lib/libc/stdio/wbuf.c

   1 /*      $NetBSD: wbuf.c,v 1.15 2012/03/15 18:22:31 christos Exp $       */
   2
   3 /*-
   4  * Copyright (c) 1990, 1993
   5  *      The Regents of the University of California.  All rights reserved.
   6  *
   7  * This code is derived from software contributed to Berkeley by
   8  * Chris Torek.
   9  *
  10  * Redistribution and use in source and binary forms, with or without
  11  * modification, are permitted provided that the following conditions
  12  * are met:
  13  * 1. Redistributions of source code must retain the above copyright
  14  *    notice, this list of conditions and the following disclaimer.
  15  * 2. Redistributions in binary form must reproduce the above copyright
  16  *    notice, this list of conditions and the following disclaimer in the
  17  *    documentation and/or other materials provided with the distribution.
  18  * 3. Neither the name of the University nor the names of its contributors
  19  *    may be used to endorse or promote products derived from this software
  20  *    without specific prior written permission.
  21  *
  22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  32  * SUCH DAMAGE.
  33  */
  34
  35 #include <sys/cdefs.h>
  36 #if defined(LIBC_SCCS) && !defined(lint)
  37 #if 0
  38 static char sccsid[] = "@(#)wbuf.c      8.1 (Berkeley) 6/4/93";
  39 #else
  40 __RCSID("$NetBSD: wbuf.c,v 1.15 2012/03/15 18:22:31 christos Exp $");
  41 #endif
  42 #endif /* LIBC_SCCS and not lint */
  43
  44 #include <assert.h>
  45 #include <errno.h>
  46 #include <stdio.h>
  47 #include "reentrant.h"
  48 #include "local.h"
  49
  50 /*
  51  * Write the given character into the (probably full) buffer for
  52  * the given file.  Flush the buffer out if it is or becomes full,
  53  * or if c=='\n' and the file is line buffered.
  54  */
  55 int
  56 __swbuf(int c, FILE *fp)
  57 {
  58         int n;
  59
  60         _DIAGASSERT(fp != NULL);
  61
  62         _SET_ORIENTATION(fp, -1);
  63
  64         /*
  65          * In case we cannot write, or longjmp takes us out early,
  66          * make sure _w is 0 (if fully- or un-buffered) or -_bf._size
  67          * (if line buffered) so that we will get called again.
  68          * If we did not do this, a sufficient number of putc()
  69          * calls might wrap _w from negative to positive.
  70          */
  71         fp->_w = fp->_lbfsize;
  72         if (cantwrite(fp)) {
  73                 errno = EBADF;
  74                 return EOF;
  75         }
  76         c = (unsigned char)c;
  77
  78         /*
  79          * If it is completely full, flush it out.  Then, in any case,
  80          * stuff c into the buffer.  If this causes the buffer to fill
  81          * completely, or if c is '\n' and the file is line buffered,
  82          * flush it (perhaps a second time).  The second flush will always
  83          * happen on unbuffered streams, where _bf._size==1; fflush()
  84          * guarantees that putc() will always call wbuf() by setting _w
  85          * to 0, so we need not do anything else.
  86          */
  87         _DIAGASSERT(__type_fit(int, fp->_p - fp->_bf._base));
  88         n = (int)(fp->_p - fp->_bf._base);
  89         if (n >= fp->_bf._size) {
  90                 if (fflush(fp))
  91                         return EOF;
  92                 n = 0;
  93         }
  94         fp->_w--;
  95         *fp->_p++ = c;
  96         if (++n == fp->_bf._size || (fp->_flags & __SLBF && c == '\n'))
  97                 if (fflush(fp))
  98                         return EOF;
  99         return c;
 100 }