stdio/FreeBSD/wbuf.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  * 4. Neither the name of the University nor the names of its contributors
  17  *    may be used to endorse or promote products derived from this software
  18  *    without specific prior written permission.
  19  *
  20  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  30  * SUCH DAMAGE.
  31  */
  32
  33 #if defined(LIBC_SCCS) && !defined(lint)
  34 static char sccsid[] = "@(#)wbuf.c      8.1 (Berkeley) 6/4/93";
  35 #endif /* LIBC_SCCS and not lint */
  36 #include <sys/cdefs.h>
  37 __FBSDID("$FreeBSD: src/lib/libc/stdio/wbuf.c,v 1.12 2007/01/09 00:28:08 imp Exp $");
  38
  39 #include <stdio.h>
  40 #include <errno.h>
  41 #include "local.h"
  42
  43 /*
  44  * Write the given character into the (probably full) buffer for
  45  * the given file.  Flush the buffer out if it is or becomes full,
  46  * or if c=='\n' and the file is line buffered.
  47  *
  48  * Non-MT-safe
  49  */
  50 int
  51 __swbuf(c, fp)
  52         int c;
  53         FILE *fp;
  54 {
  55         int n;
  56
  57         /*
  58          * In case we cannot write, or longjmp takes us out early,
  59          * make sure _w is 0 (if fully- or un-buffered) or -_bf._size
  60          * (if line buffered) so that we will get called again.
  61          * If we did not do this, a sufficient number of putc()
  62          * calls might wrap _w from negative to positive.
  63          */
  64         fp->_w = fp->_lbfsize;
  65         if (prepwrite(fp) != 0) {
  66                 errno = EBADF;
  67                 return (EOF);
  68         }
  69         c = (unsigned char)c;
  70
  71         ORIENT(fp, -1);
  72
  73         /*
  74          * If it is completely full, flush it out.  Then, in any case,
  75          * stuff c into the buffer.  If this causes the buffer to fill
  76          * completely, or if c is '\n' and the file is line buffered,
  77          * flush it (perhaps a second time).  The second flush will always
  78          * happen on unbuffered streams, where _bf._size==1; fflush()
  79          * guarantees that putc() will always call wbuf() by setting _w
  80          * to 0, so we need not do anything else.
  81          */
  82         n = fp->_p - fp->_bf._base;
  83         if (n >= fp->_bf._size) {
  84                 if (__fflush(fp))
  85                         return (EOF);
  86                 n = 0;
  87         }
  88         fp->_w--;
  89         *fp->_p++ = c;
  90         if (++n == fp->_bf._size || (fp->_flags & __SLBF && c == '\n'))
  91                 if (__fflush(fp))
  92                         return (EOF);
  93         return (c);
  94 }