Fix building ASAN instrumented executables with custom entrypoints

chrome/installer/mini_installer/mini_installer.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // mini_installer.exe is the first exe that is run when chrome is being
 // installed or upgraded. It is designed to be extremely small (~5KB with no
 // extra resources linked) and it has two main jobs:
 //   1) unpack the resources (possibly decompressing some)
 //   2) run the real installer (setup.exe) with appropriate flags.
 //
 // In order to be really small the app doesn't link against the CRT and
 // defines the following compiler/linker flags:
 //   EnableIntrinsicFunctions="true" compiler: /Oi
 //   BasicRuntimeChecks="0"
 //   BufferSecurityCheck="false" compiler: /GS-
 //   EntryPointSymbol="MainEntryPoint" linker: /ENTRY
 //   IgnoreAllDefaultLibraries="true" linker: /NODEFAULTLIB
-//   OptimizeForWindows98="1"  liker: /OPT:NOWIN98
+//   OptimizeForWindows98="1" linker: /OPT:NOWIN98
 //   linker: /SAFESEH:NO
 
 // have the linker merge the sections, saving us ~500 bytes.
 #pragma comment(linker, "/MERGE:.rdata=.text")
 
 #include <windows.h>
 
 // #define needed to link in RtlGenRandom(), a.k.a. SystemFunction036.  See the
 // "Community Additions" comment on MSDN here:
 // http://msdn.microsoft.com/en-us/library/windows/desktop/aa387694.aspx
@@ skipping 859 matching lines @@
 
 }  // namespace mini_installer
 
 int MainEntryPoint() {
   mini_installer::ProcessExitResult result =
       mini_installer::WMain(::GetModuleHandle(NULL));
 
   ::ExitProcess(result.exit_code);
 }
 
+#if defined(ADDRESS_SANITIZER)
+// Executables instrumented with ASAN need CRT functions. We do not use
+// the /ENTRY switch for ASAN instrumented executable and a "main" function
+// is required.
+int WINAPI WinMain(HINSTANCE hInstance,
+                   HINSTANCE hPrevInstance,
+                   LPSTR lpCmdLine,
+                   int nCmdShow) {
+  MainEntryPoint();
+  return 0;
+}
+#endif
+
 // VC Express editions don't come with the memset CRT obj file and linking to
 // the obj files between versions becomes a bit problematic. Therefore,
 // simply implement memset.
 //
 // This also avoids having to explicitly set the __sse2_available hack when
 // linking with both the x64 and x86 obj files which is required when not
 // linking with the std C lib in certain instances (including Chromium) with
 // MSVC.  __sse2_available determines whether to use SSE2 intructions with
 // std C lib routines, and is set by MSVC's std C lib implementation normally.
 extern "C" {
 #pragma function(memset)
 void* memset(void* dest, int c, size_t count) {
   void* start = dest;
   while (count--) {
     *reinterpret_cast<char*>(dest) = static_cast<char>(c);
     dest = reinterpret_cast<char*>(dest) + 1;
   }
   return start;
 }
 }  // extern "C"