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, wasm_val_t args[], size_t num_args, int32_t expected) { 58 wasm_val_t results[1]; 59 wasm_trap_t *trap = NULL; 60 wasmtime_error_t *error = wasmtime_func_call(func, args, num_args, results, 1, &trap); 61 if (error != NULL || trap != NULL) 62 exit_with_error("failed to call function", error, trap); 63 if (results[0].of.i32 != expected) { 64 printf("> Error on result\n"); 65 exit(1); 66 } 67 } 68 69 void check_call0(wasm_func_t* func, int32_t expected) { 70 check_call(func, NULL, 0, expected); 71 } 72 73 void check_call1(wasm_func_t* func, int32_t arg, int32_t expected) { 74 wasm_val_t args[] = { {.kind = WASM_I32, .of = {.i32 = arg}} }; 75 check_call(func, args, 1, expected); 76 } 77 78 void check_call2(wasm_func_t* func, int32_t arg1, int32_t arg2, int32_t expected) { 79 wasm_val_t args[2] = { 80 {.kind = WASM_I32, .of = {.i32 = arg1}}, 81 {.kind = WASM_I32, .of = {.i32 = arg2}} 82 }; 83 check_call(func, args, 2, expected); 84 } 85 86 void check_ok(wasm_func_t* func, wasm_val_t args[], size_t num_args) { 87 wasm_trap_t *trap = NULL; 88 wasmtime_error_t *error = wasmtime_func_call(func, args, num_args, NULL, 0, &trap); 89 if (error != NULL || trap != NULL) 90 exit_with_error("failed to call function", error, trap); 91 } 92 93 void check_ok2(wasm_func_t* func, int32_t arg1, int32_t arg2) { 94 wasm_val_t args[2] = { 95 {.kind = WASM_I32, .of = {.i32 = arg1}}, 96 {.kind = WASM_I32, .of = {.i32 = arg2}} 97 }; 98 check_ok(func, args, 2); 99 } 100 101 void check_trap(wasm_func_t* func, wasm_val_t args[], size_t num_args, size_t num_results) { 102 wasm_val_t results[1]; 103 assert(num_results <= 1); 104 wasm_trap_t *trap = NULL; 105 wasmtime_error_t *error = wasmtime_func_call(func, args, num_args, results, num_results, &trap); 106 if (error != NULL) 107 exit_with_error("failed to call function", error, NULL); 108 if (trap == NULL) { 109 printf("> Error on result, expected trap\n"); 110 exit(1); 111 } 112 wasm_trap_delete(trap); 113 } 114 115 void check_trap1(wasm_func_t* func, int32_t arg) { 116 wasm_val_t args[1] = { {.kind = WASM_I32, .of = {.i32 = arg}} }; 117 check_trap(func, args, 1, 1); 118 } 119 120 void check_trap2(wasm_func_t* func, int32_t arg1, int32_t arg2) { 121 wasm_val_t args[2] = { 122 {.kind = WASM_I32, .of = {.i32 = arg1}}, 123 {.kind = WASM_I32, .of = {.i32 = arg2}} 124 }; 125 check_trap(func, args, 2, 0); 126 } 127 128 int main(int argc, const char* argv[]) { 129 // Initialize. 130 printf("Initializing...\n"); 131 wasm_engine_t* engine = wasm_engine_new(); 132 wasm_store_t* store = wasm_store_new(engine); 133 134 // Load our input file to parse it next 135 FILE* file = fopen("examples/memory.wat", "r"); 136 if (!file) { 137 printf("> Error loading file!\n"); 138 return 1; 139 } 140 fseek(file, 0L, SEEK_END); 141 size_t file_size = ftell(file); 142 fseek(file, 0L, SEEK_SET); 143 wasm_byte_vec_t wat; 144 wasm_byte_vec_new_uninitialized(&wat, file_size); 145 if (fread(wat.data, file_size, 1, file) != 1) { 146 printf("> Error loading module!\n"); 147 return 1; 148 } 149 fclose(file); 150 151 // Parse the wat into the binary wasm format 152 wasm_byte_vec_t binary; 153 wasmtime_error_t *error = wasmtime_wat2wasm(&wat, &binary); 154 if (error != NULL) 155 exit_with_error("failed to parse wat", error, NULL); 156 wasm_byte_vec_delete(&wat); 157 158 // Compile. 159 printf("Compiling module...