feat(c-api) Implement cross-compilation API in C

CHANGELOG.md

@@ -8,6 +8,7 @@
 ## **[Unreleased]**
 
 ### Added
+- [#2072](https://github.com/wasmerio/wasmer/pull/2072) Add `wasm_config_set_target`, along with `wasm_target_t`, `wasm_triple_t` and `wasm_cpu_features_t` in the unstable C API.
 - [#2059](https://github.com/wasmerio/wasmer/pull/2059) Ability to capture `stdout` and `stderr` with WASI in the C API.
 - [#2040](https://github.com/wasmerio/wasmer/pull/2040) Add `InstanceHandle::vmoffsets` to expose the offsets of the `vmctx` region.
 - [#2026](https://github.com/wasmerio/wasmer/pull/2010) Expose trap code of a `RuntimeError`, if it's a `Trap`.

lib/c-api/Cargo.toml

@@ -27,6 +27,7 @@ wasmer-engine-native = { version = "1.0.1", path = "../engine-native", optional
 wasmer-engine-object-file = { version = "1.0.1", path = "../engine-object-file", optional = true }
 wasmer-wasi = { version = "1.0.1", path = "../wasi", optional = true }
 wasmer-types = { version = "1.0.1", path = "../wasmer-types" }
+enumset = "1.0"
 cfg-if = "1.0"
 lazy_static = "1.4"
 libc = { version = "^0.2", default-features = false }

lib/c-api/build.rs

@@ -427,8 +427,20 @@ fn exclude_items_from_wasm_c_api(builder: Builder) -> Builder {
         .exclude_item("wasi_version_t")
         .exclude_item("wasm_config_set_compiler")
         .exclude_item("wasm_config_set_engine")
+        .exclude_item("wasm_config_set_target")
+        .exclude_item("wasm_cpu_features_add")
+        .exclude_item("wasm_cpu_features_delete")
+        .exclude_item("wasm_cpu_features_new")
+        .exclude_item("wasm_cpu_features_t")
         .exclude_item("wasm_module_name")
         .exclude_item("wasm_module_set_name")
+        .exclude_item("wasm_target_delete")
+        .exclude_item("wasm_target_new")
+        .exclude_item("wasm_target_t")
+        .exclude_item("wasm_triple_delete")
+        .exclude_item("wasm_triple_new")
+        .exclude_item("wasm_triple_new_from_host")
+        .exclude_item("wasm_triple_t")
         .exclude_item("wasmer_compiler_t")
         .exclude_item("wasmer_engine_t")
         .exclude_item("wat2wasm")

lib/c-api/src/wasm_c_api/engine.rs

@@ -1,3 +1,5 @@
+pub use super::unstable::engine::wasm_config_set_target;
+use super::unstable::target_lexicon::wasm_target_t;
 use crate::error::{update_last_error, CApiError};
 use cfg_if::cfg_if;
 use std::sync::Arc;
@@ -93,6 +95,7 @@ pub struct wasm_config_t {
     engine: wasmer_engine_t,
     #[cfg(feature = "compiler")]
     compiler: wasmer_compiler_t,
+    pub(super) target: Option<Box<wasm_target_t>>,
 }
 
 /// Create a new default Wasmer configuration.
@@ -396,7 +399,7 @@ pub unsafe extern "C" fn wasm_engine_delete(_engine: Option<Box<wasm_engine_t>>)
 /// cbindgen:ignore
 #[no_mangle]
 pub extern "C" fn wasm_engine_new_with_config(
-    config: Box<wasm_config_t>,
+    config: Option<Box<wasm_config_t>>,
 ) -> Option<Box<wasm_engine_t>> {
     #[allow(dead_code)]
     fn return_with_error<M>(msg: M) -> Option<Box<wasm_engine_t>>
@@ -408,7 +411,9 @@ pub extern "C" fn wasm_engine_new_with_config(
         });
 
         return None;
-    };
+    }
+
+    let config = config?;
 
