running plugin
 uint8_t *extism_current_plugin_memory(ExtismCurrentPlugin *plugin);
 ```
 
+---
+
+### `extism_current_plugin_host_context`
+
+Get access to the host context, passed in using `extism_plugin_call_with_host_context`
+
+```c
+void *extism_current_plugin_host_context(ExtismCurrentPlugin *plugin);
+```
+
+---
+
+
 ### `extism_current_plugin_memory_alloc`
 
 Allocate a memory block in the currently running plugin
@@ -148,6 +220,8 @@ Allocate a memory block in the currently running plugin
 uint64_t extism_current_plugin_memory_alloc(ExtismCurrentPlugin *plugin, ExtismSize n);
 ```
 
+---
+
 ### `extism_current_plugin_memory_length`
 
 Get the length of an allocated block
@@ -156,6 +230,8 @@ Get the length of an allocated block
 ExtismSize extism_current_plugin_memory_length(ExtismCurrentPlugin *plugin, ExtismSize n);
 ```
 
+---
+
 ### `extism_current_plugin_memory_free`
 
 Free an allocated memory block
@@ -164,6 +240,8 @@ Free an allocated memory block
 void extism_current_plugin_memory_free(ExtismCurrentPlugin *plugin, uint64_t ptr);
 ```
 
+---
+
 ### `extism_function_new`
 Create a new host function
 - `name`: function name, this should be valid UTF-8
@@ -190,6 +268,8 @@ ExtismFunction *extism_function_new(const char *name,
                                     void (*free_user_data)(void *_));
 ```
 
+---
+
 ### `extism_function_set_namespace`
 
 Set the namespace of an `ExtismFunction`
@@ -198,6 +278,8 @@ Set the namespace of an `ExtismFunction`
 void extism_function_set_namespace(ExtismFunction *ptr, const char *namespace_);
 ```
 
+---
+
 ### `extism_function_free`
 
 Free an `ExtismFunction`
@@ -206,6 +288,8 @@ Free an `ExtismFunction`
 void extism_function_free(ExtismFunction *ptr);
 ```
 
+---
+
 ### `extism_plugin_cancel_handle`
 
 Get handle for plugin cancellation
@@ -214,6 +298,8 @@ Get handle for plugin cancellation
 const ExtismCancelHandle *extism_plugin_cancel_handle(const ExtismPlugin *plugin);
 ```
 
+---
+
 ### `extism_plugin_cancel`
 
 Cancel a running plugin from another thread
@@ -222,12 +308,14 @@ Cancel a running plugin from another thread
 bool extism_plugin_cancel(const ExtismCancelHandle *handle);
 ```
 
+---
+
 ## Type definitions:
 
 ### `ExtismPlugin`
 
 ```c
-typedef int32_t ExtismPlugin;
+typedef struct ExtismPlugin ExtismPlugin;
 ```
 
 ### `ExtismSize`
@@ -259,3 +347,5 @@ typedef struct ExtismCurrentPlugin ExtismCurrentPlugin;
 ```c
 typedef struct ExtismCancelHandle ExtismCancelHandle;
 ```
+
+

libextism/Makefile

@@ -4,7 +4,7 @@ build:
 
 .PHONY: static
 static:
-	$(CC) -g -o example example.c -l:libextism.a -lm
+	$(CC) -g -o example example.c -l:libextism.a -lm -lpthread
 
 # if needed, set PKG_CONFIG_PATH= to the directory with extism*.pc installed
 LDFLAGS=`pkg-config --libs extism`

libextism/README.md

@@ -56,7 +56,6 @@ Since you may not have an Extism plug-in on hand to test, let's load a demo plug
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
-#include <unistd.h>
 
 void print_plugin_output(ExtismPlugin *plugin, int32_t rc){
   if (rc != EXTISM_SUCCESS) {
@@ -64,9 +63,9 @@ void print_plugin_output(ExtismPlugin *plugin, int32_t rc){
     return;
   }
 
-  size_t outlen = extism_plugin_output_length(plugin);
+  ExtismSize outlen = extism_plugin_output_length(plugin);
   const uint8_t *out = extism_plugin_output_data(plugin);
-  write(STDOUT_FILENO, out, outlen);
+  fwrite(out, 1, outlen, stdout);
 }
 
 int main(void) {
@@ -106,9 +105,9 @@ if (rc != EXTISM_SUCCESS) {
   exit(2);
 }
 
-size_t outlen = extism_plugin_output_length(plugin);
+ExtismSize outlen = extism_plugin_output_length(plugin);
 const uint8_t *out = extism_plugin_output_data(plugin);
-write(STDOUT_FILENO, out, outlen);
+fwrite(out, 1, outlen, stdout);
 ```
 
 Will print
@@ -171,7 +170,6 @@ We want to expose two functions to our plugin, `kv_write(key: String, value: Byt
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
-#include <unistd.h>
 
 // A stubbed out KV store
 typedef struct KVStore KVStore;
@@ -184,14 +182,14 @@ extern const uint32_t fake_kv_store_get(KVStore *kv, const char *key,
 
 // Our host functions to access the fake KV store
 void kv_get(ExtismCurrentPlugin *plugin, const ExtismVal *inputs,
-            size_t ninputs, ExtismVal *outputs, size_t noutputs,
+            ExtismSize ninputs, ExtismVal *outputs, ExtismSize noutputs,
             void *userdata) {
   // Cast the userdata pointer
   KVStore *kv = (KVStore *)userdata;
 
   // Get the offset to the key in the plugin memory
   uint64_t offs = inputs[0].v.i64;
-  size_t keylen = extism_current_plugin_memory_length(plugin, offs);
+  ExtismSize keylen = extism_current_plugin_memory_length(plugin, offs);
 
   // Allocate a new block to return
   uint64_t outoffs =
@@ -205,23 +203,23 @@ void kv_get(ExtismCurrentPlugin *plugin, const ExtismVal *inputs,
   *(uint64_t *)(extism_current_plugin_memory(plugin) + outoffs) = value;
 
   // Return the offset to our allocated block
-  outputs[0].t = PTR;
+  outputs[0].t = EXTISM_PTR;
   outputs[0].v.i64 = outoffs;
 }
 
 void kv_set(ExtismCurrentPlugin *plugin, const ExtismVal *inputs,
-            size_t ninputs, ExtismVal *outputs, size_t noutputs,
+            ExtismSize ninputs, ExtismVal *outputs, ExtismSize noutputs,
             void *userdata) {
   // Cast the userdata pointer
   KVStore *kv = (KVStore *)userdata;
 
   // Get the offset to the key in the plugin memory
   uint64_t keyoffs = inputs[0].v.i64;
-  size_t keylen = extism_current_plugin_memory_length(plugin, keyoffs);
+  ExtismSize keylen = extism_current_plugin_memory_length(plugin, keyoffs);
 
