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setvbuf.c revision 1.1 
      1 /*-
      2  * Copyright (c) 1990 The Regents of the University of California.
      3  * 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 sccsid[] = "@(#)setvbuf.c	5.2 (Berkeley) 2/1/91";
     39 #endif /* LIBC_SCCS and not lint */
     40 
     41 #include <stdio.h>
     42 #include <stdlib.h>
     43 #include "local.h"
     44 
     45 /*
     46  * Set one of the three kinds of buffering, optionally including
     47  * a buffer.
     48  */
     49 setvbuf(fp, buf, mode, size)
     50 	register FILE *fp;
     51 	char *buf;
     52 	register int mode;
     53 	register size_t size;
     54 {
     55 
     56 	/*
     57 	 * Verify arguments.  The `int' limit on `size' is due to this
     58 	 * particular implementation.
     59 	 */
     60 	if ((mode != _IOFBF && mode != _IOLBF && mode != _IONBF) ||
     61 	    (int)size < 0)
     62 		return (EOF);
     63 
     64 	/*
     65 	 * Write current buffer, if any; drop read count, if any.
     66 	 * Make sure putc() will not think fp is line buffered.
     67 	 * Free old buffer if it was from malloc().  Clear line and
     68 	 * non buffer flags, and clear malloc flag.
     69 	 */
     70 	(void) __sflush(fp);
     71 	fp->_r = 0;
     72 	fp->_lbfsize = 0;
     73 	if (fp->_flags & __SMBF)
     74 		free((void *)fp->_bf._base);
     75 	fp->_flags &= ~(__SLBF|__SNBF|__SMBF);
     76 
     77 	/*
     78 	 * Now put back whichever flag is needed, and fix _lbfsize
     79 	 * if line buffered.  Ensure output flush on exit if the
     80 	 * stream will be buffered at all.
     81 	 */
     82 	switch (mode) {
     83 
     84 	case _IONBF:
     85 		fp->_flags |= __SNBF;
     86 		fp->_bf._base = fp->_p = fp->_nbuf;
     87 		fp->_bf._size = 1;
     88 		break;
     89 
     90 	case _IOLBF:
     91 		fp->_flags |= __SLBF;
     92 		fp->_lbfsize = -size;
     93 		/* FALLTHROUGH */
     94 
     95 	case _IOFBF:
     96 		/* no flag */
     97 		__cleanup = _cleanup;
     98 		fp->_bf._base = fp->_p = (unsigned char *)buf;
     99 		fp->_bf._size = size;
    100 		break;
    101 	}
    102 
    103 	/*
    104 	 * Patch up write count if necessary.
    105 	 */
    106 	if (fp->_flags & __SWR)
    107 		fp->_w = fp->_flags & (__SLBF|__SNBF) ? 0 : size;
    108 
    109 	return (0);
    110 }
    111