     cfg_if! {
         if #[cfg(feature = "compiler")] {
@@ -447,7 +452,13 @@ pub extern "C" fn wasm_engine_new_with_config(
                 wasmer_engine_t::JIT => {
                     cfg_if! {
                         if #[cfg(feature = "jit")] {
-                            Arc::new(JIT::new(compiler_config).engine())
+                            let mut builder = JIT::new(compiler_config);
+
+                            if let Some(target) = config.target {
+                                builder = builder.target(target.inner);
+                            }
+
+                            Arc::new(builder.engine())
                         } else {
                             return return_with_error("Wasmer has not been compiled with the `jit` feature.");
                         }
@@ -456,7 +467,13 @@ pub extern "C" fn wasm_engine_new_with_config(
                 wasmer_engine_t::NATIVE => {
                     cfg_if! {
                         if #[cfg(feature = "native")] {
-                            Arc::new(Native::new(compiler_config).engine())
+                            let mut builder = Native::new(compiler_config);
+
+                            if let Some(target) = config.target {
+                                builder = builder.target(target.inner);
+                            }
+
+                            Arc::new(builder.engine())
                         } else {
                             return return_with_error("Wasmer has not been compiled with the `native` feature.");
                         }
@@ -467,7 +484,13 @@ pub extern "C" fn wasm_engine_new_with_config(
                         // There are currently no uses of the object-file engine + compiler from the C API.
                         // So we run in headless mode.
                         if #[cfg(feature = "object-file")] {
-                            Arc::new(ObjectFile::headless().engine())
+                            let mut builder = ObjectFile::headless();
+
+                            if let Some(target) = config.target {
+                                builder = builder.target(target.inner);
+                            }
+
+                            Arc::new(builder.engine())
                         } else {
                             return return_with_error("Wasmer has not been compiled with the `object-file` feature.");
                         }
@@ -480,7 +503,13 @@ pub extern "C" fn wasm_engine_new_with_config(
                 wasmer_engine_t::JIT => {
                     cfg_if! {
                         if #[cfg(feature = "jit")] {
-                            Arc::new(JIT::headless().engine())
+                            let mut builder = JIT::headless();
+
+                            if let Some(target) = config.target {
+                                builder = builder.target(target.inner);
+                            }
+
+                            Arc::new(builder.engine())
                         } else {
                             return return_with_error("Wasmer has not been compiled with the `jit` feature.");
                         }
@@ -489,7 +518,13 @@ pub extern "C" fn wasm_engine_new_with_config(
                 wasmer_engine_t::NATIVE => {
                     cfg_if! {
                         if #[cfg(feature = "native")] {
-                            Arc::new(Native::headless().engine())
+                            let mut builder = Native::headless();
+
+                            if let Some(target) = config.target {
+                                builder = builder.target(target.inner);
+                            }
+
+                            Arc::new(builder.engine())
                         } else {
                             return return_with_error("Wasmer has not been compiled with the `native` feature.");
                         }
@@ -498,7 +533,13 @@ pub extern "C" fn wasm_engine_new_with_config(
                 wasmer_engine_t::OBJECT_FILE => {
                     cfg_if! {
                         if #[cfg(feature = "object-file")] {
-                            Arc::new(ObjectFile::headless().engine())
+                            let mut builder = ObjectFile::headless();
+
+                            if let Some(target) = config.target {
+                                builder = builder.target(target.inner);
+                            }
+
+                            Arc::new(builder.engine())
                         } else {
                             return return_with_error("Wasmer has not been compiled with the `object-file` feature.");
                         }

lib/c-api/src/wasm_c_api/externals/function.rs

@@ -106,7 +106,7 @@ pub unsafe extern "C" fn wasm_func_new_with_env(
     struct WrapperEnv {
         env: *mut c_void,
         finalizer: Option<wasm_env_finalizer_t>,
-    };
+    }
 
     // Only relevant when using multiple threads in the C API;
     // Synchronization will be done via the C API / on the C side.

lib/c-api/src/wasm_c_api/macros.rs

@@ -467,16 +467,19 @@ macro_rules! wasm_declare_own {
 
 #[macro_export]
 macro_rules! c_try {
-    ($expr:expr) => {{
+    ($expr:expr; otherwise $return:expr) => {{
         let res: Result<_, _> = $expr;
         match res {
             Ok(val) => val,
             Err(err) => {
                 crate::error::update_last_error(err);
-                return None;
+                return $return;
             }
         }
     }};
+    ($expr:expr) => {{
+        c_try!($expr; otherwise None)
+    }};
     ($expr:expr, $e:expr) => {{
         let opt: Option<_> = $expr;
         c_try!(opt.ok_or_else(|| $e))

lib/c-api/src/wasm_c_api/unstable/engine.rs

@@ -0,0 +1,49 @@
+//! Unstable non-standard Wasmer-specific types for the
+//! `wasm_engine_t` and siblings.
+
+use super::super::engine::wasm_config_t;
+use super::target_lexicon::wasm_target_t;
+
+/// Unstable non-standard Wasmer-specific API to update the
+/// configuration to specify a particular target for the engine.
+///
+/// # Example
+///
+/// ```rust
+/// # use inline_c::assert_c;
+/// # fn main() {
+/// #    (assert_c! {
+/// # #include "tests/wasmer_wasm.h"
+/// #
+/// int main() {
+///     // Create the configuration.
+///     wasm_config_t* config = wasm_config_new();
+///
+///     // Set the target.
+///     {
+///         wasm_triple_t* triple = wasm_triple_new_from_host();
+///         wasm_cpu_features_t* cpu_features = wasm_cpu_features_new();
+///         wasm_target_t* target = wasm_target_new(triple, cpu_features);
+///
+///         wasm_config_set_target(config, target);
+///     }
+///
+///     // Create the engine.
+///     wasm_engine_t* engine = wasm_engine_new_with_config(config);
+///
+///     // Check we have an engine!
+///     assert(engine);
+///
+///     // Free everything.
+///     wasm_engine_delete(engine);
+///
+///     return 0;
+/// }
+/// #    })
+/// #    .success();
+/// # }
+/// ```
+#[no_mangle]
+pub extern "C" fn wasm_config_set_target(config: &mut wasm_config_t, target: Box<wasm_target_t>) {
+    config.target = Some(target);
+}

lib/c-api/src/wasm_c_api/unstable/mod.rs

@@ -1 +1,3 @@
+pub mod engine;
 pub mod module;
+pub mod target_lexicon;