   // Get the offset to the value in the plugin memory
   uint64_t valueoffs = inputs[1].v.i64;
-  size_t valuelen = extism_current_plugin_memory_length(plugin, valueoffs);
+  ExtismSize valuelen = extism_current_plugin_memory_length(plugin, valueoffs);
 
   // Set key => value
   fake_kv_store_set(
@@ -234,13 +232,13 @@ int main(void) {
   const char *manifest = "{\"wasm\": [{\"url\": "
                          "\"https://github.com/extism/plugins/releases/latest/"
                          "download/count_vowels_kvstore.wasm\"}]}";
-  const ExtismValType kv_get_inputs[] = {PTR};
-  const ExtismValType kv_get_outputs[] = {PTR};
+  const ExtismValType kv_get_inputs[] = {EXTISM_PTR};
+  const ExtismValType kv_get_outputs[] = {EXTISM_PTR};
   ExtismFunction *kv_get_fn = extism_function_new(
       "kv_get", kv_get_inputs, 1, kv_get_outputs, 1, kv_get, kv, NULL);
 
-  const ExtismValType kv_set_inputs[] = {PTR};
-  const ExtismValType kv_set_outputs[] = {PTR};
+  const ExtismValType kv_set_inputs[] = {EXTISM_PTR};
+  const ExtismValType kv_set_outputs[] = {EXTISM_PTR};
   ExtismFunction *kv_set_fn = extism_function_new(
       "kv_set", kv_set_inputs, 1, kv_set_outputs, 1, kv_set, kv, NULL);
   const ExtismFunction *functions[] = {kv_get_fn};
@@ -288,5 +286,3 @@ print_plugin_output(plugin, extism_plugin_call(plugin, "count_vowels",
 # => Writing value=6 from key=count-vowels"
 # => {"count": 3, "total": 6, "vowels": "aeiouAEIOU"}
 ```
-
-

libextism/example.c

@@ -9,7 +9,7 @@
 #include <sys/stat.h>
 #include <unistd.h>
 
-void log_handler(const char *line, uintptr_t length) {
+void log_handler(const char *line, ExtismSize length) {
   fwrite(line, length, 1, stderr);
 }
 
@@ -63,8 +63,8 @@ int main(int argc, char *argv[]) {
 
   size_t len = 0;
   uint8_t *data = read_file("../wasm/code-functions.wasm", &len);
-  ExtismValType inputs[] = {PTR};
-  ExtismValType outputs[] = {PTR};
+  ExtismValType inputs[] = {EXTISM_PTR};
+  ExtismValType outputs[] = {EXTISM_PTR};
   ExtismFunction *f =
       extism_function_new("hello_world", inputs, 1, outputs, 1, hello_world,
                           "Hello, again!", free_data);

libextism/extism-static.pc.in

@@ -5,6 +5,6 @@ includedir=${prefix}/include
 Version: 1.0.0
 Name: Extism
 Description: The framework for building with WebAssembly (wasm).
-Libs: -L${libdir} -l:libextism.a
-Libs.private: -lm
+Libs: ${libdir}/libextism.a
+Libs.private: -lm -lpthread
 Cflags: -I${includedir}

libextism/extism.pc.in

@@ -6,5 +6,5 @@ Version: 1.0.0
 Name: Extism
 Description: The framework for building with WebAssembly (wasm).
 Libs: -L${libdir} -lextism
-Libs.private: -lm
+Libs.private: -lm -lpthread
 Cflags: -I${includedir}

manifest/Cargo.toml

@@ -10,7 +10,7 @@ version.workspace = true
 
 [dependencies]
 serde = { version = "1", features = ["derive"] }
-base64 = "~0.21"
+base64 = "~0.22"
 schemars = { version = "0.8", optional = true }
 serde_json = "1"
 

manifest/schema.json

@@ -38,7 +38,8 @@
       "description": "Memory options",
       "default": {
         "max_http_response_bytes": null,
-        "max_pages": null
+        "max_pages": null,
+        "max_var_bytes": null
       },
       "allOf": [
         {
@@ -47,7 +48,7 @@
       ]
     },
     "timeout_ms": {
-      "description": "The plugin timeout, by default this is set to 30s",
+      "description": "The plugin timeout in milliseconds",
       "default": null,
       "type": [
         "integer",
@@ -89,6 +90,16 @@
           ],
           "format": "uint32",
           "minimum": 0.0
+        },
+        "max_var_bytes": {
+          "description": "The maximum number of bytes allowed to be used by plugin vars. Setting this to 0 will disable Extism vars. The default value is 1mb.",
+          "default": 1048576,
+          "type": [
+            "integer",
+            "null"
+          ],
+          "format": "uint64",
+          "minimum": 0.0
         }
       },
       "additionalProperties": false

manifest/src/lib.rs

@@ -10,12 +10,45 @@ pub type ManifestMemory = MemoryOptions;
 #[serde(deny_unknown_fields)]
 pub struct MemoryOptions {
     /// The max number of WebAssembly pages that should be allocated
-    #[serde(alias = "max")]
     pub max_pages: Option<u32>,
 
     /// The maximum number of bytes allowed in an HTTP response
     #[serde(default)]
     pub max_http_response_bytes: Option<u64>,
+
+    /// The maximum number of bytes allowed to be used by plugin vars. Setting this to 0
+    /// will disable Extism vars. The default value is 1mb.
+    #[serde(default = "default_var_bytes")]
+    pub max_var_bytes: Option<u64>,
+}
+
+impl MemoryOptions {
+    /// Create an empty `MemoryOptions` value
+    pub fn new() -> Self {
+        Default::default()
+    }
+
+    /// Set max pages
+    pub fn with_max_pages(mut self, pages: u32) -> Self {
+        self.max_pages = Some(pages);
+        self
+    }
+
+    /// Set max HTTP response size
+    pub fn with_max_http_response_bytes(mut self, bytes: u64) -> Self {
+        self.max_http_response_bytes = Some(bytes);
+        self
+    }
+
+    /// Set max size of Extism vars
+    pub fn with_max_var_bytes(mut self, bytes: u64) -> Self {
+        self.max_var_bytes = Some(bytes);
+        self
+    }
+}
+
+fn default_var_bytes() -> Option<u64> {
+    Some(1024 * 1024)
 }
 
 /// Generic HTTP request structure
@@ -28,7 +61,6 @@ pub struct HttpRequest {
 
     /// Request headers
     #[serde(default)]
-    #[serde(alias = "header")]
     pub headers: std::collections::BTreeMap<String, String>,
 
     /// Request method
@@ -249,7 +281,7 @@ pub struct Manifest {
     #[serde(default)]
     pub allowed_paths: Option<BTreeMap<PathBuf, PathBuf>>,
 
-    /// The plugin timeout, by default this is set to 30s
+    /// The plugin timeout in milliseconds
     #[serde(default)]
     pub timeout_ms: Option<u64>,
 }

runtime/Cargo.toml

@@ -9,15 +9,15 @@ repository.workspace = true
 version.workspace = true
 
 [dependencies]
-wasmtime = ">= 14.0.0, < 18.0.0"
-wasmtime-wasi = ">= 14.0.0, < 18.0.0"
+wasmtime = ">= 20.0.0, < 22.0.0"
+wasi-common = ">= 20.0.0, < 22.0.0"
 anyhow = "1"
 serde = {version = "1", features = ["derive"]}
 serde_json = "1"
 toml = "0.8"
 sha2 = "0.10"
 tracing = "0.1"
-tracing-subscriber = {version = "0.3", features = ["std", "env-filter", "fmt"]}
+tracing-subscriber = {version = "0.3.18", features = ["std", "env-filter", "fmt"]}
 url = "2"
 glob = "0.3"
 ureq = {version = "2.5", optional=true}

runtime/README.md

@@ -12,7 +12,7 @@ To use the `extism` crate, you can add it to your Cargo file:
 
