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wbuf.c revision 1.13 
      1 /*	$NetBSD: wbuf.c,v 1.13 2003/08/07 16:43:35 agc 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 1.13 2003/08/07 16:43:35 agc 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(c, fp)
     57 	int c;
     58 	FILE *fp;
     59 {
     60 	int n;
     61 
     62 	_DIAGASSERT(fp != NULL);
     63 
     64 	_SET_ORIENTATION(fp, -1);
     65 
     66 	/*
     67 	 * In case we cannot write, or longjmp takes us out early,
     68 	 * make sure _w is 0 (if fully- or un-buffered) or -_bf._size
     69 	 * (if line buffered) so that we will get called again.
     70 	 * If we did not do this, a sufficient number of putc()
     71 	 * calls might wrap _w from negative to positive.
     72 	 */
     73 	fp->_w = fp->_lbfsize;
     74 	if (cantwrite(fp)) {
     75 		errno = EBADF;
     76 		return (EOF);
     77 	}
     78 	c = (unsigned char)c;
     79 
     80 	/*
     81 	 * If it is completely full, flush it out.  Then, in any case,
     82 	 * stuff c into the buffer.  If this causes the buffer to fill
     83 	 * completely, or if c is '\n' and the file is line buffered,
     84 	 * flush it (perhaps a second time).  The second flush will always
     85 	 * happen on unbuffered streams, where _bf._size==1; fflush()
     86 	 * guarantees that putc() will always call wbuf() by setting _w
     87 	 * to 0, so we need not do anything else.
     88 	 */
     89 	n = fp->_p - fp->_bf._base;
     90 	if (n >= fp->_bf._size) {
     91 		if (fflush(fp))
     92 			return (EOF);
     93 		n = 0;
     94 	}
     95 	fp->_w--;
     96 	*fp->_p++ = c;
     97 	if (++n == fp->_bf._size || (fp->_flags & __SLBF && c == '\n'))
     98 		if (fflush(fp))
     99 			return (EOF);
    100 	return (c);
    101 }
    102