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/memory.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 memory 14 ./memory 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. 18 19 Also note that this example was taken from 20 https://github.com/WebAssembly/wasm-c-api/blob/master/example/memory.c 21 originally 22 */ 23 24 #include <inttypes.h> 25 #include <stdio.h> 26 #include <stdlib.h> 27 #include <string.h> 28 #include <wasm.h> 29 #include <wasmtime.h> 30 31 static void exit_with_error(const char *message, wasmtime_error_t *error, wasm_trap_t *trap); 32 33 wasm_memory_t* get_export_memory(const wasm_extern_vec_t* exports, size_t i) { 34 if (exports->size <= i || !wasm_extern_as_memory(exports->data[i])) { 35 printf("> Error accessing memory export %zu!\n", i); 36 exit(1); 37 } 38 return wasm_extern_as_memory(exports->data[i]); 39 } 40 41 wasm_func_t* get_export_func(const wasm_extern_vec_t* exports, size_t i) { 42 if (exports->size <= i || !wasm_extern_as_func(exports->data[i])) { 43 printf("> Error accessing function export %zu!\n", i); 44 exit(1); 45 } 46 return wasm_extern_as_func(exports->data[i]); 47 } 48 49 50 void check(bool success) { 51 if (!success) { 52 printf("> Error, expected success\n"); 53 exit(1); 54 } 55 } 56 57 void check_call(wasm_func_t* func, const wasm_val_vec_t* args_vec, int32_t expected) { 58 wasm_val_t results[1]; 59 wasm_val_vec_t results_vec = WASM_ARRAY_VEC(results); 60 wasm_trap_t *trap = NULL; 61 wasmtime_error_t *error = wasmtime_func_call(func, args_vec, &results_vec, &trap); 62 if (error != NULL || trap != NULL) 63 exit_with_error("failed to call function", error, trap); 64 if (results[0].of.i32 != expected) { 65 printf("> Error on result\n"); 66 exit(1); 67 } 68 } 69 70 void check_call0(wasm_func_t* func, int32_t expected) { 71 wasm_val_vec_t args_vec = WASM_EMPTY_VEC; 72 check_call(func, &args_vec, expected); 73 } 74 75 void check_call1(wasm_func_t* func, int32_t arg, int32_t expected) { 76 wasm_val_t args[] = { WASM_I32_VAL(arg) }; 77 wasm_val_vec_t args_vec = WASM_ARRAY_VEC(args); 78 check_call(func, &args_vec, expected); 79 } 80 81 void check_call2(wasm_func_t* func, int32_t arg1, int32_t arg2, int32_t expected) { 82 wasm_val_t args[] = { WASM_I32_VAL(arg1), WASM_I32_VAL(arg2) }; 83 wasm_val_vec_t args_vec = WASM_ARRAY_VEC(args); 84 check_call(func, &args_vec, expected); 85 } 86 87 void check_ok(wasm_func_t* func, const wasm_val_vec_t* args_vec) { 88 wasm_trap_t *trap = NULL; 89 wasm_val_vec_t results_vec = WASM_EMPTY_VEC; 90 wasmtime_error_t *error = wasmtime_func_call(func, args_vec, &results_vec, &trap); 91 if (error != NULL || trap != NULL) 92 exit_with_error("failed to call function", error, trap); 93 } 94 95 void check_ok2(wasm_func_t* func, int32_t arg1, int32_t arg2) { 96 wasm_val_t args[] = { WASM_I32_VAL(arg1), WASM_I32_VAL(arg2) }; 97 wasm_val_vec_t args_vec = WASM_ARRAY_VEC(args); 98 check_ok(func, &args_vec); 99 } 100 101 void check_trap(wasm_func_t* func, const wasm_val_vec_t* args_vec, size_t num_results) { 102 assert(num_results <= 1); 103 wasm_val_t results[1]; 104 wasm_val_vec_t results_vec; 105 results_vec.data = results; 106 results_vec.size = num_results; 107 wasm_trap_t *trap = NULL; 108 wasmtime_error_t *error = wasmtime_func_call(func, args_vec, &results_vec, &trap); 109 if (error != NULL) 110 exit_with_error("failed to call function", error, NULL); 111 if (trap == NULL) { 112 printf("> Error on result, expected trap\n"); 113 exit(1); 114 } 115 wasm_trap_delete(trap); 116 } 117 118 void check_trap1(wasm_func_t* func, int32_t arg) { 119 wasm_val_t args[] = { WASM_I32_VAL(arg) }; 120 wasm_val_vec_t args_vec = WASM_ARRAY_VEC(args); 121 check_trap(func, &args_vec, 1); 122 } 123 124 void check_trap2(wasm_func_t* func, int32_t arg1, int32_t arg2) { 125 wasm_val_t args[] = { WASM_I32_VAL(arg1), WASM_I32_VAL(arg2) }; 126 wasm_val_vec_t args_vec = WASM_ARRAY_VEC(args); 127 check_trap(func, &args_vec, 0); 128 } 129 130 int main(int argc, const char* argv[]) { 131 // Initialize. 132 printf("Initializing...\n"); 133 wasm_engine_t* engine = wasm_engine_new(); 134 wasm_store_t* store = wasm_store_new(engine); 135 136 // Load our input file to parse it next 137 FILE* file = fopen("examples/memory.wat", "r"); 138 if (!file) { 139 printf("> Error loading file!