 ```toml
 [dependencies]
-extism = "1.0.0"
+extism = "1.2.0"
 ```
 
 ## Environment variables
@@ -201,7 +201,7 @@ fn main() {
 }
 ```
 
-> *Note*: In order to write host functions you should get familiar with the methods on the [Extism::CurrentPlugin](https://docs.rs/extism/latest/extism/struct.CurrentPlugin.html) and [Extism::CurrentPlugin](https://docs.rs/extism/latest/extism/struct.UserData.html) types.
+> *Note*: In order to write host functions you should get familiar with the methods on the [CurrentPlugin](https://docs.rs/extism/latest/extism/struct.CurrentPlugin.html) and [UserData](https://docs.rs/extism/latest/extism/enum.UserData.html) types.
 
 Now we can invoke the event:
 

runtime/build.rs

@@ -7,7 +7,7 @@ fn main() {
 #define EXTISM_SUCCESS 0
 
 /** An alias for I64 to signify an Extism pointer */
-#define PTR I64
+#define EXTISM_PTR ExtismValType_I64
 ";
     if let Ok(x) = cbindgen::Builder::new()
         .with_crate(".")

runtime/examples/linking.rs

@@ -2,6 +2,8 @@ use extism::*;
 
 fn main() {
     let manifest = Manifest::new([
+        // upper.wat provides an export called `host_reflect` that takes a string
+        // and returns the same string uppercased
         Wasm::File {
             // See https://github.com/extism/plugins/blob/main/upper.wat
             path: "../wasm/upper.wasm".into(),
@@ -10,6 +12,9 @@ fn main() {
                 hash: None,
             },
         },
+        // reflect expects host_reflect to be imported: https://github.com/extism/plugins/blob/e5578bbbdd87f9936a0a8d36df629768b2eff6bb/reflect/src/lib.rs#L5
+        // Extism will link the export from upper.wat to the import of reflect.rs at runtime so it
+        // can call it
         Wasm::File {
             // See https://github.com/extism/plugins/tree/main/reflect
             path: "../wasm/reflect.wasm".into(),

runtime/extism.h

@@ -10,7 +10,7 @@
 #define EXTISM_SUCCESS 0
 
 /** An alias for I64 to signify an Extism pointer */
-#define PTR I64
+#define EXTISM_PTR ExtismValType_I64
 
 
 /**
@@ -20,31 +20,31 @@ typedef enum {
   /**
    * Signed 32 bit integer.
    */
-  I32,
+  ExtismValType_I32,
   /**
    * Signed 64 bit integer.
    */
-  I64,
+  ExtismValType_I64,
   /**
    * Floating point 32 bit integer.
    */
-  F32,
+  ExtismValType_F32,
   /**
    * Floating point 64 bit integer.
    */
-  F64,
+  ExtismValType_F64,
   /**
    * A 128 bit number.
    */
-  V128,
+  ExtismValType_V128,
   /**
    * A reference to a Wasm function.
    */
-  FuncRef,
+  ExtismValType_FuncRef,
   /**
    * A reference to opaque data in the Wasm instance.
    */
-  ExternRef,
+  ExtismValType_ExternRef,
 } ExtismValType;
 
 /**
@@ -113,6 +113,12 @@ extern "C" {
  */
 const uint8_t *extism_plugin_id(ExtismPlugin *plugin);
 
+/**
+ * Get the current plugin's associated host context data. Returns null if call was made without
+ * host context.
+ */
+void *extism_current_plugin_host_context(ExtismCurrentPlugin *plugin);
+
 /**
  * Returns a pointer to the memory of the currently running plugin
  * NOTE: this should only be called from host functions.
@@ -231,6 +237,20 @@ int32_t extism_plugin_call(ExtismPlugin *plugin,
                            const uint8_t *data,
                            ExtismSize data_len);
 
+/**
+ * Call a function with host context.
+ *
+ * `func_name`: is the function to call
+ * `data`: is the input data
+ * `data_len`: is the length of `data`
+ * `host_context`: a pointer to context data that will be available in host functions
+ */
+int32_t extism_plugin_call_with_host_context(ExtismPlugin *plugin,
+                                             const char *func_name,
+                                             const uint8_t *data,
+                                             ExtismSize data_len,
+                                             void *host_context);
+
 /**
  * Get the error associated with a `Plugin`
  */

runtime/src/current_plugin.rs

@@ -15,6 +15,7 @@ pub struct CurrentPlugin {
     pub(crate) available_pages: Option<u32>,
     pub(crate) memory_limiter: Option<MemoryLimiter>,
     pub(crate) id: uuid::Uuid,
+    pub(crate) start_time: std::time::Instant,
 }
 
 unsafe impl Send for CurrentPlugin {}
@@ -62,6 +63,11 @@ impl wasmtime::ResourceLimiter for MemoryLimiter {
 }
 
 impl CurrentPlugin {
+    /// Gets `Plugin`'s ID
+    pub fn id(&self) -> uuid::Uuid {
+        self.id
+    }
+
     /// Get a `MemoryHandle` from a memory offset
     pub fn memory_handle(&mut self, offs: u64) -> Option<MemoryHandle> {
         if offs == 0 {
@@ -181,6 +187,23 @@ impl CurrentPlugin {
         anyhow::bail!("{} unable to locate extism memory", self.id)
     }
 
