1 /* 2 Example of instantiating of the WebAssembly module and invoking its exported 3 function. 4 5 You can compile and run this example on Linux with: 6 7 cargo build --release -p wasmtime-c-api 8 cc examples/interrupt.c \ 9 -I crates/c-api/include \ 10 -I crates/c-api/wasm-c-api/include \ 11 target/release/libwasmtime.a \ 12 -lpthread -ldl -lm \ 13 -o interrupt 14 ./interrupt 15 16 Note that on Windows and macOS the command will be similar, but you'll need 17 to tweak the `-lpthread` and such annotations as well as the name of the 18 `libwasmtime.a` file on Windows. 19 20 You can also build using cmake: 21 22 mkdir build && cd build && cmake .. && cmake --build . --target wasmtime-interrupt 23 */ 24 25 #include <assert.h> 26 #include <stdio.h> 27 #include <stdlib.h> 28 #include <wasm.h> 29 #include <wasmtime.h> 30 31 #ifdef _WIN32 32 static void spawn_interrupt(wasm_engine_t *engine) { 33 wasmtime_engine_increment_epoch(engine); 34 } 35 #else 36 #include <pthread.h> 37 #include <time.h> 38 39 static void* helper(void *_engine) { 40 wasm_engine_t *engine = _engine; 41 struct timespec sleep_dur; 42 sleep_dur.tv_sec = 1; 43 sleep_dur.tv_nsec = 0; 44 nanosleep(&sleep_dur, NULL); 45 printf("Sending an interrupt\n"); 46 wasmtime_engine_increment_epoch(engine); 47 return 0; 48 } 49 50 static void spawn_interrupt(wasm_engine_t *engine) { 51 pthread_t child; 52 int rc = pthread_create(&child, NULL, helper, engine); 53 assert(rc == 0); 54 } 55 #endif 56 57 static void exit_with_error(const char *message, wasmtime_error_t *error, wasm_trap_t *trap); 58 59 int main() { 60 // Create a `wasm_store_t` with interrupts enabled 61 wasm_config_t *config = wasm_config_new(); 62 assert(config != NULL); 63 wasmtime_config_epoch_interruption_set(config, true); 64 wasm_engine_t *engine = wasm_engine_new_with_config(config); 65 assert(engine != NULL); 66 wasmtime_store_t *store = wasmtime_store_new(engine, NULL, NULL); 67 assert(store != NULL); 68 wasmtime_context_t *context = wasmtime_store_context(store); 69 70 // Configure the epoch deadline after which WebAssembly code will trap. 71 wasmtime_context_set_epoch_deadline(context, 1); 72 73 // Read our input file, which in this case is a wasm text file. 74 FILE* file = fopen("examples/interrupt.wat", "r"); 75 assert(file != NULL); 76 fseek(file, 0L, SEEK_END); 77 size_t file_size = ftell(file); 78 fseek(file, 0L, SEEK_SET); 79 wasm_byte_vec_t wat; 80 wasm_byte_vec_new_uninitialized(&wat, file_size); 81 assert(fread(wat.data, file_size, 1, file) == 1); 82 fclose(file); 83 84 // Parse the wat into the binary wasm format 85 wasm_byte_vec_t wasm; 86 wasmtime_error_t *error = wasmtime_wat2wasm(wat.data, wat.size, &wasm); 87 if (error != NULL) 88 exit_with_error("failed to parse wat", error, NULL); 89 wasm_byte_vec_delete(&wat); 90 91 // Now that we've got our binary webassembly we can compile our module. 92 wasmtime_module_t *module = NULL; 93 error = wasmtime_module_new(engine, (uint8_t*) wasm.data, wasm.size, &module); 94 wasm_byte_vec_delete(&wasm); 95 if (error != NULL) 96 exit_with_error("failed to compile module", error, NULL); 97 98 wasm_trap_t *trap = NULL; 99 wasmtime_instance_t instance; 100 error = wasmtime_instance_new(context, module, NULL, 0, &instance, &trap); 101 if (error != NULL || trap != NULL) 102 exit_with_error("failed to instantiate", error, trap); 103 wasmtime_module_delete(module); 104 105 // Lookup our `run` export function 106 wasmtime_extern_t run; 107 bool ok = wasmtime_instance_export_get(context, &instance, "run", 3, &run); 108 assert(ok); 109 assert(run.kind == WASMTIME_EXTERN_FUNC); 110 111 // Spawn a thread to send us an interrupt after a period of time. 112 spawn_interrupt(engine); 113 114 // And call it! 115 printf("Entering infinite loop...\n"); 116 error = wasmtime_func_call(context, &run.of.func, NULL, 0, NULL, 0, &trap); 117 assert(error == NULL); 118 assert(trap != NULL); 119 printf("Got a trap!...\n"); 120 121 wasmtime_store_delete(store); 122 wasm_engine_delete(engine); 123 return 0; 124 } 125 126 static void exit_with_error(const char *message, wasmtime_error_t *error, wasm_trap_t *trap) { 127 fprintf(stderr, "error: %s\n", message); 128 wasm_byte_vec_t error_message; 129 if (error != NULL) { 130 wasmtime_error_message(error, &error_message); 131 wasmtime_error_delete(error); 132 } else { 133 wasm_trap_message(trap, &error_message); 134 wasm_trap_delete(trap); 135 } 136 fprintf(stderr, "%.*s\n", (int) error_message.size, error_message.data); 137 wasm_byte_vec_delete(&error_message); 138 exit(1); 139 } 140