27 Aug
2012
27 Aug
'12
1:45 p.m.
Hi.
Please see the inlined answers.
Timo Kreuzer a écrit :
Hi,
I don't agree with these changes.
If we need a DllEntry in the lib, then we should use the one that is
provided by mingw-w64 (all this code is 100% mingw-w64). It simply
returns true (thats exactly what the one in MS CRT does) and works for
gcc and MSVC.
There is DllEntryPoint in the code base, but no DllMain. Is it what
you
are talking about?
Also what's the point of
DisableThreadLibraryCalls() here? As you wrote
yourself, no DllMain only means "I have nothing more to initialize than
the CRT". But this disables the CRT thread initializion, too.
You have a
point. If nothing is given, then the programmer could assume
that nothing happens.
Regarding CRT thread initialization: DisableThreadLibraryCalls means
that the DLLs ahs nothing to initialize on thread creation, and that the
loader can gain some performance in skipping this DLL. We have some Dlls
that call it, and if this is a problem with our CRT, then this is bad.
Quoting MSDN:
"Do not call this function from a DLL that is linked to the static C
run-time library (CRT). The static CRT requires DLL_THREAD_ATTACH and
DLL_THREAD_DETATCH notifications to function properly"
Reading between the lines, that means that every CRT thread
initialization is done in msvcrt.dll, and nowhere else. What we link
statically to our DLLs shouldn't have anything to do on thread
initializations.
There is also no need for weak symbols, we can simply
call the stub
DllMain, since it doesn't (shouldn't) do anything.
As said in the comment,
link.exe choses symbols defined in the object
files it is given, and then in the libraries. So adding a stubbed
version of dllmain in our library is harmless (unless someone puts his
DllMain in a static library and links to that library.) I don't really
know about ld behaviour regarding this case, and the
"--allow-multiple-definition" option of ld (see
http://sourceware.org/binutils/docs-2.22/ld/Options.html#Options )
scares me.
Regards,
Timo
Regards.
Jérôme
Am 27.08.2012 01:31, schrieb jgardou(a)svn.reactos.org:
Author: jgardou
Date: Sun Aug 26 23:31:49 2012
New Revision: 57171
URL: http://svn.reactos.org/svn/reactos?rev=57171&view=rev
Log:
[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".
Added:
trunk/reactos/lib/sdk/crt/startup/mscdllmain.c (with props)
Modified:
trunk/reactos/lib/sdk/crt/msvcrtex.cmake
trunk/reactos/lib/sdk/crt/startup/crtdll.c
Modified: trunk/reactos/lib/sdk/crt/msvcrtex.cmake
URL:
http://svn.reactos.org/svn/reactos/trunk/reactos/lib/sdk/crt/msvcrtex.cmake…
==============================================================================
--- trunk/reactos/lib/sdk/crt/msvcrtex.cmake [iso-8859-1] (original)
+++ trunk/reactos/lib/sdk/crt/msvcrtex.cmake [iso-8859-1] Sun Aug 26
23:31:49 2012
@@ -66,7 +66,9 @@
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()
Modified: trunk/reactos/lib/sdk/crt/startup/crtdll.c
URL:
http://svn.reactos.org/svn/reactos/trunk/reactos/lib/sdk/crt/startup/crtdll…
==============================================================================
--- trunk/reactos/lib/sdk/crt/startup/crtdll.c [iso-8859-1] (original)
+++ trunk/reactos/lib/sdk/crt/startup/crtdll.c [iso-8859-1] Sun Aug 26
23:31:49 2012
@@ -50,7 +50,19 @@
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 @@
}
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);
}
Added: trunk/reactos/lib/sdk/crt/startup/mscdllmain.c
URL:
http://svn.reactos.org/svn/reactos/trunk/reactos/lib/sdk/crt/startup/mscdll…
==============================================================================
--- trunk/reactos/lib/sdk/crt/startup/mscdllmain.c (added)
+++ trunk/reactos/lib/sdk/crt/startup/mscdllmain.c [iso-8859-1] Sun
Aug 26 23:31:49 2012
@@ -1,0 +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;
+}
Propchange: trunk/reactos/lib/sdk/crt/startup/mscdllmain.c
------------------------------------------------------------------------------
svn:eol-style = native
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