rom/dos/lockdoslist.c

   1 /*
   2     Copyright © 1995-2007, 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     HISTORY
  50         04-06-07    sonic   merged back from MorphOS source code
  51         29-10-95    digulla automatically created from
  52                             dos_lib.fd and clib/dos_protos.h
  53
  54 *****************************************************************************/
  55 {
  56     AROS_LIBFUNC_INIT
  57
  58     struct DosInfo *di = BADDR(DOSBase->dl_Root->rn_Info);
  59
  60     D(bug("LockDosList: flags = $%lx\n", flags));
  61
  62     if (((flags & (LDF_READ|LDF_WRITE)) != LDF_READ &&
  63          (flags & (LDF_READ|LDF_WRITE)) != LDF_WRITE) ||
  64         (flags & ~(LDF_READ|LDF_WRITE|LDF_DEVICES|LDF_VOLUMES|LDF_ASSIGNS|LDF_ENTRY|LDF_DELETE)))
  65         return NULL;
  66
  67     if (flags & LDF_ALL)
  68     {
  69         if (flags & LDF_WRITE)
  70             ObtainSemaphore(&di->di_DevLock);
  71         else
  72             ObtainSemaphoreShared(&di->di_DevLock);
  73     }
  74
  75     if (flags & LDF_ENTRY)
  76     {
  77         if (flags & LDF_WRITE)
  78             ObtainSemaphore(&di->di_EntryLock);
  79         else
  80             ObtainSemaphoreShared(&di->di_EntryLock);
  81     }
  82
  83     if (flags & LDF_DELETE)
  84     {
  85         if (flags & LDF_WRITE)
  86             ObtainSemaphore(&di->di_DeleteLock);
  87         else
  88             ObtainSemaphoreShared(&di->di_DeleteLock);
  89     }
  90
  91 /* This strange thing came from MorphOS.
  92     Forbid(); */
  93
  94     return (struct DosList *)&DOSBase->dl_DevInfo;
  95
  96     AROS_LIBFUNC_EXIT
  97 } /* LockDosList */