rom/dos/lockdoslist.c

   1 /*
   2     Copyright © 1995-2013, The AROS Development Team. All rights reserved.
   3     $Id$
   4
   5     Desc:
   6     Lang: english
   7 */
   8 #include <aros/debug.h>
   9 #include <proto/exec.h>
  10 #include "dos_intern.h"
  11
  12 /*****************************************************************************
  13
  14     NAME */
  15 #include <proto/dos.h>
  16
  17         AROS_LH1(struct DosList *, LockDosList,
  18
  19 /*  SYNOPSIS */
  20         AROS_LHA(ULONG, flags, D1),
  21
  22 /*  LOCATION */
  23         struct DosLibrary *, DOSBase, 109, Dos)
  24
  25 /*  FUNCTION
  26         Waits until the desired dos lists are free then gets a lock on them.
  27         A handle is returned that can be used for FindDosEntry().
  28         Calls to this function nest, i.e. you must call UnLockDosList()
  29         as often as you called LockDosList(). Always lock all lists
  30         at once - do not try to get a lock on one of them then on another.
  31
  32     INPUTS
  33         flags - what lists to lock
  34
  35     RESULT
  36         Handle to the dos list. This is not a direct pointer
  37         to the first list element but to a pseudo element instead.
  38
  39     NOTES
  40
  41     EXAMPLE
  42
  43     BUGS
  44
  45     SEE ALSO
  46
  47     INTERNALS
  48
  49 *****************************************************************************/
  50 {
  51     AROS_LIBFUNC_INIT
  52
  53     struct DosInfo *di = BADDR(DOSBase->dl_Root->rn_Info);
  54
  55     D(bug("LockDosList: flags = $%lx\n", flags));
  56
  57     if (((flags & (LDF_READ|LDF_WRITE)) != LDF_READ &&
  58          (flags & (LDF_READ|LDF_WRITE)) != LDF_WRITE) ||
  59         (flags & ~(LDF_READ|LDF_WRITE|LDF_DEVICES|LDF_VOLUMES|LDF_ASSIGNS|LDF_ENTRY|LDF_DELETE)))
  60         return NULL;
  61
  62     if (flags & LDF_ALL)
  63     {
  64         if (flags & LDF_WRITE)
  65             ObtainSemaphore(&di->di_DevLock);
  66         else
  67             ObtainSemaphoreShared(&di->di_DevLock);
  68     }
  69
  70     if (flags & LDF_ENTRY)
  71     {
  72         if (flags & LDF_WRITE)
  73             ObtainSemaphore(&di->di_EntryLock);
  74         else
  75             ObtainSemaphoreShared(&di->di_EntryLock);
  76     }
  77
  78     if (flags & LDF_DELETE)
  79     {
  80         if (flags & LDF_WRITE)
  81             ObtainSemaphore(&di->di_DeleteLock);
  82         else
  83             ObtainSemaphoreShared(&di->di_DeleteLock);
  84     }
  85
  86 /* This strange thing came from MorphOS.
  87     Forbid(); */
  88
  89     return (struct DosList *)&di->di_DevInfo;
  90
  91     AROS_LIBFUNC_EXIT
  92 } /* LockDosList */