win: Adds delay load hook to allow renaming exe.

Fix inherited by @piscisaureus's work:
 * nodejs/node#1251 and
 * nodejs/node#1266

Issue URL: #4.
PR URL: rvagg#5.

addon.gypi

@@ -1,7 +1,9 @@
 {
   'target_defaults': {
     'type': 'loadable_module',
+    'win_delay_load_hook': 'false',
     'product_prefix': '',
+
     'include_dirs': [
       '<(node_root_dir)/src',
       '<(node_root_dir)/deps/uv/include',
@@ -13,11 +15,34 @@
         'product_extension': 'node',
         'defines': [ 'BUILDING_NODE_EXTENSION' ],
       }],
+
       ['_type=="static_library"', {
         # set to `1` to *disable* the -T thin archive 'ld' flag.
         # older linkers don't support this flag.
         'standalone_static_library': '<(standalone_static_library)'
       }],
+
+      ['_win_delay_load_hook=="true"', {
+        # If the has the 'win_delay_load_hook' option set to 'true', link a
+        # delay-load hook into the DLL. That hook ensures that the addon
+        # will work regardless of whether the node/iojs binary is named
+        # node.exe, iojs.exe, or something else.
+        'conditions': [
+          [ 'OS=="win"', {
+            'sources': [
+              'src/win_delay_load_hook.c',
+            ],
+            'msvs_settings': {
+              'VCLinkerTool': {
+                'DelayLoadDLLs': [ 'iojs.exe', 'node.exe' ],
+                # Don't print a linker warning when no imports from either .exe
+                # are used.
+                'AdditionalOptions': [ '/ignore:4199' ],
+              },
+            },
+          }],
+        ],
+      }],
     ],
 
     'conditions': [

src/win_delay_load_hook.c

@@ -0,0 +1,32 @@
+/*
+ * When this file is linked to a DLL, it sets up a delay-load hook that
+ * intervenes when the DLL is trying to load 'node.exe' or 'iojs.exe'
+ * dynamically. Instead of trying to locate the .exe file it'll just return
+ * a handle to the process image.
+ *
+ * This allows compiled addons to work when node.exe or iojs.exe is renamed.
+ */
+
+#ifdef _MSC_VER
+
+#define WIN32_LEAN_AND_MEAN
+#include <windows.h>
+
+#include <delayimp.h>
+#include <string.h>
+
+static FARPROC WINAPI load_exe_hook(unsigned int event, DelayLoadInfo* info) {
+  if (event != dliNotePreLoadLibrary)
+    return NULL;
+
+  if (_stricmp(info->szDll, "iojs.exe") != 0 &&
+      _stricmp(info->szDll, "node.exe") != 0)
+    return NULL;
+
+  HMODULE m = GetModuleHandle(NULL);
+  return (FARPROC) m;
+}
+
+PfnDliHook __pfnDliNotifyHook2 = load_exe_hook;
+
+#endif