+    pub fn host_context<T: Clone + 'static>(&mut self) -> Result<T, Error> {
+        let (linker, mut store) = self.linker_and_store();
+        let Some(Extern::Global(xs)) = linker.get(&mut store, EXTISM_ENV_MODULE, "extism_context")
+        else {
+            anyhow::bail!("unable to locate an extism kernel global: extism_context",)
+        };
+
+        let Val::ExternRef(Some(xs)) = xs.get(&mut store) else {
+            anyhow::bail!("expected extism_context to be an externref value",)
+        };
+
+        match xs.data(&mut store)?.downcast_ref::<T>().cloned() {
+            Some(xs) => Ok(xs.clone()),
+            None => anyhow::bail!("could not downcast extism_context",),
+        }
+    }
+
     pub fn memory_alloc(&mut self, n: u64) -> Result<MemoryHandle, Error> {
         if n == 0 {
             return Ok(MemoryHandle {
@@ -288,25 +311,29 @@ impl CurrentPlugin {
         id: uuid::Uuid,
     ) -> Result<Self, Error> {
         let wasi = if wasi {
-            let auth = wasmtime_wasi::ambient_authority();
-            let mut ctx = wasmtime_wasi::WasiCtxBuilder::new();
-            for (k, v) in manifest.config.iter() {
-                ctx.env(k, v)?;
-            }
+            let auth = wasi_common::sync::ambient_authority();
+            let random = wasi_common::sync::random_ctx();
+            let clocks = wasi_common::sync::clocks_ctx();
+            let sched = wasi_common::sync::sched_ctx();
+            let table = wasi_common::Table::new();
+            let ctx = wasi_common::WasiCtx::new(random, clocks, sched, table);
 
             if let Some(a) = &manifest.allowed_paths {
                 for (k, v) in a.iter() {
-                    let d = wasmtime_wasi::Dir::open_ambient_dir(k, auth)?;
-                    ctx.preopened_dir(d, v)?;
+                    let file = Box::new(wasi_common::sync::dir::Dir::from_cap_std(
+                        wasi_common::sync::Dir::open_ambient_dir(k, auth)?,
+                    ));
+                    ctx.push_preopened_dir(file, v)?;
                 }
             }
 
             // Enable WASI output, typically used for debugging purposes
             if std::env::var("EXTISM_ENABLE_WASI_OUTPUT").is_ok() {
-                ctx.inherit_stdout().inherit_stderr();
+                ctx.set_stderr(Box::new(wasi_common::sync::stdio::stderr()));
+                ctx.set_stdout(Box::new(wasi_common::sync::stdio::stdout()));
             }
 
-            Some(Wasi { ctx: ctx.build() })
+            Some(Wasi { ctx })
         } else {
             None
         };
@@ -331,6 +358,7 @@ impl CurrentPlugin {
             available_pages,
             memory_limiter,
             id,
+            start_time: std::time::Instant::now(),
         })
     }
 
@@ -441,6 +469,18 @@ impl CurrentPlugin {
         let length = self.memory_length(offs).unwrap_or_default();
         (offs, length)
     }
+
+    /// Returns the remaining time before a plugin will timeout, or
+    /// `None` if no timeout is configured in the manifest
+    pub fn time_remaining(&self) -> Option<std::time::Duration> {
+        if let Some(x) = &self.manifest.timeout_ms {
+            let elapsed = &self.start_time.elapsed().as_millis();
+            let ms_left = x.saturating_sub(*elapsed as u64);
+            return Some(std::time::Duration::from_millis(ms_left));
+        }
+
+        None
+    }
 }
 
 impl Internal for CurrentPlugin {
@@ -452,14 +492,6 @@ impl Internal for CurrentPlugin {
         unsafe { &mut *self.store }
     }
 
-    fn linker(&self) -> &Linker<CurrentPlugin> {
-        unsafe { &*self.linker }
-    }
-
-    fn linker_mut(&mut self) -> &mut Linker<CurrentPlugin> {
-        unsafe { &mut *self.linker }
-    }
-
     fn linker_and_store(&mut self) -> (&mut Linker<CurrentPlugin>, &mut Store<CurrentPlugin>) {
         unsafe { (&mut *self.linker, &mut *self.store) }
     }

runtime/src/function.rs

@@ -4,6 +4,7 @@ use wasmtime::Caller;
 use crate::{error, trace, CurrentPlugin, Error};
 
 /// An enumeration of all possible value types in WebAssembly.
+/// cbindgen:prefix-with-name
 #[derive(Debug, Clone, Hash, Eq, PartialEq)]
 #[repr(C)]
 pub enum ValType {
@@ -37,8 +38,13 @@ impl From<wasmtime::ValType> for ValType {
             F32 => ValType::F32,
             F64 => ValType::F64,
             V128 => ValType::V128,
-            FuncRef => ValType::FuncRef,
-            ExternRef => ValType::ExternRef,
+            Ref(t) => {
+                if t.heap_type().is_func() {
+                    ValType::FuncRef
+                } else {
+                    ValType::ExternRef
+                }
+            }
         }
     }
 }
@@ -52,8 +58,8 @@ impl From<ValType> for wasmtime::ValType {
             F32 => wasmtime::ValType::F32,
             F64 => wasmtime::ValType::F64,
             V128 => wasmtime::ValType::V128,
-            FuncRef => wasmtime::ValType::FuncRef,
-            ExternRef => wasmtime::ValType::ExternRef,
+            FuncRef => wasmtime::ValType::FUNCREF,
+            ExternRef => wasmtime::ValType::EXTERNREF,
         }
     }
 }
@@ -71,7 +77,9 @@ pub struct CPtr {
 /// UserDataHandle is an untyped version of `UserData` that is stored inside `Function` to keep a live reference.
 #[derive(Clone)]
 pub(crate) enum UserDataHandle {
+    #[allow(dead_code)]
     C(Arc<CPtr>),
+    #[allow(dead_code)]
     Rust(Arc<std::sync::Mutex<dyn std::any::Any>>),
 }
 
@@ -168,8 +176,8 @@ pub struct Function {
     /// Module name
     pub(crate) namespace: Option<String>,
 
-    /// Function type
-    pub(crate) ty: wasmtime::FuncType,
+    pub(crate) params: Vec<ValType>,
+    pub(crate) results: Vec<ValType>,
 
     /// Function handle
     pub(crate) f: Arc<FunctionInner>,
@@ -182,8 +190,8 @@ impl Function {
     /// Create a new host function
     pub fn new<T: 'static, F>(
         name: impl Into<String>,
-        args: impl IntoIterator<Item = ValType>,
-        returns: impl IntoIterator<Item = ValType>,
+        params: impl IntoIterator<Item = ValType>,
+        results: impl IntoIterator<Item = ValType>,
         user_data: UserData<T>,
         f: F,
     ) -> Function
@@ -195,13 +203,13 @@ impl Function {
     {
         let data = user_data.clone();
         let name = name.into();
-        let args = args.into_iter().map(wasmtime::ValType::from);
-        let returns = returns.into_iter().map(wasmtime::ValType::from);
-        let ty = wasmtime::FuncType::new(args, returns);
-        trace!("Creating function {name}: type={ty:?}");
+        let params = params.into_iter().collect();
+        let results = results.into_iter().collect();
+        trace!("Creating function {name}: params={params:?}, results={results:?}");
         Function {
             name,
-            ty,
+            params,
+            results,
             f: Arc::new(
                 move |mut caller: Caller<_>, inp: &[Val], outp: &mut [Val]| {
                     let x = data.clone();
@@ -216,6 +224,22 @@ impl Function {
         }
     }
 
