fix(runtime): fix Deno.hostname on windows (denoland#16530)

cli/tests/unit/os_test.ts

@@ -208,6 +208,18 @@ Deno.test(
  },
 );
 
+Deno.test(
+ { permissions: { run: [Deno.execPath()], read: true } },
+ // See https://github.com/denoland/deno/issues/16527
+ async function hostnameWithoutOtherNetworkUsages() {
+ const { stdout } = await Deno.spawn(Deno.execPath(), {
+ args: ["eval", "-p", "Deno.hostname()"],
+ });
+ const hostname = new TextDecoder().decode(stdout).trim();
+ assert(hostname.length > 0);
+ },
+);
+
 Deno.test({ permissions: { sys: false } }, function hostnamePerm() {
  assertThrows(() => {
  Deno.hostname();

runtime/ops/os/sys_info.rs

@@ -1,4 +1,6 @@
 // Copyright 2018-2022 the Deno authors. All rights reserved. MIT license.
+#[cfg(target_family = "windows")]
+use std::sync::Once;
 
 type LoadAvg = (f64, f64, f64);
 const DEFAULT_LOADAVG: LoadAvg = (0.0, 0.0, 0.0);
@@ -112,6 +114,9 @@ pub fn os_release() -> String {
  }
 }
 
+#[cfg(target_family = "windows")]
+static WINSOCKET_INIT: Once = Once::new();
+
 pub fn hostname() -> String {
  #[cfg(target_family = "unix")]
  // SAFETY: `sysconf` returns a system constant.
@@ -131,13 +136,25 @@ pub fn hostname() -> String {
  #[cfg(target_family = "windows")]
  {
  use std::ffi::OsString;
+ use std::mem;
  use std::os::windows::ffi::OsStringExt;
+ use winapi::shared::minwindef::MAKEWORD;
  use winapi::um::winsock2::GetHostNameW;
+ use winapi::um::winsock2::WSAStartup;
 
  let namelen = 256;
  let mut name: Vec<u16> = vec![0u16; namelen];
+ // Start winsock to make `GetHostNameW` work correctly
+ // https://github.com/retep998/winapi-rs/issues/296
+ WINSOCKET_INIT.call_once(|| unsafe {
+ let mut data = mem::zeroed();
+ let wsa_startup_result = WSAStartup(MAKEWORD(2, 2), &mut data);
+ if wsa_startup_result != 0 {
+ panic!("Failed to start winsocket");
+ }
+ });
  let err =
- // SAFETY: length of wide string is 256 chars or less. 
+ // SAFETY: length of wide string is 256 chars or less.
  // https://learn.microsoft.com/en-us/windows/win32/api/winsock2/nf-winsock2-gethostnamew
  unsafe { GetHostNameW(name.as_mut_ptr(), namelen as libc::c_int) };