[PATCH v3 0/4] QGA VSS Logging

[PATCH v3 0/4] QGA VSS Logging

[Konstantin Kostiuk]

Print all VSS error and trace to debugger and stderr.

v3 -> v2:
  Reformat few log lines
  Move G_GNUC_PRINTF attribute to the declaration

v2: https://patchew.org/QEMU/20230707083105.746811-1-kkostiuk@redhat.com/

v2 -> v1:
  Rename debug macro
  Move log code to function

v1: https://patchew.org/QEMU/20230705141205.525776-1-kkostiuk@redhat.com/


Konstantin Kostiuk (4):
  QGA VSS: Add wrapper to send log to debugger and stderr
  QGA VSS: Replace 'fprintf(stderr' with PRINT_DEBUG
  QGA VSS: Print error in err_set
  QGA VSS: Add log in functions begin/end

 qga/vss-win32/install.cpp   | 45 +++++++++++++++++++++++++++-----
 qga/vss-win32/meson.build   |  2 +-
 qga/vss-win32/provider.cpp  |  3 +++
 qga/vss-win32/requester.cpp | 51 ++++++++++++++++++++++++++++++++-----
 qga/vss-win32/vss-debug.cpp | 31 ++++++++++++++++++++++
 qga/vss-win32/vss-debug.h   | 25 ++++++++++++++++++
 6 files changed, 143 insertions(+), 14 deletions(-)
 create mode 100644 qga/vss-win32/vss-debug.cpp
 create mode 100644 qga/vss-win32/vss-debug.h

--
2.34.1

[PATCH v3 1/4] QGA VSS: Add wrapper to send log to debugger and stderr

[Konstantin Kostiuk]

Signed-off-by: Konstantin Kostiuk <kkostiuk@redhat.com>
---
 qga/vss-win32/meson.build   |  2 +-
 qga/vss-win32/vss-debug.cpp | 31 +++++++++++++++++++++++++++++++
 qga/vss-win32/vss-debug.h   | 25 +++++++++++++++++++++++++
 3 files changed, 57 insertions(+), 1 deletion(-)
 create mode 100644 qga/vss-win32/vss-debug.cpp
 create mode 100644 qga/vss-win32/vss-debug.h

diff --git a/qga/vss-win32/meson.build b/qga/vss-win32/meson.build
index 9483ccd3b8..0ac918910b 100644
--- a/qga/vss-win32/meson.build
+++ b/qga/vss-win32/meson.build
@@ -7,7 +7,7 @@ link_args = cc.get_supported_link_arguments([
 
 qga_vss = shared_module(
   'qga-vss',
-  ['requester.cpp', 'provider.cpp', 'install.cpp', genh],
+  ['requester.cpp', 'provider.cpp', 'install.cpp', 'vss-debug.cpp', genh],
   name_prefix: '',
   cpp_args: ['-Wno-unknown-pragmas', '-Wno-delete-non-virtual-dtor', '-Wno-non-virtual-dtor'],
   link_args: link_args,
diff --git a/qga/vss-win32/vss-debug.cpp b/qga/vss-win32/vss-debug.cpp
new file mode 100644
index 0000000000..5d6f37944b
--- /dev/null
+++ b/qga/vss-win32/vss-debug.cpp
@@ -0,0 +1,31 @@
+/*
+ * QEMU Guest Agent VSS debug declarations
+ *
+ * Copyright (C) 2023 Red Hat Inc
+ *
+ * Authors:
+ *  Konstantin Kostiuk <kkostiuk@redhat.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ */
+
+#include "qemu/osdep.h"
+#include "vss-debug.h"
+#include "vss-common.h"
+
+void qga_debug_internal(const char *funcname, const char *fmt, ...)  {
+    char user_sting[512] = {0};
+    char full_string[640] = {0};
+
+    va_list args;
+    va_start(args, fmt);
+    vsnprintf(user_sting, 512, fmt, args);
+    va_end(args);
+
+    snprintf(full_string, 640, QGA_PROVIDER_NAME "[%lu]: %s %s\n",
+             GetCurrentThreadId(), funcname, user_sting);
+
+    OutputDebugString(full_string);
+    fprintf(stderr, "%s", full_string);
+}
diff --git a/qga/vss-win32/vss-debug.h b/qga/vss-win32/vss-debug.h
new file mode 100644
index 0000000000..7800457392
--- /dev/null
+++ b/qga/vss-win32/vss-debug.h
@@ -0,0 +1,25 @@
+/*
+ * QEMU Guest Agent VSS debug declarations
+ *
+ * Copyright (C) 2023 Red Hat Inc
+ *
+ * Authors:
+ *  Konstantin Kostiuk <kkostiuk@redhat.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ */
+
+#include "qemu/osdep.h"
+#include <vss-handles.h>
+
+#ifndef VSS_DEBUG_H
+#define VSS_DEBUG_H
+
+void qga_debug_internal(const char *funcname, const char *fmt, ...) G_GNUC_PRINTF(2, 3);
+
+#define qga_debug(fmt, ...) qga_debug_internal(__func__, fmt, ## __VA_ARGS__)
+#define qga_debug_begin qga_debug("begin")
+#define qga_debug_end qga_debug("end")
+
+#endif
-- 
2.34.1

[PATCH v3 2/4] QGA VSS: Replace 'fprintf(stderr' with PRINT_DEBUG

[Konstantin Kostiuk]

Signed-off-by: Konstantin Kostiuk <kkostiuk@redhat.com>
---
 qga/vss-win32/install.cpp   | 12 ++++++------
 qga/vss-win32/requester.cpp |  9 +++++----
 2 files changed, 11 insertions(+), 10 deletions(-)

diff --git a/qga/vss-win32/install.cpp b/qga/vss-win32/install.cpp
index ff93b08a9e..9bd2c52b70 100644
--- a/qga/vss-win32/install.cpp
+++ b/qga/vss-win32/install.cpp
@@ -13,6 +13,7 @@
 #include "qemu/osdep.h"
 
 #include "vss-common.h"
+#include "vss-debug.h"
 #ifdef HAVE_VSS_SDK
 #include <vscoordint.h>
 #else
@@ -54,7 +55,7 @@ void errmsg(DWORD err, const char *text)
                   FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS,
                   NULL, err, MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
                   (char *)&msg, 0, NULL);
-    fprintf(stderr, "%.*s. (Error: %lx) %s\n", len, text, err, msg);
+    qga_debug("%.*s. (Error: %lx) %s\n", len, text, err, msg);
     LocalFree(msg);
 }
 
@@ -219,7 +220,7 @@ static HRESULT QGAProviderRemove(ICatalogCollection *coll, int i, void *arg)
 {
     HRESULT hr;
 
