1 /* 2 Example of compiling, instantiating, and linking two WebAssembly modules 3 together. 4 5 You can compile and run this example on Linux with: 6 7 cargo build --release -p wasmtime-c-api 8 cc examples/linking.c \ 9 -I crates/c-api/include \ 10 target/release/libwasmtime.a \ 11 -lpthread -ldl -lm \ 12 -o linking 13 ./linking 14 15 Note that on Windows and macOS the command will be similar, but you'll need 16 to tweak the `-lpthread` and such annotations. 17 18 You can also build using cmake: 19 20 mkdir build && cd build && cmake .. && cmake --build . --target wasmtime-linking 21 */ 22 23 #include <assert.h> 24 #include <stdio.h> 25 #include <stdlib.h> 26 #include <wasi.h> 27 #include <wasm.h> 28 #include <wasmtime.h> 29 30 #define MIN(a, b) ((a) < (b) ? (a) : (b)) 31 32 static void exit_with_error(const char *message, wasmtime_error_t *error, 33 wasm_trap_t *trap); 34 static void read_wat_file(wasm_engine_t *engine, wasm_byte_vec_t *bytes, 35 const char *file); 36 37 int main() { 38 // Set up our context 39 wasm_engine_t *engine = wasm_engine_new(); 40 assert(engine != NULL); 41 wasmtime_store_t *store = wasmtime_store_new(engine, NULL, NULL); 42 assert(store != NULL); 43 wasmtime_context_t *context = wasmtime_store_context(store); 44 45 wasm_byte_vec_t linking1_wasm, linking2_wasm; 46 read_wat_file(engine, &linking1_wasm, "examples/linking1.wat"); 47 read_wat_file(engine, &linking2_wasm, "examples/linking2.wat"); 48 49 // Compile our two modules 50 wasmtime_error_t *error; 51 wasmtime_module_t *linking1_module = NULL; 52 wasmtime_module_t *linking2_module = NULL; 53 error = wasmtime_module_new(engine, (uint8_t *)linking1_wasm.data, 54 linking1_wasm.size, &linking1_module); 55 if (error != NULL) 56 exit_with_error("failed to compile linking1", error, NULL); 57 error = wasmtime_module_new(engine, (uint8_t *)linking2_wasm.data, 58 linking2_wasm.size, &linking2_module); 59 if (error != NULL) 60 exit_with_error("failed to compile linking2", error, NULL); 61 wasm_byte_vec_delete(&linking1_wasm); 62 wasm_byte_vec_delete(&linking2_wasm); 63 64 // Configure WASI and store it within our `wasmtime_store_t` 65 wasi_config_t *wasi_config = wasi_config_new(); 66 assert(wasi_config); 67 wasi_config_inherit_argv(wasi_config); 68 wasi_config_inherit_env(wasi_config); 69 wasi_config_inherit_stdin(wasi_config); 70 wasi_config_inherit_stdout(wasi_config); 71 wasi_config_inherit_stderr(wasi_config); 72 wasm_trap_t *trap = NULL; 73 error = wasmtime_context_set_wasi(context, wasi_config); 74 if (error != NULL) 75 exit_with_error("failed to instantiate wasi", NULL, trap); 76 77 // Create our linker which will be linking our modules together, and then add 78 // our WASI instance to it. 79 wasmtime_linker_t *linker = wasmtime_linker_new(engine); 80 error = wasmtime_linker_define_wasi(linker); 81 if (error != NULL) 82 exit_with_error("failed to link wasi", error, NULL); 83 84 // Instantiate `linking2` with our linker. 85 wasmtime_instance_t linking2; 86 error = wasmtime_linker_instantiate(linker, context, linking2_module, 87 &linking2, &trap); 88 if (error != NULL || trap != NULL) 89 exit_with_error("failed to instantiate linking2", error, trap); 90 91 // Register our new `linking2` instance with the linker 92 error = wasmtime_linker_define_instance(linker, context, "linking2", 93 strlen("linking2"), &linking2); 94 if (error != NULL) 95 exit_with_error("failed to link linking2", error, NULL); 96 97 // Instantiate `linking1` with the linker now that `linking2` is defined 98 wasmtime_instance_t linking1; 99 error = wasmtime_linker_instantiate(linker, context, linking1_module, 100 &linking1, &trap); 101 if (error != NULL || trap != NULL) 102 exit_with_error("failed to instantiate linking1", error, trap); 103 104 // Lookup our `run` export function 105 wasmtime_extern_t run; 106 bool ok = wasmtime_instance_export_get(context, &linking1, "run", 3, &run); 107 assert(ok); 108 assert(run.kind == WASMTIME_EXTERN_FUNC); 109 error = wasmtime_func_call(context, &run.of.func, NULL, 0, NULL, 0, &trap); 110 if (error != NULL || trap != NULL) 111 exit_with_error("failed to call run", error, trap); 112 113 // Clean up after ourselves at this point 114 wasmtime_linker_delete(linker); 115 wasmtime_module_delete(linking1_module); 116 wasmtime_module_delete(linking2_module); 117 wasmtime_store_delete(store); 118 wasm_engine_delete(engine); 119 return 0; 120 } 121 122 static void read_wat_file(wasm_engine_t *engine, wasm_byte_vec_t *bytes, 123 const char *filename) { 124 wasm_byte_vec_t wat; 125 // Load our input file to parse it next 126 FILE *file = fopen(filename, "r"); 127 if (!file) { 128 printf("> Error loading file!\n"); 129 exit(1); 130 } 131 fseek(file, 0L, SEEK_END); 132 size_t file_size = ftell(file); 133 wasm_byte_vec_new_uninitialized(&wat, file_size); 134 fseek(file, 0L, SEEK_SET); 135 if (fread(wat.data, file_size, 1, file) != 1) { 136 printf("> Error loading module!\n"); 137 exit(1); 138 } 139 fclose(file); 140 141 // Parse the wat into the binary wasm format 142 wasmtime_error_t *error = wasmtime_wat2wasm(wat.data, wat.size, bytes); 143 if (error != NULL) 144 exit_with_error("failed to parse wat", error, NULL); 145 wasm_byte_vec_delete(&wat); 146 } 147 148 static void exit_with_error(const char *message, wasmtime_error_t *error, 149 wasm_trap_t *trap) { 150 fprintf(stderr, "error: %s\n", message); 151 wasm_byte_vec_t error_message; 152 if (error != NULL) { 153 wasmtime_error_message(error, &error_message); 154 wasmtime_error_delete(error); 155 } else { 156 wasm_trap_message(trap, &error_message); 157 wasm_trap_delete(trap); 158 } 159 fprintf(stderr, "%.*s\n", (int)error_message.size, error_message.data); 160 wasm_byte_vec_delete(&error_message); 161 exit(1); 162 } 163