wiretap/buffer.c

   1 /* buffer.c
   2  *
   3  * $Id$
   4  *
   5  * Wiretap Library
   6  * Copyright (c) 1998 by Gilbert Ramirez <gram@alumni.rice.edu>
   7  *
   8  * This program is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU General Public License
  10  * as published by the Free Software Foundation; either version 2
  11  * of the License, or (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License
  19  * along with this program; if not, write to the Free Software
  20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  21  *
  22  */
  23 #include "config.h"
  24
  25 #include <stdio.h>
  26 #include <stdlib.h>
  27 #include <string.h>
  28 #include <glib.h>
  29
  30 #include "buffer.h"
  31
  32 /* Initializes a buffer with a certain amount of allocated space */
  33 void
  34 buffer_init(Buffer* buffer, gsize space)
  35 {
  36         buffer->data = (guint8*)g_malloc(space);
  37         buffer->allocated = space;
  38         buffer->start = 0;
  39         buffer->first_free = 0;
  40 }
  41
  42 /* Frees the memory used by a buffer, and the buffer struct */
  43 void
  44 buffer_free(Buffer* buffer)
  45 {
  46         g_free(buffer->data);
  47 }
  48
  49 /* Assures that there are 'space' bytes at the end of the used space
  50         so that another routine can copy directly into the buffer space. After
  51         doing that, the routine will also want to run
  52         buffer_increase_length(). */
  53 void
  54 buffer_assure_space(Buffer* buffer, gsize space)
  55 {
  56         gsize available_at_end = buffer->allocated - buffer->first_free;
  57         gsize space_used;
  58         gboolean space_at_beginning;
  59
  60         /* If we've got the space already, good! */
  61         if (space <= available_at_end) {
  62                 return;
  63         }
  64
  65         /* Maybe we don't have the space available at the end, but we would
  66                 if we moved the used space back to the beginning of the
  67                 allocation. The buffer could have become fragmented through lots
  68                 of calls to buffer_remove_start(). I'm using buffer->start as the
  69                 same as 'available_at_start' in this comparison. */
  70
  71         /* or maybe there's just no more room. */
  72
  73         space_at_beginning = buffer->start >= space;
  74         if (space_at_beginning || buffer->start > 0) {
  75                 space_used = buffer->first_free - buffer->start;
  76                 /* this memory copy better be safe for overlapping memory regions! */
  77                 memmove(buffer->data, buffer->data + buffer->start, space_used);
  78                 buffer->start = 0;
  79                 buffer->first_free = space_used;
  80         }
  81         /*if (buffer->start >= space) {*/
  82         if (space_at_beginning) {
  83                 return;
  84         }
  85
  86         /* We'll allocate more space */
  87         buffer->allocated += space + 1024;
  88         buffer->data = (guint8*)g_realloc(buffer->data, buffer->allocated);
  89 }
  90
  91 void
  92 buffer_append(Buffer* buffer, guint8 *from, gsize bytes)
  93 {
  94         buffer_assure_space(buffer, bytes);
  95         memcpy(buffer->data + buffer->first_free, from, bytes);
  96         buffer->first_free += bytes;
  97 }
  98
  99 void
 100 buffer_remove_start(Buffer* buffer, gsize bytes)
 101 {
 102         if (buffer->start + bytes > buffer->first_free) {
 103                 g_error("buffer_remove_start trying to remove %" G_GINT64_MODIFIER "u bytes. s=%" G_GINT64_MODIFIER "u ff=%" G_GINT64_MODIFIER "u!\n",
 104                         (guint64)bytes, (guint64)buffer->start,
 105                         (guint64)buffer->first_free);
 106                 /** g_error() does an abort() and thus never returns **/
 107         }
 108         buffer->start += bytes;
 109
 110         if (buffer->start == buffer->first_free) {
 111                 buffer->start = 0;
 112                 buffer->first_free = 0;
 113         }
 114 }
 115
 116
 117 #ifndef SOME_FUNCTIONS_ARE_DEFINES
 118 void
 119 buffer_clean(Buffer* buffer)
 120 {
 121         buffer_remove_start(buffer, buffer_length(buffer));
 122 }
 123 #endif
 124
 125 #ifndef SOME_FUNCTIONS_ARE_DEFINES
 126 void
 127 buffer_increase_length(Buffer* buffer, gsize bytes)
 128 {
 129         buffer->first_free += bytes;
 130 }
 131 #endif
 132
 133 #ifndef SOME_FUNCTIONS_ARE_DEFINES
 134 gsize
 135 buffer_length(Buffer* buffer)
 136 {
 137         return buffer->first_free - buffer->start;
 138 }
 139 #endif
 140
 141 #ifndef SOME_FUNCTIONS_ARE_DEFINES
 142 guint8 *
 143 buffer_start_ptr(Buffer* buffer)
 144 {
 145         return buffer->data + buffer->start;
 146 }
 147 #endif
 148
 149 #ifndef SOME_FUNCTIONS_ARE_DEFINES
 150 guint8 *
 151 buffer_end_ptr(Buffer* buffer)
 152 {
 153         return buffer->data + buffer->first_free;
 154 }
 155 #endif
 156
 157 #ifndef SOME_FUNCTIONS_ARE_DEFINES
 158 void
 159 buffer_append_buffer(Buffer* buffer, Buffer* src_buffer)
 160 {
 161         buffer_append(buffer, buffer_start_ptr(src_buffer), buffer_length(src_buffer));
 162 }
 163 #endif