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