qga-vss: Write hex value of error in log

QGA-VSS writes error using error_setg_win32_internal,
which call g_win32_error_message.

g_win32_error_message - translate a Win32 error code
(as returned by GetLastError()) into the corresponding message.

In the same time, we call error_setg_win32_internal with
error codes from different Windows componets like VSS or
Performance monitor that provides different codes and
can't be converted with g_win32_error_message. In this
case, the empty suffix will be returned so error will be
masked.

This commit directly add hex value of error code.

Reproduce:
 - Run QGA command: {"execute": "guest-fsfreeze-freeze-list", "arguments": {"mountpoints": ["D:"]}}

QGA error example:
 - before changes:
  {"error": {"class": "GenericError", "desc": "failed to add D: to snapshot set: "}}
 - after changes:
  {"error": {"class": "GenericError", "desc": "failed to add D: to snapshot set: Windows error 0x8004230e: "}}

Reviewed-by: Yan Vugenfirer <yvugenfi@redhat.com>
Link: https://lore.kernel.org/qemu-devel/20250825135311.138330-1-kkostiuk@redhat.com
Signed-off-by: Kostiantyn Kostiuk <kkostiuk@redhat.com>

1 files changed, 3 insertions, 2 deletions

diff --git a/qga/vss-win32/requester.cpp b/qga/vss-win32/requester.cpp
index bc260abb96..5615955b6f 100644
--- a/qga/vss-win32/requester.cpp
+++ b/qga/vss-win32/requester.cpp
@@ -28,8 +28,9 @@
 
 #define err_set(e, err, fmt, ...) {                                         \
     (e)->error_setg_win32_wrapper((e)->errp, __FILE__, __LINE__, __func__,  \
-                                   err, fmt, ## __VA_ARGS__);               \
-    qga_debug(fmt, ## __VA_ARGS__);                                         \
+                                   err, fmt ": Windows error 0x%lx",        \
+                                   ## __VA_ARGS__, err);                    \
+    qga_debug(fmt ": Windows error 0x%lx", ## __VA_ARGS__, err);            \
 }
 /* Bad idea, works only when (e)->errp != NULL: */
 #define err_is_set(e) ((e)->errp && *(e)->errp)