+    pub(crate) fn ty(&self, engine: &wasmtime::Engine) -> wasmtime::FuncType {
+        wasmtime::FuncType::new(
+            engine,
+            self.params
+                .iter()
+                .cloned()
+                .map(wasmtime::ValType::from)
+                .collect::<Vec<_>>(),
+            self.results
+                .iter()
+                .cloned()
+                .map(wasmtime::ValType::from)
+                .collect::<Vec<_>>(),
+        )
+    }
+
     /// Host function name
     pub fn name(&self) -> &str {
         &self.name
@@ -239,9 +263,14 @@ impl Function {
         self
     }
 
-    /// Get function type
-    pub fn ty(&self) -> &wasmtime::FuncType {
-        &self.ty
+    /// Get param types
+    pub fn params(&self) -> &[ValType] {
+        &self.params
+    }
+
+    /// Get result types
+    pub fn results(&self) -> &[ValType] {
+        &self.results
     }
 }
 

runtime/src/internal.rs

@@ -3,7 +3,7 @@ use crate::*;
 /// WASI context
 pub struct Wasi {
     /// wasi
-    pub ctx: wasmtime_wasi::WasiCtx,
+    pub ctx: wasi_common::WasiCtx,
 }
 
 /// InternalExt provides a unified way of acessing `memory`, `store` and `internal` values
@@ -12,10 +12,6 @@ pub(crate) trait Internal {
 
     fn store_mut(&mut self) -> &mut Store<CurrentPlugin>;
 
-    fn linker(&self) -> &Linker<CurrentPlugin>;
-
-    fn linker_mut(&mut self) -> &mut Linker<CurrentPlugin>;
-
     fn linker_and_store(&mut self) -> (&mut Linker<CurrentPlugin>, &mut Store<CurrentPlugin>);
 
     fn current_plugin(&self) -> &CurrentPlugin {

runtime/src/manifest.rs

@@ -47,9 +47,13 @@ fn to_module(engine: &Engine, wasm: &extism_manifest::Wasm) -> Result<(String, M
             let name = meta.name.as_deref().unwrap_or(MAIN_KEY).to_string();
 
             // Load file
-            let mut buf = Vec::new();
-            let mut file = std::fs::File::open(path)?;
-            file.read_to_end(&mut buf)?;
+            let buf = std::fs::read(path).map_err(|err| {
+                Error::msg(format!(
+                    "Unable to load Wasm file \"{}\": {}",
+                    path.display(),
+                    err.kind()
+                ))
+            })?;
 
             check_hash(&meta.hash, &buf)?;
             Ok((name, Module::new(engine, buf)?))

runtime/src/pdk.rs

@@ -97,19 +97,13 @@ pub(crate) fn var_set(
 ) -> Result<(), Error> {
     let data: &mut CurrentPlugin = caller.data_mut();
 
-    let mut size = 0;
-    for v in data.vars.values() {
-        size += v.len();
+    if data.manifest.memory.max_var_bytes.is_some_and(|x| x == 0) {
+        anyhow::bail!("Vars are disabled by this host")
     }
 
     let voffset = args!(input, 1, i64) as u64;
-
-    // If the store is larger than 100MB then stop adding things
-    if size > 1024 * 1024 * 100 && voffset != 0 {
-        return Err(Error::msg("Variable store is full"));
-    }
-
     let key_offs = args!(input, 0, i64) as u64;
+
     let key = {
         let handle = match data.memory_handle(key_offs) {
             Some(h) => h,
@@ -132,6 +126,22 @@ pub(crate) fn var_set(
         None => anyhow::bail!("invalid handle offset for var value: {voffset}"),
     };
 
+    let mut size = std::mem::size_of::<String>()
+        + std::mem::size_of::<Vec<u8>>()
+        + key.len()
+        + handle.length as usize;
+
+    for (k, v) in data.vars.iter() {
+        size += k.len();
+        size += v.len();
+        size += std::mem::size_of::<String>() + std::mem::size_of::<Vec<u8>>();
+    }
+
+    // If the store is larger than the configured size, or 1mb by default, then stop adding things
+    if size > data.manifest.memory.max_var_bytes.unwrap_or(1024 * 1024) as usize && voffset != 0 {
+        return Err(Error::msg("Variable store is full"));
+    }
+
     let value = data.memory_bytes(handle)?.to_vec();
 
     // Insert the value from memory into the `vars` map
@@ -207,6 +217,11 @@ pub(crate) fn http_request(
             r = r.set(k, v);
         }
 
+        // Set HTTP timeout to respect the manifest timeout
+        if let Some(remaining) = data.time_remaining() {
+            r = r.timeout(remaining);
+        }
+
         let res = if body_offset > 0 {
             let handle = match data.memory_handle(body_offset) {
                 Some(h) => h,
@@ -226,11 +241,18 @@ pub(crate) fn http_request(
                 Some(res.into_reader())
             }
             Err(e) => {
+                // Catch timeout and return
+                if let Some(d) = data.time_remaining() {
+                    if e.kind() == ureq::ErrorKind::Io && d.as_nanos() == 0 {
+                        anyhow::bail!("timeout");
+                    }
+                }
+                let msg = e.to_string();
                 if let Some(res) = e.into_response() {
                     data.http_status = res.status();
                     Some(res.into_reader())
                 } else {
-                    None
+                    return Err(Error::msg(msg));
                 }
             }
         };

runtime/src/plugin.rs

@@ -1,4 +1,5 @@
 use std::{
+    any::Any,
     collections::{BTreeMap, BTreeSet},
     path::PathBuf,
 };
@@ -100,14 +101,6 @@ impl Internal for Plugin {
         &mut self.store
     }
 
-    fn linker(&self) -> &Linker<CurrentPlugin> {
-        &self.linker
-    }
-
-    fn linker_mut(&mut self) -> &mut Linker<CurrentPlugin> {
-        &mut self.linker
-    }
-
     fn linker_and_store(&mut self) -> (&mut Linker<CurrentPlugin>, &mut Store<CurrentPlugin>) {
         (&mut self.linker, &mut self.store)
     }
@@ -193,6 +186,12 @@ fn add_module<T: 'static>(
     }
 
     for import in module.imports() {
+        let module = import.module();
+
+        if module == EXTISM_ENV_MODULE && !matches!(import.ty(), ExternType::Func(_)) {
+            anyhow::bail!("linked modules cannot access non-function exports of extism kernel");
+        }
+
         if !linked.contains(import.module()) {
             if let Some(m) = modules.get(import.module()) {
                 add_module(
@@ -213,6 +212,73 @@ fn add_module<T: 'static>(
     Ok(())
 }
 
