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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
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45
examples/fib-debug/main.c
View File

@@ -8,6 +8,8 @@
#define own
static void exit_with_error(const char *message, wasmtime_error_t *error, wasm_trap_t *trap);
int main(int argc, const char* argv[]) {
// Configuring engine to support generating of DWARF info.
// lldb can be used to attach to the program and observe
@@ -40,11 +42,10 @@ int main(int argc, const char* argv[]) {
// Compile.
printf("Compiling module...\n");
own wasm_module_t* module = wasm_module_new(store, &binary);
if (!module) {
printf("> Error compiling module!\n");
return 1;
}
wasm_module_t *module = NULL;
wasmtime_error_t* error = wasmtime_module_new(store, &binary, &module);
if (!module)
exit_with_error("failed to compile module", error, NULL);
wasm_byte_vec_delete(&binary);
// Figure out which export is the `fib` export
@@ -68,12 +69,12 @@ int main(int argc, const char* argv[]) {
// Instantiate.
printf("Instantiating module...\n");
own wasm_instance_t* instance =
wasm_instance_new(store, module, NULL, NULL);
if (!instance) {
printf("> Error instantiating module!\n");
return 1;
}
wasm_instance_t* instance = NULL;
wasm_trap_t *trap = NULL;
error = wasmtime_instance_new(module, NULL, 0, &instance, &trap);
if (error != NULL || trap != NULL)
exit_with_error("failed to instantiate", error, trap);
wasm_module_delete(module);
// Extract export.
printf("Extracting export...\n");
@@ -84,23 +85,21 @@ int main(int argc, const char* argv[]) {
return 1;
}
// Getting second export (first is memory).
const wasm_func_t* run_func = wasm_extern_as_func(exports.data[fib_idx]);
wasm_func_t* run_func = wasm_extern_as_func(exports.data[fib_idx]);
if (run_func == NULL) {
printf("> Error accessing export!\n");
return 1;
}
wasm_module_delete(module);
wasm_instance_delete(instance);
// Call.
printf("Calling fib...\n");
wasm_val_t params[1] = { {.kind = WASM_I32, .of = {.i32 = 6}} };
wasm_val_t results[1];
if (wasm_func_call(run_func, params, results)) {
printf("> Error calling function!\n");
return 1;
}
error = wasmtime_func_call(run_func, params, 1, results, 1, &trap);
if (error != NULL || trap != NULL)
exit_with_error("failed to call function", error, trap);
wasm_extern_vec_delete(&exports);
@@ -116,3 +115,15 @@ int main(int argc, const char* argv[]) {
return 0;
}
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);
}