rom/dos/attemptlockdoslist.c

   1 /*
   2     Copyright © 1995-2001, The AROS Development Team. All rights reserved.
   3     $Id$
   4
   5     Desc:
   6     Lang: English
   7 */
   8 #include <proto/exec.h>
   9 #include "dos_intern.h"
  10
  11 /*****************************************************************************
  12
  13     NAME */
  14 #include <proto/dos.h>
  15
  16         AROS_LH1(struct DosList *, AttemptLockDosList,
  17
  18 /*  SYNOPSIS */
  19         AROS_LHA(ULONG, flags, D1),
  20
  21 /*  LOCATION */
  22         struct DosLibrary *, DOSBase, 111, Dos)
  23
  24 /*  FUNCTION
  25         Tries to get a lock on some of the dos lists. If all went
  26         well a handle is returned that can be used for FindDosEntry().
  27         Don't try to busy wait until the lock can be granted - use
  28         LockDosList() instead.
  29
  30     INPUTS
  31         flags  --  what lists to lock
  32
  33     RESULT
  34         Handle to the dos list or NULL. This is not a direct pointer
  35         to the first list element but to a pseudo element instead.
  36
  37     NOTES
  38
  39     EXAMPLE
  40
  41     BUGS
  42
  43     SEE ALSO
  44
  45     INTERNALS
  46
  47 *****************************************************************************/
  48 {
  49     AROS_LIBFUNC_INIT
  50     AROS_LIBBASE_EXT_DECL(struct DosLibrary *,DOSBase)
  51
  52     if(flags & LDF_WRITE)
  53     {
  54         if(!AttemptSemaphore(&DOSBase->dl_DosListLock))
  55             return NULL;
  56     }
  57     else
  58     {
  59         if(!AttemptSemaphoreShared(&DOSBase->dl_DosListLock))
  60             return NULL;
  61     }
  62
  63     return (struct DosList *)&DOSBase->dl_DevInfo;
  64
  65     AROS_LIBFUNC_EXIT
  66 } /* AttemptLockDosList */