advapi32/service: Cater better for domain in test.

dlls/advapi32/tests/service.c

@@ -140,8 +140,8 @@ static void test_open_svc(void)
 static void test_create_delete_svc(void)
 {
     SC_HANDLE scm_handle, svc_handle1;
-    CHAR username[UNLEN + 1], *domain;
-    DWORD user_size = UNLEN + 1, domain_size = 0;
+    CHAR username[UNLEN + 1], domain[MAX_PATH];
+    DWORD user_size = UNLEN + 1;
     CHAR account[UNLEN + 3];
     static const CHAR servicename         [] = "Winetest";
     static const CHAR pathname            [] = "we_dont_care.exe";
@@ -155,14 +155,10 @@ static void test_create_delete_svc(void)
     /* Get the username and turn it into an account to be used in some tests */
     GetUserNameA(username, &user_size);
     /* Get the domainname to cater for that situation */
-    GetComputerNameEx(ComputerNameDnsDomain, NULL, &domain_size);
-    domain = HeapAlloc(GetProcessHeap(), 0, domain_size);
-    GetComputerNameEx(ComputerNameDnsDomain, domain, &domain_size);
-    if (domain_size > 1)
+    if (GetEnvironmentVariableA("USERDOMAIN", domain, MAX_PATH))
         sprintf(account, "%s\\%s", domain, username);
     else
         sprintf(account, ".\\%s", username);
-    HeapFree(GetProcessHeap(), 0, domain);
 
     /* All NULL */
     SetLastError(0xdeadbeef);