ntdll: Add a helper function to retrieve the NT headers of the main exe.

dlls/ntdll/unix/server.c

@@ -1454,7 +1454,7 @@ void server_init_process(void)
 void CDECL server_init_process_done( void *relay )
 {
     PEB *peb = NtCurrentTeb()->Peb;
-    IMAGE_NT_HEADERS *nt = RtlImageNtHeader( peb->ImageBaseAddress );
+    IMAGE_NT_HEADERS *nt = get_exe_nt_header();
     void *entry = (char *)peb->ImageBaseAddress + nt->OptionalHeader.AddressOfEntryPoint;
     NTSTATUS status;
     int suspend;

dlls/ntdll/unix/unix_private.h

@@ -264,6 +264,12 @@ static inline void ascii_to_unicode( WCHAR *dst, const char *src, size_t len )
     while (len--) *dst++ = (unsigned char)*src++;
 }
 
+static inline IMAGE_NT_HEADERS *get_exe_nt_header(void)
+{
+    IMAGE_DOS_HEADER *module = (IMAGE_DOS_HEADER *)NtCurrentTeb()->Peb->ImageBaseAddress;
+    return (IMAGE_NT_HEADERS *)((char *)module + module->e_lfanew);
+}
+
 static inline size_t ntdll_wcslen( const WCHAR *str )
 {
     const WCHAR *s = str;

dlls/ntdll/unix/virtual.c

@@ -2728,7 +2728,7 @@ NTSTATUS CDECL virtual_alloc_thread_stack( INITIAL_TEB *stack, SIZE_T reserve_si
 
     if (!reserve_size || !commit_size)
     {
-        IMAGE_NT_HEADERS *nt = RtlImageNtHeader( NtCurrentTeb()->Peb->ImageBaseAddress );
+        IMAGE_NT_HEADERS *nt = get_exe_nt_header();
         if (!reserve_size) reserve_size = nt->OptionalHeader.SizeOfStackReserve;
         if (!commit_size) commit_size = nt->OptionalHeader.SizeOfStackCommit;
     }
@@ -3325,7 +3325,7 @@ void CDECL virtual_release_address_space(void)
  */
 void CDECL virtual_set_large_address_space(void)
 {
-    IMAGE_NT_HEADERS *nt = RtlImageNtHeader( NtCurrentTeb()->Peb->ImageBaseAddress );
+    IMAGE_NT_HEADERS *nt = get_exe_nt_header();
 
     if (!(nt->FileHeader.Characteristics & IMAGE_FILE_LARGE_ADDRESS_AWARE)) return;
     /* no large address space on win9x */