-    fprintf(stderr, "Removing COM+ Application: %s\n", QGA_PROVIDER_NAME);
+    qga_debug("Removing COM+ Application: %s", QGA_PROVIDER_NAME);
     chk(coll->Remove(i));
 out:
     return hr;
@@ -304,9 +305,8 @@ STDAPI COMRegister(void)
     }
     strcpy(tlbPath, dllPath);
     strcpy(tlbPath+n-3, "tlb");
-    fprintf(stderr, "Registering " QGA_PROVIDER_NAME ":\n");
-    fprintf(stderr, "  %s\n", dllPath);
-    fprintf(stderr, "  %s\n", tlbPath);
+    qga_debug("Registering " QGA_PROVIDER_NAME ": %s %s",
+              dllPath, tlbPath);
     if (!PathFileExists(tlbPath)) {
         hr = HRESULT_FROM_WIN32(ERROR_FILE_NOT_FOUND);
         errmsg(hr, "Failed to lookup tlb");
@@ -517,7 +517,7 @@ namespace _com_util
         }
 
         if (mbstowcs(bstr, ascii, len) == (size_t)-1) {
-            fprintf(stderr, "Failed to convert string '%s' into BSTR", ascii);
+            qga_debug("Failed to convert string '%s' into BSTR", ascii);
             bstr[0] = 0;
         }
         return bstr;
diff --git a/qga/vss-win32/requester.cpp b/qga/vss-win32/requester.cpp
index 3e998af4a8..e85b9bc633 100644
--- a/qga/vss-win32/requester.cpp
+++ b/qga/vss-win32/requester.cpp
@@ -12,6 +12,7 @@
 
 #include "qemu/osdep.h"
 #include "vss-common.h"
+#include "vss-debug.h"
 #include "requester.h"
 #include "install.h"
 #include <vswriter.h>
@@ -59,13 +60,13 @@ STDAPI requester_init(void)
         NULL, -1, NULL, NULL, RPC_C_AUTHN_LEVEL_PKT_PRIVACY,
         RPC_C_IMP_LEVEL_IDENTIFY, NULL, EOAC_NONE, NULL);
     if (FAILED(hr)) {
-        fprintf(stderr, "failed to CoInitializeSecurity (error %lx)\n", hr);
+        qga_debug("failed to CoInitializeSecurity (error %lx)", hr);
         return hr;
     }
 
     hLib = LoadLibraryA("VSSAPI.DLL");
     if (!hLib) {
-        fprintf(stderr, "failed to load VSSAPI.DLL\n");
+        qga_debug("failed to load VSSAPI.DLL");
         return HRESULT_FROM_WIN32(GetLastError());
     }
 
@@ -78,14 +79,14 @@ STDAPI requester_init(void)
 #endif
         );
     if (!pCreateVssBackupComponents) {
-        fprintf(stderr, "failed to get proc address from VSSAPI.DLL\n");
+        qga_debug("failed to get proc address from VSSAPI.DLL");
         return HRESULT_FROM_WIN32(GetLastError());
     }
 
     pVssFreeSnapshotProperties = (t_VssFreeSnapshotProperties)
         GetProcAddress(hLib, "VssFreeSnapshotProperties");
     if (!pVssFreeSnapshotProperties) {
-        fprintf(stderr, "failed to get proc address from VSSAPI.DLL\n");
+        qga_debug("failed to get proc address from VSSAPI.DLL");
         return HRESULT_FROM_WIN32(GetLastError());
     }
 
-- 
2.34.1

[PATCH v3 3/4] QGA VSS: Print error in err_set

[Konstantin Kostiuk]

Signed-off-by: Konstantin Kostiuk <kkostiuk@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
---
 qga/vss-win32/requester.cpp | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/qga/vss-win32/requester.cpp b/qga/vss-win32/requester.cpp
index e85b9bc633..f3eafacfc1 100644
--- a/qga/vss-win32/requester.cpp
+++ b/qga/vss-win32/requester.cpp
@@ -26,9 +26,11 @@
 
 #define DEFAULT_VSS_BACKUP_TYPE VSS_BT_FULL
 
-#define err_set(e, err, fmt, ...)                                           \
-    ((e)->error_setg_win32_wrapper((e)->errp, __FILE__, __LINE__, __func__, \
-                                   err, fmt, ## __VA_ARGS__))
+#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__);                                         \
+}
 /* Bad idea, works only when (e)->errp != NULL: */
 #define err_is_set(e) ((e)->errp && *(e)->errp)
 /* To lift this restriction, error_propagate(), like we do in QEMU code */
-- 
2.34.1

[PATCH v3 4/4] QGA VSS: Add log in functions begin/end

[Konstantin Kostiuk]

Signed-off-by: Konstantin Kostiuk <kkostiuk@redhat.com>
---
 qga/vss-win32/install.cpp   | 33 +++++++++++++++++++++++++++++++++
 qga/vss-win32/provider.cpp  |  3 +++
 qga/vss-win32/requester.cpp | 34 ++++++++++++++++++++++++++++++++++
 3 files changed, 70 insertions(+)

diff --git a/qga/vss-win32/install.cpp b/qga/vss-win32/install.cpp
index 9bd2c52b70..6865c04d8a 100644
--- a/qga/vss-win32/install.cpp
+++ b/qga/vss-win32/install.cpp
@@ -100,6 +100,8 @@ HRESULT put_Value(ICatalogObject *pObj, LPCWSTR name, T val)
 /* Lookup Administrators group name from winmgmt */
 static HRESULT GetAdminName(_bstr_t *name)
 {
+    qga_debug_begin;
+
     HRESULT hr;
     COMPointer<IWbemLocator> pLoc;
     COMPointer<IWbemServices> pSvc;
@@ -142,6 +144,7 @@ static HRESULT GetAdminName(_bstr_t *name)
     }
 
 out:
+    qga_debug_end;
     return hr;
 }
 
@@ -149,6 +152,8 @@ out:
 static HRESULT getNameByStringSID(
     const wchar_t *sid, LPWSTR buffer, LPDWORD bufferLen)
 {
+    qga_debug_begin;
+
     HRESULT hr = S_OK;
     PSID psid = NULL;
     SID_NAME_USE groupType;
@@ -168,6 +173,7 @@ static HRESULT getNameByStringSID(
     LocalFree(psid);
 
 out:
+    qga_debug_end;
     return hr;
 }
 
@@ -175,6 +181,8 @@ out:
 static HRESULT QGAProviderFind(
     HRESULT (*found)(ICatalogCollection *, int, void *), void *arg)
 {
+    qga_debug_begin;
+
     HRESULT hr;
     COMInitializer initializer;
     COMPointer<IUnknown> pUnknown;
@@ -205,12 +213,15 @@ static HRESULT QGAProviderFind(
     chk(pColl->SaveChanges(&n));
 
 out:
+    qga_debug_end;
     return hr;
 }
 
 /* Count QGA VSS provider in COM+ Application Catalog */
 static HRESULT QGAProviderCount(ICatalogCollection *coll, int i, void *arg)
 {
+    qga_debug_begin;
+
     (*(int *)arg)++;
     return S_OK;
 }
@@ -218,28 +229,35 @@ static HRESULT QGAProviderCount(ICatalogCollection *coll, int i, void *arg)
 /* Remove QGA VSS provider from COM+ Application Catalog Collection */
 static HRESULT QGAProviderRemove(ICatalogCollection *coll, int i, void *arg)
 {
+    qga_debug_begin;
     HRESULT hr;
 
     qga_debug("Removing COM+ Application: %s", QGA_PROVIDER_NAME);
     chk(coll->Remove(i));
 out:
+    qga_debug_end;
     return hr;
 }
 
