release/src/router/rp-l2tp/handlers/dstring.c

   1 /***********************************************************************
   2 *
   3 * l2tp/handlers/dstring.c
   4 *
   5 * Implements simple buffer which grows to accomodate accumulated string
   6 * data
   7 *
   8 * Copyright (C) 2002 by Roaring Penguin Software Inc.
   9 *
  10 * This software may be distributed under the terms of the GNU General
  11 * Public License, Version 2, or (at your option) any later version.
  12 *
  13 * LIC: GPL
  14 *
  15 ***********************************************************************/
  16
  17 static char const RCSID[] =
  18 "$Id: dstring.c,v 1.1.48.1 2005/08/08 12:05:25 honor Exp $";
  19
  20 #define INITIAL_SIZE 128
  21 #define GROW_FACTOR 2
  22
  23 #include "dstring.h"
  24 #include <stdlib.h>
  25 #include <string.h>
  26
  27 static int
  28 expand_for_size(dynstring *str, size_t len)
  29 {
  30     size_t newlen;
  31
  32     if (len >= str->alloc_size * GROW_FACTOR) {
  33         newlen = len + 1;
  34     } else {
  35         newlen = str->alloc_size * GROW_FACTOR;
  36     }
  37
  38     str->data = realloc(str->data, newlen);
  39     if (!str->data) {
  40         str->alloc_size = 0;
  41         str->actual_size = 0;
  42         return -1;
  43     }
  44
  45     str->alloc_size = newlen;
  46     return 0;
  47 }
  48
  49 /**********************************************************************
  50 * %FUNCTION: dynstring_init
  51 * %ARGUMENTS:
  52 *  str -- a dynstring structure
  53 * %RETURNS:
  54 *  0 on success; -1 on failure
  55 * %DESCRIPTION:
  56 *  Initializes dynamic string
  57 ***********************************************************************/
  58 int
  59 dynstring_init(dynstring *str)
  60 {
  61     str->data = malloc(INITIAL_SIZE);
  62     if (!str->data) return -1;
  63
  64     str->alloc_size = INITIAL_SIZE;
  65     str->actual_size = 0;
  66     str->data[0] = 0;
  67     return 0;
  68 }
  69
  70 /**********************************************************************
  71 * %FUNCTION: dynstring_free
  72 * %ARGUMENTS:
  73 *  str -- a dynstring structure
  74 * %RETURNS:
  75 *  Nothing
  76 * %DESCRIPTION:
  77 *  Frees resources used by dynamic string
  78 ***********************************************************************/
  79 void
  80 dynstring_free(dynstring *str)
  81 {
  82     if (str->data) {
  83         free(str->data);
  84         str->data = NULL;
  85     }
  86     str->alloc_size = 0;
  87     str->actual_size = 0;
  88 }
  89
  90 /**********************************************************************
  91 * %FUNCTION: dynstring_append
  92 * %ARGUMENTS:
  93 *  str -- dynamic string
  94 *  s2 -- string to append
  95 * %RETURNS:
  96 *  -1 on failure; 0 on success
  97 * %DESCRIPTION:
  98 *  Appends s2 to str
  99 ***********************************************************************/
 100 int
 101 dynstring_append(dynstring *str, char const *s2)
 102 {
 103     return dynstring_append_len(str, s2, strlen(s2));
 104 }
 105
 106 /**********************************************************************
 107 * %FUNCTION: dynstring_append_len
 108 * %ARGUMENTS:
 109 *  str -- dynamic string
 110 *  s2 -- string to append
 111 *  len -- length of s2
 112 * %RETURNS:
 113 *  -1 on failure; 0 on success
 114 * %DESCRIPTION:
 115 *  Appends s2 to str
 116 ***********************************************************************/
 117 int
 118 dynstring_append_len(dynstring *str, char const *s2, size_t len)
 119 {
 120     if (!len) return 0;
 121     if (!str->data) return -1;
 122
 123     if (len + str->actual_size >= str->alloc_size) {
 124         if (expand_for_size(str, str->actual_size + len) < 0) {
 125             return -1;
 126         }
 127     }
 128
 129     memcpy(str->data + str->actual_size, s2, len);
 130     str->actual_size += len;
 131     str->data[str->actual_size] = 0;
 132     return 0;
 133 }
 134
 135 char const *
 136 dynstring_data(dynstring *str)
 137 {
 138     return str->data;
 139 }