Home | History | Annotate | Line # | Download | only in stdio
wbuf.c revision 1.3 
      1 /*-
      2  * Copyright (c) 1990 The Regents of the University of California.
      3  * 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 #if defined(LIBC_SCCS) && !defined(lint)
     38 /*static char *sccsid = "from: @(#)wbuf.c	5.6 (Berkeley) 1/20/91";*/
     39 static char *rcsid = "$Id: wbuf.c,v 1.3 1993/08/26 00:47:41 jtc Exp $";
     40 #endif /* LIBC_SCCS and not lint */
     41 
     42 #include <stdio.h>
     43 #include "local.h"
     44 
     45 /*
     46  * Write the given character into the (probably full) buffer for
     47  * the given file.  Flush the buffer out if it is or becomes full,
     48  * or if c=='\n' and the file is line buffered.
     49  */
     50 __swbuf(c, fp)
     51 	register int c;
     52 	register FILE *fp;
     53 {
     54 	register int n;
     55 
     56 	/*
     57 	 * In case we cannot write, or longjmp takes us out early,
     58 	 * make sure _w is 0 (if fully- or un-buffered) or -_bf._size
     59 	 * (if line buffered) so that we will get called again.
     60 	 * If we did not do this, a sufficient number of putc()
     61 	 * calls might wrap _w from negative to positive.
     62 	 */
     63 	fp->_w = fp->_lbfsize;
     64 	if (cantwrite(fp))
     65 		return (EOF);
     66 	c = (unsigned char)c;
     67 
     68 	/*
     69 	 * If it is completely full, flush it out.  Then, in any case,
     70 	 * stuff c into the buffer.  If this causes the buffer to fill
     71 	 * completely, or if c is '\n' and the file is line buffered,
     72 	 * flush it (perhaps a second time).  The second flush will always
     73 	 * happen on unbuffered streams, where _bf._size==1; fflush()
     74 	 * guarantees that putc() will always call wbuf() by setting _w
     75 	 * to 0, so we need not do anything else.
     76 	 */
     77 	n = fp->_p - fp->_bf._base;
     78 	if (n >= fp->_bf._size) {
     79 		if (fflush(fp))
     80 			return (EOF);
     81 		n = 0;
     82 	}
     83 	fp->_w--;
     84 	*fp->_p++ = c;
     85 	if (++n == fp->_bf._size || (fp->_flags & __SLBF && c == '\n'))
     86 		if (fflush(fp))
     87 			return (EOF);
     88 	return (c);
     89 }
     90