 /* Unregister this module from COM+ Applications Catalog */
 STDAPI COMUnregister(void)
 {
+    qga_debug_begin;
+
     HRESULT hr;
 
     DllUnregisterServer();
     chk(QGAProviderFind(QGAProviderRemove, NULL));
 out:
+    qga_debug_end;
     return hr;
 }
 
 /* Register this module to COM+ Applications Catalog */
 STDAPI COMRegister(void)
 {
+    qga_debug_begin;
+
     HRESULT hr;
     COMInitializer initializer;
     COMPointer<IUnknown> pUnknown;
@@ -259,12 +277,14 @@ STDAPI COMRegister(void)
 
     if (!g_hinstDll) {
         errmsg(E_FAIL, "Failed to initialize DLL");
+        qga_debug_end;
         return E_FAIL;
     }
 
     chk(QGAProviderFind(QGAProviderCount, (void *)&count));
     if (count) {
         errmsg(E_ABORT, "QGA VSS Provider is already installed");
+        qga_debug_end;
         return E_ABORT;
     }
 
@@ -354,6 +374,7 @@ out:
         COMUnregister();
     }
 
+    qga_debug_end;
     return hr;
 }
 
@@ -369,6 +390,8 @@ STDAPI_(void) CALLBACK DLLCOMUnregister(HWND, HINSTANCE, LPSTR, int)
 
 static BOOL CreateRegistryKey(LPCTSTR key, LPCTSTR value, LPCTSTR data)
 {
+    qga_debug_begin;
+
     HKEY  hKey;
     LONG  ret;
     DWORD size;
@@ -389,6 +412,7 @@ static BOOL CreateRegistryKey(LPCTSTR key, LPCTSTR value, LPCTSTR data)
     RegCloseKey(hKey);
 
 out:
+    qga_debug_end;
     if (ret != ERROR_SUCCESS) {
         /* As we cannot printf within DllRegisterServer(), show a dialog. */
         errmsg_dialog(ret, "Cannot add registry", key);
@@ -400,6 +424,8 @@ out:
 /* Register this dll as a VSS provider */
 STDAPI DllRegisterServer(void)
 {
+    qga_debug_begin;
+
     COMInitializer initializer;
     COMPointer<IVssAdmin> pVssAdmin;
     HRESULT hr = E_FAIL;
@@ -478,12 +504,15 @@ out:
         DllUnregisterServer();
     }
 
+    qga_debug_end;
     return hr;
 }
 
 /* Unregister this VSS hardware provider from the system */
 STDAPI DllUnregisterServer(void)
 {
+    qga_debug_begin;
+
     TCHAR key[256];
     COMInitializer initializer;
     COMPointer<IVssAdmin> pVssAdmin;
@@ -501,6 +530,7 @@ STDAPI DllUnregisterServer(void)
     SHDeleteKey(HKEY_CLASSES_ROOT, key);
     SHDeleteKey(HKEY_CLASSES_ROOT, g_szProgid);
 
+    qga_debug_end;
     return S_OK; /* Uninstall should never fail */
 }
 
@@ -527,6 +557,8 @@ namespace _com_util
 /* Stop QGA VSS provider service using Winsvc API  */
 STDAPI StopService(void)
 {
+    qga_debug_begin;
+
     HRESULT hr = S_OK;
     SC_HANDLE manager = OpenSCManager(NULL, NULL, SC_MANAGER_ALL_ACCESS);
     SC_HANDLE service = NULL;
@@ -551,5 +583,6 @@ STDAPI StopService(void)
 out:
     CloseServiceHandle(service);
     CloseServiceHandle(manager);
+    qga_debug_end;
     return hr;
 }
diff --git a/qga/vss-win32/provider.cpp b/qga/vss-win32/provider.cpp
index 1b885e24ee..cc72e5ef1b 100644
--- a/qga/vss-win32/provider.cpp
+++ b/qga/vss-win32/provider.cpp
@@ -12,6 +12,7 @@
 
 #include "qemu/osdep.h"
 #include "vss-common.h"
+#include "vss-debug.h"
 #ifdef HAVE_VSS_SDK
 #include <vscoordint.h>
 #else
@@ -529,9 +530,11 @@ STDAPI DllCanUnloadNow()
 EXTERN_C
 BOOL WINAPI DllMain(HINSTANCE hinstDll, DWORD dwReason, LPVOID lpReserved)
 {
+    qga_debug("begin, reason = %lu", dwReason);
     if (dwReason == DLL_PROCESS_ATTACH) {
         g_hinstDll = hinstDll;
         DisableThreadLibraryCalls(hinstDll);
     }
+    qga_debug_end;
     return TRUE;
 }
diff --git a/qga/vss-win32/requester.cpp b/qga/vss-win32/requester.cpp
index f3eafacfc1..9884c65e70 100644
--- a/qga/vss-win32/requester.cpp
+++ b/qga/vss-win32/requester.cpp
@@ -57,6 +57,8 @@ static struct QGAVSSContext {
 
 STDAPI requester_init(void)
 {
+    qga_debug_begin;
+
     COMInitializer initializer; /* to call CoInitializeSecurity */
     HRESULT hr = CoInitializeSecurity(
         NULL, -1, NULL, NULL, RPC_C_AUTHN_LEVEL_PKT_PRIVACY,
@@ -92,11 +94,14 @@ STDAPI requester_init(void)
         return HRESULT_FROM_WIN32(GetLastError());
     }
 
+    qga_debug_end;
     return S_OK;
 }
 
 static void requester_cleanup(void)
 {
+    qga_debug_begin;
+
     if (vss_ctx.hEventFrozen) {
         CloseHandle(vss_ctx.hEventFrozen);
         vss_ctx.hEventFrozen = NULL;
@@ -118,10 +123,13 @@ static void requester_cleanup(void)
         vss_ctx.pVssbc = NULL;
     }
     vss_ctx.cFrozenVols = 0;
+    qga_debug_end;
 }
 
