mirror of
https://github.com/fluencelabs/wasmer
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133 lines
3.7 KiB
Markdown
133 lines
3.7 KiB
Markdown
<p align="center">
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<a href="https://wasmer.io" target="_blank" rel="noopener noreferrer">
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<img width="400" src="https://raw.githubusercontent.com/wasmerio/wasmer/master/logo.png" alt="Wasmer logo">
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</a>
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</p>
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<p align="center">
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<a href="https://circleci.com/gh/wasmerio/wasmer/">
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<img src="https://img.shields.io/circleci/project/github/wasmerio/wasmer/master.svg" alt="Build Status">
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</a>
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<a href="https://github.com/wasmerio/wasmer/blob/master/LICENSE">
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<img src="https://img.shields.io/github/license/wasmerio/wasmer.svg" alt="License">
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</a>
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<a href="https://spectrum.chat/wasmer">
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<img src="https://withspectrum.github.io/badge/badge.svg" alt="Join the Wasmer Community">
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</a>
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<a href="https://crates.io/crates/wasmer-runtime-c-api">
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<img src="https://img.shields.io/crates/d/wasmer-runtime-c-api.svg" alt="Number of downloads from crates.io">
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</a>
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<a href="https://docs.rs/wasmer-runtime-c-api">
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<img src="https://docs.rs/wasmer-runtime-c-api/badge.svg" alt="Read our API documentation">
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</a>
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</p>
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# Wasmer Runtime C API
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Wasmer is a standalone JIT WebAssembly runtime, aiming to be fully
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compatible with Emscripten, Rust and Go. [Learn
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more](https://github.com/wasmerio/wasmer).
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This crate exposes a C and a C++ API for the Wasmer runtime.
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# Usage
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The C and C++ header files can be found in the source tree of this
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crate, respectively [`wasmer.h`][wasmer_h] and
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[`wasmer.hh`][wasmer_hh]. They are automatically generated, and always
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up-to-date in this repository.
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Here is a simple example to use the C API:
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```c
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#include <stdio.h>
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#include "../wasmer.h"
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#include <assert.h>
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#include <stdint.h>
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int main()
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{
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// Read the Wasm file bytes.
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FILE *file = fopen("sum.wasm", "r");
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fseek(file, 0, SEEK_END);
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long len = ftell(file);
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uint8_t *bytes = malloc(len);
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fseek(file, 0, SEEK_SET);
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fread(bytes, 1, len, file);
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fclose(file);
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// Prepare the imports.
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wasmer_import_t imports[] = {};
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// Instantiate!
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wasmer_instance_t *instance = NULL;
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wasmer_result_t instantiation_result = wasmer_instantiate(&instance, bytes, len, imports, 0);
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assert(instantiation_result == WASMER_OK);
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// Let's call a function.
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// Start by preparing the arguments.
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// Value of argument #1 is `7i32`.
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wasmer_value_t argument_one;
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argument_one.tag = WASM_I32;
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argument_one.value.I32 = 7;
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// Value of argument #2 is `8i32`.
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wasmer_value_t argument_two;
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argument_two.tag = WASM_I32;
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argument_two.value.I32 = 8;
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// Prepare the arguments.
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wasmer_value_t arguments[] = {argument_one, argument_two};
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// Prepare the return value.
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wasmer_value_t result_one;
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wasmer_value_t results[] = {result_one};
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// Call the `sum` function with the prepared arguments and the return value.
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wasmer_result_t call_result = wasmer_instance_call(instance, "sum", arguments, 2, results, 1);
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// Let's display the result.
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printf("Call result: %d\n", call_result);
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printf("Result: %d\n", results[0].value.I32);
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// `sum(7, 8) == 15`.
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assert(results[0].value.I32 == 15);
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assert(call_result == WASMER_OK);
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wasmer_instance_destroy(instance);
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return 0;
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}
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```
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# Testing
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The tests can be run via `cargo test`, such as:
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```sh
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$ cargo test -- --nocapture
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```
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To run tests manually, enter the `lib/runtime-c-api/tests` directory
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and run the following commands:
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```sh
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$ cmake .
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$ make
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$ make test
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```
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# License
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Wasmer is primarily distributed under the terms of the [MIT
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license][mit-license] ([LICENSE][license]).
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[wasmer_h]: ./wasmer.h
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[wasmer_hh]: ./wasmer.hh
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[mit-license]: http://opensource.org/licenses/MIT
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[license]: https://github.com/wasmerio/wasmer/blob/master/LICENSE
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