\n"); 140 return 1; 141 } 142 fseek(file, 0L, SEEK_END); 143 size_t file_size = ftell(file); 144 fseek(file, 0L, SEEK_SET); 145 wasm_byte_vec_t wat; 146 wasm_byte_vec_new_uninitialized(&wat, file_size); 147 if (fread(wat.data, file_size, 1, file) != 1) { 148 printf("> Error loading module!\n"); 149 return 1; 150 } 151 fclose(file); 152 153 // Parse the wat into the binary wasm format 154 wasm_byte_vec_t binary; 155 wasmtime_error_t *error = wasmtime_wat2wasm(&wat, &binary); 156 if (error != NULL) 157 exit_with_error("failed to parse wat", error, NULL); 158 wasm_byte_vec_delete(&wat); 159 160 // Compile. 161 printf("Compiling module...\n"); 162 wasm_module_t* module = NULL; 163 error = wasmtime_module_new(engine, &binary, &module); 164 if (error) 165 exit_with_error("failed to compile module", error, NULL); 166 wasm_byte_vec_delete(&binary); 167 168 // Instantiate. 169 printf("Instantiating module...\n"); 170 wasm_instance_t* instance = NULL; 171 wasm_trap_t *trap = NULL; 172 wasm_extern_vec_t imports = WASM_EMPTY_VEC; 173 error = wasmtime_instance_new(store, module, &imports, &instance, &trap); 174 if (!instance) 175 exit_with_error("failed to instantiate", error, trap); 176 177 // Extract export. 178 printf("Extracting exports...\n"); 179 wasm_extern_vec_t exports; 180 wasm_instance_exports(instance, &exports); 181 size_t i = 0; 182 wasm_memory_t* memory = get_export_memory(&exports, i++); 183 wasm_func_t* size_func = get_export_func(&exports, i++); 184 wasm_func_t* load_func = get_export_func(&exports, i++); 185 wasm_func_t* store_func = get_export_func(&exports, i++); 186 187 wasm_module_delete(module); 188 189 // Try cloning. 190 wasm_memory_t* copy = wasm_memory_copy(memory); 191 wasm_memory_delete(copy); 192 193 // Check initial memory. 194 printf("Checking memory...\n"); 195 check(wasm_memory_size(memory) == 2); 196 check(wasm_memory_data_size(memory) == 0x20000); 197 check(wasm_memory_data(memory)[0] == 0); 198 check(wasm_memory_data(memory)[0x1000] == 1); 199 check(wasm_memory_data(memory)[0x1003] == 4); 200 201 check_call0(size_func, 2); 202 check_call1(load_func, 0, 0); 203 check_call1(load_func, 0x1000, 1); 204 check_call1(load_func, 0x1003, 4); 205 check_call1(load_func, 0x1ffff, 0); 206 check_trap1(load_func, 0x20000); 207 208 // Mutate memory. 209 printf("Mutating memory...\n"); 210 wasm_memory_data(memory)[0x1003] = 5; 211 check_ok2(store_func, 0x1002, 6); 212 check_trap2(store_func, 0x20000, 0); 213 214 check(wasm_memory_data(memory)[0x1002] == 6); 215 check(wasm_memory_data(memory)[0x1003] == 5); 216 check_call1(load_func, 0x1002, 6); 217 check_call1(load_func, 0x1003, 5); 218 219 // Grow memory. 220 printf("Growing memory...\n"); 221 check(wasm_memory_grow(memory, 1)); 222 check(wasm_memory_size(memory) == 3); 223 check(wasm_memory_data_size(memory) == 0x30000); 224 225 check_call1(load_func, 0x20000, 0); 226 check_ok2(store_func, 0x20000, 0); 227 check_trap1(load_func, 0x30000); 228 check_trap2(store_func, 0x30000, 0); 229 230 check(! wasm_memory_grow(memory, 1)); 231 check(wasm_memory_grow(memory, 0)); 232 233 wasm_extern_vec_delete(&exports); 234 wasm_instance_delete(instance); 235 236 // Create stand-alone memory. 237 printf("Creating stand-alone memory...\n"); 238 wasm_limits_t limits = {5, 5}; 239 wasm_memorytype_t* memorytype = wasm_memorytype_new(&limits); 240 wasm_memory_t* memory2 = wasm_memory_new(store, memorytype); 241 check(wasm_memory_size(memory2) == 5); 242 check(! wasm_memory_grow(memory2, 1)); 243 check(wasm_memory_grow(memory2, 0)); 244 245 wasm_memorytype_delete(memorytype); 246 wasm_memory_delete(memory2); 247 248 // Shut down. 249 printf("Shutting down...\n"); 250 wasm_store_delete(store); 251 wasm_engine_delete(engine); 252 253 // All done. 254 printf("Done.\n"); 255 return 0; 256 } 257 258 static void exit_with_error(const char *message, wasmtime_error_t *error, wasm_trap_t *trap) { 259 fprintf(stderr, "error: %s\n", message); 260 wasm_byte_vec_t error_message; 261 if (error != NULL) { 262 wasmtime_error_message(error, &error_message); 263 wasmtime_error_delete(error); 264 } else { 265 wasm_trap_message(trap, &error_message); 266 wasm_trap_delete(trap); 267 } 268 fprintf(stderr, "%.*s\n", (int) error_message.size, error_message.data); 269 wasm_byte_vec_delete(&error_message); 270 exit(1); 271 } 272