rom/dos/adddosentry.c

   1 /*
   2     Copyright © 1995-2010, 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 #include "../devs/filesys/packet/packet.h"
  13
  14 #define DEBUG 0
  15 #include <aros/debug.h>
  16
  17 /*****************************************************************************
  18
  19     NAME */
  20 #include <proto/dos.h>
  21
  22         AROS_LH1(LONG, AddDosEntry,
  23
  24 /*  SYNOPSIS */
  25         AROS_LHA(struct DosList *, dlist, D1),
  26
  27 /*  LOCATION */
  28         struct DosLibrary *, DOSBase, 113, Dos)
  29
  30 /*  FUNCTION
  31         Adds a given dos list entry to the dos list. Automatically
  32         locks the list for writing. There may be not more than one device
  33         or assign node of the same name. There are no restrictions on
  34         volume nodes.
  35
  36     INPUTS
  37         dlist - pointer to dos list entry.
  38
  39     RESULT
  40         != 0 if all went well, 0 otherwise.
  41
  42     NOTES
  43         Since anybody who wants to use a device or volume node in the
  44         dos list has to lock the list, filesystems may be called with
  45         the dos list locked. So if you want to add a dos list entry
  46         out of a filesystem don't just wait on the lock but serve all
  47         incoming requests until the dos list is free instead.
  48
  49     EXAMPLE
  50
  51     BUGS
  52
  53     SEE ALSO
  54
  55     INTERNALS
  56         Behaviour of this function is slightly different from AmigaOS 3.x
  57         and MorphOS. Instead of LDF_WRITE it locks DosList with LDF_READ
  58         flag. This is done because in AROS handlers are run with DosList
  59         locked with LDF_READ flag and this could cause a lockup if we use
  60         LDF_WRITE here.
  61
  62         Due to nature of the DosList it is safe to read the list while
  63         someone is adding a node, adding operation is atomic to other
  64         readers. The only problem here would happen if more than one
  65         process attempts to add a DosNode at the same time. In order to
  66         avoid this race condition we make this call single-threaded
  67         using an LDF_ENTRY lock in LDF_WRITE mode.
  68
  69         LDF_ENTRY is NOT touched when a handler is started up in this
  70         dos.library implementation. LDF_DELETE is not used at all.
  71
  72 *****************************************************************************/
  73 {
  74     AROS_LIBFUNC_INIT
  75
  76     LONG            success = 1;
  77     struct DosList *dl, *scan;
  78
  79     if (dlist == NULL) return success;
  80
  81     D(bug("[AddDosEntry] Adding '%b' from Task '%s'\n", dlist->dol_Name,
  82         FindTask(NULL)->tc_Node.ln_Name));
  83     dl = LockDosList(LDF_ALL | LDF_READ);
  84
  85     /* If the passed entry has dol_Task defined, then it's a packet-based
  86      * handler, and probably doesn't have valid dol_DevName, dol_Device and
  87      * dol_Unit fields, which will be needed. So we search through the DOS
  88      * list looking for the packet.handler entry for the same process, and
  89      * fill in the values from there.
  90      *
  91      * This all falls down if the handler does somehow know these fields and
  92      * adds different values. We can't just test for NULL, as the handler may
  93      * not have cleared it. I can't think of a single good reason why a
  94      * handler would do this, so I'm not worrying about it for now.
  95      *
  96      * It will also break if the handler has set dol_Task to something other
  97      * than its original packet.handler task. In that case we won't be able to
  98      * match it correctly in the DOS list, and so the three fields will remain
  99      * bogus, probably causing crashes shortly after. Again, I'll worry about
 100      * it if and when it happens.
 101      */
 102     if (dlist->dol_Task != NULL) {
 103         for (scan = dl; scan != NULL; scan = BADDR(scan->dol_Next))
 104             if (scan->dol_Task == dlist->dol_Task && scan->dol_Type == DLT_DEVICE) {
 105                 /* Do patching only if found DeviceNode belongs to packet.handler. Otherwise do not touch anything.
 106                    This lets filesystems with own IOFS wrappers to set up dol_Task field on their own. This can be
 107                    used for example to enable utilities to pass packets directly to the filesystem without the need
 108                    to interact with wrapper. This will be used by SFS - Pavel Fedin <sonic.amiga@gmail.com> */
 109                 if (!strcmp(scan->dol_Ext.dol_AROS.dol_Device->dd_Library.lib_Node.ln_Name, "packet.handler")) {
 110                     struct ph_handle *vol_handle;
 111
 112                     dlist->dol_Ext.dol_AROS.dol_DevName = AROS_BSTR_ADDR(dlist->dol_Name);
 113                     dlist->dol_Ext.dol_AROS.dol_Device = scan->dol_Ext.dol_AROS.dol_Device;
 114
 115                     /* A separate handle needs to be allocated for each volume,
 116                      * because it may need to stay around after its original
 117                      * DOS device has been destroyed */
 118                     vol_handle = AllocMem(sizeof(struct ph_handle),
 119                         MEMF_PUBLIC);
 120                     if (vol_handle != NULL)
 121                     {
 122                         CopyMem(scan->dol_Ext.dol_AROS.dol_Unit, vol_handle,
 123                             sizeof(struct ph_handle));
 124                         vol_handle->msgport = dlist->dol_Task;
 125                         vol_handle->volume = dlist;
 126                         dlist->dol_Ext.dol_AROS.dol_Unit =
 127                             (struct Unit *)vol_handle;
 128                     }
 129                     else
 130                         success = 0;
 131                 }
 132                 break;
 133             }
 134     }
 135     /* Software ported from AmigaOS may be unaware of dol_DevName existance.
 136      * In this case dol_DevName will be NULL (this assumes that it allocates
 137      * the DosNode in a system-friendly manner using AllocDosObject().
 138      */
 139     if (!dlist->dol_Ext.dol_AROS.dol_DevName) {
 140         dlist->dol_Ext.dol_AROS.dol_DevName = AROS_BSTR_ADDR(dlist->dol_Name);
 141         D(bug("[AddDosEntry] Filling in dol_DevName: %s\n", dlist->dol_Ext.dol_AROS.dol_DevName));
 142     }
 143
 144     LockDosList(LDF_ENTRY|LDF_WRITE);
 145     if(dlist->dol_Type != DLT_VOLUME)
 146     {
 147         while(TRUE)
 148         {
 149             dl = BADDR(dl->dol_Next);
 150
 151             if(dl == NULL)
 152                 break;
 153
 154             if(dl->dol_Type != DLT_VOLUME &&
 155                !Stricmp(dl->dol_Ext.dol_AROS.dol_DevName, dlist->dol_Ext.dol_AROS.dol_DevName))
 156             {
 157                 D(bug("[AddDosEntry] Name clash for %08lx->dol_DevName: %s and %08lx->dol_DevName %s\n", dl, dl->dol_Ext.dol_AROS.dol_DevName, dlist, dlist->dol_Ext.dol_AROS.dol_DevName));
 158                 success = 0;
 159                 break;
 160             }
 161         }
 162     }
 163
 164     if(success)
 165     {
 166         struct DosInfo *dinf = BADDR(DOSBase->dl_Root->rn_Info);
 167
 168         dlist->dol_Next = dinf->di_DevInfo;
 169         dinf->di_DevInfo = MKBADDR(dlist);
 170     }
 171
 172     UnLockDosList(LDF_ENTRY|LDF_WRITE);
 173     UnLockDosList(LDF_ALL | LDF_READ);
 174
 175     return success;
 176
 177     AROS_LIBFUNC_EXIT
 178 } /* AddDosEntry */