feat(go-sdk): add wasi hostcalls used by the Go SDK

The full Go sdk imports hostcalls not currently exported to the wasm
module, making the wasm module fail on instantiation. Per discussion
with the Go core maintainers, these functions do not need to be
implemented, but they must be present.

Signed-off-by: Matt Leon <mattleon@google.com>

include/proxy-wasm/exports.h

@@ -118,6 +118,8 @@ Word grpc_stream(Word service_ptr, Word service_size, Word service_name_ptr, Wor
 Word grpc_cancel(Word token);
 Word grpc_close(Word token);
 Word grpc_send(Word token, Word message_ptr, Word message_size, Word end_stream);
+Word secure_getenv(Word name);
+Word getpid();
 
 Word set_tick_period_milliseconds(Word tick_period_milliseconds);
 Word get_current_time_nanoseconds(Word result_uint64_ptr);
@@ -146,6 +148,12 @@ Word wasi_unstable_args_sizes_get(Word argc_ptr, Word argv_buf_size_ptr);
 void wasi_unstable_proc_exit(Word);
 Word wasi_unstable_clock_time_get(Word, uint64_t, Word);
 Word wasi_unstable_random_get(Word, Word);
+Word wasi_unstable_fd_filestat_get(Word fd, Word statOut);
+Word wasi_unstable_fd_readdir(Word fd, Word buf, Word buf_len, int64_t cookie, Word bufused);
+Word wasi_unstable_path_filestat_get(Word fd, Word flags, Word path, Word path_len, Word statOut);
+Word wasi_unstable_fd_fdstat_set_flags(Word fd, Word flags);
+Word wasi_unstable_sched_yield();
+Word wasi_unstable_poll_oneoff(Word in, Word out, Word nsubscriptions, Word nevents);
 Word pthread_equal(Word left, Word right);
 void emscripten_notify_memory_growth(Word);
 
@@ -163,7 +171,8 @@ void emscripten_notify_memory_growth(Word);
                                   _f(get_current_time_nanoseconds) _f(define_metric)               \
                                       _f(increment_metric) _f(record_metric) _f(get_metric)        \
                                           _f(set_effective_context) _f(done)                       \
-                                              _f(call_foreign_function)
+                                              _f(call_foreign_function) _f(getpid)                 \
+                                                  _f(secure_getenv)
 
 #define FOR_ALL_HOST_FUNCTIONS_ABI_SPECIFIC(_f)                                                    \
   _f(get_configuration) _f(continue_request) _f(continue_response) _f(clear_route_cache)           \
@@ -172,7 +181,9 @@ void emscripten_notify_memory_growth(Word);
 #define FOR_ALL_WASI_FUNCTIONS(_f)                                                                 \
   _f(fd_write) _f(fd_read) _f(fd_seek) _f(fd_close) _f(fd_fdstat_get) _f(environ_get)              \
       _f(environ_sizes_get) _f(args_get) _f(args_sizes_get) _f(clock_time_get) _f(random_get)      \
-          _f(proc_exit) _f(path_open) _f(fd_prestat_get) _f(fd_prestat_dir_name)
+          _f(proc_exit) _f(path_open) _f(fd_prestat_get) _f(fd_prestat_dir_name)                   \
+              _f(fd_filestat_get) _f(fd_readdir) _f(path_filestat_get) _f(fd_fdstat_set_flags)     \
+                  _f(sched_yield) _f(poll_oneoff)
 
 // Helpers to generate a stub to pass to VM, in place of a restricted proxy-wasm capability.
 #define _CREATE_PROXY_WASM_STUB(_fn)                                                               \

include/proxy-wasm/wasm_vm.h

@@ -111,6 +111,7 @@ using WasmCallback_WWl = Word (*)(Word, int64_t);
 using WasmCallback_WWlWW = Word (*)(Word, int64_t, Word, Word);
 using WasmCallback_WWm = Word (*)(Word, uint64_t);
 using WasmCallback_WWmW = Word (*)(Word, uint64_t, Word);
+using WasmCallback_WWWWlW = Word (*)(Word, Word, Word, int64_t, Word);
 using WasmCallback_WWWWWWllWW = Word (*)(Word, Word, Word, Word, Word, int64_t, int64_t, Word,
                                          Word);
 using WasmCallback_dd = double (*)(double);
@@ -130,8 +131,9 @@ using WasmCallback_dd = double (*)(double);
                                               _f(proxy_wasm::WasmCallback_WWlWW)                   \
                                                   _f(proxy_wasm::WasmCallback_WWm)                 \
                                                       _f(proxy_wasm::WasmCallback_WWmW)            \
-                                                          _f(proxy_wasm::WasmCallback_WWWWWWllWW)  \
-                                                              _f(proxy_wasm::WasmCallback_dd)
+                                                         _f(proxy_wasm::WasmCallback_WWWWlW)       \
+                                                            _f(proxy_wasm::WasmCallback_WWWWWWllWW)\
+                                                               _f(proxy_wasm::WasmCallback_dd)
 
 enum class Cloneable {
   NotCloneable,      // VMs can not be cloned and should be created from scratch.

src/exports.cc

@@ -885,6 +885,10 @@ void wasi_unstable_proc_exit(Word /*exit_code*/) {
   context->error("wasi_unstable proc_exit");
 }
 
+Word wasi_unstable_sched_yield() { return 0; }
+
+Word wasi_unstable_poll_oneoff(Word in, Word out, Word nsubscriptions, Word nevents) { return 0; }
+
 Word pthread_equal(Word left, Word right) { return static_cast<uint64_t>(left == right); }
 
 void emscripten_notify_memory_growth(Word /*memory_index*/) {}
@@ -925,5 +929,29 @@ Word get_log_level(Word result_level_uint32_ptr) {
   return WasmResult::Ok;
 }
 
+Word wasi_unstable_fd_fdstat_set_flags(Word fd, Word flags) {
+  // Don't support reading of any files.
+  return 52; // __WASI_ERRNO_ENOSYS
+}
+
+Word wasi_unstable_fd_filestat_get(Word fd, Word statOut) {
+  // Don't support reading of any files.
+  return 52; // __WASI_ERRNO_ENOSYS
+}
+
+Word wasi_unstable_fd_readdir(Word fd, Word buf, Word buf_len, int64_t cookie, Word bufused) {
+  // Don't support reading of any files.
+  return 52; // __WASI_ERRNO_ENOSYS
+}
+
+Word wasi_unstable_path_filestat_get(Word fd, Word flags, Word path, Word path_len, Word statOut) {
+  // Don't support reading of any files.
+  return 52; // __WASI_ERRNO_ENOSYS
+}
+
+Word secure_getenv(Word name) { return 0; }
+
+Word getpid() { return 4; }
+
 } // namespace exports
 } // namespace proxy_wasm

src/wasm.cc

@@ -109,6 +109,8 @@ void WasmBase::registerCallbacks() {
       "env", #_fn, &exports::_fn,                                                                  \
       &ConvertFunctionWordToUint32<decltype(exports::_fn),                                         \
                                    exports::_fn>::convertFunctionWordToUint32)
+  _REGISTER(secure_getenv);
+  _REGISTER(getpid);
   _REGISTER(pthread_equal);
   _REGISTER(emscripten_notify_memory_growth);
 #undef _REGISTER