[PATCH v2 1/3] secur32: Improve NameSamCompatible format in GetUserNameExW.

[Maxim Karasev]

From: Maxim Karasev

---
 dlls/secur32/secur32.c | 60 +++++++++++++++++++++++++++---------------
 1 file changed, 39 insertions(+), 21 deletions(-)

diff --git a/dlls/secur32/secur32.c b/dlls/secur32/secur32.c
index d703757bae7..beb52d7d6da 100644
--- a/dlls/secur32/secur32.c
+++ b/dlls/secur32/secur32.c
@@ -1108,31 +1108,49 @@ BOOLEAN WINAPI GetUserNameExW(
     {
     case NameSamCompatible:
         {
-            WCHAR samname[UNLEN + 1 + MAX_COMPUTERNAME_LENGTH + 1];
-            LPWSTR out;
-            DWORD len;
+            WCHAR *output;
+            DWORD len = 0;
+            BOOL status;

-            /* This assumes the current user is always a local account */
-            len = MAX_COMPUTERNAME_LENGTH + 1;
-            if (GetComputerNameW(samname, &len))
+            status = GetComputerNameExW(ComputerNameDnsHostname, NULL, &len);
+            if (status || GetLastError() != ERROR_MORE_DATA)
             {
-                out = samname + lstrlenW(samname);
-                *out++ = '\';
-                len = UNLEN + 1;
-                if (GetUserNameW(out, &len))
-                {
-                    if (lstrlenW(samname) < *nSize)
-                    {
-                        lstrcpyW(lpNameBuffer, samname);
-                        *nSize = lstrlenW(samname);
-                        return TRUE;
-                    }
+                ERR("GetComputerNameExW expected ERROR_MORE_DATA, error %lu\n", GetLastError());
+                return FALSE;
+            }

-                    SetLastError(ERROR_MORE_DATA);
-                    *nSize = lstrlenW(samname) + 1;
-                }
+            output = HeapAlloc(GetProcessHeap(), 0, sizeof(WCHAR) * (len + 1 + UNLEN + 1));
+
+            status = GetComputerNameExW(ComputerNameDnsHostname, output, &len);
+            if (!status)
+            {
+                ERR("GetComputerNameExW failed, error %lu\n", GetLastError());
+                return FALSE;
             }
-            return FALSE;
+
+            wcscat(output, L"\");
+
+            len = UNLEN + 1;
+
+            status = GetUserNameW(&output[wcslen(output)], &len);
+            if (!status)
+            {
+                ERR("GetUserNameW failed, error %lu\n", GetLastError());
+                return FALSE;
+            }
+
+            if (lstrlenW(output) >= *nSize)
+            {
+                TRACE("Output buffer too small\n");
+                SetLastError(ERROR_MORE_DATA);
+                *nSize = lstrlenW(output) + 1;
+                return FALSE;
+            }
+
+            lstrcpyW(lpNameBuffer, output);
+            *nSize = lstrlenW(output);
+
+            return TRUE;
         }

case NameUnknown: