src/system/libroot/posix/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. 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 #include <stdio.h>
  38 #include <errno.h>
  39
  40 #include <errno_private.h>
  41
  42 #include "local.h"
  43
  44 /*
  45  * Write the given character into the (probably full) buffer for
  46  * the given file.  Flush the buffer out if it is or becomes full,
  47  * or if c=='\n' and the file is line buffered.
  48  */
  49 int
  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                 __set_errno(EBADF);
  66                 return (EOF);
  67         }
  68         c = (unsigned char)c;
  69
  70         /*
  71          * If it is completely full, flush it out.  Then, in any case,
  72          * stuff c into the buffer.  If this causes the buffer to fill
  73          * completely, or if c is '\n' and the file is line buffered,
  74          * flush it (perhaps a second time).  The second flush will always
  75          * happen on unbuffered streams, where _bf._size==1; fflush()
  76          * guarantees that putc() will always call wbuf() by setting _w
  77          * to 0, so we need not do anything else.
  78          */
  79         n = fp->_p - fp->_bf._base;
  80         if (n >= fp->_bf._size) {
  81                 if (fflush(fp))
  82                         return (EOF);
  83                 n = 0;
  84         }
  85         fp->_w--;
  86         *fp->_p++ = c;
  87         if (++n == fp->_bf._size || (fp->_flags & __SLBF && c == '\n'))
  88                 if (fflush(fp))
  89                         return (EOF);
  90         return (c);
  91 }