usr/src/lib/libast/common/sfio/sfsk.c

   1 /***********************************************************************
   2 *                                                                      *
   3 *               This software is part of the ast package               *
   4 *          Copyright (c) 1985-2010 AT&T Intellectual Property          *
   5 *                      and is licensed under the                       *
   6 *                  Common Public License, Version 1.0                  *
   7 *                    by AT&T Intellectual Property                     *
   8 *                                                                      *
   9 *                A copy of the License is available at                 *
  10 *            http://www.opensource.org/licenses/cpl1.0.txt             *
  11 *         (with md5 checksum 059e8cd6165cb4c31e351f2b69388fd9)         *
  12 *                                                                      *
  13 *              Information and Software Systems Research               *
  14 *                            AT&T Research                             *
  15 *                           Florham Park NJ                            *
  16 *                                                                      *
  17 *                 Glenn Fowler <gsf@research.att.com>                  *
  18 *                  David Korn <dgk@research.att.com>                   *
  19 *                   Phong Vo <kpv@research.att.com>                    *
  20 *                                                                      *
  21 ***********************************************************************/
  22 #include        "sfhdr.h"
  23
  24 /*      Seek function that knows discipline
  25 **
  26 **      Written by Kiem-Phong Vo.
  27 */
  28 #if __STD_C
  29 Sfoff_t sfsk(Sfio_t* f, Sfoff_t addr, int type, Sfdisc_t* disc)
  30 #else
  31 Sfoff_t sfsk(f,addr,type,disc)
  32 Sfio_t*         f;
  33 Sfoff_t         addr;
  34 int             type;
  35 Sfdisc_t*       disc;
  36 #endif
  37 {
  38         Sfoff_t         p;
  39         reg Sfdisc_t*   dc;
  40         reg ssize_t     s;
  41         reg int         local, mode;
  42         SFMTXDECL(f);
  43
  44         SFMTXENTER(f, (Sfoff_t)(-1));
  45
  46         GETLOCAL(f,local);
  47         if(!local && !(f->bits&SF_DCDOWN))
  48         {       if((mode = f->mode&SF_RDWR) != (int)f->mode && _sfmode(f,mode,0) < 0)
  49                         SFMTXRETURN(f, (Sfoff_t)(-1));
  50                 if(SFSYNC(f) < 0)
  51                         SFMTXRETURN(f, (Sfoff_t)(-1));
  52 #ifdef MAP_TYPE
  53                 if(f->mode == SF_READ && (f->bits&SF_MMAP) && f->data)
  54                 {       SFMUNMAP(f, f->data, f->endb-f->data);
  55                         f->data = NIL(uchar*);
  56                 }
  57 #endif
  58                 f->next = f->endb = f->endr = f->endw = f->data;
  59         }
  60
  61         if((type &= (SEEK_SET|SEEK_CUR|SEEK_END)) > SEEK_END)
  62                 SFMTXRETURN(f, (Sfoff_t)(-1));
  63
  64         for(;;)
  65         {       dc = disc;
  66                 if(f->flags&SF_STRING)
  67                 {       SFSTRSIZE(f);
  68                         if(type == SEEK_SET)
  69                                 s = (ssize_t)addr;
  70                         else if(type == SEEK_CUR)
  71                                 s = (ssize_t)(addr + f->here);
  72                         else    s = (ssize_t)(addr + f->extent);
  73                 }
  74                 else
  75                 {       SFDISC(f,dc,seekf);
  76                         if(dc && dc->seekf)
  77                         {       SFDCSK(f,addr,type,dc,p);
  78                         }
  79                         else
  80                         {       p = syslseekf(f->file,(sfoff_t)addr,type);
  81                         }
  82                         if(p >= 0)
  83                                 SFMTXRETURN(f,p);
  84                         s = -1;
  85                 }
  86
  87                 if(local)
  88                         SETLOCAL(f);
  89                 switch(_sfexcept(f,SF_SEEK,s,dc))
  90                 {
  91                 case SF_EDISC:
  92                 case SF_ECONT:
  93                         if(f->flags&SF_STRING)
  94                                 SFMTXRETURN(f, (Sfoff_t)s);
  95                         goto do_continue;
  96                 default:
  97                         SFMTXRETURN(f, (Sfoff_t)(-1));
  98                 }
  99
 100         do_continue:
 101                 for(dc = f->disc; dc; dc = dc->disc)
 102                         if(dc == disc)
 103                                 break;
 104                 disc = dc;
 105         }
 106 }