\n"); 160 wasm_module_t* module = NULL; 161 error = wasmtime_module_new(engine, &binary, &module); 162 if (error) 163 exit_with_error("failed to compile module", error, NULL); 164 wasm_byte_vec_delete(&binary); 165 166 // Instantiate. 167 printf("Instantiating module...\n"); 168 wasm_instance_t* instance = NULL; 169 wasm_trap_t *trap = NULL; 170 error = wasmtime_instance_new(store, module, NULL, 0, &instance, &trap); 171 if (!instance) 172 exit_with_error("failed to instantiate", error, trap); 173 174 // Extract export. 175 printf("Extracting exports...\n"); 176 wasm_extern_vec_t exports; 177 wasm_instance_exports(instance, &exports); 178 size_t i = 0; 179 wasm_memory_t* memory = get_export_memory(&exports, i++); 180 wasm_func_t* size_func = get_export_func(&exports, i++); 181 wasm_func_t* load_func = get_export_func(&exports, i++); 182 wasm_func_t* store_func = get_export_func(&exports, i++); 183 184 wasm_module_delete(module); 185 186 // Try cloning. 187 wasm_memory_t* copy = wasm_memory_copy(memory); 188 wasm_memory_delete(copy); 189 190 // Check initial memory. 191 printf("Checking memory...\n"); 192 check(wasm_memory_size(memory) == 2); 193 check(wasm_memory_data_size(memory) == 0x20000); 194 check(wasm_memory_data(memory)[0] == 0); 195 check(wasm_memory_data(memory)[0x1000] == 1); 196 check(wasm_memory_data(memory)[0x1003] == 4); 197 198 check_call0(size_func, 2); 199 check_call1(load_func, 0, 0); 200 check_call1(load_func, 0x1000, 1); 201 check_call1(load_func, 0x1003, 4); 202 check_call1(load_func, 0x1ffff, 0); 203 check_trap1(load_func, 0x20000); 204 205 // Mutate memory. 206 printf("Mutating memory...\n"); 207 wasm_memory_data(memory)[0x1003] = 5; 208 check_ok2(store_func, 0x1002, 6); 209 check_trap2(store_func, 0x20000, 0); 210 211 check(wasm_memory_data(memory)[0x1002] == 6); 212 check(wasm_memory_data(memory)[0x1003] == 5); 213 check_call1(load_func, 0x1002, 6); 214 check_call1(load_func, 0x1003, 5); 215 216 // Grow memory. 217 printf("Growing memory...\n"); 218 check(wasm_memory_grow(memory, 1)); 219 check(wasm_memory_size(memory) == 3); 220 check(wasm_memory_data_size(memory) == 0x30000); 221 222 check_call1(load_func, 0x20000, 0); 223 check_ok2(store_func, 0x20000, 0); 224 check_trap1(load_func, 0x30000); 225 check_trap2(store_func, 0x30000, 0); 226 227 check(! wasm_memory_grow(memory, 1)); 228 check(wasm_memory_grow(memory, 0)); 229 230 wasm_extern_vec_delete(&exports); 231 wasm_instance_delete(instance); 232 233 // Create stand-alone memory. 234 printf("Creating stand-alone memory...\n"); 235 wasm_limits_t limits = {5, 5}; 236 wasm_memorytype_t* memorytype = wasm_memorytype_new(&limits); 237 wasm_memory_t* memory2 = wasm_memory_new(store, memorytype); 238 check(wasm_memory_size(memory2) == 5); 239 check(! wasm_memory_grow(memory2, 1)); 240 check(wasm_memory_grow(memory2, 0)); 241 242 wasm_memorytype_delete(memorytype); 243 wasm_memory_delete(memory2); 244 245 // Shut down. 246 printf("Shutting down...\n"); 247 wasm_store_delete(store); 248 wasm_engine_delete(engine); 249 250 // All done. 251 printf("Done.\n"); 252 return 0; 253 } 254 255 static void exit_with_error(const char *message, wasmtime_error_t *error, wasm_trap_t *trap) { 256 fprintf(stderr, "error: %s\n", message); 257 wasm_byte_vec_t error_message; 258 if (error != NULL) { 259 wasmtime_error_message(error, &error_message); 260 wasmtime_error_delete(error); 261 } else { 262 wasm_trap_message(trap, &error_message); 263 wasm_trap_delete(trap); 264 } 265 fprintf(stderr, "%.*s\n", (int) error_message.size, error_message.data); 266 wasm_byte_vec_delete(&error_message); 267 exit(1); 268 } 269