 STDAPI requester_deinit(void)
 {
+    qga_debug_begin;
+
     requester_cleanup();
 
     pCreateVssBackupComponents = NULL;
@@ -131,11 +139,14 @@ STDAPI requester_deinit(void)
         hLib = NULL;
     }
 
+    qga_debug_end;
     return S_OK;
 }
 
 static HRESULT WaitForAsync(IVssAsync *pAsync)
 {
+    qga_debug_begin;
+
     HRESULT ret, hr;
 
     do {
@@ -151,11 +162,14 @@ static HRESULT WaitForAsync(IVssAsync *pAsync)
         }
     } while (ret == VSS_S_ASYNC_PENDING);
 
+    qga_debug_end;
     return ret;
 }
 
 static void AddComponents(ErrorSet *errset)
 {
+    qga_debug_begin;
+
     unsigned int cWriters, i;
     VSS_ID id, idInstance, idWriter;
     BSTR bstrWriterName = NULL;
@@ -237,17 +251,21 @@ out:
     if (pComponent && info) {
         pComponent->FreeComponentInfo(info);
     }
+    qga_debug_end;
 }
 
 DWORD get_reg_dword_value(HKEY baseKey, LPCSTR subKey, LPCSTR valueName,
                           DWORD defaultData)
 {
+    qga_debug_begin;
+
     DWORD regGetValueError;
     DWORD dwordData;
     DWORD dataSize = sizeof(DWORD);
 
     regGetValueError = RegGetValue(baseKey, subKey, valueName, RRF_RT_DWORD,
                                    NULL, &dwordData, &dataSize);
+    qga_debug_end;
     if (regGetValueError  != ERROR_SUCCESS) {
         return defaultData;
     }
@@ -262,6 +280,8 @@ bool is_valid_vss_backup_type(VSS_BACKUP_TYPE vssBT)
 VSS_BACKUP_TYPE get_vss_backup_type(
     VSS_BACKUP_TYPE defaultVssBT = DEFAULT_VSS_BACKUP_TYPE)
 {
+    qga_debug_begin;
+
     VSS_BACKUP_TYPE vssBackupType;
 
     vssBackupType = static_cast<VSS_BACKUP_TYPE>(
@@ -269,6 +289,7 @@ VSS_BACKUP_TYPE get_vss_backup_type(
                                                 QGA_PROVIDER_REGISTRY_ADDRESS,
                                                 "VssOption",
                                                 defaultVssBT));
+    qga_debug_end;
     if (!is_valid_vss_backup_type(vssBackupType)) {
         return defaultVssBT;
     }
@@ -277,6 +298,8 @@ VSS_BACKUP_TYPE get_vss_backup_type(
 
 void requester_freeze(int *num_vols, void *mountpoints, ErrorSet *errset)
 {
+    qga_debug_begin;
+
     COMPointer<IVssAsync> pAsync;
     HANDLE volume;
     HRESULT hr;
@@ -292,6 +315,7 @@ void requester_freeze(int *num_vols, void *mountpoints, ErrorSet *errset)
 
     if (vss_ctx.pVssbc) { /* already frozen */
         *num_vols = 0;
+        qga_debug("finished, already frozen");
         return;
     }
 
@@ -449,6 +473,7 @@ void requester_freeze(int *num_vols, void *mountpoints, ErrorSet *errset)
         }
     }
 
+    qga_debug("preparing for backup");
     hr = vss_ctx.pVssbc->PrepareForBackup(pAsync.replace());
     if (SUCCEEDED(hr)) {
         hr = WaitForAsync(pAsync);
@@ -472,6 +497,7 @@ void requester_freeze(int *num_vols, void *mountpoints, ErrorSet *errset)
      * CQGAVssProvider::CommitSnapshots will kick vss_ctx.hEventFrozen
      * after the applications and filesystems are frozen.
      */
+    qga_debug("do snapshot set");
     hr = vss_ctx.pVssbc->DoSnapshotSet(&vss_ctx.pAsyncSnapshot);
     if (FAILED(hr)) {
         err_set(errset, hr, "failed to do snapshot set");
@@ -518,6 +544,7 @@ void requester_freeze(int *num_vols, void *mountpoints, ErrorSet *errset)
         *num_vols = vss_ctx.cFrozenVols = num_fixed_drives;
     }
 
+    qga_debug("end successful");
     return;
 
 out:
@@ -528,11 +555,14 @@ out:
 out1:
     requester_cleanup();
     CoUninitialize();
+
+    qga_debug_end;
 }
 
 
 void requester_thaw(int *num_vols, void *mountpints, ErrorSet *errset)
 {
+    qga_debug_begin;
     COMPointer<IVssAsync> pAsync;
 
     if (!vss_ctx.hEventThaw) {
@@ -541,6 +571,8 @@ void requester_thaw(int *num_vols, void *mountpints, ErrorSet *errset)
          * and no volumes must be frozen. We return without an error.
          */
         *num_vols = 0;
+        qga_debug("finished, no volumes were frozen");
+
         return;
     }
 
@@ -597,4 +629,6 @@ void requester_thaw(int *num_vols, void *mountpints, ErrorSet *errset)
 
     CoUninitialize();
     StopService();
+
+    qga_debug_end;
 }
-- 
2.34.1

Re: [PATCH v3 1/4] QGA VSS: Add wrapper to send log to debugger and stderr

[Philippe Mathieu-Daudé]

On 7/7/23 11:22, Konstantin Kostiuk wrote:
> Signed-off-by: Konstantin Kostiuk <kkostiuk@redhat.com>
> ---
>   qga/vss-win32/meson.build   |  2 +-
>   qga/vss-win32/vss-debug.cpp | 31 +++++++++++++++++++++++++++++++
>   qga/vss-win32/vss-debug.h   | 25 +++++++++++++++++++++++++
>   3 files changed, 57 insertions(+), 1 deletion(-)
>   create mode 100644 qga/vss-win32/vss-debug.cpp
>   create mode 100644 qga/vss-win32/vss-debug.h


> diff --git a/qga/vss-win32/vss-debug.cpp b/qga/vss-win32/vss-debug.cpp
> new file mode 100644
> index 0000000000..5d6f37944b
> --- /dev/null
> +++ b/qga/vss-win32/vss-debug.cpp
> @@ -0,0 +1,31 @@
> +/*
> + * QEMU Guest Agent VSS debug declarations
> + *
> + * Copyright (C) 2023 Red Hat Inc
> + *
> + * Authors:
> + *  Konstantin Kostiuk <kkostiuk@redhat.com>
> + *
> + * This work is licensed under the terms of the GNU GPL, version 2 or later.
> + * See the COPYING file in the top-level directory.
> + */
> +
> +#include "qemu/osdep.h"
> +#include "vss-debug.h"
> +#include "vss-common.h"
> +
> +void qga_debug_internal(const char *funcname, const char *fmt, ...)  {
> +    char user_sting[512] = {0};

