Crate wasmer_runtime_c_api

Wasmer Runtime C API

Wasmer is a standalone JIT WebAssembly runtime, aiming to be fully compatible with Emscripten, Rust and Go. Learn more.

This crate exposes a C and 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 and wasmer.hh. They are automatically generated, and always up-to-date in this repository.

Here is a simple example to use the C API:

#include <stdio.h>
#include "wasmer.h"
#include <assert.h>
#include <stdint.h>

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;
}

Modules

error	Read runtime errors.
export	Create, read, destroy export definitions (function, global, memory and table) on an instance.
global	Create, set, get and destroy global variables of an instance.
import	Create, read, destroy import definitions (function, global, memory and table) on an instance.
instance	Instantiate a module, call functions, and read exports.
memory	Create, read, write, grow, destroy memory of an instance.
module	Compile, validate, instantiate, serialize, and destroy modules.
table	Create, grow, destroy tables of an instance.
trampoline	Trampoline emitter for transforming function calls.
value	Create and map Rust to WebAssembly values.

Structs

wasmer_byte_array
wasmer_limit_option_t	The wasmer_limit_option_t struct represents an optional limit for wasmer_limits_t.
wasmer_limits_t	The wasmer_limits_t struct is a type that describes a memory options. See the wasmer_memory_t struct or the wasmer_memory_new() function to get more information.

Enums

wasmer_result_t

The wasmer_result_t enum is a type that represents either a success, or a failure.