+fn relink(
+    engine: &Engine,
+    mut store: &mut Store<CurrentPlugin>,
+    imports: &[Function],
+    modules: &BTreeMap<String, Module>,
+    with_wasi: bool,
+) -> Result<(InstancePre<CurrentPlugin>, Linker<CurrentPlugin>), Error> {
+    let mut linker = Linker::new(engine);
+    // Define PDK functions
+    macro_rules! add_funcs {
+            ($($name:ident($($args:expr),*) $(-> $($r:expr),*)?);* $(;)?) => {
+                $(
+                    let t = FuncType::new(&engine, [$($args),*], [$($($r),*)?]);
+                    linker.func_new(EXTISM_ENV_MODULE, stringify!($name), t, pdk::$name)?;
+                )*
+            };
+        }
+
+    // Add builtins
+    use wasmtime::ValType::*;
+    add_funcs!(
+        config_get(I64) -> I64;
+        var_get(I64) -> I64;
+        var_set(I64, I64);
+        http_request(I64, I64) -> I64;
+        http_status_code() -> I32;
+        log_warn(I64);
+        log_info(I64);
+        log_debug(I64);
+        log_error(I64);
+    );
+
+    let mut linked = BTreeSet::new();
+    linker.module(&mut store, EXTISM_ENV_MODULE, &modules[EXTISM_ENV_MODULE])?;
+    linked.insert(EXTISM_ENV_MODULE.to_string());
+
+    // If wasi is enabled then add it to the linker
+    if with_wasi {
+        wasi_common::sync::add_to_linker(&mut linker, |x: &mut CurrentPlugin| {
+            &mut x.wasi.as_mut().unwrap().ctx
+        })?;
+    }
+
+    for f in imports {
+        let name = f.name();
+        let ns = f.namespace().unwrap_or(EXTISM_USER_MODULE);
+        unsafe {
+            linker.func_new(ns, name, f.ty(engine).clone(), &*(f.f.as_ref() as *const _))?;
+        }
+    }
+
+    for (name, module) in modules.iter() {
+        add_module(
+            store,
+            &mut linker,
+            &mut linked,
+            modules,
+            name.clone(),
+            module,
+        )?;
+    }
+
+    let main = &modules[MAIN_KEY];
+    let instance_pre = linker.instantiate_pre(main)?;
+    Ok((instance_pre, linker))
+}
+
 impl Plugin {
     /// Create a new plugin from a Manifest or WebAssembly module, and host functions. The `with_wasi`
     /// parameter determines whether or not the module should be executed with WASI enabled.
@@ -239,7 +305,8 @@ impl Plugin {
             .coredump_on_trap(debug_options.coredump.is_some())
             .profiler(debug_options.profiling_strategy)
             .wasm_tail_call(true)
-            .wasm_function_references(true);
+            .wasm_function_references(true)
+            .wasm_gc(true);
 
         match cache_dir {
             Some(None) => (),
@@ -275,64 +342,9 @@ impl Plugin {
         );
         store.set_epoch_deadline(1);
 
-        let mut linker = Linker::new(&engine);
-        let mut imports: Vec<_> = imports.into_iter().collect();
-        // Define PDK functions
-        macro_rules! add_funcs {
-            ($($name:ident($($args:expr),*) $(-> $($r:expr),*)?);* $(;)?) => {
-                $(
-                    let t = FuncType::new([$($args),*], [$($($r),*)?]);
-                    linker.func_new(EXTISM_ENV_MODULE, stringify!($name), t, pdk::$name)?;
-                )*
-            };
-        }
+        let imports: Vec<Function> = imports.into_iter().collect();
+        let (instance_pre, linker) = relink(&engine, &mut store, &imports, &modules, with_wasi)?;
 
-        // Add builtins
-        use wasmtime::ValType::*;
-        add_funcs!(
-            config_get(I64) -> I64;
-            var_get(I64) -> I64;
-            var_set(I64, I64);
-            http_request(I64, I64) -> I64;
-            http_status_code() -> I32;
-            log_warn(I64);
-            log_info(I64);
-            log_debug(I64);
-            log_error(I64);
-        );
-
-        let mut linked = BTreeSet::new();
-        linker.module(&mut store, EXTISM_ENV_MODULE, &modules[EXTISM_ENV_MODULE])?;
-        linked.insert(EXTISM_ENV_MODULE.to_string());
-
-        // If wasi is enabled then add it to the linker
-        if with_wasi {
-            wasmtime_wasi::add_to_linker(&mut linker, |x: &mut CurrentPlugin| {
-                &mut x.wasi.as_mut().unwrap().ctx
-            })?;
-        }
-
-        for f in &mut imports {
-            let name = f.name();
-            let ns = f.namespace().unwrap_or(EXTISM_USER_MODULE);
-            unsafe {
-                linker.func_new(ns, name, f.ty().clone(), &*(f.f.as_ref() as *const _))?;
-            }
-        }
-
-        for (name, module) in modules.iter() {
-            add_module(
-                &mut store,
-                &mut linker,
-                &mut linked,
-                &modules,
-                name.clone(),
-                module,
-            )?;
-        }
-
-        let main = &modules[MAIN_KEY];
-        let instance_pre = linker.instantiate_pre(main)?;
         let timer_tx = Timer::tx();
         let mut plugin = Plugin {
             modules,
@@ -370,6 +382,7 @@ impl Plugin {
         if self.store_needs_reset {
             let engine = self.store.engine().clone();
             let internal = self.current_plugin_mut();
+            let with_wasi = internal.wasi.is_some();
             self.store = Store::new(
                 &engine,
                 CurrentPlugin::new(
@@ -380,6 +393,16 @@ impl Plugin {
                 )?,
             );
             self.store.set_epoch_deadline(1);
+
+            let (instance_pre, linker) = relink(
+                &engine,
+                &mut self.store,
+                &self._functions,
+                &self.modules,
+                with_wasi,
+            )?;
+            self.linker = linker;
+            self.instance_pre = instance_pre;
             let store = &mut self.store as *mut _;
             let linker = &mut self.linker as *mut _;
             let current_plugin = self.current_plugin_mut();
@@ -390,14 +413,7 @@ impl Plugin {
                     .limiter(|internal| internal.memory_limiter.as_mut().unwrap());
             }
 
-            let main = &self.modules[MAIN_KEY];
-            for (name, module) in self.modules.iter() {
-                if name != MAIN_KEY {
-                    self.linker.module(&mut self.store, name, module)?;
-                }
-            }
             self.instantiations = 0;
-            self.instance_pre = self.linker.instantiate_pre(main)?;
             **instance_lock = None;
             self.store_needs_reset = false;
         }
@@ -450,7 +466,7 @@ impl Plugin {
                 if let Some(f) = x.func() {
                     let (params, mut results) = (f.params(), f.results());
                     match (params.len(), results.len()) {
-                        (0, 1) => results.next() == Some(wasmtime::ValType::I32),
+                        (0, 1) => matches!(results.next(), Some(wasmtime::ValType::I32)),
                         (0, 0) => true,
                         _ => false,
                     }
@@ -462,7 +478,12 @@ impl Plugin {
     }
 
