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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

55
examples/gcd.c
View File

@@ -23,7 +23,7 @@ to tweak the `-lpthread` and such annotations.
#include <wasm.h>
#include <wasmtime.h>
static void print_trap(wasm_trap_t *trap);
static void exit_with_error(const char *message, wasmtime_error_t *error, wasm_trap_t *trap);
int main() {
int ret = 0;
@@ -51,23 +51,23 @@ int main() {
fclose(file);
// Parse the wat into the binary wasm format
wasm_byte_vec_t wasm, error;
if (wasmtime_wat2wasm(&wat, &wasm, &error) == 0) {
fprintf(stderr, "failed to parse wat %.*s\n", (int) error.size, error.data);
goto free_store;
}
wasm_byte_vec_t wasm;
wasmtime_error_t *error = wasmtime_wat2wasm(&wat, &wasm);
if (error != NULL)
exit_with_error("failed to parse wat", error, NULL);
wasm_byte_vec_delete(&wat);
// Compile and instantiate our module
wasm_module_t *module = wasm_module_new(store, &wasm);
wasm_module_t *module = NULL;
error = wasmtime_module_new(store, &wasm, &module);
if (module == NULL)
exit_with_error("failed to compile module", error, NULL);
wasm_byte_vec_delete(&wasm);
assert(module != NULL);
wasm_trap_t *trap = NULL;
wasm_instance_t *instance = wasm_instance_new(store, module, NULL, &trap);
if (instance == NULL) {
print_trap(trap);
goto free_module;
}
wasm_instance_t *instance = NULL;
error = wasmtime_instance_new(module, NULL, 0, &instance, &trap);
if (instance == NULL)
exit_with_error("failed to instantiate", error, trap);
// Lookup our `gcd` export function
wasm_extern_vec_t externs;
@@ -85,11 +85,9 @@ int main() {
params[0].of.i32 = a;
params[1].kind = WASM_I32;
params[1].of.i32 = b;
trap = wasm_func_call(gcd, params, results);
if (trap != NULL) {
print_trap(trap);
goto free_instance;
}
error = wasmtime_func_call(gcd, params, 2, results, 1, &trap);
if (error != NULL || trap != NULL)
exit_with_error("failed to call gcd", error, trap);
assert(results[0].kind == WASM_I32);
printf("gcd(%d, %d) = %d\n", a, b, results[0].of.i32);
@@ -97,22 +95,23 @@ int main() {
// Clean up after ourselves at this point
ret = 0;
free_instance:
wasm_extern_vec_delete(&externs);
wasm_instance_delete(instance);
free_module:
wasm_module_delete(module);
free_store:
wasm_store_delete(store);
wasm_engine_delete(engine);
return ret;
}
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);
} else {
wasm_trap_message(trap, &error_message);
}
fprintf(stderr, "%.*s\n", (int) error_message.size, error_message.data);
wasm_byte_vec_delete(&error_message);
exit(1);
}