stdio/wbuf.c

   1 /*
   2  * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * The contents of this file constitute Original Code as defined in and
   7  * are subject to the Apple Public Source License Version 1.1 (the
   8  * "License").  You may not use this file except in compliance with the
   9  * License.  Please obtain a copy of the License at
  10  * http://www.apple.com/publicsource and read it before using this file.
  11  *
  12  * This Original Code and all software distributed under the License are
  13  * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  14  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  15  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  16  * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
  17  * License for the specific language governing rights and limitations
  18  * under the License.
  19  *
  20  * @APPLE_LICENSE_HEADER_END@
  21  */
  22 /*
  23  * Copyright (c) 1990, 1993
  24  *      The Regents of the University of California.  All rights reserved.
  25  *
  26  * This code is derived from software contributed to Berkeley by
  27  * Chris Torek.
  28  *
  29  * Redistribution and use in source and binary forms, with or without
  30  * modification, are permitted provided that the following conditions
  31  * are met:
  32  * 1. Redistributions of source code must retain the above copyright
  33  *    notice, this list of conditions and the following disclaimer.
  34  * 2. Redistributions in binary form must reproduce the above copyright
  35  *    notice, this list of conditions and the following disclaimer in the
  36  *    documentation and/or other materials provided with the distribution.
  37  * 3. All advertising materials mentioning features or use of this software
  38  *    must display the following acknowledgement:
  39  *      This product includes software developed by the University of
  40  *      California, Berkeley and its contributors.
  41  * 4. Neither the name of the University nor the names of its contributors
  42  *    may be used to endorse or promote products derived from this software
  43  *    without specific prior written permission.
  44  *
  45  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  46  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  47  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  48  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  49  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  50  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  51  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  52  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  53  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  54  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  55  * SUCH DAMAGE.
  56  */
  57
  58
  59 #include <stdio.h>
  60 #include "local.h"
  61
  62 /*
  63  * Write the given character into the (probably full) buffer for
  64  * the given file.  Flush the buffer out if it is or becomes full,
  65  * or if c=='\n' and the file is line buffered.
  66  */
  67 int
  68 __swbuf(c, fp)
  69         register int c;
  70         register FILE *fp;
  71 {
  72         register int n;
  73
  74         /*
  75          * In case we cannot write, or longjmp takes us out early,
  76          * make sure _w is 0 (if fully- or un-buffered) or -_bf._size
  77          * (if line buffered) so that we will get called again.
  78          * If we did not do this, a sufficient number of putc()
  79          * calls might wrap _w from negative to positive.
  80          */
  81         fp->_w = fp->_lbfsize;
  82         if (cantwrite(fp))
  83                 return (EOF);
  84         c = (unsigned char)c;
  85
  86         /*
  87          * If it is completely full, flush it out.  Then, in any case,
  88          * stuff c into the buffer.  If this causes the buffer to fill
  89          * completely, or if c is '\n' and the file is line buffered,
  90          * flush it (perhaps a second time).  The second flush will always
  91          * happen on unbuffered streams, where _bf._size==1; fflush()
  92          * guarantees that putc() will always call wbuf() by setting _w
  93          * to 0, so we need not do anything else.
  94          */
  95         n = fp->_p - fp->_bf._base;
  96         if (n >= fp->_bf._size) {
  97                 if (fflush(fp))
  98                         return (EOF);
  99                 n = 0;
 100         }
 101         fp->_w--;
 102         *fp->_p++ = c;
 103         if (++n == fp->_bf._size || (fp->_flags & __SLBF && c == '\n'))
 104                 if (fflush(fp))
 105                         return (EOF);
 106         return (c);
 107 }