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/*
Example of instantiating a WebAssembly which uses WASI imports.
You can compile and run this example on Linux with:
cmake examples/
cargo build --release -p wasmtime-c-api
cc examples/wasi/main.c \
-I crates/c-api/include \
target/release/libwasmtime.a \
-lpthread -ldl -lm \
-o wasi
./wasi
Note that on Windows and macOS the command will be similar, but you'll need
to tweak the `-lpthread` and such annotations.
You can also build using cmake:
mkdir build && cd build && cmake .. && cmake --build . --target wasmtime-wasi
*/
#include <assert.h>
#include <stdio.h>
#include <stdlib.h>
#include <wasi.h>
#include <wasm.h>
#include <wasmtime.h>
#define MIN(a, b) ((a) < (b) ? (a) : (b))
static void exit_with_error(const char *message, wasmtime_error_t *error,
wasm_trap_t *trap);
int main() {
// Set up our context
wasm_engine_t *engine = wasm_engine_new();
assert(engine != NULL);
wasmtime_store_t *store = wasmtime_store_new(engine, NULL, NULL);
assert(store != NULL);
wasmtime_context_t *context = wasmtime_store_context(store);
// Create a linker with WASI functions defined
wasmtime_linker_t *linker = wasmtime_linker_new(engine);
wasmtime_error_t *error = wasmtime_linker_define_wasi(linker);
if (error != NULL)
exit_with_error("failed to link wasi", error, NULL);
wasm_byte_vec_t wasm;
// Load our input file to parse it next
FILE *file = fopen("target/wasm32-wasip1/debug/wasi.wasm", "rb");
if (!file) {
printf("> Error loading file!\n");
exit(1);
}
fseek(file, 0L, SEEK_END);
size_t file_size = ftell(file);
wasm_byte_vec_new_uninitialized(&wasm, file_size);
fseek(file, 0L, SEEK_SET);
if (fread(wasm.data, file_size, 1, file) != 1) {
printf("> Error loading module!\n");
exit(1);
}
fclose(file);
// Compile our modules
wasmtime_module_t *module = NULL;
error = wasmtime_module_new(engine, (uint8_t *)wasm.data, wasm.size, &module);
if (!module)
exit_with_error("failed to compile module", error, NULL);
wasm_byte_vec_delete(&wasm);
// Instantiate wasi
wasi_config_t *wasi_config = wasi_config_new();
assert(wasi_config);
wasi_config_inherit_argv(wasi_config);
wasi_config_inherit_env(wasi_config);
wasi_config_inherit_stdin(wasi_config);
wasi_config_inherit_stdout(wasi_config);
wasi_config_inherit_stderr(wasi_config);
wasm_trap_t *trap = NULL;
error = wasmtime_context_set_wasi(context, wasi_config);
if (error != NULL)
exit_with_error("failed to instantiate WASI", error, NULL);
// Instantiate the module
error = wasmtime_linker_module(linker, context, "", 0, module);
if (error != NULL)
exit_with_error("failed to instantiate module", error, NULL);
// Run it.
wasmtime_func_t func;
error = wasmtime_linker_get_default(linker, context, "", 0, &func);
if (error != NULL)
exit_with_error("failed to locate default export for module", error, NULL);
error = wasmtime_func_call(context, &func, NULL, 0, NULL, 0, &trap);
if (error != NULL || trap != NULL)
exit_with_error("error calling default export", error, trap);
// Clean up after ourselves at this point
wasmtime_module_delete(module);
wasmtime_store_delete(store);
wasm_engine_delete(engine);
return 0;
}
static void exit_with_error(const char *message, wasmtime_error_t *error,
wasm_trap_t *trap) {
fprintf(stderr, "error: %s\n", message);
wasm_byte_vec_t error_message;
if (error != NULL) {
wasmtime_error_message(error, &error_message);
wasmtime_error_delete(error);
} else {
wasm_trap_message(trap, &error_message);
wasm_trap_delete(trap);
}
fprintf(stderr, "%.*s\n", (int)error_message.size, error_message.data);
wasm_byte_vec_delete(&error_message);
exit(1);
}
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