"user_string"

> +    char full_string[640] = {0};
> +
> +    va_list args;
> +    va_start(args, fmt);
> +    vsnprintf(user_sting, 512, fmt, args);

ARRAY_SIZE(user_string)

> +    va_end(args);
> +
> +    snprintf(full_string, 640, QGA_PROVIDER_NAME "[%lu]: %s %s\n",
> +             GetCurrentThreadId(), funcname, user_sting);

if (snprintf() <= 0) { return; }

> +
> +    OutputDebugString(full_string);
> +    fprintf(stderr, "%s", full_string);

Format unused:

fputs(full_string, stderr);

> +}

With the changes:
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>

Re: [PATCH v3 2/4] QGA VSS: Replace 'fprintf(stderr' with PRINT_DEBUG

[Philippe Mathieu-Daudé]

On 7/7/23 11:22, Konstantin Kostiuk wrote:
> Signed-off-by: Konstantin Kostiuk <kkostiuk@redhat.com>
> ---
>   qga/vss-win32/install.cpp   | 12 ++++++------
>   qga/vss-win32/requester.cpp |  9 +++++----
>   2 files changed, 11 insertions(+), 10 deletions(-)


> @@ -304,9 +305,8 @@ STDAPI COMRegister(void)
>       }
>       strcpy(tlbPath, dllPath);
>       strcpy(tlbPath+n-3, "tlb");
> -    fprintf(stderr, "Registering " QGA_PROVIDER_NAME ":\n");
> -    fprintf(stderr, "  %s\n", dllPath);
> -    fprintf(stderr, "  %s\n", tlbPath);
> +    qga_debug("Registering " QGA_PROVIDER_NAME ": %s %s",
> +              dllPath, tlbPath);

Previous has 3 "\n", not necessary? Otherwise:

Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>

>       if (!PathFileExists(tlbPath)) {
>           hr = HRESULT_FROM_WIN32(ERROR_FILE_NOT_FOUND);
>           errmsg(hr, "Failed to lookup tlb");

Re: [PATCH v3 2/4] QGA VSS: Replace 'fprintf(stderr' with PRINT_DEBUG

[Konstantin Kostiuk]

[-- Attachment #1: Type: text/plain, Size: 1133 bytes --]

On Fri, Jul 7, 2023 at 1:34 PM Philippe Mathieu-Daudé <philmd@linaro.org>
wrote:

> On 7/7/23 11:22, Konstantin Kostiuk wrote:
> > Signed-off-by: Konstantin Kostiuk <kkostiuk@redhat.com>
> > ---
> >   qga/vss-win32/install.cpp   | 12 ++++++------
> >   qga/vss-win32/requester.cpp |  9 +++++----
> >   2 files changed, 11 insertions(+), 10 deletions(-)
>
>
> > @@ -304,9 +305,8 @@ STDAPI COMRegister(void)
> >       }
> >       strcpy(tlbPath, dllPath);
> >       strcpy(tlbPath+n-3, "tlb");
> > -    fprintf(stderr, "Registering " QGA_PROVIDER_NAME ":\n");
> > -    fprintf(stderr, "  %s\n", dllPath);
> > -    fprintf(stderr, "  %s\n", tlbPath);
> > +    qga_debug("Registering " QGA_PROVIDER_NAME ": %s %s",
> > +              dllPath, tlbPath);
>
> Previous has 3 "\n", not necessary? Otherwise:
>

I think 3 "\n" is not necessary. The line is still human-readable.


>
> Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
>
> >       if (!PathFileExists(tlbPath)) {
> >           hr = HRESULT_FROM_WIN32(ERROR_FILE_NOT_FOUND);
> >           errmsg(hr, "Failed to lookup tlb");
>
>
>

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Re: [PATCH v3 1/4] QGA VSS: Add wrapper to send log to debugger and stderr

[Konstantin Kostiuk]

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On Fri, Jul 7, 2023 at 1:33 PM Philippe Mathieu-Daudé <philmd@linaro.org>
wrote:

> On 7/7/23 11:22, Konstantin Kostiuk wrote:
> > Signed-off-by: Konstantin Kostiuk <kkostiuk@redhat.com>
> > ---
> >   qga/vss-win32/meson.build   |  2 +-
> >   qga/vss-win32/vss-debug.cpp | 31 +++++++++++++++++++++++++++++++
> >   qga/vss-win32/vss-debug.h   | 25 +++++++++++++++++++++++++
> >   3 files changed, 57 insertions(+), 1 deletion(-)
> >   create mode 100644 qga/vss-win32/vss-debug.cpp
> >   create mode 100644 qga/vss-win32/vss-debug.h
>
>
> > diff --git a/qga/vss-win32/vss-debug.cpp b/qga/vss-win32/vss-debug.cpp
> > new file mode 100644
> > index 0000000000..5d6f37944b
> > --- /dev/null
> > +++ b/qga/vss-win32/vss-debug.cpp
> > @@ -0,0 +1,31 @@
> > +/*
> > + * QEMU Guest Agent VSS debug declarations
> > + *
> > + * Copyright (C) 2023 Red Hat Inc
> > + *
> > + * Authors:
> > + *  Konstantin Kostiuk <kkostiuk@redhat.com>
> > + *
> > + * This work is licensed under the terms of the GNU GPL, version 2 or
> later.
> > + * See the COPYING file in the top-level directory.
> > + */
> > +
> > +#include "qemu/osdep.h"
> > +#include "vss-debug.h"
> > +#include "vss-common.h"
> > +
> > +void qga_debug_internal(const char *funcname, const char *fmt, ...)  {
> > +    char user_sting[512] = {0};
>
> "user_string"
>
> > +    char full_string[640] = {0};
> > +
> > +    va_list args;
> > +    va_start(args, fmt);
> > +    vsnprintf(user_sting, 512, fmt, args);
>
> ARRAY_SIZE(user_string)
>

I have a problem with ARRAY_SIZE define.

