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       ---
       wbuf.c (3483B)
       ---
            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  * 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 rcsid[] = "$OpenBSD: wbuf.c,v 1.4 1997/05/31 22:41:32 tholo Exp $";
           39 #endif /* LIBC_SCCS and not lint */
           40 
           41 #include <stdio.h>
           42 #include <errno.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 int
           51 __swbuf(c, fp)
           52         register int c;
           53         register FILE *fp;
           54 {
           55         register 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 (cantwrite(fp)) {
           66                 errno = EBADF;
           67                 return (EOF);
           68         }
           69         c = (unsigned char)c;
           70 
           71         /*
           72          * If it is completely full, flush it out.  Then, in any case,
           73          * stuff c into the buffer.  If this causes the buffer to fill
           74          * completely, or if c is '\n' and the file is line buffered,
           75          * flush it (perhaps a second time).  The second flush will always
           76          * happen on unbuffered streams, where _bf._size==1; fflush()
           77          * guarantees that putc() will always call wbuf() by setting _w
           78          * to 0, so we need not do anything else.
           79          */
           80         n = fp->_p - fp->_bf._base;
           81         if (n >= fp->_bf._size) {
           82                 if (fflush(fp))
           83                         return (EOF);
           84                 n = 0;
           85         }
           86         fp->_w--;
           87         *fp->_p++ = c;
           88         if (++n == fp->_bf._size || (fp->_flags & __SLBF && c == '\n'))
           89                 if (fflush(fp))
           90                         return (EOF);
           91         return (c);
           92 }