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Add Wasmtime-specific C API functions to return errors (#1467)

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* Add Wasmtime-specific C API functions to return errors

This commit adds new `wasmtime_*` symbols to the C API, many of which
mirror the existing counterparts in the `wasm.h` header. These APIs are
enhanced in a number of respects:

* Detailed error information is now available through a
  `wasmtime_error_t`. Currently this only exposes one function which is
  to extract a string version of the error.

* There is a distinction now between traps and errors during
  instantiation and function calling. Traps only happen if wasm traps,
  and errors can happen for things like runtime type errors when
  interacting with the API.

* APIs have improved safety with respect to embedders where the lengths
  of arrays are now taken as explicit parameters rather than assumed
  from other parameters.

* Handle trap updates

* Update C examples

* Fix memory.c compile on MSVC

* Update test assertions

* Refactor C slightly

* Bare-bones .NET update

* Remove bogus nul handling
This commit is contained in:
Alex Crichton
2020-04-06 15:13:06 -05:00
committed by GitHub
parent 78c548dc8f
commit bd374fd6fc
30 changed files with 817 additions and 403 deletions
Download Patch File Download Diff File Expand all files Collapse all files

93
examples/linking.c
View File

@@ -26,7 +26,7 @@ to tweak the `-lpthread` and such annotations.
#define MIN(a, b) ((a) < (b) ? (a) : (b))
static void print_trap(wasm_trap_t *trap);
static void exit_with_error(const char *message, wasmtime_error_t *error, wasm_trap_t *trap);
static void read_wat_file(wasm_engine_t *engine, wasm_byte_vec_t *bytes, const char *file);
int main() {
@@ -42,10 +42,15 @@ int main() {
read_wat_file(engine, &linking2_wasm, "examples/linking2.wat");
// Compile our two modules
wasm_module_t *linking1_module = wasm_module_new(store, &linking1_wasm);
assert(linking1_module != NULL);
wasm_module_t *linking2_module = wasm_module_new(store, &linking2_wasm);
assert(linking2_module != NULL);
wasmtime_error_t *error;
wasm_module_t *linking1_module = NULL;
wasm_module_t *linking2_module = NULL;
error = wasmtime_module_new(store, &linking1_wasm, &linking1_module);
if (error != NULL)
exit_with_error("failed to compile linking1", error, NULL);
error = wasmtime_module_new(store, &linking2_wasm, &linking2_module);
if (error != NULL)
exit_with_error("failed to compile linking2", error, NULL);
wasm_byte_vec_delete(&linking1_wasm);
wasm_byte_vec_delete(&linking2_wasm);
@@ -59,45 +64,35 @@ int main() {
wasi_config_inherit_stderr(wasi_config);
wasm_trap_t *trap = NULL;
wasi_instance_t *wasi = wasi_instance_new(store, "wasi_snapshot_preview1", wasi_config, &trap);
if (wasi == NULL) {
print_trap(trap);
exit(1);
}
if (wasi == NULL)
exit_with_error("failed to instantiate wasi", NULL, trap);
// Create our linker which will be linking our modules together, and then add
// our WASI instance to it.
wasmtime_linker_t *linker = wasmtime_linker_new(store);
bool ok = wasmtime_linker_define_wasi(linker, wasi);
assert(ok);
error = wasmtime_linker_define_wasi(linker, wasi);
if (error != NULL)
exit_with_error("failed to link wasi", error, NULL);
// Instantiate `linking2` with our linker.
wasm_instance_t *linking2 = wasmtime_linker_instantiate(linker, linking2_module, &trap);
if (linking2 == NULL) {
if (trap == NULL) {
printf("> failed to link!\n");
} else {
print_trap(trap);
}
exit(1);
}
wasm_instance_t *linking2;
error = wasmtime_linker_instantiate(linker, linking2_module, &linking2, &trap);
if (error != NULL || trap != NULL)
exit_with_error("failed to instantiate linking2", error, trap);
// Register our new `linking2` instance with the linker
wasm_name_t linking2_name;
linking2_name.data = "linking2";
linking2_name.size = strlen(linking2_name.data);
ok = wasmtime_linker_define_instance(linker, &linking2_name, linking2);
assert(ok);
error = wasmtime_linker_define_instance(linker, &linking2_name, linking2);
if (error != NULL)
exit_with_error("failed to link linking2", error, NULL);
// Instantiate `linking1` with the linker now that `linking2` is defined
wasm_instance_t *linking1 = wasmtime_linker_instantiate(linker, linking1_module, &trap);
if (linking1 == NULL) {
if (trap == NULL) {
printf("> failed to link!\n");
} else {
print_trap(trap);
}
exit(1);
}
wasm_instance_t *linking1;
error = wasmtime_linker_instantiate(linker, linking1_module, &linking1, &trap);
if (error != NULL || trap != NULL)
exit_with_error("failed to instantiate linking1", error, trap);
// Lookup our `run` export function
wasm_extern_vec_t linking1_externs;
@@ -105,11 +100,9 @@ int main() {
assert(linking1_externs.size == 1);
wasm_func_t *run = wasm_extern_as_func(linking1_externs.data[0]);
assert(run != NULL);
trap = wasm_func_call(run, NULL, NULL);
if (trap != NULL) {
print_trap(trap);
exit(1);
}
error = wasmtime_func_call(run, NULL, 0, NULL, 0, &trap);
if (error != NULL || trap != NULL)
exit_with_error("failed to call run", error, trap);
// Clean up after ourselves at this point
wasm_extern_vec_delete(&linking1_externs);
@@ -146,19 +139,23 @@ static void read_wat_file(
fclose(file);
// Parse the wat into the binary wasm format
wasm_byte_vec_t error;
if (wasmtime_wat2wasm(&wat, bytes, &error) == 0) {
fprintf(stderr, "failed to parse wat %.*s\n", (int) error.size, error.data);
exit(1);
}
wasmtime_error_t *error = wasmtime_wat2wasm(&wat, bytes);
if (error != NULL)
exit_with_error("failed to parse wat", error, NULL);
wasm_byte_vec_delete(&wat);
}
static void print_trap(wasm_trap_t *trap) {
assert(trap != NULL);
wasm_message_t message;
wasm_trap_message(trap, &message);
fprintf(stderr, "failed to instantiate module %.*s\n", (int) message.size, message.data);
wasm_byte_vec_delete(&message);
wasm_trap_delete(trap);
static void exit_with_error(const char *message, wasmtime_error_t *error, wasm_trap_t *trap) {
fprintf(stderr, "error: %s\n", message);
wasm_byte_vec_t error_message;
if (error != NULL) {
wasmtime_error_message(error, &error_message);
wasmtime_error_delete(error);
} else {
wasm_trap_message(trap, &error_message);
wasm_trap_delete(trap);
}
fprintf(stderr, "%.*s\n", (int) error_message.size, error_message.data);
wasm_byte_vec_delete(&error_message);
exit(1);
}