advapi32: add more helper functions

[Robert Reif]

Add ADVAPI_GetComputerNameW and make ADVAPI_IsLocalComputer use it.
Add ADVAPI_GetComputerSid.

Applies on top of previous patch.
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diff -pu wine.cvs/dlls/advapi32/advapi32_misc.h wine/dlls/advapi32/advapi32_misc.h
--- wine.cvs/dlls/advapi32/advapi32_misc.h	2006-07-29 08:59:38.000000000 -0400
+++ wine/dlls/advapi32/advapi32_misc.h	2006-07-29 08:44:32.000000000 -0400
@@ -21,6 +21,8 @@
 #define __WINE_ADVAPI32MISC_H
 
 const char * debugstr_sid(PSID sid);
+LPCWSTR ADVAPI_GetComputerNameW();
 BOOL ADVAPI_IsLocalComputer(LPCWSTR ServerName);
+BOOL ADVAPI_GetComputerSid(PSID sid);
 
 #endif /* __WINE_ADVAPI32MISC_H */
diff -pu wine.cvs/dlls/advapi32/security.c wine/dlls/advapi32/security.c
--- wine.cvs/dlls/advapi32/security.c	2006-07-29 08:59:38.000000000 -0400
+++ wine/dlls/advapi32/security.c	2006-07-29 09:05:13.000000000 -0400
@@ -319,29 +319,77 @@ static void GetWorldAccessACL(PACL pACL)
 }
 
 /************************************************************
+ *                ADVAPI_GetComputerNameW
+ *
+ * Gets the local computer name.
+ */
+LPCWSTR ADVAPI_GetComputerNameW()
+{
+    static WCHAR buf[MAX_COMPUTERNAME_LENGTH + 1];
+    DWORD dwSize = sizeof(buf);
+    if (!GetComputerNameW(buf, &dwSize))
+        buf[0] = 0;
+    return buf;
+}
+
+/************************************************************
  *                ADVAPI_IsLocalComputer
  *
  * Checks whether the server name indicates local machine.
  */
 BOOL ADVAPI_IsLocalComputer(LPCWSTR ServerName)
 {
-    DWORD dwSize = MAX_COMPUTERNAME_LENGTH + 1;
     BOOL Result;
-    LPWSTR buf;
+    LPCWSTR buf;
 
     if (!ServerName || !ServerName[0])
         return TRUE;
     
-    buf = HeapAlloc(GetProcessHeap(), 0, dwSize * sizeof(WCHAR));
-    Result = GetComputerNameW(buf,  &dwSize);
-    if (Result && (ServerName[0] == '\\') && (ServerName[1] == '\\'))
+    buf = ADVAPI_GetComputerNameW();
+    if ((ServerName[0] == '\\') && (ServerName[1] == '\\'))
         ServerName += 2;
-    Result = Result && !lstrcmpW(ServerName, buf);
-    HeapFree(GetProcessHeap(), 0, buf);
+    Result = !lstrcmpW(ServerName, buf);
 
     return Result;
 }
 
+/************************************************************
+ *                ADVAPI_GetComputerSid
+ *
+ * Reads the computer SID from the registry.
+ */
+BOOL ADVAPI_GetComputerSid(PSID sid)
+{
+    HKEY key;
+    LONG ret;
+                                                                                
+    if ((ret = RegOpenKeyExA(HKEY_LOCAL_MACHINE,
+        "SECURITY\\SAM\\Domains\\Account", 0,
+        KEY_READ, &key)) == ERROR_SUCCESS)
+    {
+        static const WCHAR V[] = { 'V',0 };
+        DWORD size = 0;
+        ret = RegQueryValueExW(key, V, NULL, NULL, NULL, &size);
+        if (ret == ERROR_MORE_DATA || ret == ERROR_SUCCESS)
+        {
+            BYTE * data = HeapAlloc(GetProcessHeap(), 0, size);
+            if (data)
+            {
+                if ((ret = RegQueryValueExW(key, V, NULL, NULL,
+                     data, &size)) == ERROR_SUCCESS)
+                {
+                    /* the SID is in the last 24 bytes of the binary data */
+                    CopyMemory(sid, &data[size-24], 24);
+                    return TRUE;
+                }
+            }
+        }
+        RegCloseKey(key);
+    }
+                                                                                
+    return FALSE;
+}
+
 /*	##############################
 	######	TOKEN FUNCTIONS ######
 	##############################