rom/dos/adddosentry.c

   1 /*
   2     Copyright © 1995-2007, The AROS Development Team. All rights reserved.
   3     $Id$
   4
   5     Desc:
   6     Lang: english
   7 */
   8 #define DEBUG 0
   9
  10 #include <aros/debug.h>
  11 #include <dos/dosextens.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 implmentation. LDF_DELETE is not used at all.
  69
  70 *****************************************************************************/
  71 {
  72     AROS_LIBFUNC_INIT
  73
  74     LONG            success = 1;
  75     struct DosList *dl, *scan;
  76
  77     if (dlist == NULL) return success;
  78
  79     D(bug("[AddDosEntry] Adding %b\n", dlist->dol_Name));
  80     dl = LockDosList(LDF_ALL | LDF_READ);
  81
  82     /* If the passed entry has dol_Task defined, then it's a packet-based
  83      * handler, and probably doesn't have valid dol_DevName, dol_Device and
  84      * dol_Unit fields, which will be needed. So we search through the DOS
  85      * list looking for the packet.handler entry for the same process, and
  86      * fill in the values from there.
  87      *
  88      * This all falls down if the handler does somehow know these fields and
  89      * adds different values. We can't just test for NULL, as the handler may
  90      * not have cleared it. I can't think of a single good reason why a
  91      * handler would do this, so I'm not worrying about it for now.
  92      *
  93      * It will also break if the handler has set dol_Task to something other
  94      * than its original packet.handler task. In that case we won't be able to
  95      * match it correctly in the DOS list, and so the three fields will remain
  96      * bogus, probably causing crashes shortly after. Again, I'll worry about
  97      * it if and when it happens.
  98      */
  99     if (dlist->dol_Task != NULL) {
 100         for (scan = dl; scan != NULL; scan = scan->dol_Next)
 101             if (scan->dol_Task == dlist->dol_Task && scan->dol_Type == DLT_DEVICE) {
 102                 dlist->dol_Ext.dol_AROS.dol_DevName = AROS_BSTR_ADDR(dlist->dol_Name);
 103                 dlist->dol_Ext.dol_AROS.dol_Device = scan->dol_Ext.dol_AROS.dol_Device;
 104                 dlist->dol_Ext.dol_AROS.dol_Unit = scan->dol_Ext.dol_AROS.dol_Unit;
 105                 break;
 106             }
 107     }
 108     /* Software ported from AmigaOS may be unaware of dol_DevName existance.
 109      * In this case dol_DevName will be NULL (this assumes that it allocates
 110      * the DosNode in a system-friendly manner using AllocDosObject().
 111      */
 112     if (!dlist->dol_Ext.dol_AROS.dol_DevName) {
 113         dlist->dol_Ext.dol_AROS.dol_DevName = AROS_BSTR_ADDR(dlist->dol_Name);
 114         D(bug("[AddDosEntry] Filling in dol_DevName: %s\n", dlist->dol_Ext.dol_AROS.dol_DevName));
 115     }
 116
 117     LockDosList(LDF_ENTRY|LDF_WRITE);
 118     if(dlist->dol_Type != DLT_VOLUME)
 119     {
 120         while(TRUE)
 121         {
 122             dl = dl->dol_Next;
 123
 124             if(dl == NULL)
 125                 break;
 126
 127             if(dl->dol_Type != DLT_VOLUME &&
 128                !Stricmp(dl->dol_Ext.dol_AROS.dol_DevName, dlist->dol_Ext.dol_AROS.dol_DevName))
 129             {
 130                 success = 0;
 131                 break;
 132             }
 133         }
 134     }
 135
 136     if(success)
 137     {
 138         dlist->dol_Next = DOSBase->dl_DevInfo;
 139         DOSBase->dl_DevInfo = dlist;
 140     }
 141
 142     UnLockDosList(LDF_ENTRY|LDF_WRITE);
 143     UnLockDosList(LDF_ALL | LDF_READ);
 144
 145     return success;
 146
 147     AROS_LIBFUNC_EXIT
 148 } /* AddDosEntry */