usr/src/lib/libast/common/sfio/sfpurge.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 /*      Delete all pending data in the buffer
  25 **
  26 **      Written by Kiem-Phong Vo.
  27 */
  28
  29 #if __STD_C
  30 int sfpurge(Sfio_t* f)
  31 #else
  32 int sfpurge(f)
  33 Sfio_t* f;
  34 #endif
  35 {
  36         reg int mode;
  37         SFMTXDECL(f);
  38
  39         SFMTXENTER(f,-1);
  40
  41         if((mode = f->mode&SF_RDWR) != (int)f->mode && _sfmode(f,mode|SF_SYNCED,0) < 0)
  42                 SFMTXRETURN(f, -1);
  43
  44         if((f->flags&SF_IOCHECK) && f->disc && f->disc->exceptf)
  45                 (void)(*f->disc->exceptf)(f,SF_PURGE,(Void_t*)((int)1),f->disc);
  46
  47         if(f->disc == _Sfudisc)
  48                 (void)sfclose((*_Sfstack)(f,NIL(Sfio_t*)));
  49
  50         /* cannot purge read string streams */
  51         if((f->flags&SF_STRING) && (f->mode&SF_READ) )
  52                 goto done;
  53
  54         SFLOCK(f,0);
  55
  56         /* if memory map must be a read stream, pretend data is gone */
  57 #ifdef MAP_TYPE
  58         if(f->bits&SF_MMAP)
  59         {       f->here -= f->endb - f->next;
  60                 if(f->data)
  61                 {       SFMUNMAP(f,f->data,f->endb-f->data);
  62                         (void)SFSK(f,f->here,SEEK_SET,f->disc);
  63                 }
  64                 SFOPEN(f,0);
  65                 SFMTXRETURN(f, 0);
  66         }
  67 #endif
  68
  69         switch(f->mode&~SF_LOCK)
  70         {
  71         default :
  72                 SFOPEN(f,0);
  73                 SFMTXRETURN(f, -1);
  74         case SF_WRITE :
  75                 f->next = f->data;
  76                 if(!f->proc || !(f->flags&SF_READ) || !(f->mode&SF_WRITE) )
  77                         break;
  78
  79                 /* 2-way pipe, must clear read buffer */
  80                 (void)_sfmode(f,SF_READ,1);
  81                 /* fall through */
  82         case SF_READ:
  83                 if(f->extent >= 0 && f->endb > f->next)
  84                 {       f->here -= f->endb-f->next;
  85                         (void)SFSK(f,f->here,SEEK_SET,f->disc);
  86                 }
  87                 f->endb = f->next = f->data;
  88                 break;
  89         }
  90
  91         SFOPEN(f,0);
  92
  93 done:
  94         if((f->flags&SF_IOCHECK) && f->disc && f->disc->exceptf)
  95                 (void)(*f->disc->exceptf)(f,SF_PURGE,(Void_t*)((int)0),f->disc);
  96
  97         SFMTXRETURN(f, 0);
  98 }