usr/src/lib/libast/common/sfio/sfset.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 /*      Set some control flags or file descript for the stream
  25 **
  26 **      Written by Kiem-Phong Vo.
  27 */
  28
  29 #if __STD_C
  30 int sfset(Sfio_t* f, int flags, int set)
  31 #else
  32 int sfset(f,flags,set)
  33 Sfio_t*         f;
  34 int             flags;
  35 int             set;
  36 #endif
  37 {
  38         reg int oflags;
  39         SFMTXDECL(f);
  40
  41         SFMTXENTER(f,0);
  42
  43         if(flags == 0 && set == 0)
  44                 SFMTXRETURN(f, (f->flags&SF_FLAGS));
  45
  46         if((oflags = (f->mode&SF_RDWR)) != (int)f->mode && _sfmode(f,oflags,0) < 0)
  47                 SFMTXRETURN(f, 0);
  48
  49         if(flags == 0)
  50                 SFMTXRETURN(f, (f->flags&SF_FLAGS));
  51
  52         SFLOCK(f,0);
  53
  54         /* preserve at least one rd/wr flag */
  55         oflags = f->flags;
  56         if(!(f->bits&SF_BOTH) || (flags&SF_RDWR) == SF_RDWR )
  57                 flags &= ~SF_RDWR;
  58
  59         /* set the flag */
  60         if(set)
  61                 f->flags |=  (flags&SF_SETS);
  62         else    f->flags &= ~(flags&SF_SETS);
  63
  64         /* must have at least one of read/write */
  65         if(!(f->flags&SF_RDWR))
  66                 f->flags |= (oflags&SF_RDWR);
  67
  68         if(f->extent < 0)
  69                 f->flags &= ~SF_APPENDWR;
  70
  71         /* turn to appropriate mode as necessary */
  72         if((flags &= SF_RDWR) )
  73         {       if(!set)
  74                 {       if(flags == SF_READ)
  75                                 flags = SF_WRITE;
  76                         else    flags = SF_READ;
  77                 }
  78                 if((flags == SF_WRITE && !(f->mode&SF_WRITE)) ||
  79                    (flags == SF_READ && !(f->mode&(SF_READ|SF_SYNCED))) )
  80                         (void)_sfmode(f,flags,1);
  81         }
  82
  83         /* if not shared or unseekable, public means nothing */
  84         if(!(f->flags&SF_SHARE) || f->extent < 0)
  85                 f->flags &= ~SF_PUBLIC;
  86
  87         SFOPEN(f,0);
  88         SFMTXRETURN(f, (oflags&SF_FLAGS));
  89 }