rom/dos/adddosentry.c

   1 /*
   2     Copyright © 1995-2011, The AROS Development Team. All rights reserved.
   3     $Id$
   4
   5     Desc:
   6     Lang: english
   7 */
   8
   9 #include <aros/debug.h>
  10 #include <dos/dosextens.h>
  11 #include <proto/exec.h>
  12 #include <proto/utility.h>
  13 #include "dos_intern.h"
  14
  15 /*****************************************************************************
  16
  17     NAME */
  18 #include <proto/dos.h>
  19
  20         AROS_LH1(LONG, AddDosEntry,
  21
  22 /*  SYNOPSIS */
  23         AROS_LHA(struct DosList *, dlist, D1),
  24
  25 /*  LOCATION */
  26         struct DosLibrary *, DOSBase, 113, Dos)
  27
  28 /*  FUNCTION
  29         Adds a given dos list entry to the dos list. Automatically
  30         locks the list for writing. There may be not more than one device
  31         or assign node of the same name. There are no restrictions on
  32         volume nodes.
  33
  34     INPUTS
  35         dlist - pointer to dos list entry.
  36
  37     RESULT
  38         != 0 if all went well, 0 otherwise.
  39
  40     NOTES
  41         Since anybody who wants to use a device or volume node in the
  42         dos list has to lock the list, filesystems may be called with
  43         the dos list locked. So if you want to add a dos list entry
  44         out of a filesystem don't just wait on the lock but serve all
  45         incoming requests until the dos list is free instead.
  46
  47     EXAMPLE
  48
  49     BUGS
  50
  51     SEE ALSO
  52
  53     INTERNALS
  54         Behaviour of this function is slightly different from AmigaOS 3.x
  55         and MorphOS. Instead of LDF_WRITE it locks DosList with LDF_READ
  56         flag. This is done because in AROS handlers are run with DosList
  57         locked with LDF_READ flag and this could cause a lockup if we use
  58         LDF_WRITE here.
  59
  60         Due to nature of the DosList it is safe to read the list while
  61         someone is adding a node, adding operation is atomic to other
  62         readers. The only problem here would happen if more than one
  63         process attempts to add a DosNode at the same time. In order to
  64         avoid this race condition we make this call single-threaded
  65         using an LDF_ENTRY lock in LDF_WRITE mode.
  66
  67         LDF_ENTRY is NOT touched when a handler is started up in this
  68         dos.library implementation. LDF_DELETE is not used at all.
  69
  70 *****************************************************************************/
  71 {
  72     AROS_LIBFUNC_INIT
  73
  74     LONG success = DOSTRUE;
  75     struct DosList *dl;
  76
  77     if (dlist == NULL)
  78         return success;
  79
  80     D(bug("[AddDosEntry] Adding '%b' type %d from addr %x Task '%s'\n",
  81         dlist->dol_Name, dlist->dol_Type, dlist,
  82         FindTask(NULL)->tc_Node.ln_Name));
  83
  84     dl = LockDosList(LDF_ALL | LDF_READ);
  85
  86     LockDosList(LDF_ENTRY|LDF_WRITE);
  87     if(dlist->dol_Type != DLT_VOLUME)
  88     {
  89         while(TRUE)
  90         {
  91             dl = BADDR(dl->dol_Next);
  92
  93             if(dl == NULL)
  94                 break;
  95
  96             if(dl->dol_Type != DLT_VOLUME && !CMPBSTR(dl->dol_Name, dlist->dol_Name))
  97             {
  98                 D(bug("[AddDosEntry] Name clash for %08lx->dol_Name: %b and %08lx->dol_Name %b\n", dl, dl->dol_Name, dlist, dlist->dol_Name));
  99                 success = DOSFALSE;
 100                 break;
 101             }
 102         }
 103     }
 104
 105     if(success)
 106     {
 107         struct DosInfo *dinf = BADDR(DOSBase->dl_Root->rn_Info);
 108
 109         dlist->dol_Next = dinf->di_DevInfo;
 110         dinf->di_DevInfo = MKBADDR(dlist);
 111     }
 112
 113     UnLockDosList(LDF_ENTRY|LDF_WRITE);
 114     UnLockDosList(LDF_ALL | LDF_READ);
 115
 116     return success;
 117
 118     AROS_LIBFUNC_EXIT
 119 } /* AddDosEntry */