Message ID | 20181016102627.18676-2-simon@rozman.si |
---|---|
State | Accepted |
Headers | show |
Series | [Openvpn-devel,1/5] Set output name to libopenvpnmsica.dll in MSVC builds too | expand |
Hi Simon,
This approach keeps 'goes in DLL' next to the function itself, which I like. If
you're interested, another possible approach here is to use .DEF files with
MSVC, which can also do symbol aliasing:
https://docs.microsoft.com/en-us/cpp/build/exporting-from-a-dll-using-def-files
I would expect mingw to support .DEF files as well, but I don't know.
Only x86 Win32 functions are actually __stdcall; x64, ARM32, and ARM64
all ignore the token because the architectural calling convention makes it
meaningless:
https://msdn.microsoft.com/en-us/library/zxk0tw93.aspx
This is why the names don't get mangled. Of course, it's then inconsistent.
Export name consistency is needed so CustomActions can reference the
export symbol name, right?
Jon
-----Original Message-----
From: Simon Rozman <simon@rozman.si>
Sent: Tuesday, October 16, 2018 3:26 AM
To: openvpn-devel@lists.sourceforge.net
Subject: [Openvpn-devel] [PATCH 2/5] Prevent __stdcall name mangling of MSVC
Using `extern "C" __declspec(dllexport) __stdcall`, Win32 MSVC compiler
exports the functions are as `_name@N`. Exporting functions using
`/EXPORT` linker flag allows us to specify exact function name.
Note: The 64-bit MSVC compiler does not exhibit `__stdcall` name-
mangling.
---
src/openvpnmsica/openvpnmsica.c | 12 ++++++++++++
src/openvpnmsica/openvpnmsica.h | 14 +++++++++++---
2 files changed, 23 insertions(+), 3 deletions(-)
diff --git a/src/openvpnmsica/openvpnmsica.c b/src/openvpnmsica/openvpnmsica.c
index 82333991..3b90ce05 100644
--- a/src/openvpnmsica/openvpnmsica.c
+++ b/src/openvpnmsica/openvpnmsica.c
@@ -145,6 +145,10 @@ openvpnmsica_setup_sequence_filename(
UINT __stdcall
FindTAPInterfaces(_In_ MSIHANDLE hInstall)
{
+#ifdef _MSC_VER
+#pragma comment(linker, DLLEXP_EXPORT)
+#endif
+
#ifdef _DEBUG
MessageBox(NULL, TEXT("Attach debugger!"), TEXT(__FUNCTION__) TEXT(" v") TEXT(PACKAGE_VERSION), MB_OK);
#endif
@@ -247,6 +251,10 @@ cleanup_CoInitialize:
UINT __stdcall
EvaluateTAPInterfaces(_In_ MSIHANDLE hInstall)
{
+#ifdef _MSC_VER
+#pragma comment(linker, DLLEXP_EXPORT)
+#endif
+
#ifdef _DEBUG
MessageBox(NULL, TEXT("Attach debugger!"), TEXT(__FUNCTION__) TEXT(" v") TEXT(PACKAGE_VERSION), MB_OK);
#endif
@@ -505,6 +513,10 @@ cleanup_exec_seq:
UINT __stdcall
ProcessDeferredAction(_In_ MSIHANDLE hInstall)
{
+#ifdef _MSC_VER
+#pragma comment(linker, DLLEXP_EXPORT)
+#endif
+
#ifdef _DEBUG
MessageBox(NULL, TEXT("Attach debugger!"), TEXT(__FUNCTION__) TEXT(" v") TEXT(PACKAGE_VERSION), MB_OK);
#endif
diff --git a/src/openvpnmsica/openvpnmsica.h b/src/openvpnmsica/openvpnmsica.h
index 3a64fbaa..bb8e28ec 100644
--- a/src/openvpnmsica/openvpnmsica.h
+++ b/src/openvpnmsica/openvpnmsica.h
@@ -55,6 +55,14 @@ extern DWORD openvpnmsica_tlsidx_session;
extern "C" {
#endif
+#ifdef __GNUC__
+#define DLLEXP_DECL __declspec(dllexport)
+#else
+#define DLLEXP_DECL
+#define DLLEXP_EXPORT "/EXPORT:"__FUNCTION__"="__FUNCDNAME__
+#endif
+
+
/**
* Find existing TAP interfaces and set TAPINTERFACES property with semicolon delimited list
* of installed TAP interface GUIDs.
