usr/src/lib/libast/common/sfio/sfclrlock.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 /*      Function to clear a locked stream.
  25 **      This is useful for programs that longjmp from the mid of an sfio function.
  26 **      There is no guarantee on data integrity in such a case.
  27 **
  28 **      Written by Kiem-Phong Vo
  29 */
  30 #if __STD_C
  31 int sfclrlock(Sfio_t* f)
  32 #else
  33 int sfclrlock(f)
  34 Sfio_t  *f;
  35 #endif
  36 {
  37         int     rv;
  38         SFMTXDECL(f);
  39
  40         /* already closed */
  41         if(f && (f->mode&SF_AVAIL))
  42                 return 0;
  43
  44         SFMTXENTER(f,0);
  45
  46         /* clear error bits */
  47         f->flags &= ~(SF_ERROR|SF_EOF);
  48
  49         /* clear peek locks */
  50         if(f->mode&SF_PKRD)
  51         {       f->here -= f->endb-f->next;
  52                 f->endb = f->next;
  53         }
  54
  55         SFCLRBITS(f);
  56
  57         /* throw away all lock bits except for stacking state SF_PUSH */
  58         f->mode &= (SF_RDWR|SF_INIT|SF_POOL|SF_PUSH|SF_SYNCED|SF_STDIO);
  59
  60         rv = (f->mode&SF_PUSH) ? 0 : (f->flags&SF_FLAGS);
  61
  62         SFMTXRETURN(f, rv);
  63 }