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 .. && \ 23 cmake --build . --target wasmtime-interrupt 24 */ 25 26 #include <assert.h> 27 #include <stdio.h> 28 #include <stdlib.h> 29 #include <wasm.h> 30 #include <wasmtime.h> 31 32 #ifdef _WIN32 33 static void spawn_interrupt(wasm_engine_t *engine) { 34 wasmtime_engine_increment_epoch(engine); 35 } 36 #else 37 #include <pthread.h> 38 #include <time.h> 39 40 static void *helper(void *_engine) { 41 wasm_engine_t *engine = _engine; 42 struct timespec sleep_dur; 43 sleep_dur.tv_sec = 1; 44 sleep_dur.tv_nsec = 0; 45 nanosleep(&sleep_dur, NULL); 46 printf("Sending an interrupt\n"); 47 wasmtime_engine_increment_epoch(engine); 48 return 0; 49 } 50 51 static void spawn_interrupt(wasm_engine_t *engine) { 52 pthread_t child; 53 int rc = pthread_create(&child, NULL, helper, engine); 54 assert(rc == 0); 55 } 56 #endif 57 58 static void exit_with_error(const char *message, wasmtime_error_t *error, 59 wasm_trap_t *trap); 60 61 int main() { 62 // Create a `wasm_store_t` with interrupts enabled 63 wasm_config_t *config = wasm_config_new(); 64 assert(config != NULL); 65 wasmtime_config_epoch_interruption_set(config, true); 66 wasm_engine_t *engine = wasm_engine_new_with_config(config); 67 assert(engine != NULL); 68 wasmtime_store_t *store = wasmtime_store_new(engine, NULL, NULL); 69 assert(store != NULL); 70 wasmtime_context_t *context = wasmtime_store_context(store); 71 72 // Configure the epoch deadline after which WebAssembly code will trap. 73 wasmtime_context_set_epoch_deadline(context, 1); 74 75 // Read our input file, which in this case is a wasm text file. 76 FILE *file = fopen("examples/interrupt.wat", "r"); 77 assert(file != NULL); 78 fseek(file, 0L, SEEK_END); 79 size_t file_size = ftell(file); 80 fseek(file, 0L, SEEK_SET); 81 wasm_byte_vec_t wat; 82 wasm_byte_vec_new_uninitialized(&wat, file_size); 83 if (fread(wat.data, file_size, 1, file) != 1) { 84 printf("> Error loading module!\n"); 85 return 1; 86 } 87 fclose(file); 88 89 // Parse the wat into the binary wasm format 90 wasm_byte_vec_t wasm; 91 wasmtime_error_t *error = wasmtime_wat2wasm(wat.data, wat.size, &wasm); 92 if (error != NULL) 93 exit_with_error("failed to parse wat", error, NULL); 94 wasm_byte_vec_delete(&wat); 95 96 // Now that we've got our binary webassembly we can compile our module. 97 wasmtime_module_t *module = NULL; 98 error = wasmtime_module_new(engine, (uint8_t *)wasm.data, wasm.size, &module); 99 wasm_byte_vec_delete(&wasm); 100 if (error != NULL) 101 exit_with_error("failed to compile module", error, NULL); 102 103 wasm_trap_t *trap = NULL; 104 wasmtime_instance_t instance; 105 error = wasmtime_instance_new(context, module, NULL, 0, &instance, &trap); 106 if (error != NULL || trap != NULL) 107 exit_with_error("failed to instantiate", error, trap); 108 wasmtime_module_delete(module); 109 110 // Lookup our `run` export function 111 wasmtime_extern_t run; 112 bool ok = wasmtime_instance_export_get(context, &instance, "run", 3, &run); 113 assert(ok); 114 assert(run.kind == WASMTIME_EXTERN_FUNC); 115 116 // Spawn a thread to send us an interrupt after a period of time. 117 spawn_interrupt(engine); 118 119 // And call it! 120 printf("Entering infinite loop...\n"); 121 error = wasmtime_func_call(context, &run.of.func, NULL, 0, NULL, 0, &trap); 122 assert(error == NULL); 123 assert(trap != NULL); 124 printf("Got a trap!...\n"); 125 126 wasmtime_store_delete(store); 127 wasm_engine_delete(engine); 128 return 0; 129 } 130 131 static void exit_with_error(const char *message, wasmtime_error_t *error, 132 wasm_trap_t *trap) { 133 fprintf(stderr, "error: %s\n", message); 134 wasm_byte_vec_t error_message; 135 if (error != NULL) { 136 wasmtime_error_message(error, &error_message); 137 wasmtime_error_delete(error); 138 } else { 139 wasm_trap_message(trap, &error_message); 140 wasm_trap_delete(trap); 141 } 142 fprintf(stderr, "%.*s\n", (int)error_message.size, error_message.data); 143 wasm_byte_vec_delete(&error_message); 144 exit(1); 145 } 146