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141 lines
4.3 KiB
141 lines
4.3 KiB
/*
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Example of instantiating of the WebAssembly module and invoking its exported
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function.
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You can compile and run this example on Linux with:
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cargo build --release -p wasmtime-c-api
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cc examples/interrupt.c \
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-I crates/c-api/include \
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-I crates/c-api/wasm-c-api/include \
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target/release/libwasmtime.a \
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-lpthread -ldl -lm \
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-o interrupt
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./interrupt
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Note that on Windows and macOS the command will be similar, but you'll need
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to tweak the `-lpthread` and such annotations as well as the name of the
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`libwasmtime.a` file on Windows.
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*/
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#include <assert.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <wasm.h>
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#include <wasmtime.h>
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#ifdef _WIN32
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static void spawn_interrupt(wasmtime_interrupt_handle_t *handle) {
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wasmtime_interrupt_handle_interrupt(handle);
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wasmtime_interrupt_handle_delete(handle);
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}
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#else
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#include <pthread.h>
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#include <time.h>
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static void* helper(void *_handle) {
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wasmtime_interrupt_handle_t *handle = _handle;
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struct timespec sleep_dur;
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sleep_dur.tv_sec = 1;
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sleep_dur.tv_nsec = 0;
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nanosleep(&sleep_dur, NULL);
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printf("Sending an interrupt\n");
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wasmtime_interrupt_handle_interrupt(handle);
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wasmtime_interrupt_handle_delete(handle);
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}
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static void spawn_interrupt(wasmtime_interrupt_handle_t *handle) {
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pthread_t child;
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int rc = pthread_create(&child, NULL, helper, handle);
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assert(rc == 0);
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}
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#endif
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static void exit_with_error(const char *message, wasmtime_error_t *error, wasm_trap_t *trap);
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int main() {
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// Create a `wasm_store_t` with interrupts enabled
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wasm_config_t *config = wasm_config_new();
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assert(config != NULL);
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wasmtime_config_interruptable_set(config, true);
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wasm_engine_t *engine = wasm_engine_new_with_config(config);
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assert(engine != NULL);
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wasm_store_t *store = wasm_store_new(engine);
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assert(store != NULL);
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// Create our interrupt handle we'll use later
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wasmtime_interrupt_handle_t *handle = wasmtime_interrupt_handle_new(store);
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assert(handle != NULL);
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// Read our input file, which in this case is a wasm text file.
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FILE* file = fopen("examples/interrupt.wat", "r");
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assert(file != NULL);
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fseek(file, 0L, SEEK_END);
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size_t file_size = ftell(file);
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fseek(file, 0L, SEEK_SET);
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wasm_byte_vec_t wat;
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wasm_byte_vec_new_uninitialized(&wat, file_size);
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assert(fread(wat.data, file_size, 1, file) == 1);
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fclose(file);
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// Parse the wat into the binary wasm format
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wasm_byte_vec_t wasm;
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wasmtime_error_t *error = wasmtime_wat2wasm(&wat, &wasm);
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if (error != NULL)
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exit_with_error("failed to parse wat", error, NULL);
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wasm_byte_vec_delete(&wat);
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// Now that we've got our binary webassembly we can compile our module.
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wasm_module_t *module = NULL;
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wasm_trap_t *trap = NULL;
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wasm_instance_t *instance = NULL;
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error = wasmtime_module_new(engine, &wasm, &module);
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wasm_byte_vec_delete(&wasm);
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if (error != NULL)
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exit_with_error("failed to compile module", error, NULL);
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error = wasmtime_instance_new(store, module, NULL, 0, &instance, &trap);
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if (instance == NULL)
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exit_with_error("failed to instantiate", error, trap);
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// Lookup our `run` export function
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wasm_extern_vec_t externs;
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wasm_instance_exports(instance, &externs);
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assert(externs.size == 1);
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wasm_func_t *run = wasm_extern_as_func(externs.data[0]);
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assert(run != NULL);
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// Spawn a thread to send us an interrupt after a period of time.
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spawn_interrupt(handle);
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// And call it!
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printf("Entering infinite loop...\n");
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error = wasmtime_func_call(run, NULL, 0, NULL, 0, &trap);
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assert(error == NULL);
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assert(trap != NULL);
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printf("Got a trap!...\n");
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// `trap` can be inspected here to see the trap message has an interrupt in it
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wasm_trap_delete(trap);
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wasm_extern_vec_delete(&externs);
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wasm_instance_delete(instance);
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wasm_module_delete(module);
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wasm_store_delete(store);
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wasm_engine_delete(engine);
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return 0;
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}
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static void exit_with_error(const char *message, wasmtime_error_t *error, wasm_trap_t *trap) {
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fprintf(stderr, "error: %s\n", message);
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wasm_byte_vec_t error_message;
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if (error != NULL) {
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wasmtime_error_message(error, &error_message);
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wasmtime_error_delete(error);
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} else {
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wasm_trap_message(trap, &error_message);
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wasm_trap_delete(trap);
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}
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fprintf(stderr, "%.*s\n", (int) error_message.size, error_message.data);
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wasm_byte_vec_delete(&error_message);
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exit(1);
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}
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