usr.bin/fmt/buffer.h

   1 /*      $NetBSD: buffer.h,v 1.3 2006/01/04 22:05:26 christos 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 }