     // Store input in memory and re-initialize `Internal` pointer
-    pub(crate) fn set_input(&mut self, input: *const u8, mut len: usize) -> Result<(), Error> {
+    pub(crate) fn set_input(
+        &mut self,
+        input: *const u8,
+        mut len: usize,
+        host_context: Option<Rooted<ExternRef>>,
+    ) -> Result<(), Error> {
         self.output = Output::default();
         self.clear_error()?;
         let id = self.id.to_string();
@@ -496,6 +517,13 @@ impl Plugin {
             )?;
         }
 
+        if let Some(Extern::Global(ctxt)) =
+            self.linker
+                .get(&mut self.store, EXTISM_ENV_MODULE, "extism_context")
+        {
+            ctxt.set(&mut self.store, Val::ExternRef(host_context))?;
+        }
+
         Ok(())
     }
 
@@ -588,7 +616,7 @@ impl Plugin {
                     if let Some(reactor_init) = reactor_init {
                         reactor_init.call(&mut store, &[], &mut [])?;
                     }
-                    let mut results = vec![Val::null(); init.ty(&store).results().len()];
+                    let mut results = vec![Val::I32(0); init.ty(&store).results().len()];
                     init.call(
                         &mut store,
                         &[Val::I32(0), Val::I32(0)],
@@ -673,6 +701,7 @@ impl Plugin {
         lock: &mut std::sync::MutexGuard<Option<Instance>>,
         name: impl AsRef<str>,
         input: impl AsRef<[u8]>,
+        host_context: Option<Rooted<ExternRef>>,
     ) -> Result<i32, (Error, i32)> {
         let name = name.as_ref();
         let input = input.as_ref();
@@ -686,7 +715,7 @@ impl Plugin {
 
         self.instantiate(lock).map_err(|e| (e, -1))?;
 
-        self.set_input(input.as_ptr(), input.len())
+        self.set_input(input.as_ptr(), input.len(), host_context)
             .map_err(|x| (x, -1))?;
 
         let func = match self.get_func(lock, name) {
@@ -717,9 +746,10 @@ impl Plugin {
             .expect("Timer should start");
         self.store.epoch_deadline_trap();
         self.store.set_epoch_deadline(1);
+        self.current_plugin_mut().start_time = std::time::Instant::now();
 
         // Call the function
-        let mut results = vec![wasmtime::Val::null(); n_results];
+        let mut results = vec![wasmtime::Val::I32(0); n_results];
         let mut res = func.call(self.store_mut(), &[], results.as_mut_slice());
 
         // Stop timer
@@ -804,13 +834,7 @@ impl Plugin {
                     }
                 }
 
-                let wasi_exit_code = e
-                    .downcast_ref::<wasmtime_wasi::I32Exit>()
-                    .map(|e| e.0)
-                    .or_else(|| {
-                        e.downcast_ref::<wasmtime_wasi::preview2::I32Exit>()
-                            .map(|e| e.0)
-                    });
+                let wasi_exit_code = e.downcast_ref::<wasi_common::I32Exit>().map(|e| e.0);
                 if let Some(exit_code) = wasi_exit_code {
                     debug!(
                         plugin = self.id.to_string(),
@@ -873,7 +897,33 @@ impl Plugin {
         let lock = self.instance.clone();
         let mut lock = lock.lock().unwrap();
         let data = input.to_bytes()?;
-        self.raw_call(&mut lock, name, data)
+        self.raw_call(&mut lock, name, data, None)
+            .map_err(|e| e.0)
+            .and_then(move |rc| {
+                if rc != 0 {
+                    Err(Error::msg(format!("Returned non-zero exit code: {rc}")))
+                } else {
+                    self.output()
+                }
+            })
+    }
+
+    pub fn call_with_host_context<'a, 'b, T, U, C>(
+        &'b mut self,
+        name: impl AsRef<str>,
+        input: T,
+        host_context: C,
+    ) -> Result<U, Error>
+    where
+        T: ToBytes<'a>,
+        U: FromBytes<'b>,
+        C: Any + Send + Sync + 'static,
+    {
+        let lock = self.instance.clone();
+        let mut lock = lock.lock().unwrap();
+        let data = input.to_bytes()?;
+        let ctx = ExternRef::new(&mut self.store, host_context)?;
+        self.raw_call(&mut lock, name, data, Some(ctx))
             .map_err(|e| e.0)
             .and_then(move |_| self.output())
     }
@@ -892,7 +942,7 @@ impl Plugin {
         let lock = self.instance.clone();
         let mut lock = lock.lock().unwrap();
         let data = input.to_bytes().map_err(|e| (e, -1))?;
-        self.raw_call(&mut lock, name, data)
+        self.raw_call(&mut lock, name, data, None)
             .and_then(move |_| self.output().map_err(|e| (e, -1)))
     }
 

runtime/src/sdk.rs

@@ -41,9 +41,9 @@ pub type ExtismFunctionType = extern "C" fn(
 /// Log drain callback
 pub type ExtismLogDrainFunctionType = extern "C" fn(data: *const std::ffi::c_char, size: Size);
 
-impl From<&wasmtime::Val> for ExtismVal {
-    fn from(value: &wasmtime::Val) -> Self {
-        match value.ty() {
+impl ExtismVal {
+    fn from_val(value: &wasmtime::Val, ctx: impl AsContext) -> Self {
+        match value.ty(ctx) {
             wasmtime::ValType::I32 => ExtismVal {
                 t: ValType::I32,
                 v: ValUnion {
@@ -84,6 +84,24 @@ pub unsafe extern "C" fn extism_plugin_id(plugin: *mut Plugin) -> *const u8 {
     plugin.id.as_bytes().as_ptr()
 }
 
+/// Get the current plugin's associated host context data. Returns null if call was made without
+/// host context.
+#[no_mangle]
+pub unsafe extern "C" fn extism_current_plugin_host_context(
+    plugin: *mut CurrentPlugin,
+) -> *mut std::ffi::c_void {
+    if plugin.is_null() {
+        return std::ptr::null_mut();
+    }
+
+    let plugin = &mut *plugin;
+    if let Ok(CVoidContainer(ptr)) = plugin.host_context::<CVoidContainer>() {
+        ptr
+    } else {
+        std::ptr::null_mut()
+    }
+}
+
 /// Returns a pointer to the memory of the currently running plugin
 /// NOTE: this should only be called from host functions.
 #[no_mangle]
@@ -200,7 +218,11 @@ pub unsafe extern "C" fn extism_function_new(
         output_types.clone(),
         user_data,
         move |plugin, inputs, outputs, user_data| {
-            let inputs: Vec<_> = inputs.iter().map(ExtismVal::from).collect();
+            let store = &*plugin.store;
+            let inputs: Vec<_> = inputs
+                .iter()
+                .map(|x| ExtismVal::from_val(x, store))
+                .collect();
             let mut output_tmp: Vec<_> = output_types
                 .iter()
                 .map(|t| ExtismVal {
@@ -389,20 +411,6 @@ pub unsafe extern "C" fn extism_plugin_config(
             }
         };
 
