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