../qga/vss-win32/vss-debug.cpp: In function 'void qga_debug_internal(const
char*, const char*, ...)':
/src/include/qemu/compiler.h:70:12: error: types may not be defined in
'sizeof' expressions
   70 |     struct { \
      |            ^
/src/include/qemu/compiler.h:78:43: note: in expansion of macro
'QEMU_BUILD_BUG_ON_STRUCT'
   78 | #define QEMU_BUILD_BUG_ON_ZERO(x)
(sizeof(QEMU_BUILD_BUG_ON_STRUCT(x)) - \
      |                                           ^~~~~~~~~~~~~~~~~~~~~~~~
/src/include/qemu/osdep.h:474:24: note: in expansion of macro
'QEMU_BUILD_BUG_ON_ZERO'
  474 |                        QEMU_BUILD_BUG_ON_ZERO(!QEMU_IS_ARRAY(x)))
      |                        ^~~~~~~~~~~~~~~~~~~~~~
../qga/vss-win32/vss-debug.cpp:23:32: note: in expansion of macro
'ARRAY_SIZE'
   23 |     if (vsnprintf(user_string, ARRAY_SIZE(user_string), fmt, args)
<= 0) {
      |                                ^~~~~~~~~~
/src/include/qemu/osdep.h:470:57: error: expected primary-expression before
'typeof'
  470 | #define QEMU_IS_ARRAY(x) (!__builtin_types_compatible_p(typeof(x), \
      |                                                         ^~~~~~
/src/include/qemu/compiler.h:71:14: note: in definition of macro
'QEMU_BUILD_BUG_ON_STRUCT'
   71 |         int:(x) ? -1 : 1; \
      |              ^
/src/include/qemu/osdep.h:474:24: note: in expansion of macro
'QEMU_BUILD_BUG_ON_ZERO'
  474 |                        QEMU_BUILD_BUG_ON_ZERO(!QEMU_IS_ARRAY(x)))
      |                        ^~~~~~~~~~~~~~~~~~~~~~
/src/include/qemu/osdep.h:474:48: note: in expansion of macro
'QEMU_IS_ARRAY'
  474 |                        QEMU_BUILD_BUG_ON_ZERO(!QEMU_IS_ARRAY(x)))


Can you help with this?


> > +    va_end(args);
> > +
> > +    snprintf(full_string, 640, QGA_PROVIDER_NAME "[%lu]: %s %s\n",
> > +             GetCurrentThreadId(), funcname, user_sting);
>
> if (snprintf() <= 0) { return; }
>
> > +
> > +    OutputDebugString(full_string);
> > +    fprintf(stderr, "%s", full_string);
>
> Format unused:
>
> fputs(full_string, stderr);
>
> > +}
>
> With the changes:
> Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
>
>

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Re: [PATCH v3 1/4] QGA VSS: Add wrapper to send log to debugger and stderr

[Philippe Mathieu-Daudé]

On 7/7/23 16:24, Konstantin Kostiuk wrote:
> 
> 
> On Fri, Jul 7, 2023 at 1:33 PM Philippe Mathieu-Daudé <philmd@linaro.org 
> <mailto:philmd@linaro.org>> wrote:
> 
>     On 7/7/23 11:22, Konstantin Kostiuk wrote:
>      > Signed-off-by: Konstantin Kostiuk <kkostiuk@redhat.com
>     <mailto:kkostiuk@redhat.com>>
>      > ---
>      >   qga/vss-win32/meson.build   |  2 +-
>      >   qga/vss-win32/vss-debug.cpp | 31 +++++++++++++++++++++++++++++++
>      >   qga/vss-win32/vss-debug.h   | 25 +++++++++++++++++++++++++
>      >   3 files changed, 57 insertions(+), 1 deletion(-)
>      >   create mode 100644 qga/vss-win32/vss-debug.cpp
>      >   create mode 100644 qga/vss-win32/vss-debug.h
> 
> 
>      > diff --git a/qga/vss-win32/vss-debug.cpp
>     b/qga/vss-win32/vss-debug.cpp
>      > new file mode 100644
>      > index 0000000000..5d6f37944b
>      > --- /dev/null
>      > +++ b/qga/vss-win32/vss-debug.cpp
>      > @@ -0,0 +1,31 @@
>      > +/*
>      > + * QEMU Guest Agent VSS debug declarations
>      > + *
>      > + * Copyright (C) 2023 Red Hat Inc
>      > + *
>      > + * Authors:
>      > + *  Konstantin Kostiuk <kkostiuk@redhat.com
>     <mailto:kkostiuk@redhat.com>>
>      > + *
>      > + * This work is licensed under the terms of the GNU GPL, version
>     2 or later.
>      > + * See the COPYING file in the top-level directory.
>      > + */
>      > +
>      > +#include "qemu/osdep.h"
>      > +#include "vss-debug.h"
>      > +#include "vss-common.h"
>      > +
>      > +void qga_debug_internal(const char *funcname, const char *fmt,
>     ...)  {
>      > +    char user_sting[512] = {0};
> 
>     "user_string"
> 
>      > +    char full_string[640] = {0};
>      > +
>      > +    va_list args;
>      > +    va_start(args, fmt);
>      > +    vsnprintf(user_sting, 512, fmt, args);
> 
>     ARRAY_SIZE(user_string)
> 
> 
> I have a problem with ARRAY_SIZE define.
> 
> ../qga/vss-win32/vss-debug.cpp: In function 'void 
> qga_debug_internal(const char*, const char*, ...)':
> /src/include/qemu/compiler.h:70:12: error: types may not be defined in 
> 'sizeof' expressions
>     70 |     struct { \
>        |            ^
> /src/include/qemu/compiler.h:78:43: note: in expansion of macro 
> 'QEMU_BUILD_BUG_ON_STRUCT'
>     78 | #define QEMU_BUILD_BUG_ON_ZERO(x) 
> (sizeof(QEMU_BUILD_BUG_ON_STRUCT(x)) - \
>        |                                           ^~~~~~~~~~~~~~~~~~~~~~~~
> /src/include/qemu/osdep.h:474:24: note: in expansion of macro 
> 'QEMU_BUILD_BUG_ON_ZERO'
>    474 |                        QEMU_BUILD_BUG_ON_ZERO(!QEMU_IS_ARRAY(x)))
>        |                        ^~~~~~~~~~~~~~~~~~~~~~
> ../qga/vss-win32/vss-debug.cpp:23:32: note: in expansion of macro 
> 'ARRAY_SIZE'
>     23 |     if (vsnprintf(user_string, ARRAY_SIZE(user_string), fmt, 
> args) <= 0) {
>        |                                ^~~~~~~~~~
> /src/include/qemu/osdep.h:470:57: error: expected primary-expression 
> before 'typeof'
>    470 | #define QEMU_IS_ARRAY(x) 
> (!__builtin_types_compatible_p(typeof(x), \
>        |                                                         ^~~~~~
> /src/include/qemu/compiler.h:71:14: note: in definition of macro 
> 'QEMU_BUILD_BUG_ON_STRUCT'
>     71 |         int:(x) ? -1 : 1; \
>        |              ^
> /src/include/qemu/osdep.h:474:24: note: in expansion of macro 
> 'QEMU_BUILD_BUG_ON_ZERO'
>    474 |                        QEMU_BUILD_BUG_ON_ZERO(!QEMU_IS_ARRAY(x)))
>        |                        ^~~~~~~~~~~~~~~~~~~~~~
> /src/include/qemu/osdep.h:474:48: note: in expansion of macro 
> 'QEMU_IS_ARRAY'
>    474 |                        QEMU_BUILD_BUG_ON_ZERO(!QEMU_IS_ARRAY(x)))
> 
> Can you help with this?

