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