add wasi api path_filestat_get

Author: johnlanni

include/proxy-wasm/exports.h

@@ -155,6 +155,7 @@ Word wasi_unstable_clock_time_get(Word, uint64_t, Word);
 Word wasi_unstable_random_get(Word, Word);
 Word pthread_equal(Word left, Word right);
 void emscripten_notify_memory_growth(Word);
+Word wasi_unstable_path_filestat_get(Word fd, Word flags, Word path, Word path_len, Word buf);
 
 // Support for embedders, not exported to Wasm.
 
@@ -181,7 +182,7 @@ void emscripten_notify_memory_growth(Word);
   _f(fd_write) _f(fd_read) _f(fd_seek) _f(fd_close) _f(fd_fdstat_get) _f(fd_fdstat_set_flags)      \
       _f(environ_get) _f(environ_sizes_get) _f(args_get) _f(args_sizes_get) _f(clock_time_get)     \
           _f(random_get) _f(sched_yield) _f(poll_oneoff) _f(proc_exit) _f(path_open)               \
-              _f(fd_prestat_get) _f(fd_prestat_dir_name)
+              _f(fd_prestat_get) _f(fd_prestat_dir_name) _f(path_filestat_get)
 
 // Helpers to generate a stub to pass to VM, in place of a restricted proxy-wasm capability.
 #define _CREATE_PROXY_WASM_STUB(_fn)                                                               \

src/exports.cc

@@ -784,6 +784,14 @@ Word wasi_unstable_fd_close(Word /*fd*/) {
   return 0;
 }
 
+// __wasi_errno_t __wasi_path_filestat_get(__wasi_fd_t fd,__wasi_lookupflags_t flags,const char
+// *path,size_t path_len,__wasi_filestat_t *buf);
+
+Word wasi_unstable_path_filestat_get(Word /*fd*/, Word /*flags*/, Word /*path*/, Word /*path_len*/,
+                                     Word /*buf*/) {
+  return 58; // __WASI_ENOTSUP
+}
+
 // __wasi_errno_t __wasi_fd_fdstat_get(__wasi_fd_t fd, __wasi_fdstat_t *stat)
 Word wasi_unstable_fd_fdstat_get(Word fd, Word statOut) {
   // We will only support this interface on stdout and stderr

src/wasm.cc

@@ -416,7 +416,8 @@ void WasmBase::startVm(ContextBase *root_context) {
              "wasi_unstable.random_get", "wasi_snapshot_preview1.random_get",
              // Go runtime initialization
              "wasi_unstable.fd_fdstat_get", "wasi_snapshot_preview1.fd_fdstat_get",
-             "wasi_unstable.fd_fdstat_set_flags", "wasi_snapshot_preview1.fd_fdstat_set_flags"});
+             "wasi_unstable.fd_fdstat_set_flags", "wasi_snapshot_preview1.fd_fdstat_set_flags",
+             "wasi_unstable.path_filestat_get"});
   if (_initialize_) {
     // WASI reactor.
     _initialize_(root_context);