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buffer.h revision 1.4 
      1 /*	$NetBSD: buffer.h,v 1.4 2008/04/28 20:24:12 martin 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  *
     19  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     21  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     23  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     27  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     29  * POSSIBILITY OF SUCH DAMAGE.
     30  */
     31 
     32 #include <stddef.h>
     33 #include <stdio.h>
     34 #include <stdlib.h>
     35 #include <err.h>
     36 
     37 #define BUF_SIZE	BUFSIZ
     38 struct buffer {
     39 	char *ptr;
     40 	char *bptr;
     41 	char *eptr;
     42 };
     43 
     44 static void
     45 buf_init(struct buffer *buf)
     46 {
     47 	buf->ptr = buf->bptr = malloc(BUF_SIZE);
     48 	if (buf->ptr == NULL)
     49 		err(1, "Cannot allocate buffer");
     50 	buf->eptr = buf->ptr + BUF_SIZE;
     51 }
     52 
     53 static void
     54 buf_end(struct buffer *buf)
     55 {
     56 	free(buf->bptr);
     57 }
     58 
     59 static void
     60 buf_grow(struct buffer *buf, size_t minsize)
     61 {
     62 	ptrdiff_t diff;
     63 	size_t len = (buf->eptr - buf->bptr) +
     64 	    (minsize > BUF_SIZE ? minsize : BUF_SIZE);
     65 	char *nptr = realloc(buf->bptr, len);
     66 
     67 	if (nptr == NULL)
     68 		err(1, "Cannot grow buffer");
     69 
     70 	if (nptr == buf->bptr) {
     71 		buf->eptr = buf->bptr + len;
     72 		return;
     73 	}
     74 
     75 	diff = nptr - buf->bptr;
     76 	buf->bptr += diff;
     77 	buf->eptr = buf->bptr + len;
     78 	buf->ptr += diff;
     79 }
     80 
     81 static inline void
     82 buf_putc(struct buffer *buf, char c)
     83 {
     84 	if (buf->ptr >= buf->eptr)
     85 		buf_grow(buf, 1);
     86 	*buf->ptr++ = c;
     87 }
     88 
     89 static inline void
     90 buf_reset(struct buffer *buf)
     91 {
     92 	buf->ptr = buf->bptr;
     93 }
     94 
     95 static inline char
     96 buf_unputc(struct buffer *buf)
     97 {
     98 	return buf->ptr > buf->bptr ? *--buf->ptr : '\0';
     99 }
    100