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wbuf.c revision 1.10 
      1 /*	$NetBSD: wbuf.c,v 1.10 1999/09/20 04:39:35 lukem 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. All advertising materials mentioning features or use of this software
     19  *    must display the following acknowledgement:
     20  *	This product includes software developed by the University of
     21  *	California, Berkeley and its contributors.
     22  * 4. Neither the name of the University nor the names of its contributors
     23  *    may be used to endorse or promote products derived from this software
     24  *    without specific prior written permission.
     25  *
     26  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     27  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     28  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     29  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     30  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     31  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     32  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     33  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     34  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     35  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     36  * SUCH DAMAGE.
     37  */
     38 
     39 #include <sys/cdefs.h>
     40 #if defined(LIBC_SCCS) && !defined(lint)
     41 #if 0
     42 static char sccsid[] = "@(#)wbuf.c	8.1 (Berkeley) 6/4/93";
     43 #else
     44 __RCSID("$NetBSD: wbuf.c,v 1.10 1999/09/20 04:39:35 lukem Exp $");
     45 #endif
     46 #endif /* LIBC_SCCS and not lint */
     47 
     48 #include <assert.h>
     49 #include <errno.h>
     50 #include <stdio.h>
     51 #include "local.h"
     52 
     53 /*
     54  * Write the given character into the (probably full) buffer for
     55  * the given file.  Flush the buffer out if it is or becomes full,
     56  * or if c=='\n' and the file is line buffered.
     57  */
     58 int
     59 __swbuf(c, fp)
     60 	int c;
     61 	FILE *fp;
     62 {
     63 	int n;
     64 
     65 	_DIAGASSERT(fp != NULL);
     66 
     67 	/*
     68 	 * In case we cannot write, or longjmp takes us out early,
     69 	 * make sure _w is 0 (if fully- or un-buffered) or -_bf._size
     70 	 * (if line buffered) so that we will get called again.
     71 	 * If we did not do this, a sufficient number of putc()
     72 	 * calls might wrap _w from negative to positive.
     73 	 */
     74 	fp->_w = fp->_lbfsize;
     75 	if (cantwrite(fp)) {
     76 		errno = EBADF;
     77 		return (EOF);
     78 	}
     79 	c = (unsigned char)c;
     80 
     81 	/*
     82 	 * If it is completely full, flush it out.  Then, in any case,
     83 	 * stuff c into the buffer.  If this causes the buffer to fill
     84 	 * completely, or if c is '\n' and the file is line buffered,
     85 	 * flush it (perhaps a second time).  The second flush will always
     86 	 * happen on unbuffered streams, where _bf._size==1; fflush()
     87 	 * guarantees that putc() will always call wbuf() by setting _w
     88 	 * to 0, so we need not do anything else.
     89 	 */
     90 	n = fp->_p - fp->_bf._base;
     91 	if (n >= fp->_bf._size) {
     92 		if (fflush(fp))
     93 			return (EOF);
     94 		n = 0;
     95 	}
     96 	fp->_w--;
     97 	*fp->_p++ = c;
     98 	if (++n == fp->_bf._size || (fp->_flags & __SLBF && c == '\n'))
     99 		if (fflush(fp))
    100 			return (EOF);
    101 	return (c);
    102 }
    103