1 /* 2 Example of compiling, instantiating, and linking two WebAssembly modules 3 together. 4 5 You can build using cmake: 6 7 mkdir build && cd build && cmake .. && cmake --build . --target wasmtime-linking 8 */ 9 10 #include <assert.h> 11 #include <stdio.h> 12 #include <stdlib.h> 13 #include <wasi.h> 14 #include <wasm.h> 15 #include <wasmtime.h> 16 17 #define MIN(a, b) ((a) < (b) ? (a) : (b)) 18 19 static void exit_with_error(const char *message, wasmtime_error_t *error, 20 wasm_trap_t *trap); 21 static void read_wat_file(wasm_engine_t *engine, wasm_byte_vec_t *bytes, 22 const char *file); 23 24 int main() { 25 // Set up our context 26 wasm_engine_t *engine = wasm_engine_new(); 27 assert(engine != NULL); 28 wasmtime_store_t *store = wasmtime_store_new(engine, NULL, NULL); 29 assert(store != NULL); 30 wasmtime_context_t *context = wasmtime_store_context(store); 31 32 wasm_byte_vec_t linking1_wasm, linking2_wasm; 33 read_wat_file(engine, &linking1_wasm, "examples/linking1.wat"); 34 read_wat_file(engine, &linking2_wasm, "examples/linking2.wat"); 35 36 // Compile our two modules 37 wasmtime_error_t *error; 38 wasmtime_module_t *linking1_module = NULL; 39 wasmtime_module_t *linking2_module = NULL; 40 error = wasmtime_module_new(engine, (uint8_t *)linking1_wasm.data, 41 linking1_wasm.size, &linking1_module); 42 if (error != NULL) 43 exit_with_error("failed to compile linking1", error, NULL); 44 error = wasmtime_module_new(engine, (uint8_t *)linking2_wasm.data, 45 linking2_wasm.size, &linking2_module); 46 if (error != NULL) 47 exit_with_error("failed to compile linking2", error, NULL); 48 wasm_byte_vec_delete(&linking1_wasm); 49 wasm_byte_vec_delete(&linking2_wasm); 50 51 // Configure WASI and store it within our `wasmtime_store_t` 52 wasi_config_t *wasi_config = wasi_config_new(); 53 assert(wasi_config); 54 wasi_config_inherit_argv(wasi_config); 55 wasi_config_inherit_env(wasi_config); 56 wasi_config_inherit_stdin(wasi_config); 57 wasi_config_inherit_stdout(wasi_config); 58 wasi_config_inherit_stderr(wasi_config); 59 wasm_trap_t *trap = NULL; 60 error = wasmtime_context_set_wasi(context, wasi_config); 61 if (error != NULL) 62 exit_with_error("failed to instantiate wasi", NULL, trap); 63 64 // Create our linker which will be linking our modules together, and then add 65 // our WASI instance to it. 66 wasmtime_linker_t *linker = wasmtime_linker_new(engine); 67 error = wasmtime_linker_define_wasi(linker); 68 if (error != NULL) 69 exit_with_error("failed to link wasi", error, NULL); 70 71 // Instantiate `linking2` with our linker. 72 wasmtime_instance_t linking2; 73 error = wasmtime_linker_instantiate(linker, context, linking2_module, 74 &linking2, &trap); 75 if (error != NULL || trap != NULL) 76 exit_with_error("failed to instantiate linking2", error, trap); 77 78 // Register our new `linking2` instance with the linker 79 error = wasmtime_linker_define_instance(linker, context, "linking2", 80 strlen("linking2"), &linking2); 81 if (error != NULL) 82 exit_with_error("failed to link linking2", error, NULL); 83 84 // Instantiate `linking1` with the linker now that `linking2` is defined 85 wasmtime_instance_t linking1; 86 error = wasmtime_linker_instantiate(linker, context, linking1_module, 87 &linking1, &trap); 88 if (error != NULL || trap != NULL) 89 exit_with_error("failed to instantiate linking1", error, trap); 90 91 // Lookup our `run` export function 92 wasmtime_extern_t run; 93 bool ok = wasmtime_instance_export_get(context, &linking1, "run", 3, &run); 94 assert(ok); 95 assert(run.kind == WASMTIME_EXTERN_FUNC); 96 error = wasmtime_func_call(context, &run.of.func, NULL, 0, NULL, 0, &trap); 97 if (error != NULL || trap != NULL) 98 exit_with_error("failed to call run", error, trap); 99 100 // Clean up after ourselves at this point 101 wasmtime_linker_delete(linker); 102 wasmtime_module_delete(linking1_module); 103 wasmtime_module_delete(linking2_module); 104 wasmtime_store_delete(store); 105 wasm_engine_delete(engine); 106 return 0; 107 } 108 109 static void read_wat_file(wasm_engine_t *engine, wasm_byte_vec_t *bytes, 110 const char *filename) { 111 wasm_byte_vec_t wat; 112 // Load our input file to parse it next 113 FILE *file = fopen(filename, "r"); 114 if (!file) { 115 printf("> Error loading file!\n"); 116 exit(1); 117 } 118 fseek(file, 0L, SEEK_END); 119 size_t file_size = ftell(file); 120 wasm_byte_vec_new_uninitialized(&wat, file_size); 121 fseek(file, 0L, SEEK_SET); 122 if (fread(wat.data, file_size, 1, file) != 1) { 123 printf("> Error loading module!\n"); 124 exit(1); 125 } 126 fclose(file); 127 128 // Parse the wat into the binary wasm format 129 wasmtime_error_t *error = wasmtime_wat2wasm(wat.data, wat.size, bytes); 130 if (error != NULL) 131 exit_with_error("failed to parse wat", error, NULL); 132 wasm_byte_vec_delete(&wat); 133 } 134 135 static void exit_with_error(const char *message, wasmtime_error_t *error, 136 wasm_trap_t *trap) { 137 fprintf(stderr, "error: %s\n", message); 138 wasm_byte_vec_t error_message; 139 if (error != NULL) { 140 wasmtime_error_message(error, &error_message); 141 wasmtime_error_delete(error); 142 } else { 143 wasm_trap_message(trap, &error_message); 144 wasm_trap_delete(trap); 145 } 146 fprintf(stderr, "%.*s\n", (int)error_message.size, error_message.data); 147 wasm_byte_vec_delete(&error_message); 148 exit(1); 149 } 150