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buffer.h revision 1.2 
      1 /*	$NetBSD: buffer.h,v 1.2 2005/12/24 20:52:20 perry Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 2005 The NetBSD Foundation, Inc.
      5  * All rights reserved.
      6  *
      7  * This code is derived from software contributed to The NetBSD Foundation
      8  * by Christos Zoulas.
      9  *
     10  * Redistribution and use in source and binary forms, with or without
     11  * modification, are permitted provided that the following conditions
     12  * are met:
     13  * 1. Redistributions of source code must retain the above copyright
     14  *    notice, this list of conditions and the following disclaimer.
     15  * 2. Redistributions in binary form must reproduce the above copyright
     16  *    notice, this list of conditions and the following disclaimer in the
     17  *    documentation and/or other materials provided with the distribution.
     18  * 3. All advertising materials mentioning features or use of this software
     19  *    must display the following acknowledgement:
     20  *        This product includes software developed by the NetBSD
     21  *        Foundation, Inc. and its contributors.
     22  * 4. Neither the name of The NetBSD Foundation nor the names of its
     23  *    contributors may be used to endorse or promote products derived
     24  *    from this software without specific prior written permission.
     25  *
     26  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     27  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     28  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     29  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     30  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     31  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     32  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     33  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     34  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     35  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     36  * POSSIBILITY OF SUCH DAMAGE.
     37  */
     38 
     39 #include <stddef.h>
     40 #include <stdio.h>
     41 #include <stdlib.h>
     42 #include <err.h>
     43 
     44 struct buffer {
     45 	char *ptr;
     46 	char *bptr;
     47 	char *eptr;
     48 };
     49 
     50 static void
     51 buf_init(struct buffer *buf)
     52 {
     53 	buf->ptr = buf->bptr = malloc(BUFSIZ);
     54 	if (buf->ptr == NULL)
     55 		err(1, "Cannot allocate buffer");
     56 	buf->eptr = buf->ptr + BUFSIZ;
     57 }
     58 
     59 static void
     60 buf_end(struct buffer *buf)
     61 {
     62 	free(buf->bptr);
     63 }
     64 
     65 static void
     66 buf_grow(struct buffer *buf, size_t minsize)
     67 {
     68 	ptrdiff_t diff;
     69 	size_t len = (buf->eptr - buf->bptr) +
     70 	    minsize > BUFSIZ ? minsize : BUFSIZ;
     71 	char *nptr = realloc(buf->bptr, len);
     72 
     73 	if (nptr == NULL)
     74 		err(1, "Cannot grow buffer");
     75 
     76 	if (nptr == buf->bptr)
     77 		return;
     78 
     79 	diff = nptr - buf->bptr;
     80 	buf->bptr += diff;
     81 	buf->eptr = buf->bptr + len;
     82 	buf->ptr += diff;
     83 }
     84 
     85 static inline void
     86 buf_putc(struct buffer *buf, char c)
     87 {
     88 	if (buf->ptr >= buf->eptr)
     89 		buf_grow(buf, 1);
     90 	*buf->ptr++ = c;
     91 }
     92 
     93 static inline void
     94 buf_reset(struct buffer *buf)
     95 {
     96 	buf->ptr = buf->bptr;
     97 }
     98 
     99 static inline char
    100 buf_unputc(struct buffer *buf)
    101 {
    102 	return buf->ptr > buf->bptr ? *--buf->ptr : '\0';
    103 }
    104