src/system/libroot/posix/stdio/wsetup.c

   1 /*-
   2  * Copyright (c) 1990, 1993
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * This code is derived from software contributed to Berkeley by
   6  * Chris Torek.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  * 3. All advertising materials mentioning features or use of this software
  17  *    must display the following acknowledgement:
  18  *      This product includes software developed by the University of
  19  *      California, Berkeley and its contributors.
  20  * 4. Neither the name of the University nor the names of its contributors
  21  *    may be used to endorse or promote products derived from this software
  22  *    without specific prior written permission.
  23  *
  24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  34  * SUCH DAMAGE.
  35  */
  36
  37 #include <stdio.h>
  38 #include <stdlib.h>
  39 #include "local.h"
  40
  41 /*
  42  * Various output routines call wsetup to be sure it is safe to write,
  43  * because either _flags does not include __SWR, or _buf is NULL.
  44  * _wsetup returns 0 if OK to write, nonzero otherwise.
  45  */
  46 int
  47 __swsetup(fp)
  48         register FILE *fp;
  49 {
  50         /* make sure stdio is set up */
  51         if (!__sdidinit)
  52                 __sinit();
  53
  54         /*
  55          * If we are not writing, we had better be reading and writing.
  56          */
  57         if ((fp->_flags & __SWR) == 0) {
  58                 if ((fp->_flags & __SRW) == 0)
  59                         return (EOF);
  60                 if (fp->_flags & __SRD) {
  61                         /* clobber any ungetc data */
  62                         if (HASUB(fp))
  63                                 FREEUB(fp);
  64                         fp->_flags &= ~(__SRD|__SEOF);
  65                         fp->_r = 0;
  66                         fp->_p = fp->_bf._base;
  67                 }
  68                 fp->_flags |= __SWR;
  69         }
  70
  71         /*
  72          * Make a buffer if necessary, then set _w.
  73          */
  74         if (fp->_bf._base == NULL)
  75                 __smakebuf(fp);
  76         if (fp->_flags & __SLBF) {
  77                 /*
  78                  * It is line buffered, so make _lbfsize be -_bufsize
  79                  * for the putc() macro.  We will change _lbfsize back
  80                  * to 0 whenever we turn off __SWR.
  81                  */
  82                 fp->_w = 0;
  83                 fp->_lbfsize = -fp->_bf._size;
  84         } else
  85                 fp->_w = fp->_flags & __SNBF ? 0 : fp->_bf._size;
  86         return (0);
  87 }