cde/programs/dtksh/ksh93/src/lib/libast/sfio/sfpurge.c

   1 /*
   2  * CDE - Common Desktop Environment
   3  *
   4  * Copyright (c) 1993-2012, The Open Group. All rights reserved.
   5  *
   6  * These libraries and programs are free software; you can
   7  * redistribute them and/or modify them under the terms of the GNU
   8  * Lesser General Public License as published by the Free Software
   9  * Foundation; either version 2 of the License, or (at your option)
  10  * any later version.
  11  *
  12  * These libraries and programs are distributed in the hope that
  13  * they will be useful, but WITHOUT ANY WARRANTY; without even the
  14  * implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
  15  * PURPOSE. See the GNU Lesser General Public License for more
  16  * details.
  17  *
  18  * You should have received a copy of the GNU Lesser General Public
  19  * License along with these librararies and programs; if not, write
  20  * to the Free Software Foundation, Inc., 51 Franklin Street, Fifth
  21  * Floor, Boston, MA 02110-1301 USA
  22  */
  23 /* $XConsortium: sfpurge.c /main/3 1995/11/01 18:33:41 rswiston $ */
  24 /***************************************************************
  25 *                                                              *
  26 *                      AT&T - PROPRIETARY                      *
  27 *                                                              *
  28 *         THIS IS PROPRIETARY SOURCE CODE LICENSED BY          *
  29 *                          AT&T CORP.                          *
  30 *                                                              *
  31 *                Copyright (c) 1995 AT&T Corp.                 *
  32 *                     All Rights Reserved                      *
  33 *                                                              *
  34 *           This software is licensed by AT&T Corp.            *
  35 *       under the terms and conditions of the license in       *
  36 *       http://www.research.att.com/orgs/ssr/book/reuse        *
  37 *                                                              *
  38 *               This software was created by the               *
  39 *           Software Engineering Research Department           *
  40 *                    AT&T Bell Laboratories                    *
  41 *                                                              *
  42 *               For further information contact                *
  43 *                     gsf@research.att.com                     *
  44 *                                                              *
  45 ***************************************************************/
  46 #include        "sfhdr.h"
  47
  48 /*      Delete all pending data in the buffer
  49 **
  50 **      Written by Kiem-Phong Vo (07/08/91)
  51 */
  52
  53 #if __STD_C
  54 sfpurge(reg Sfio_t* f)
  55 #else
  56 sfpurge(f)
  57 reg Sfio_t      *f;
  58 #endif
  59 {
  60         reg int mode;
  61
  62         if((mode = f->mode&SF_RDWR) != f->mode && _sfmode(f,mode,0) < 0)
  63                 return -1;
  64
  65         if(f->disc == _Sfudisc)
  66                 (void)sfclose((*_Sfstack)(f,NIL(Sfile_t*)));
  67
  68         /* cannot purge read string streams */
  69         if((f->flags&SF_STRING) && (f->mode&SF_READ) )
  70                 goto done;
  71
  72         SFLOCK(f,0);
  73
  74         /* if memory map must be a read stream, pretend data is gone */
  75 #ifdef MAP_TYPE
  76         if(f->flags&SF_MMAP)
  77         {       f->here -= f->endb - f->next;
  78                 if(f->data)
  79                 {       (void)munmap((caddr_t)f->data,f->endb-f->data);
  80                         SFSK(f,f->here,0,f->disc);
  81                         f->endb = f->endr = f->endw =
  82                         f->next = f->data = NIL(uchar*);
  83                 }
  84
  85                 SFOPEN(f,0);
  86                 return 0;
  87         }
  88 #endif
  89
  90         switch(f->mode&~SF_LOCK)
  91         {
  92         default :
  93                 return -1;
  94         case SF_WRITE :
  95                 f->next = f->data;
  96                 if((f->flags&(SF_PROCESS|SF_RDWR)) != (SF_PROCESS|SF_RDWR))
  97                         break;
  98
  99                 /* 2-way pipe, must clear read buffer */
 100                 (void)_sfmode(f,SF_READ,1);
 101                 /* fall through */
 102         case SF_READ:
 103                 if(f->extent >= 0 && f->endb > f->next)
 104                 {       f->here -= f->endb-f->next;
 105                         SFSK(f,f->here,0,f->disc);
 106                 }
 107                 f->endb = f->next = f->data;
 108                 break;
 109         }
 110
 111         SFOPEN(f,0);
 112
 113 done:
 114         if((f->flags&SF_IOCHECK) && f->disc && f->disc->exceptf)
 115                 (void)(*f->disc->exceptf)(f,SF_PURGE,f->disc);
 116
 117         return 0;
 118 }