# Wasmer Runtime C API Wasmer is a standalone JIT WebAssembly runtime, aiming to be fully compatible with WASI, Emscripten, Rust and Go. [Learn more](https://github.com/wasmerio/wasmer). This crate exposes a C and a C++ API for the Wasmer runtime. # Usage The C and C++ header files can be found in the source tree of this crate, respectively [`wasmer.h`][wasmer_h] and [`wasmer.hh`][wasmer_hh]. They are automatically generated, and always up-to-date in this repository. The runtime shared library (so, dll, dylib) can also be downloaded in Wasmer [release page](https://github.com/wasmerio/wasmer/releases). You can find the full C API documentation here: https://wasmerio.github.io/wasmer/c/runtime-c-api/ Here is a simple example to use the C API: ```c #include #include "../wasmer.h" #include #include int main() { // Read the Wasm file bytes. FILE *file = fopen("sum.wasm", "r"); fseek(file, 0, SEEK_END); long len = ftell(file); uint8_t *bytes = malloc(len); fseek(file, 0, SEEK_SET); fread(bytes, 1, len, file); fclose(file); // Prepare the imports. wasmer_import_t imports[] = {}; // Instantiate! wasmer_instance_t *instance = NULL; wasmer_result_t instantiation_result = wasmer_instantiate(&instance, bytes, len, imports, 0); assert(instantiation_result == WASMER_OK); // Let's call a function. // Start by preparing the arguments. // Value of argument #1 is `7i32`. wasmer_value_t argument_one; argument_one.tag = WASM_I32; argument_one.value.I32 = 7; // Value of argument #2 is `8i32`. wasmer_value_t argument_two; argument_two.tag = WASM_I32; argument_two.value.I32 = 8; // Prepare the arguments. wasmer_value_t arguments[] = {argument_one, argument_two}; // Prepare the return value. wasmer_value_t result_one; wasmer_value_t results[] = {result_one}; // Call the `sum` function with the prepared arguments and the return value. wasmer_result_t call_result = wasmer_instance_call(instance, "sum", arguments, 2, results, 1); // Let's display the result. printf("Call result: %d\n", call_result); printf("Result: %d\n", results[0].value.I32); // `sum(7, 8) == 15`. assert(results[0].value.I32 == 15); assert(call_result == WASMER_OK); wasmer_instance_destroy(instance); return 0; } ``` # Testing Tests are run using the release build of the library. If you make changes or compile with non-default features, please ensure you rebuild in release mode for the tests to see the changes. The tests can be run via `cargo test`, such as: ```sh $ cargo test --release -- --nocapture ``` To run tests manually, enter the `lib/runtime-c-api/tests` directory and run the following commands: ```sh $ cmake . $ make $ make test ``` # License Wasmer is primarily distributed under the terms of the [MIT license][mit-license] ([LICENSE][license]). [wasmer_h]: ./wasmer.h [wasmer_hh]: ./wasmer.hh [mit-license]: http://opensource.org/licenses/MIT [license]: https://github.com/wasmerio/wasmer/blob/master/LICENSE