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/*
This file is part of GNUnet
Copyright (C) 2012 GNUnet e.V.
GNUnet is free software: you can redistribute it and/or modify it
under the terms of the GNU General Public License as published
by the Free Software Foundation, either version 3 of the License,
or (at your option) any later version.
GNUnet is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Affero General Public License for more details.
*/
/**
* @file src/regex/regex_test_random.c
* @brief functions for creating random regular expressions and strings
* @author Maximilian Szengel
*/
#include "platform.h"
#include "regex_test_lib.h"
#include "gnunet_crypto_lib.h"
#include "regex_internal.h"
/**
* Get a (pseudo) random valid literal for building a regular expression.
*
* @return random valid literal
*/
static char
get_random_literal ()
{
uint32_t ridx;
ridx =
GNUNET_CRYPTO_random_u32 (GNUNET_CRYPTO_QUALITY_WEAK,
(uint32_t) strlen (ALLOWED_LITERALS));
return ALLOWED_LITERALS[ridx];
}
/**
* Generate a (pseudo) random regular expression of length 'rx_length', as well
* as a (optional) string that will be matched by the generated regex. The
* returned regex needs to be freed.
*
* @param rx_length length of the random regex.
* @param matching_str (optional) pointer to a string that will contain a string
* that will be matched by the generated regex, if
* 'matching_str' pointer was not NULL. Make sure you
* allocated at least rx_length+1 bytes for this sting.
*
* @return NULL if 'rx_length' is 0, a random regex of length 'rx_length', which
* needs to be freed, otherwise.
*/
char *
REGEX_TEST_generate_random_regex (size_t rx_length, char *matching_str)
{
char *rx;
char *rx_p;
char *matching_strp;
unsigned int i;
unsigned int char_op_switch;
unsigned int last_was_op;
int rx_op;
char current_char;
if (0 == rx_length)
return NULL;
if (NULL != matching_str)
matching_strp = matching_str;
else
matching_strp = NULL;
rx = GNUNET_malloc (rx_length + 1);
rx_p = rx;
current_char = 0;
last_was_op = 1;
for (i = 0; i < rx_length; i++)
{
char_op_switch = GNUNET_CRYPTO_random_u32 (GNUNET_CRYPTO_QUALITY_WEAK, 2);
if (0 == char_op_switch && !last_was_op)
{
last_was_op = 1;
rx_op = GNUNET_CRYPTO_random_u32 (GNUNET_CRYPTO_QUALITY_WEAK, 4);
switch (rx_op)
{
case 0:
current_char = '+';
break;
case 1:
current_char = '*';
break;
case 2:
current_char = '?';
break;
case 3:
if (i < rx_length - 1) /* '|' cannot be at the end */
current_char = '|';
else
current_char = get_random_literal ();
break;
}
}
else
{
current_char = get_random_literal ();
last_was_op = 0;
}
if (NULL != matching_strp &&
(current_char != '+' && current_char != '*' && current_char != '?' &&
current_char != '|'))
{
*matching_strp = current_char;
matching_strp++;
}
*rx_p = current_char;
rx_p++;
}
*rx_p = '\0';
if (NULL != matching_strp)
*matching_strp = '\0';
return rx;
}
/**
* Generate a random string of maximum length 'max_len' that only contains literals allowed
* in a regular expression. The string might be 0 chars long but is garantueed
* to be shorter or equal to 'max_len'.
*
* @param max_len maximum length of the string that should be generated.
*
* @return random string that needs to be freed.
*/
char *
REGEX_TEST_generate_random_string (size_t max_len)
{
unsigned int i;
char *str;
size_t len;
if (1 > max_len)
return GNUNET_strdup ("");
len = (size_t) GNUNET_CRYPTO_random_u32 (GNUNET_CRYPTO_QUALITY_WEAK, max_len);
str = GNUNET_malloc (len + 1);
for (i = 0; i < len; i++)
{
str[i] = get_random_literal ();
}
str[i] = '\0';
return str;
}
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