Eh no clue, maybe not C++ compliant?

Fall back to sizeof() ¯\_(ツ)_/¯

> 
> 
>      > +    va_end(args);
>      > +
>      > +    snprintf(full_string, 640, QGA_PROVIDER_NAME "[%lu]: %s %s\n",
>      > +             GetCurrentThreadId(), funcname, user_sting);
> 
>     if (snprintf() <= 0) { return; }
> 
>      > +
>      > +    OutputDebugString(full_string);
>      > +    fprintf(stderr, "%s", full_string);
> 
>     Format unused:
> 
>     fputs(full_string, stderr);
> 
>      > +}
> 
>     With the changes:
>     Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org
>     <mailto:philmd@linaro.org>>
> 

Re: [PATCH v3 1/4] QGA VSS: Add wrapper to send log to debugger and stderr

[Konstantin Kostiuk]

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On Fri, Jul 7, 2023 at 6:36 PM Philippe Mathieu-Daudé <philmd@linaro.org>
wrote:

> On 7/7/23 16:24, Konstantin Kostiuk wrote:
> >
> >
> > On Fri, Jul 7, 2023 at 1:33 PM Philippe Mathieu-Daudé <philmd@linaro.org
> > <mailto:philmd@linaro.org>> wrote:
> >
> >     On 7/7/23 11:22, Konstantin Kostiuk wrote:
> >      > Signed-off-by: Konstantin Kostiuk <kkostiuk@redhat.com
> >     <mailto:kkostiuk@redhat.com>>
> >      > ---
> >      >   qga/vss-win32/meson.build   |  2 +-
> >      >   qga/vss-win32/vss-debug.cpp | 31 +++++++++++++++++++++++++++++++
> >      >   qga/vss-win32/vss-debug.h   | 25 +++++++++++++++++++++++++
> >      >   3 files changed, 57 insertions(+), 1 deletion(-)
> >      >   create mode 100644 qga/vss-win32/vss-debug.cpp
> >      >   create mode 100644 qga/vss-win32/vss-debug.h
> >
> >
> >      > diff --git a/qga/vss-win32/vss-debug.cpp
> >     b/qga/vss-win32/vss-debug.cpp
> >      > new file mode 100644
> >      > index 0000000000..5d6f37944b
> >      > --- /dev/null
> >      > +++ b/qga/vss-win32/vss-debug.cpp
> >      > @@ -0,0 +1,31 @@
> >      > +/*
> >      > + * QEMU Guest Agent VSS debug declarations
> >      > + *
> >      > + * Copyright (C) 2023 Red Hat Inc
> >      > + *
> >      > + * Authors:
> >      > + *  Konstantin Kostiuk <kkostiuk@redhat.com
> >     <mailto:kkostiuk@redhat.com>>
> >      > + *
> >      > + * This work is licensed under the terms of the GNU GPL, version
> >     2 or later.
> >      > + * See the COPYING file in the top-level directory.
> >      > + */
> >      > +
> >      > +#include "qemu/osdep.h"
> >      > +#include "vss-debug.h"
> >      > +#include "vss-common.h"
> >      > +
> >      > +void qga_debug_internal(const char *funcname, const char *fmt,
> >     ...)  {
> >      > +    char user_sting[512] = {0};
> >
> >     "user_string"
> >
> >      > +    char full_string[640] = {0};
> >      > +
> >      > +    va_list args;
> >      > +    va_start(args, fmt);
> >      > +    vsnprintf(user_sting, 512, fmt, args);
> >
> >     ARRAY_SIZE(user_string)
> >
> >
> > I have a problem with ARRAY_SIZE define.
> >
> > ../qga/vss-win32/vss-debug.cpp: In function 'void
> > qga_debug_internal(const char*, const char*, ...)':
> > /src/include/qemu/compiler.h:70:12: error: types may not be defined in
> > 'sizeof' expressions
> >     70 |     struct { \
> >        |            ^
> > /src/include/qemu/compiler.h:78:43: note: in expansion of macro
> > 'QEMU_BUILD_BUG_ON_STRUCT'
> >     78 | #define QEMU_BUILD_BUG_ON_ZERO(x)
> > (sizeof(QEMU_BUILD_BUG_ON_STRUCT(x)) - \
> >        |
> ^~~~~~~~~~~~~~~~~~~~~~~~
> > /src/include/qemu/osdep.h:474:24: note: in expansion of macro
> > 'QEMU_BUILD_BUG_ON_ZERO'
> >    474 |
>  QEMU_BUILD_BUG_ON_ZERO(!QEMU_IS_ARRAY(x)))
> >        |                        ^~~~~~~~~~~~~~~~~~~~~~
> > ../qga/vss-win32/vss-debug.cpp:23:32: note: in expansion of macro
> > 'ARRAY_SIZE'
> >     23 |     if (vsnprintf(user_string, ARRAY_SIZE(user_string), fmt,
> > args) <= 0) {
> >        |                                ^~~~~~~~~~
> > /src/include/qemu/osdep.h:470:57: error: expected primary-expression
> > before 'typeof'
> >    470 | #define QEMU_IS_ARRAY(x)
> > (!__builtin_types_compatible_p(typeof(x), \
> >        |                                                         ^~~~~~
> > /src/include/qemu/compiler.h:71:14: note: in definition of macro
> > 'QEMU_BUILD_BUG_ON_STRUCT'
> >     71 |         int:(x) ? -1 : 1; \
> >        |              ^
> > /src/include/qemu/osdep.h:474:24: note: in expansion of macro
> > 'QEMU_BUILD_BUG_ON_ZERO'
> >    474 |
>  QEMU_BUILD_BUG_ON_ZERO(!QEMU_IS_ARRAY(x)))
> >        |                        ^~~~~~~~~~~~~~~~~~~~~~
> > /src/include/qemu/osdep.h:474:48: note: in expansion of macro
> > 'QEMU_IS_ARRAY'
> >    474 |
>  QEMU_BUILD_BUG_ON_ZERO(!QEMU_IS_ARRAY(x)))
> >
> > Can you help with this?
>
> Eh no clue, maybe not C++ compliant?
>
> Fall back to sizeof() ¯\_(ツ)_/¯
>
>
You are right, When I rename the file to vss-debug.c the error disappears.
What is the better solution:
1) use vss-debug.c and extern "C" { #include "vss-debug.h" } in CPP files
2) just use sizeof() in CPP


> >
> >
> >      > +    va_end(args);
> >      > +
> >      > +    snprintf(full_string, 640, QGA_PROVIDER_NAME "[%lu]: %s
> %s\n",
> >      > +             GetCurrentThreadId(), funcname, user_sting);
> >
> >     if (snprintf() <= 0) { return; }
> >
> >      > +
> >      > +    OutputDebugString(full_string);
> >      > +    fprintf(stderr, "%s", full_string);
> >
> >     Format unused:
> >
> >     fputs(full_string, stderr);
> >
> >      > +}
> >
> >     With the changes:
> >     Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org
> >     <mailto:philmd@linaro.org>>
> >
>
>

