On 12/16/25 1:53 AM, Kostiantyn Kostiuk wrote:
Hi
On Tue, Dec 16, 2025 at 8:26 AM Marc-André Lureau
<[email protected] <mailto:[email protected]>> wrote:
Hi
On Mon, Dec 15, 2025 at 8:57 PM <[email protected]
<mailto:[email protected]>> wrote:
From: Nguyen Dinh Phi <[email protected]
<mailto:[email protected]>>
Newer versions of MinGW-w64 provide ConvertStringToBSTR() in the
_com_util namespace via <comutil.h>. This causes a redefinition
error when building qemu-ga on Windows with these toolchains.
Add a meson check to detect whether ConvertStringToBSTR is already
available, and conditionally compile our fallback implementation
only when the system does not provide one.
Signed-off-by: Nguyen Dinh Phi <[email protected]
<mailto:[email protected]>>
---
meson.build | 12 ++++++++++++
qga/vss-win32/install.cpp | 2 ++
2 files changed, 14 insertions(+)
diff --git a/meson.build b/meson.build
index c5710a6a47..60a980e610 100644
--- a/meson.build
+++ b/meson.build
@@ -3299,6 +3299,18 @@ endif
# Detect host pointer size for the target configuration loop.
host_long_bits = cc.sizeof('void *') * 8
+# Detect if ConvertStringToBSTR has been defined in _com_util
namespace
+if host_os == 'windows'
+ has_convert_string_to_bstr = cxx.compiles('''
+ #include <comutil.h>
+ int main() {
+ BSTR b = _com_util::ConvertStringToBSTR("test");
+ return b ? 0 : 1;
+ }
+ ''')
+ config_host_data.set('CONFIG_CONVERT_STRING_TO_BSTR',
has_convert_string_to_bstr)
+endif
+
########################
# Target configuration #
########################
diff --git a/qga/vss-win32/install.cpp b/qga/vss-win32/install.cpp
index 7b25d9098b..5b7a8e9bc5 100644
--- a/qga/vss-win32/install.cpp
+++ b/qga/vss-win32/install.cpp
@@ -549,6 +549,7 @@ STDAPI DllUnregisterServer(void)
/* Support function to convert ASCII string into BSTR (used in
_bstr_t) */
+#ifndef CONFIG_CONVERT_STRING_TO_BSTR
I wonder if it could check __MINGW64_VERSION_MAJOR >= 14 instead of
adding a configure-time check.
@Peter Maydell <mailto:[email protected]> preferred to avoid
specific version-number checks.
See: https://gitlab.com/qemu-project/qemu/-/issues/3217#note_2935451782
<https://gitlab.com/qemu-project/qemu/-/issues/3217#note_2935451782>
I also preferred the idea of checking the real function present instead
of the version of the component.
Reviewed-by: Kostiantyn Kostiuk <[email protected]
<mailto:[email protected]>>
lgtm anyway
Reviewed-by: Marc-André Lureau <[email protected]
<mailto:[email protected]>>
namespace _com_util
{
BSTR WINAPI ConvertStringToBSTR(const char *ascii) {
@@ -566,6 +567,7 @@ namespace _com_util
return bstr;
}
}
+#endif
/* Stop QGA VSS provider service using Winsvc API */
STDAPI StopService(void)
--
2.43.0
When cross-compiling using fedora-win64-cross, it can find the function
in header but does not link it.
$ podman run --pull newer --init --rm -it -v $(pwd):$(pwd) -w $(pwd) \
docker.io/pbolinaro/qemu-ci:fedora-win64-cross \
bash -cx './configure $QEMU_CONFIGURE_OPTS && ninja -C build install'
...
[4434/4696] Linking target qga/vss-win32/qga-vss.dll
FAILED: qga/vss-win32/qga-vss.dll
x86_64-w64-mingw32-g++ -m64 -o qga/vss-win32/qga-vss.dll
qga/vss-win32/qga-vss.dll.p/requester.cpp.obj
qga/vss-win32/qga-vss.dll.p/provider.cpp.obj
qga/vss-win32/qga-vss.dll.p/install.cpp.obj
qga/vss-win32/qga-vss.dll.p/vss-debug.cpp.obj
-Wl,--allow-shlib-undefined -shared ../qga/vss-win32/qga-vss.def
-Wl,--start-group -Wl,--out-implib=qga/vss-win32/qga-vss.dll.a
-fstack-protector-strong -Wl,--no-seh -Wl,--nxcompat -Wl,--dynamicbase
-Wl,--high-entropy-va -fstack-protector-all -fstack-protector-strong
-Wl,--add-stdcall-alias -Wl,--enable-stdcall-fixup -lws2_32 -lole32
-loleaut32 -lshlwapi -luuid -lkernel32 -luser32 -lgdi32 -lwinspool
-lshell32 -lcomdlg32 -ladvapi32 -Wl,--end-group
/usr/lib/gcc/x86_64-w64-mingw32/14.2.1/../../../../x86_64-w64-mingw32/bin/ld:
qga/vss-win32/qga-vss.dll.p/install.cpp.obj: in function
`_bstr_t::Data_t::Data_t(char const*)':
/usr/x86_64-w64-mingw32/sys-root/mingw/include/comutil.h:279:(.text+0x1dc8):
undefined reference to `_com_util::ConvertStringToBSTR(char const*)'
...
Looking into mingw files, the symbol is not there.
$ nm /usr/x86_64-w64-mingw32/sys-root/mingw/lib/lib*.a |
grep -i ConvertStringToBSTR
It's present in header file though:
/usr/x86_64-w64-mingw32/sys-root/mingw/include/comutil.h
Not sure if something is missing in mingw, or if it's missing an
attribute to say it should be available at runtime only, but in all
cases, a simple fix to the patch is:
diff --git a/meson.build b/meson.build
index ab19317f5af..113296544c4 100644
--- a/meson.build
+++ b/meson.build
@@ -3261,7 +3261,7 @@ host_long_bits = cc.sizeof('void *') * 8
# Detect if ConvertStringToBSTR has been defined in _com_util namespace
if host_os == 'windows'
- has_convert_string_to_bstr = cxx.compiles('''
+ has_convert_string_to_bstr = cxx.links('''
#include <comutil.h>
int main() {
BSTR b = _com_util::ConvertStringToBSTR("test");
I would recommend to use cxx.links instead of cxx.compiles for now.
Regards,
Pierrick
