From dec26d780478e2f77bd2a41d14065418a23407ca Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?J=C3=A9r=C3=B4me=20Gardou?= <jerome.gardou@reactos.org>
Date: Sun, 26 Aug 2012 23:31:49 +0000
Subject: [PATCH] [MINGWEX] - mark DllMain as a weak symbol for GCC. - supply a
 stubbed DllMain for MSVC. - DllMain is optional, and some DLLs don't
 implement it. That doesn't mean that they have no entry point, it means "I
 have nothing more to initialize than the CRT".

svn path=/trunk/; revision=57171
---
 reactos/lib/sdk/crt/msvcrtex.cmake       |  4 +++-
 reactos/lib/sdk/crt/startup/crtdll.c     | 18 ++++++++++++++++--
 reactos/lib/sdk/crt/startup/mscdllmain.c | 11 +++++++++++
 3 files changed, 30 insertions(+), 3 deletions(-)
 create mode 100644 reactos/lib/sdk/crt/startup/mscdllmain.c

diff --git a/reactos/lib/sdk/crt/msvcrtex.cmake b/reactos/lib/sdk/crt/msvcrtex.cmake
index bf48060f62d..fb99ca0700d 100644
--- a/reactos/lib/sdk/crt/msvcrtex.cmake
+++ b/reactos/lib/sdk/crt/msvcrtex.cmake
@@ -66,7 +66,9 @@ elseif(ARCH MATCHES amd64)
 endif()
 
 if(MSVC)
-    list(APPEND MSVCRTEX_SOURCE startup/mscmain.c)
+    list(APPEND MSVCRTEX_SOURCE 
+        startup/mscmain.c
+        startup/mscdllmain.c)
 else()
     list(APPEND MSVCRTEX_SOURCE startup/gccmain.c)
 endif()
diff --git a/reactos/lib/sdk/crt/startup/crtdll.c b/reactos/lib/sdk/crt/startup/crtdll.c
index ed3a73fd51d..019a834cf3c 100644
--- a/reactos/lib/sdk/crt/startup/crtdll.c
+++ b/reactos/lib/sdk/crt/startup/crtdll.c
@@ -50,7 +50,19 @@ extern _PVFV *__onexitend;
 
 extern int mingw_app_type;
 
+/* 
+ * It is possible that a DLL provides no DllMain entry point.
+ * Mark it as a weak symbol for GCC.
+ * Tests show that at link time, MSVC looks for a function first in the object files provided, and then
+ * in the libraries. This means that we must provide a basic implementation in msvcrtex, which will be used 
+ * if none is found in the object files provided to link.exe.
+ * This also means that we can't rely on a DllMain function implemented in a static library when linking a DLL.
+ */
+#ifdef __GNUC__
+extern WINBOOL WINAPI DllMain (HANDLE hDllHandle, DWORD dwReason, LPVOID lpreserved) __attribute__((weak));
+#else
 extern WINBOOL WINAPI DllMain (HANDLE hDllHandle, DWORD dwReason, LPVOID lpreserved);
+#endif
 
 extern WINBOOL WINAPI DllEntryPoint (HANDLE, DWORD, LPVOID);
 
@@ -198,10 +210,12 @@ __DllMainCRTStartup (HANDLE hDllHandle, DWORD dwReason, LPVOID lpreserved)
     }
   if (dwReason == DLL_PROCESS_ATTACH)
     __main ();
-  retcode = DllMain(hDllHandle,dwReason,lpreserved);
+  if(DllMain)
+    retcode = DllMain(hDllHandle,dwReason,lpreserved);
   if (dwReason == DLL_PROCESS_ATTACH && ! retcode)
     {
-	DllMain (hDllHandle, DLL_PROCESS_DETACH, lpreserved);
+    if(DllMain)
+	  DllMain (hDllHandle, DLL_PROCESS_DETACH, lpreserved);
 	DllEntryPoint (hDllHandle, DLL_PROCESS_DETACH, lpreserved);
 	_CRT_INIT (hDllHandle, DLL_PROCESS_DETACH, lpreserved);
     }
diff --git a/reactos/lib/sdk/crt/startup/mscdllmain.c b/reactos/lib/sdk/crt/startup/mscdllmain.c
new file mode 100644
index 00000000000..721e9457ab5
--- /dev/null
+++ b/reactos/lib/sdk/crt/startup/mscdllmain.c
@@ -0,0 +1,11 @@
+#include <oscalls.h>
+#define _DECL_DLLMAIN
+#include <process.h>
+
+WINBOOL WINAPI DllMain (HANDLE hDllHandle, DWORD dwReason, LPVOID lpreserved)
+{
+    /* If the DLL provides no DllMain, then chances are that it doesn't bother with thread initialization */
+    if(dwReason == DLL_PROCESS_ATTACH)
+        DisableThreadLibraryCalls(hDllHandle);
+    return TRUE;
+}