gonzui

    1: /*      $OpenBSD: wbuf.c,v 1.12 2009/11/09 00:18:28 kurt Exp $ */
    2: /*-
    3:  * Copyright (c) 1990, 1993
    4:  *      The Regents of the University of California.  All rights reserved.
    5:  *
    6:  * This code is derived from software contributed to Berkeley by
    7:  * Chris Torek.
    8:  *
    9:  * Redistribution and use in source and binary forms, with or without
   10:  * modification, are permitted provided that the following conditions
   11:  * are met:
   12:  * 1. Redistributions of source code must retain the above copyright
   13:  *    notice, this list of conditions and the following disclaimer.
   14:  * 2. Redistributions in binary form must reproduce the above copyright
   15:  *    notice, this list of conditions and the following disclaimer in the
   16:  *    documentation and/or other materials provided with the distribution.
   17:  * 3. Neither the name of the University nor the names of its contributors
   18:  *    may be used to endorse or promote products derived from this software
   19:  *    without specific prior written permission.
   20:  *
   21:  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   22:  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   23:  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   24:  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   25:  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   26:  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   27:  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   28:  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   29:  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   30:  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   31:  * SUCH DAMAGE.
   32:  */
   33: 
   34: #include <stdio.h>
   35: #include <errno.h>
   36: #include "local.h"
   37: 
   38: /*
   39:  * Write the given character into the (probably full) buffer for
   40:  * the given file.  Flush the buffer out if it is or becomes full,
   41:  * or if c=='\n' and the file is line buffered.
   42:  */
   43: int
   44: __swbuf(int c, FILE *fp)
   45: {
   46:         int n;
   47: 
   48:         _SET_ORIENTATION(fp, -1);
   49:         /*
   50:          * In case we cannot write, or longjmp takes us out early,
   51:          * make sure _w is 0 (if fully- or un-buffered) or -_bf._size
   52:          * (if line buffered) so that we will get called again.
   53:          * If we did not do this, a sufficient number of putc()
   54:          * calls might wrap _w from negative to positive.
   55:          */
   56:         fp->_w = fp->_lbfsize;
   57:         if (cantwrite(fp)) {
   58:                 __sseterr(fp, EBADF);
   59:                 return (EOF);
   60:         }
   61:         c = (unsigned char)c;
   62: 
   63:         /*
   64:          * If it is completely full, flush it out.  Then, in any case,
   65:          * stuff c into the buffer.  If this causes the buffer to fill
   66:          * completely, or if c is '\n' and the file is line buffered,
   67:          * flush it (perhaps a second time).  The second flush will always
   68:          * happen on unbuffered streams, where _bf._size==1; __sflush()
   69:          * guarantees that putc() will always call wbuf() by setting _w
   70:          * to 0, so we need not do anything else.
   71:          */
   72:         n = fp->_p - fp->_bf._base;
   73:         if (n >= fp->_bf._size) {
   74:                 if (__sflush(fp))
   75:                         return (EOF);
   76:                 n = 0;
   77:         }
   78:         fp->_w--;
   79:         *fp->_p++ = c;
   80:         if (++n == fp->_bf._size || (fp->_flags & __SLBF && c == '\n'))
   81:                 if (__sflush(fp))
   82:                         return (EOF);
   83:         return (c);
   84: }