BadVPN – Rev 1
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/**
* @file parse_number.h
* @author Ambroz Bizjak <ambrop7@gmail.com>
*
* @section LICENSE
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the author nor the
* names of its contributors may be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* @section DESCRIPTION
*
* Numeric string parsing.
*/
#ifndef BADVPN_MISC_PARSE_NUMBER_H
#define BADVPN_MISC_PARSE_NUMBER_H
#include <stdint.h>
#include <string.h>
#include <stddef.h>
#include <limits.h>
#include <misc/memref.h>
#include <misc/debug.h>
// public parsing functions
static int decode_decimal_digit (char c);
static int decode_hex_digit (char c);
static int parse_unsigned_integer (MemRef str, uintmax_t *out) WARN_UNUSED;
static int parse_unsigned_hex_integer (MemRef str, uintmax_t *out) WARN_UNUSED;
static int parse_signmag_integer (MemRef str, int *out_sign, uintmax_t *out_mag) WARN_UNUSED;
// public generation functions
static int compute_decimal_repr_size (uintmax_t x);
static void generate_decimal_repr (uintmax_t x, char *out, int repr_size);
static int generate_decimal_repr_string (uintmax_t x, char *out);
// implementation follows
// decimal representation of UINTMAX_MAX
static const char parse_number__uintmax_max_str[] = "18446744073709551615";
// make sure UINTMAX_MAX is what we think it is
static const char parse_number__uintmax_max_str_assert[(UINTMAX_MAX == UINTMAX_C(18446744073709551615)) ? 1 : -1];
static int decode_decimal_digit (char c)
{
switch (c) {
case '0': return 0;
case '1': return 1;
case '2': return 2;
case '3': return 3;
case '4': return 4;
case '5': return 5;
case '6': return 6;
case '7': return 7;
case '8': return 8;
case '9': return 9;
}
return -1;
}
static int decode_hex_digit (char c)
{
switch (c) {
case '0': return 0;
case '1': return 1;
case '2': return 2;
case '3': return 3;
case '4': return 4;
case '5': return 5;
case '6': return 6;
case '7': return 7;
case '8': return 8;
case '9': return 9;
case 'A': case 'a': return 10;
case 'B': case 'b': return 11;
case 'C': case 'c': return 12;
case 'D': case 'd': return 13;
case 'E': case 'e': return 14;
case 'F': case 'f': return 15;
}
return -1;
}
static int parse__no_overflow (const char *str, size_t str_len, uintmax_t *out)
{
uintmax_t n = 0;
while (str_len > 0) {
if (*str < '0' || *str > '9') {
return 0;
}
n = 10 * n + (*str - '0');
str++;
str_len--;
}
*out = n;
return 1;
}
int parse_unsigned_integer (MemRef str, uintmax_t *out)
{
// we do not allow empty strings
if (str.len == 0) {
return 0;
}
// remove leading zeros
while (str.len > 0 && *str.ptr == '0') {
str.ptr++;
str.len--;
}
// detect overflow
if (str.len > sizeof(parse_number__uintmax_max_str) - 1 ||
(str.len == sizeof(parse_number__uintmax_max_str) - 1 && memcmp(str.ptr, parse_number__uintmax_max_str, sizeof(parse_number__uintmax_max_str) - 1) > 0)) {
return 0;
}
// will not overflow (but can still have invalid characters)
return parse__no_overflow(str.ptr, str.len, out);
}
int parse_unsigned_hex_integer (MemRef str, uintmax_t *out)
{
uintmax_t n = 0;
if (str.len == 0) {
return 0;
}
while (str.len > 0) {
int digit = decode_hex_digit(*str.ptr);
if (digit < 0) {
return 0;
}
if (n > UINTMAX_MAX / 16) {
return 0;
}
n *= 16;
if (digit > UINTMAX_MAX - n) {
return 0;
}
n += digit;
str.ptr++;
str.len--;
}
*out = n;
return 1;
}
int parse_signmag_integer (MemRef str, int *out_sign, uintmax_t *out_mag)
{
int sign = 1;
if (str.len > 0 && (str.ptr[0] == '+' || str.ptr[0] == '-')) {
sign = 1 - 2 * (str.ptr[0] == '-');
str.ptr++;
str.len--;
}
if (!parse_unsigned_integer(str, out_mag)) {
return 0;
}
*out_sign = sign;
return 1;
}
int compute_decimal_repr_size (uintmax_t x)
{
int size = 0;
do {
size++;
x /= 10;
} while (x > 0);
return size;
}
void generate_decimal_repr (uintmax_t x, char *out, int repr_size)
{
ASSERT(out)
ASSERT(repr_size == compute_decimal_repr_size(x))
out += repr_size;
do {
*(--out) = '0' + (x % 10);
x /= 10;
} while (x > 0);
}
int generate_decimal_repr_string (uintmax_t x, char *out)
{
ASSERT(out)
int repr_size = compute_decimal_repr_size(x);
generate_decimal_repr(x, out, repr_size);
out[repr_size] = '\0';
return repr_size;
}
#endif