reactos/ntoskrnl/mm/lock.c

   1 /*
   2  * COPYRIGHT:       See COPYING in the top level directory
   3  * PROJECT:         ReactOS kernel
   4  * FILE:            mkernel/mm/lock.c
   5  * PURPOSE:         Locking/unlocking virtual memory areas
   6  * PROGRAMMER:      David Welch (welch@mcmail.com)
   7  */
   8
   9 BOOL VirtualUnlock(LPVOID lpAddress, DWORD cbSize)
  10 /*
  11  * FUNCTION: Unlocks pages from the virtual address space of the current
  12  * process
  13  * ARGUMENTS:
  14  *         lpAddress = Beginning of the region to unlock
  15  *         cbSize = Size (in bytes) of the region to unlock
  16  * RETURNS: Success or failure
  17  */
  18 {
  19    return(FALSE);
  20 }
  21
  22 BOOL VirtualLock(LPVOID lpvAddress, DWORD cbSize)
  23 /*
  24  * FUNCTION: Prevents range of memory from being swapped out
  25  * RECEIVES:
  26  *              lpvAddress - The base of the range to lock
  27  *              cbSize - The size of the range to lock
  28  * RETURNS:
  29  *              TRUE - the function succeeds
  30  *              FALSE - the function failed (use GetLastError for details)
  31  *
  32  * NOTES: I'm guessing the kernel loads every page as well as locking it.
  33  */
  34 {
  35    unsigned int first_page = PAGE_ROUND_DOWN((int)lpvAddress);
  36    unsigned int length = PAGE_ROUND_DOWN( ((int)lpvAddress) + cbSize) -
  37                          first_page;
  38    memory_area* marea=NULL;
  39    memory_area* current=NULL;
  40    unsigned int i;
  41
  42    /*
  43     * Check the process isn't trying to lock too much
  44     */
  45    if ( ((length/PAGESIZE)+1) > 30)
  46      {
  47         SetLastError(0);
  48         return(FALSE);
  49      }
  50
  51    /*
  52     * Find the corresponding vmarea(s)
  53     */
  54    marea = find_first_marea(memory_area_list_head,first_page,
  55                             length);
  56    if (marea==NULL)
  57      {
  58         SetLastError(0);
  59         return(FALSE);
  60      }
  61
  62    /*
  63     * Check the memory areas are committed, continuous and not
  64     * PAGE_NOACCESS
  65     */
  66    current=marea;
  67    if (current->base != first_page)
  68      {
  69         SetLastError(0);
  70         return(FALSE);
  71      }
  72    while (current!=NULL && current->base < (first_page+length) )
  73      {
  74         if (!(current->state & MEM_COMMIT) ||
  75             current->access & PAGE_NOACCESS)
  76           {
  77              SetLastError(0);
  78              return(FALSE);
  79           }
  80         if ( current->next==NULL)
  81           {
  82              if ((current->base + current->length) !=
  83                  (first_page+length) )
  84                {
  85                   SetLastError(0);
  86                   return(FALSE);
  87                }
  88           }
  89         else
  90           {
  91              if ( (current->base+current->length) !=
  92                  current->next->base)
  93                {
  94                   SetLastError(0);
  95                   return(FALSE);
  96                }
  97           }
  98         current=current->next;
  99      }
 100
 101    /*
 102     * Lock/load the areas in memory
 103     * (the pages aren't loaded just by touching them to avoid the
 104     * overhead of a page fault)
 105     */
 106    current=marea;
 107    while (current!=NULL && current->base < (first_page+length) )
 108      {
 109         marea->lock = TRUE;
 110         for (i=0; i<current->length; i++)
 111           {
 112              if (!current->load_page(marea,i))
 113                         {
 114                            /*
 115                             * If the page couldn't be loaded we unlock
 116                             * the locked pages and abort
 117                             */
 118                            VirtualUnlock(lpvAddress,
 119                                          current->base+i-PAGESIZE);
 120                            SetLastError(0);
 121                            return(FALSE);
 122                         }
 123           }
 124      }
 125
 126    return(TRUE);
 127 }