rom/dos/adddosentry.c

   1 /*
   2     Copyright © 1995-2012, The AROS Development Team. All rights reserved.
   3     $Id$
   4
   5     Desc: Adds a given dos list entry to the dos list.
   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 except that the time stamps must differ.
  33
  34     INPUTS
  35         dlist - Pointer to DOS list entry.
  36
  37     RESULT
  38         DOSTRUE if all went well.
  39         DOSFALSE for errors; IoErr() will return additional error code.
  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         The dlist pointer may become invalid after a call to AddDosEntry()
  49         unless you have locked the DOS list.
  50
  51     EXAMPLE
  52
  53     BUGS
  54
  55     SEE ALSO
  56         RemDosEntry(), FindDosEntry(), NextDosEntry(), LockDosList(),
  57         MakeDosEntry(), FreeDosEntry(), AttemptLockDosList()
  58
  59     INTERNALS
  60         Behavior of this function is slightly different from AmigaOS 3.x
  61         and MorphOS. Instead of LDF_WRITE it locks DosList with LDF_READ
  62         flag. This is done because in AROS handlers are run with DosList
  63         locked with LDF_READ flag and this could cause a lockup if we use
  64         LDF_WRITE here.
  65
  66         Due to nature of the DosList it is safe to read the list while
  67         someone is adding a node, adding operation is atomic to other
  68         readers. The only problem here would happen if more than one
  69         process attempts to add a DosNode at the same time. In order to
  70         avoid this race condition we make this call single-threaded
  71         using an LDF_ENTRY lock in LDF_WRITE mode.
  72
  73         LDF_ENTRY is NOT touched when a handler is started up in this
  74         dos.library implementation. LDF_DELETE is not used at all.
  75
  76 *****************************************************************************/
  77 {
  78     AROS_LIBFUNC_INIT
  79
  80     LONG success = DOSTRUE;
  81     struct DosList *dl;
  82
  83     if (dlist == NULL)
  84         return success;
  85
  86     D(bug("[AddDosEntry] Adding '%b' type %d from addr %x Task '%s'\n",
  87         dlist->dol_Name, dlist->dol_Type, dlist,
  88         FindTask(NULL)->tc_Node.ln_Name));
  89
  90     dl = LockDosList(LDF_ALL | LDF_READ);
  91
  92     LockDosList(LDF_ENTRY|LDF_WRITE);
  93     if(dlist->dol_Type != DLT_VOLUME)
  94     {
  95         while(TRUE)
  96         {
  97             dl = BADDR(dl->dol_Next);
  98
  99             if(dl == NULL)
 100                 break;
 101
 102             if(dl->dol_Type != DLT_VOLUME && !CMPBSTR(dl->dol_Name, dlist->dol_Name))
 103             {
 104                 D(bug("[AddDosEntry] Name clash for %08lx->dol_Name: %b and %08lx->dol_Name %b\n", dl, dl->dol_Name, dlist, dlist->dol_Name));
 105                 success = DOSFALSE;
 106                 break;
 107             }
 108         }
 109     }
 110
 111     if(success)
 112     {
 113         struct DosInfo *dinf = BADDR(DOSBase->dl_Root->rn_Info);
 114
 115         dlist->dol_Next = dinf->di_DevInfo;
 116         dinf->di_DevInfo = MKBADDR(dlist);
 117     }
 118
 119     UnLockDosList(LDF_ENTRY|LDF_WRITE);
 120     UnLockDosList(LDF_ALL | LDF_READ);
 121
 122     return success;
 123
 124     AROS_LIBFUNC_EXIT
 125 } /* AddDosEntry */