From 26b2e5dbb6301756644d6e4cf6ca9c49c00513d3 Mon Sep 17 00:00:00 2001
From: Nicolas Noble <nicolasnoble@users.noreply.github.com>
Date: Mon, 1 Nov 2021 12:09:59 -0700
Subject: [PATCH] win: fix build for mingw32 (#3340)

Commit e9c524aa from pull request https://github.com/libuv/libuv/pull/3149
introduced a hard dependency on `GetHostnameW`, which isn't declared
yet in mingw distributions (see
https://github.com/msys2/MINGW-packages/issues/9667).

This prevents the current version of libuv from building on many mingw
distributions, until such time the next version of mingw is released with
the correct definition for `GetHostnameW`, preventing a lot of projects
depending on libuv from building on mingw properly, as not all
distributions will update to head immediately anyway.

Instead of waiting, let's find the definition ourselves using
`GetProcAddress` and use the pointer instead.

PR-URL: https://github.com/libuv/libuv/pull/3340
---
 src/win/util.c   |  5 ++++-
 src/win/winapi.c | 10 ++++++++++
 src/win/winapi.h |  7 +++++++
 3 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/src/win/util.c b/src/win/util.c
index 88602c7e..33e874ac 100644
--- a/src/win/util.c
+++ b/src/win/util.c
@@ -1674,7 +1674,10 @@ int uv_os_gethostname(char* buffer, size_t* size) {
 
   uv__once_init(); /* Initialize winsock */
 
-  if (GetHostNameW(buf, UV_MAXHOSTNAMESIZE) != 0)
+  if (pGetHostNameW == NULL)
+    return UV_ENOSYS;
+
+  if (pGetHostNameW(buf, UV_MAXHOSTNAMESIZE) != 0)
     return uv_translate_sys_error(WSAGetLastError());
 
   convert_result = uv__convert_utf16_to_utf8(buf, -1, &utf8_str);
diff --git a/src/win/winapi.c b/src/win/winapi.c
index bb86ec8c..bf306cd8 100644
--- a/src/win/winapi.c
+++ b/src/win/winapi.c
@@ -45,12 +45,15 @@ sPowerRegisterSuspendResumeNotification pPowerRegisterSuspendResumeNotification;
 /* User32.dll function pointer */
 sSetWinEventHook pSetWinEventHook;
 
+/* ws2_32.dll function pointer */
+uv_sGetHostNameW pGetHostNameW;
 
 void uv_winapi_init(void) {
   HMODULE ntdll_module;
   HMODULE powrprof_module;
   HMODULE user32_module;
   HMODULE kernel32_module;
+  HMODULE ws2_32_module;
 
   ntdll_module = GetModuleHandleA("ntdll.dll");
   if (ntdll_module == NULL) {
@@ -134,4 +137,11 @@ void uv_winapi_init(void) {
     pSetWinEventHook = (sSetWinEventHook)
       GetProcAddress(user32_module, "SetWinEventHook");
   }
+
+  ws2_32_module = LoadLibraryA("ws2_32.dll");
+  if (ws2_32_module != NULL) {
+    pGetHostNameW = (uv_sGetHostNameW) GetProcAddress(
+        ws2_32_module,
+        "GetHostNameW");
+  }
 }
diff --git a/src/win/winapi.h b/src/win/winapi.h
index 0b66b563..d380bda4 100644
--- a/src/win/winapi.h
+++ b/src/win/winapi.h
@@ -4759,4 +4759,11 @@ extern sPowerRegisterSuspendResumeNotification pPowerRegisterSuspendResumeNotifi
 /* User32.dll function pointer */
 extern sSetWinEventHook pSetWinEventHook;
 
+/* ws2_32.dll function pointer */
+/* mingw doesn't have this definition, so let's declare it here locally */
+typedef int (WINAPI *uv_sGetHostNameW)
+            (PWSTR,
+             int);
+extern uv_sGetHostNameW pGetHostNameW;
+
 #endif /* UV_WIN_WINAPI_H_ */