@@ -64,7 +72,7 @@ extern "C" {
* @return ERROR_SUCCESS on success; An error code otherwise
* See: https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fmsdn.microsoft.com%2Fen-us%2Flibrary%2Fwindows%2Fdesktop%2Faa368072.aspx&data=02%7C01%7Cjkunkee%40microsoft.com%7C726e9ae5072942c989bf08d63351ec71%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C636752824301952450&sdata=BXt41C1200ZAAQBQBS7vOiAZ3MzuQGCVHaUuFhYwMCk%3D&reserved=0
*/
-__declspec(dllexport) UINT __stdcall
+DLLEXP_DECL UINT __stdcall
FindTAPInterfaces(_In_ MSIHANDLE hInstall);
@@ -77,7 +85,7 @@ FindTAPInterfaces(_In_ MSIHANDLE hInstall);
* @return ERROR_SUCCESS on success; An error code otherwise
* See: https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fmsdn.microsoft.com%2Fen-us%2Flibrary%2Fwindows%2Fdesktop%2Faa368072.aspx&data=02%7C01%7Cjkunkee%40microsoft.com%7C726e9ae5072942c989bf08d63351ec71%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C636752824301962454&sdata=vMBtU2AQPrfZ9xnbN4nYZfcAb2wNlIxLPqqYLwDtvUc%3D&reserved=0
*/
-__declspec(dllexport) UINT __stdcall
+DLLEXP_DECL UINT __stdcall
EvaluateTAPInterfaces(_In_ MSIHANDLE hInstall);
@@ -89,7 +97,7 @@ EvaluateTAPInterfaces(_In_ MSIHANDLE hInstall);
* @return ERROR_SUCCESS on success; An error code otherwise
* See: https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fmsdn.microsoft.com%2Fen-us%2Flibrary%2Fwindows%2Fdesktop%2Faa368072.aspx&data=02%7C01%7Cjkunkee%40microsoft.com%7C726e9ae5072942c989bf08d63351ec71%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C636752824301962454&sdata=vMBtU2AQPrfZ9xnbN4nYZfcAb2wNlIxLPqqYLwDtvUc%3D&reserved=0
*/
-__declspec(dllexport) UINT __stdcall
+DLLEXP_DECL UINT __stdcall
ProcessDeferredAction(_In_ MSIHANDLE hInstall);
#ifdef __cplusplus
Hi Jon, > This approach keeps 'goes in DLL' next to the function itself, which I > like. If you're interested, another possible approach here is to use > .DEF files with MSVC, which can also do symbol aliasing: > https://docs.microsoft.com/en-us/cpp/build/exporting-from-a-dll-using- > def-files > > I would expect mingw to support .DEF files as well, but I don't know. I did use .DEF file initially. However, when adopting the project to build with MinGW too, my limited knowledge in authoring Linux build systems didn't find a way to use .DEF files there. After some research, I have put the export declarations into the source code instead. It's ugly but it keeps both building systems happy and produces consistent DLL file. > Only x86 Win32 functions are actually __stdcall; x64, ARM32, and ARM64 > all ignore the token because the architectural calling convention makes > it > meaningless: > https://msdn.microsoft.com/en-us/library/zxk0tw93.aspx > > This is why the names don't get mangled. Of course, it's then > inconsistent. > > Export name consistency is needed so CustomActions can reference the > export symbol name, right? Exactly. That extra effort to prevent name mangling when compiling x86 DLL file pays off later when authoring MSI package. Otherwise, I would have had to introduce some "#if-s" in WiX to address different platform-specific function names. I had to pick my poison, and I choose to fix issues as close to the source as possible. Regards, Simon