-    let wasi = &mut plugin.current_plugin_mut().wasi;
-    if let Some(Wasi { ctx, .. }) = wasi {
-        for (k, v) in json.iter() {
-            match v {
-                Some(v) => {
-                    let _ = ctx.push_env(k, v);
-                }
-                None => {
-                    let _ = ctx.push_env(k, "");
-                }
-            }
-        }
-    }
-
     let id = plugin.id;
     let config = &mut plugin.current_plugin_mut().manifest.config;
     for (k, v) in json.into_iter() {
@@ -464,6 +472,31 @@ pub unsafe extern "C" fn extism_plugin_call(
     func_name: *const c_char,
     data: *const u8,
     data_len: Size,
+) -> i32 {
+    extism_plugin_call_with_host_context(plugin, func_name, data, data_len, std::ptr::null_mut())
+}
+
+#[derive(Clone)]
+#[repr(transparent)]
+struct CVoidContainer(*mut std::ffi::c_void);
+
+// "You break it, you buy it."
+unsafe impl Send for CVoidContainer {}
+unsafe impl Sync for CVoidContainer {}
+
+/// Call a function with host context.
+///
+/// `func_name`: is the function to call
+/// `data`: is the input data
+/// `data_len`: is the length of `data`
+/// `host_context`: a pointer to context data that will be available in host functions
+#[no_mangle]
+pub unsafe extern "C" fn extism_plugin_call_with_host_context(
+    plugin: *mut Plugin,
+    func_name: *const c_char,
+    data: *const u8,
+    data_len: Size,
+    host_context: *mut std::ffi::c_void,
 ) -> i32 {
     if plugin.is_null() {
         return -1;
@@ -485,8 +518,11 @@ pub unsafe extern "C" fn extism_plugin_call(
         name
     );
     let input = std::slice::from_raw_parts(data, data_len as usize);
-    let res = plugin.raw_call(&mut lock, name, input);
-
+    let r = match ExternRef::new(&mut plugin.store, CVoidContainer(host_context)) {
+        Err(e) => return plugin.return_error(&mut lock, e, -1),
+        Ok(x) => x,
+    };
+    let res = plugin.raw_call(&mut lock, name, input, Some(r));
     match res {
         Err((e, rc)) => plugin.return_error(&mut lock, e, rc),
         Ok(x) => x,
@@ -671,7 +707,7 @@ unsafe fn set_log_buffer(filter: &str) -> Result<(), Error> {
 /// Calls the provided callback function for each buffered log line.
 /// This is only needed when `extism_log_custom` is used.
 pub unsafe extern "C" fn extism_log_drain(handler: ExtismLogDrainFunctionType) {
-    if let Some(buf) = &mut LOG_BUFFER {
+    if let Some(buf) = LOG_BUFFER.as_mut() {
         if let Ok(mut buf) = buf.buffer.lock() {
             for (line, len) in buf.drain(..) {
                 handler(line.as_ptr(), len as u64);

runtime/src/tests/runtime.rs

@@ -1,3 +1,5 @@
+use extism_manifest::MemoryOptions;
+
 use crate::*;
 use std::{io::Write, time::Instant};
 
@@ -238,6 +240,34 @@ fn test_timeout() {
     assert!(err == "timeout");
 }
 
+#[test]
+fn test_http_timeout() {
+    let f = Function::new(
+        "hello_world",
+        [PTR],
+        [PTR],
+        UserData::default(),
+        hello_world,
+    );
+
+    let manifest = Manifest::new([extism_manifest::Wasm::data(WASM_HTTP)])
+        .with_timeout(std::time::Duration::from_millis(1))
+        .with_allowed_host("www.extism.org");
+    let mut plugin = Plugin::new(manifest, [f], true).unwrap();
+
+    let start = std::time::Instant::now();
+    let output: Result<&[u8], Error> =
+        plugin.call("http_request", r#"{"url": "https://www.extism.org"}"#);
+    let end = std::time::Instant::now();
+    let time = end - start;
+    let err = output.unwrap_err().root_cause().to_string();
+    println!(
+        "Timed out plugin ran for {:?}, with error: {:?}",
+        time, &err
+    );
+    assert!(err == "timeout");
+}
+
 typed_plugin!(pub TestTypedPluginGenerics {
     count_vowels<T: FromBytes<'a>>(&str) -> T
 });
@@ -305,6 +335,42 @@ fn test_toml_manifest() {
     assert_eq!(count.get("count").unwrap().as_i64().unwrap(), 1);
 }
 
+#[test]
+fn test_call_with_host_context() {
+    #[derive(Clone)]
+    struct Foo {
+        message: String,
+    }
+
+    let f = Function::new(
+        "host_reflect",
+        [PTR],
+        [PTR],
+        UserData::default(),
+        |current_plugin, _val, ret, _user_data: UserData<()>| {
+            let foo = current_plugin.host_context::<Foo>()?;
+            let hnd = current_plugin.memory_new(foo.message)?;
+            ret[0] = current_plugin.memory_to_val(hnd);
+            Ok(())
+        },
+    );
+
+    let mut plugin = Plugin::new(WASM_REFLECT, [f], true).unwrap();
+
+    let message = "hello world";
+    let output: String = plugin
+        .call_with_host_context(
+            "reflect",
+            "anything, really",
+            Foo {
+                message: message.to_string(),
+            },
+        )
+        .unwrap();
+
+    assert_eq!(output, message);
+}
+
 #[test]
 fn test_fuzz_reflect_plugin() {
     // assert!(set_log_file("stdout", Some(log::Level::Trace)));
@@ -594,6 +660,29 @@ fn test_manifest_ptr_len() {
     assert_eq!(count.get("count").unwrap().as_i64().unwrap(), 1);
 }
 
+#[test]
+fn test_no_vars() {
+    let data = br#"
+(module
+    (import "extism:host/env" "var_set" (func $var_set (param i64 i64)))
+    (import "extism:host/env" "input_offset" (func $input_offset (result i64)))
+    (func (export "test") (result i32)
+        (call $input_offset)
+        (call $input_offset)
+        (call $var_set)
+        (i32.const 0)
+    )
+)
+    "#;
+    let manifest = Manifest::new([Wasm::data(data)])
+        .with_memory_options(MemoryOptions::new().with_max_var_bytes(1));
+    let mut plugin = Plugin::new(manifest, [], true).unwrap();
+    let output: Result<(), Error> = plugin.call("test", b"A".repeat(1024));
+    assert!(output.is_err());
+    let output: Result<(), Error> = plugin.call("test", vec![]);
+    assert!(output.is_ok());
+}
+
 #[test]
 fn test_linking() {
     let manifest = Manifest::new([