1 /* 2 Example of using `externref` values. 3 4 You can build using cmake: 5 6 mkdir build && cd build && cmake .. && \ 7 cmake --build . --target wasmtime-externref 8 */ 9 10 #include <assert.h> 11 #include <stdio.h> 12 #include <stdlib.h> 13 #include <string.h> 14 #include <wasm.h> 15 #include <wasmtime.h> 16 17 static void exit_with_error(const char *message, wasmtime_error_t *error, 18 wasm_trap_t *trap); 19 20 int main() { 21 bool ok = true; 22 // Create a new configuration with Wasm reference types enabled. 23 printf("Initializing...\n"); 24 wasm_config_t *config = wasm_config_new(); 25 assert(config != NULL); 26 wasmtime_config_wasm_reference_types_set(config, true); 27 28 // Create an *engine*, which is a compilation context, with our configured 29 // options. 30 wasm_engine_t *engine = wasm_engine_new_with_config(config); 31 assert(engine != NULL); 32 33 // With an engine we can create a *store* which is a group of wasm instances 34 // that can interact with each other. 35 wasmtime_store_t *store = wasmtime_store_new(engine, NULL, NULL); 36 assert(store != NULL); 37 wasmtime_context_t *context = wasmtime_store_context(store); 38 39 // Read our input file, which in this case is a wasm text file. 40 FILE *file = fopen("examples/externref.wat", "r"); 41 assert(file != NULL); 42 fseek(file, 0L, SEEK_END); 43 size_t file_size = ftell(file); 44 fseek(file, 0L, SEEK_SET); 45 wasm_byte_vec_t wat; 46 wasm_byte_vec_new_uninitialized(&wat, file_size); 47 if (fread(wat.data, file_size, 1, file) != 1) { 48 printf("> Error loading module!\n"); 49 return 1; 50 } 51 fclose(file); 52 53 // Parse the wat into the binary wasm format 54 wasm_byte_vec_t wasm; 55 wasmtime_error_t *error = wasmtime_wat2wasm(wat.data, wat.size, &wasm); 56 if (error != NULL) 57 exit_with_error("failed to parse wat", error, NULL); 58 wasm_byte_vec_delete(&wat); 59 60 // Now that we've got our binary webassembly we can compile our module. 61 printf("Compiling module...\n"); 62 wasmtime_module_t *module = NULL; 63 error = wasmtime_module_new(engine, (uint8_t *)wasm.data, wasm.size, &module); 64 wasm_byte_vec_delete(&wasm); 65 if (error != NULL) 66 exit_with_error("failed to compile module", error, NULL); 67 68 // Instantiate the module. 69 printf("Instantiating module...\n"); 70 wasm_trap_t *trap = NULL; 71 wasmtime_instance_t instance; 72 error = wasmtime_instance_new(context, module, NULL, 0, &instance, &trap); 73 if (error != NULL || trap != NULL) 74 exit_with_error("failed to instantiate", error, trap); 75 76 printf("Creating new `externref`...\n"); 77 78 // Create a new `externref` value. 79 // 80 // Note that the NULL here is a finalizer callback, but we don't need one for 81 // this example. 82 wasmtime_externref_t externref; 83 ok = wasmtime_externref_new(context, "Hello, World!", NULL, &externref); 84 assert(ok); 85 86 // The `externref`'s wrapped data should be the string "Hello, World!". 87 void *data = wasmtime_externref_data(context, &externref); 88 assert(strcmp((char *)data, "Hello, World!") == 0); 89 90 wasmtime_extern_t item; 91 wasmtime_val_t externref_val; 92 externref_val.kind = WASMTIME_EXTERNREF; 93 externref_val.of.externref = externref; 94 95 // Lookup the `table` export. 96 printf("Touching `externref` table...\n"); 97 { 98 ok = wasmtime_instance_export_get(context, &instance, "table", 99 strlen("table"), &item); 100 assert(ok); 101 assert(item.kind == WASMTIME_EXTERN_TABLE); 102 103 // Set `table[3]` to our `externref`. 104 error = wasmtime_table_set(context, &item.of.table, 3, &externref_val); 105 if (error != NULL) 106 exit_with_error("failed to set table", error, NULL); 107 108 // `table[3]` should now be our `externref`. 109 wasmtime_val_t elem; 110 ok = wasmtime_table_get(context, &item.of.table, 3, &elem); 111 assert(ok); 112 assert(elem.kind == WASMTIME_EXTERNREF); 113 assert(strcmp((char *)wasmtime_externref_data(context, &elem.of.externref), 114 "Hello, World!") == 0); 115 wasmtime_val_unroot(&elem); 116 } 117 118 printf("Touching `externref` global...\n"); 119 120 // Lookup the `global` export. 121 { 122 ok = wasmtime_instance_export_get(context, &instance, "global", 123 strlen("global"), &item); 124 assert(ok); 125 assert(item.kind == WASMTIME_EXTERN_GLOBAL); 126 127 // Set the global to our `externref`. 128 error = wasmtime_global_set(context, &item.of.global, &externref_val); 129 if (error != NULL) 130 exit_with_error("failed to set global", error, NULL); 131 132 // Get the global, and it should return our `externref` again. 133 wasmtime_val_t global_val; 134 wasmtime_global_get(context, &item.of.global, &global_val); 135 assert(global_val.kind == WASMTIME_EXTERNREF); 136 assert(strcmp((char *)wasmtime_externref_data(context, 137 &global_val.of.externref), 138 "Hello, World!") == 0); 139 wasmtime_val_unroot(&global_val); 140 } 141 142 printf("Calling `externref` func...\n"); 143 144 // Lookup the `func` export. 145 { 146 ok = wasmtime_instance_export_get(context, &instance, "func", 147 strlen("func"), &item); 148 assert(ok); 149 assert(item.kind == WASMTIME_EXTERN_FUNC); 150 151 // And call it! 152 wasmtime_val_t results[1]; 153 error = wasmtime_func_call(context, &item.of.func, &externref_val, 1, 154 results, 1, &trap); 155 if (error != NULL || trap != NULL) 156 exit_with_error("failed to call function", error, trap); 157 158 // `func` returns the same reference we gave it, so `results[0]` should be 159 // our `externref`. 160 assert(results[0].kind == WASMTIME_EXTERNREF); 161 assert(strcmp((char *)wasmtime_externref_data(context, 162 &results[0].of.externref), 163 "Hello, World!") == 0); 164 wasmtime_val_unroot(&results[0]); 165 } 166 wasmtime_val_unroot(&externref_val); 167 168 // We can GC any now-unused references to our externref that the store is 169 // holding. 170 printf("GCing within the store...\n"); 171 wasmtime_context_gc(context); 172 173 // Clean up after ourselves at this point 174 printf("All finished!\n"); 175 176 wasmtime_store_delete(store); 177 wasmtime_module_delete(module); 178 wasm_engine_delete(engine); 179 return 0; 180 } 181 182 static void exit_with_error(const char *message, wasmtime_error_t *error, 183 wasm_trap_t *trap) { 184 fprintf(stderr, "error: %s\n", message); 185 wasm_byte_vec_t error_message; 186 if (error != NULL) { 187 wasmtime_error_message(error, &error_message); 188 wasmtime_error_delete(error); 189 } else { 190 wasm_trap_message(trap, &error_message); 191 wasm_trap_delete(trap); 192 } 193 fprintf(stderr, "%.*s\n", (int)error_message.size, error_message.data); 194 wasm_byte_vec_delete(&error_message); 195 exit(1); 196 } 197