lib/libc/stdio/wbuf.c

   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. Neither the name of the University nor the names of its contributors
  17  *    may be used to endorse or promote products derived from this software
  18  *    without specific prior written permission.
  19  *
  20  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  30  * SUCH DAMAGE.
  31  */
  32
  33 #if defined(LIBC_SCCS) && !defined(lint)
  34 static char sccsid[] = "@(#)wbuf.c      8.1 (Berkeley) 6/4/93";
  35 #endif /* LIBC_SCCS and not lint */
  36 #include <sys/cdefs.h>
  37 __FBSDID("$FreeBSD$");
  38
  39 #include <errno.h>
  40 #include <stdio.h>
  41 #include "local.h"
  42
  43 /*
  44  * Write the given character into the (probably full) buffer for
  45  * the given file.  Flush the buffer out if it is or becomes full,
  46  * or if c=='\n' and the file is line buffered.
  47  *
  48  * Non-MT-safe
  49  */
  50 int
  51 __swbuf(int c, FILE *fp)
  52 {
  53         int n;
  54
  55         /*
  56          * In case we cannot write, or longjmp takes us out early,
  57          * make sure _w is 0 (if fully- or un-buffered) or -_bf._size
  58          * (if line buffered) so that we will get called again.
  59          * If we did not do this, a sufficient number of putc()
  60          * calls might wrap _w from negative to positive.
  61          */
  62         fp->_w = fp->_lbfsize;
  63         if (prepwrite(fp) != 0) {
  64                 errno = EBADF;
  65                 return (EOF);
  66         }
  67         c = (unsigned char)c;
  68
  69         ORIENT(fp, -1);
  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 }