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 target/release/libwasmtime.a \ 11 -lpthread -ldl -lm \ 12 -o interrupt 13 ./interrupt 14 15 Note that on Windows and macOS the command will be similar, but you'll need 16 to tweak the `-lpthread` and such annotations as well as the name of the 17 `libwasmtime.a` file on Windows. 18 19 You can also build using cmake: 20 21 mkdir build && cd build && cmake .. && \ 22 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, 58 wasm_trap_t *trap); 59 60 int main() { 61 // Create a `wasm_store_t` with interrupts enabled 62 wasm_config_t *config = wasm_config_new(); 63 assert(config != NULL); 64 wasmtime_config_epoch_interruption_set(config, true); 65 wasm_engine_t *engine = wasm_engine_new_with_config(config); 66 assert(engine != NULL); 67 wasmtime_store_t *store = wasmtime_store_new(engine, NULL, NULL); 68 assert(store != NULL); 69 wasmtime_context_t *context = wasmtime_store_context(store); 70 71 // Configure the epoch deadline after which WebAssembly code will trap. 72 wasmtime_context_set_epoch_deadline(context, 1); 73 74 // Read our input file, which in this case is a wasm text file. 75 FILE *file = fopen("examples/interrupt.wat", "r"); 76 assert(file != NULL); 77 fseek(file, 0L, SEEK_END); 78 size_t file_size = ftell(file); 79 fseek(file, 0L, SEEK_SET); 80 wasm_byte_vec_t wat; 81 wasm_byte_vec_new_uninitialized(&wat, file_size); 82 if (fread(wat.data, file_size, 1, file) != 1) { 83 printf("> Error loading module!\n"); 84 return 1; 85 } 86 fclose(file); 87 88 // Parse the wat into the binary wasm format 89 wasm_byte_vec_t wasm; 90 wasmtime_error_t *error = wasmtime_wat2wasm(wat.data, wat.size, &wasm); 91 if (error != NULL) 92 exit_with_error("failed to parse wat", error, NULL); 93 wasm_byte_vec_delete(&wat); 94 95 // Now that we've got our binary webassembly we can compile our module. 96 wasmtime_module_t *module = NULL; 97 error = wasmtime_module_new(engine, (uint8_t *)wasm.data, wasm.size, &module); 98 wasm_byte_vec_delete(&wasm); 99 if (error != NULL) 100 exit_with_error("failed to compile module", error, NULL); 101 102 wasm_trap_t *trap = NULL; 103 wasmtime_instance_t instance; 104 error = wasmtime_instance_new(context, module, NULL, 0, &instance, &trap); 105 if (error != NULL || trap != NULL) 106 exit_with_error("failed to instantiate", error, trap); 107 wasmtime_module_delete(module); 108 109 // Lookup our `run` export function 110 wasmtime_extern_t run; 111 bool ok = wasmtime_instance_export_get(context, &instance, "run", 3, &run); 112 assert(ok); 113 assert(run.kind == WASMTIME_EXTERN_FUNC); 114 115 // Spawn a thread to send us an interrupt after a period of time. 116 spawn_interrupt(engine); 117 118 // And call it! 119 printf("Entering infinite loop...\n"); 120 error = wasmtime_func_call(context, &run.of.func, NULL, 0, NULL, 0, &trap); 121 assert(error == NULL); 122 assert(trap != NULL); 123 printf("Got a trap!...\n"); 124 125 wasmtime_store_delete(store); 126 wasm_engine_delete(engine); 127 return 0; 128 } 129 130 static void exit_with_error(const char *message, wasmtime_error_t *error, 131 wasm_trap_t *trap) { 132 fprintf(stderr, "error: %s\n", message); 133 wasm_byte_vec_t error_message; 134 if (error != NULL) { 135 wasmtime_error_message(error, &error_message); 136 wasmtime_error_delete(error); 137 } else { 138 wasm_trap_message(trap, &error_message); 139 wasm_trap_delete(trap); 140 } 141 fprintf(stderr, "%.*s\n", (int)error_message.size, error_message.data); 142 wasm_byte_vec_delete(&error_message); 143 exit(1); 144 } 145