Hi Jon, >> This approach keeps 'goes in DLL' next to the function itself, which I >> like. > > It's ugly but it keeps both building systems happy and produces consistent > DLL file. Fantastic. I'm sorry there isn't a more elegant solution, but I'm glad there's something that works. > I had to pick my poison, and I choose to fix issues as close to the source > as possible. Understood. Thanks for the explanation. Samuli, LGTM. Jon
Your patch has been applied to the master branch. "LGTM" from Jon (plus patch and explanation seem to make sense :-) ) commit 7d08c33cfc58eeb7286446c8d1ffd02939782332 Author: Simon Rozman Date: Tue Oct 16 12:26:24 2018 +0200 Prevent __stdcall name mangling of MSVC Acked-by: Jon Kunkee <jkunkee@microsoft.com> Message-Id: <20181016102627.18676-2-simon@rozman.si> URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg17765.html Signed-off-by: Gert Doering <gert@greenie.muc.de> -- kind regards, Gert Doering
diff --git a/src/openvpnmsica/openvpnmsica.c b/src/openvpnmsica/openvpnmsica.c index 82333991..3b90ce05 100644 --- a/src/openvpnmsica/openvpnmsica.c +++ b/src/openvpnmsica/openvpnmsica.c @@ -145,6 +145,10 @@ openvpnmsica_setup_sequence_filename( UINT __stdcall FindTAPInterfaces(_In_ MSIHANDLE hInstall) { +#ifdef _MSC_VER +#pragma comment(linker, DLLEXP_EXPORT) +#endif + #ifdef _DEBUG MessageBox(NULL, TEXT("Attach debugger!"), TEXT(__FUNCTION__) TEXT(" v") TEXT(PACKAGE_VERSION), MB_OK); #endif @@ -247,6 +251,10 @@ cleanup_CoInitialize: UINT __stdcall EvaluateTAPInterfaces(_In_ MSIHANDLE hInstall) { +#ifdef _MSC_VER +#pragma comment(linker, DLLEXP_EXPORT) +#endif + #ifdef _DEBUG MessageBox(NULL, TEXT("Attach debugger!"), TEXT(__FUNCTION__) TEXT(" v") TEXT(PACKAGE_VERSION), MB_OK); #endif @@ -505,6 +513,10 @@ cleanup_exec_seq: UINT __stdcall ProcessDeferredAction(_In_ MSIHANDLE hInstall) { +#ifdef _MSC_VER +#pragma comment(linker, DLLEXP_EXPORT) +#endif + #ifdef _DEBUG MessageBox(NULL, TEXT("Attach debugger!"), TEXT(__FUNCTION__) TEXT(" v") TEXT(PACKAGE_VERSION), MB_OK); #endif diff --git a/src/openvpnmsica/openvpnmsica.h b/src/openvpnmsica/openvpnmsica.h index 3a64fbaa..bb8e28ec 100644 --- a/src/openvpnmsica/openvpnmsica.h +++ b/src/openvpnmsica/openvpnmsica.h @@ -55,6 +55,14 @@ extern DWORD openvpnmsica_tlsidx_session; extern "C" { #endif +#ifdef __GNUC__ +#define DLLEXP_DECL __declspec(dllexport) +#else +#define DLLEXP_DECL +#define DLLEXP_EXPORT "/EXPORT:"__FUNCTION__"="__FUNCDNAME__ +#endif + + /** * Find existing TAP interfaces and set TAPINTERFACES property with semicolon delimited list * of installed TAP interface GUIDs. @@ -64,7 +72,7 @@ extern "C" { * @return ERROR_SUCCESS on success; An error code otherwise * See: https://msdn.microsoft.com/en-us/library/windows/desktop/aa368072.aspx */ -__declspec(dllexport) UINT __stdcall +DLLEXP_DECL UINT __stdcall FindTAPInterfaces(_In_ MSIHANDLE hInstall); @@ -77,7 +85,7 @@ FindTAPInterfaces(_In_ MSIHANDLE hInstall); * @return ERROR_SUCCESS on success; An error code otherwise * See: https://msdn.microsoft.com/en-us/library/windows/desktop/aa368072.aspx */ -__declspec(dllexport) UINT __stdcall +DLLEXP_DECL UINT __stdcall EvaluateTAPInterfaces(_In_ MSIHANDLE hInstall); @@ -89,7 +97,7 @@ EvaluateTAPInterfaces(_In_ MSIHANDLE hInstall); * @return ERROR_SUCCESS on success; An error code otherwise * See: https://msdn.microsoft.com/en-us/library/windows/desktop/aa368072.aspx */ -__declspec(dllexport) UINT __stdcall +DLLEXP_DECL UINT __stdcall ProcessDeferredAction(_In_ MSIHANDLE hInstall); #ifdef __cplusplus