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 .. && cmake --build . --target wasmtime-multi 8 9 Also note that this example was taken from 10 https://github.com/WebAssembly/wasm-c-api/blob/master/example/multi.c 11 originally 12 */ 13 14 #include <inttypes.h> 15 #include <stdio.h> 16 #include <stdlib.h> 17 #include <string.h> 18 #include <wasm.h> 19 #include <wasmtime.h> 20 21 static void exit_with_error(const char *message, wasmtime_error_t *error, 22 wasm_trap_t *trap); 23 24 // A function to be called from Wasm code. 25 wasm_trap_t *callback(void *env, wasmtime_caller_t *caller, 26 const wasmtime_val_t *args, size_t nargs, 27 wasmtime_val_t *results, size_t nresults) { 28 printf("Calling back...\n"); 29 printf("> %" PRIu32 " %" PRIu64 "\n", args[0].of.i32, args[1].of.i64); 30 printf("\n"); 31 32 results[0] = args[1]; 33 results[1] = args[0]; 34 return NULL; 35 } 36 37 // A function closure. 38 wasm_trap_t *closure_callback(void *env, wasmtime_caller_t *caller, 39 const wasmtime_val_t *args, size_t nargs, 40 wasmtime_val_t *results, size_t nresults) { 41 int i = *(int *)env; 42 printf("Calling back closure...\n"); 43 printf("> %d\n", i); 44 45 results[0].kind = WASMTIME_I32; 46 results[0].of.i32 = (int32_t)i; 47 return NULL; 48 } 49 50 int main(int argc, const char *argv[]) { 51 // Initialize. 52 printf("Initializing...\n"); 53 wasm_engine_t *engine = wasm_engine_new(); 54 wasmtime_store_t *store = wasmtime_store_new(engine, NULL, NULL); 55 wasmtime_context_t *context = wasmtime_store_context(store); 56 57 // Load our input file to parse it next 58 FILE *file = fopen("examples/multi.wat", "r"); 59 if (!file) { 60 printf("> Error loading file!\n"); 61 return 1; 62 } 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 binary; 76 wasmtime_error_t *error = wasmtime_wat2wasm(wat.data, wat.size, &binary); 77 if (error != NULL) 78 exit_with_error("failed to parse wat", error, NULL); 79 wasm_byte_vec_delete(&wat); 80 81 // Compile. 82 printf("Compiling module...\n"); 83 wasmtime_module_t *module = NULL; 84 error = 85 wasmtime_module_new(engine, (uint8_t *)binary.data, binary.size, &module); 86 if (error) 87 exit_with_error("failed to compile module", error, NULL); 88 wasm_byte_vec_delete(&binary); 89 90 // Create external print functions. 91 printf("Creating callback...\n"); 92 wasm_functype_t *callback_type = 93 wasm_functype_new_2_2(wasm_valtype_new_i32(), wasm_valtype_new_i64(), 94 wasm_valtype_new_i64(), wasm_valtype_new_i32()); 95 wasmtime_func_t callback_func; 96 wasmtime_func_new(context, callback_type, callback, NULL, NULL, 97 &callback_func); 98 wasm_functype_delete(callback_type); 99 100 // Instantiate. 101 printf("Instantiating module...\n"); 102 wasmtime_extern_t imports[1]; 103 imports[0].kind = WASMTIME_EXTERN_FUNC; 104 imports[0].of.func = callback_func; 105 wasmtime_instance_t instance; 106 wasm_trap_t *trap = NULL; 107 error = wasmtime_instance_new(context, module, imports, 1, &instance, &trap); 108 if (error != NULL || trap != NULL) 109 exit_with_error("failed to instantiate", error, trap); 110 wasmtime_module_delete(module); 111 112 // Extract export. 113 printf("Extracting export...\n"); 114 wasmtime_extern_t run; 115 bool ok = wasmtime_instance_export_get(context, &instance, "g", 1, &run); 116 assert(ok); 117 assert(run.kind == WASMTIME_EXTERN_FUNC); 118 119 // Call. 120 printf("Calling export...\n"); 121 wasmtime_val_t args[2]; 122 args[0].kind = WASMTIME_I32; 123 args[0].of.i32 = 1; 124 args[1].kind = WASMTIME_I64; 125 args[1].of.i64 = 2; 126 wasmtime_val_t results[2]; 127 error = wasmtime_func_call(context, &run.of.func, args, 2, results, 2, &trap); 128 if (error != NULL || trap != NULL) 129 exit_with_error("failed to call run", error, trap); 130 131 // Print result. 132 printf("Printing result...\n"); 133 printf("> %" PRIu64 " %" PRIu32 "\n", results[0].of.i64, results[1].of.i32); 134 135 assert(results[0].kind == WASMTIME_I64); 136 assert(results[0].of.i64 == 2); 137 assert(results[1].kind == WASMTIME_I32); 138 assert(results[1].of.i32 == 1); 139 140 // Shut down. 141 printf("Shutting down...\n"); 142 wasmtime_store_delete(store); 143 wasm_engine_delete(engine); 144 145 // All done. 146 printf("Done.\n"); 147 return 0; 148 } 149 150 static void exit_with_error(const char *message, wasmtime_error_t *error, 151 wasm_trap_t *trap) { 152 fprintf(stderr, "error: %s\n", message); 153 wasm_byte_vec_t error_message; 154 if (error != NULL) { 155 wasmtime_error_message(error, &error_message); 156 wasmtime_error_delete(error); 157 } else { 158 wasm_trap_message(trap, &error_message); 159 wasm_trap_delete(trap); 160 } 161 fprintf(stderr, "%.*s\n", (int)error_message.size, error_message.data); 162 wasm_byte_vec_delete(&error_message); 163 exit(1); 164 } 165