db/dbread.c

   1 /*
   2  * Copyright (c) 2000 Silicon Graphics, Inc.  All Rights Reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or modify it
   5  * under the terms of version 2 of the GNU General Public License as
   6  * published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it would be useful, but
   9  * WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
  11  *
  12  * Further, this software is distributed without any warranty that it is
  13  * free of the rightful claim of any third person regarding infringement
  14  * or the like.  Any license provided herein, whether implied or
  15  * otherwise, applies only to this software file.  Patent licenses, if
  16  * any, provided herein do not apply to combinations of this program with
  17  * other software, or any other product whatsoever.
  18  *
  19  * You should have received a copy of the GNU General Public License along
  20  * with this program; if not, write the Free Software Foundation, Inc., 59
  21  * Temple Place - Suite 330, Boston MA 02111-1307, USA.
  22  *
  23  * Contact information: Silicon Graphics, Inc., 1600 Amphitheatre Pkwy,
  24  * Mountain View, CA  94043, or:
  25  *
  26  * http://www.sgi.com
  27  *
  28  * For further information regarding this notice, see:
  29  *
  30  * http://oss.sgi.com/projects/GenInfo/SGIGPLNoticeExplan/
  31  */
  32
  33 #include <libxfs.h>
  34 #include "bmap.h"
  35 #include "data.h"
  36 #include "dbread.h"
  37 #include "io.h"
  38 #include "mount.h"
  39
  40 int
  41 dbread(void *buf, int nblocks, xfs_fileoff_t bno, int whichfork)
  42 {
  43         bmap_ext_t      bm;
  44         char            *bp;
  45         xfs_dfiloff_t   eb;
  46         xfs_dfiloff_t   end;
  47         int             i;
  48         int             nex;
  49
  50         nex = 1;
  51         end = bno + nblocks;
  52         bp = buf;
  53         while (bno < end) {
  54                 bmap(bno, end - bno, whichfork, &nex, &bm);
  55                 if (nex == 0) {
  56                         bm.startoff = end;
  57                         bm.blockcount = 1;
  58                 }
  59                 if (bm.startoff > bno) {
  60                         eb = end < bm.startoff ? end : bm.startoff;
  61                         i = (int)XFS_FSB_TO_B(mp, eb - bno);
  62                         memset(bp, 0, i);
  63                         bp += i;
  64                         bno = eb;
  65                 }
  66                 if (bno == end)
  67                         break;
  68                 if (bno > bm.startoff) {
  69                         bm.blockcount -= bno - bm.startoff;
  70                         bm.startblock += bno - bm.startoff;
  71                         bm.startoff = bno;
  72                 }
  73                 if (bm.startoff + bm.blockcount > end)
  74                         bm.blockcount = end - bm.startoff;
  75                 i = read_bbs(XFS_FSB_TO_DADDR(mp, bm.startblock),
  76                              (int)XFS_FSB_TO_BB(mp, bm.blockcount),
  77                              (void **)&bp, NULL);
  78                 if (i)
  79                         return i;
  80                 bp += XFS_FSB_TO_B(mp, bm.blockcount);
  81                 bno += bm.blockcount;
  82         }
  83         return 0;
  84 }