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Re: [PATCH v3 1/4] QGA VSS: Add wrapper to send log to debugger and stderr

[Thomas Huth]

On 07/07/2023 22.22, Konstantin Kostiuk wrote:
> 
> 
> On Fri, Jul 7, 2023 at 6:36 PM Philippe Mathieu-Daudé <philmd@linaro.org 
> <mailto:philmd@linaro.org>> wrote:
> 
>     On 7/7/23 16:24, Konstantin Kostiuk wrote:
>      >
>      >
>      > On Fri, Jul 7, 2023 at 1:33 PM Philippe Mathieu-Daudé
>     <philmd@linaro.org <mailto:philmd@linaro.org>
>      > <mailto:philmd@linaro.org <mailto:philmd@linaro.org>>> wrote:
>      >
>      >     On 7/7/23 11:22, Konstantin Kostiuk wrote:
>      >      > Signed-off-by: Konstantin Kostiuk <kkostiuk@redhat.com
>     <mailto:kkostiuk@redhat.com>
>      >     <mailto:kkostiuk@redhat.com <mailto:kkostiuk@redhat.com>>>
>      >      > ---
>      >      >   qga/vss-win32/meson.build   |  2 +-
>      >      >   qga/vss-win32/vss-debug.cpp | 31 +++++++++++++++++++++++++++++++
>      >      >   qga/vss-win32/vss-debug.h   | 25 +++++++++++++++++++++++++
>      >      >   3 files changed, 57 insertions(+), 1 deletion(-)
>      >      >   create mode 100644 qga/vss-win32/vss-debug.cpp
>      >      >   create mode 100644 qga/vss-win32/vss-debug.h
>      >
>      >
>      >      > diff --git a/qga/vss-win32/vss-debug.cpp
>      >     b/qga/vss-win32/vss-debug.cpp
>      >      > new file mode 100644
>      >      > index 0000000000..5d6f37944b
>      >      > --- /dev/null
>      >      > +++ b/qga/vss-win32/vss-debug.cpp
>      >      > @@ -0,0 +1,31 @@
>      >      > +/*
>      >      > + * QEMU Guest Agent VSS debug declarations
>      >      > + *
>      >      > + * Copyright (C) 2023 Red Hat Inc
>      >      > + *
>      >      > + * Authors:
>      >      > + *  Konstantin Kostiuk <kkostiuk@redhat.com
>     <mailto:kkostiuk@redhat.com>
>      >     <mailto:kkostiuk@redhat.com <mailto:kkostiuk@redhat.com>>>
>      >      > + *
>      >      > + * This work is licensed under the terms of the GNU GPL, version
>      >     2 or later.
>      >      > + * See the COPYING file in the top-level directory.
>      >      > + */
>      >      > +
>      >      > +#include "qemu/osdep.h"
>      >      > +#include "vss-debug.h"
>      >      > +#include "vss-common.h"
>      >      > +
>      >      > +void qga_debug_internal(const char *funcname, const char *fmt,
>      >     ...)  {
>      >      > +    char user_sting[512] = {0};
>      >
>      >     "user_string"
>      >
>      >      > +    char full_string[640] = {0};
>      >      > +
>      >      > +    va_list args;
>      >      > +    va_start(args, fmt);
>      >      > +    vsnprintf(user_sting, 512, fmt, args);
>      >
>      >     ARRAY_SIZE(user_string)
>      >
>      >
>      > I have a problem with ARRAY_SIZE define.
>      >
>      > ../qga/vss-win32/vss-debug.cpp: In function 'void
>      > qga_debug_internal(const char*, const char*, ...)':
>      > /src/include/qemu/compiler.h:70:12: error: types may not be defined in
>      > 'sizeof' expressions
>      >     70 |     struct { \
>      >        |            ^
>      > /src/include/qemu/compiler.h:78:43: note: in expansion of macro
>      > 'QEMU_BUILD_BUG_ON_STRUCT'
>      >     78 | #define QEMU_BUILD_BUG_ON_ZERO(x)
>      > (sizeof(QEMU_BUILD_BUG_ON_STRUCT(x)) - \
>      >        |                                          
>     ^~~~~~~~~~~~~~~~~~~~~~~~
>      > /src/include/qemu/osdep.h:474:24: note: in expansion of macro
>      > 'QEMU_BUILD_BUG_ON_ZERO'
>      >    474 |                      
>       QEMU_BUILD_BUG_ON_ZERO(!QEMU_IS_ARRAY(x)))
>      >        |                        ^~~~~~~~~~~~~~~~~~~~~~
>      > ../qga/vss-win32/vss-debug.cpp:23:32: note: in expansion of macro
>      > 'ARRAY_SIZE'
>      >     23 |     if (vsnprintf(user_string, ARRAY_SIZE(user_string), fmt,
>      > args) <= 0) {
>      >        |                                ^~~~~~~~~~
>      > /src/include/qemu/osdep.h:470:57: error: expected primary-expression
>      > before 'typeof'
>      >    470 | #define QEMU_IS_ARRAY(x)
>      > (!__builtin_types_compatible_p(typeof(x), \
>      >        |                                                         ^~~~~~
>      > /src/include/qemu/compiler.h:71:14: note: in definition of macro
>      > 'QEMU_BUILD_BUG_ON_STRUCT'
>      >     71 |         int:(x) ? -1 : 1; \
>      >        |              ^
>      > /src/include/qemu/osdep.h:474:24: note: in expansion of macro
>      > 'QEMU_BUILD_BUG_ON_ZERO'
>      >    474 |                      
>       QEMU_BUILD_BUG_ON_ZERO(!QEMU_IS_ARRAY(x)))
>      >        |                        ^~~~~~~~~~~~~~~~~~~~~~
>      > /src/include/qemu/osdep.h:474:48: note: in expansion of macro
>      > 'QEMU_IS_ARRAY'
>      >    474 |                      
>       QEMU_BUILD_BUG_ON_ZERO(!QEMU_IS_ARRAY(x)))
>      >
>      > Can you help with this?
> 
>     Eh no clue, maybe not C++ compliant?
> 
>     Fall back to sizeof() ¯\_(ツ)_/¯
> 
> 
> You are right, When I rename the file to vss-debug.c the error disappears.
> What is the better solution:
> 1) use vss-debug.c and extern "C" { #include "vss-debug.h" } in CPP files
> 2) just use sizeof() in CPP

I recently sent a patch to drop the logic for linking C code with C++ code:

  https://lists.gnu.org/archive/html/qemu-devel/2023-07/msg01553.html

So please go with option 2 ;-)

  Thomas