circuitpython/py/parsenumbase.c
Paul Sokolovsky 0294661da5 parsenum: Signedness issues.
char can be signedness, and using signedness types is dangerous - it can
lead to negative offsets when doing table lookups. We apparently should just
ban char usage.
2014-06-14 18:02:21 +03:00

69 lines
2.3 KiB
C

/*
* This file is part of the Micro Python project, http://micropython.org/
*
* The MIT License (MIT)
*
* Copyright (c) 2013, 2014 Damien P. George
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include "misc.h"
#include "mpconfig.h"
#include "parsenumbase.h"
// find real radix base, and strip preceding '0x', '0o' and '0b'
// puts base in *base, and returns number of bytes to skip the prefix
int mp_parse_num_base(const char *str, uint len, int *base) {
const byte *p = (const byte*)str;
int c = *(p++);
if ((*base == 0 || *base == 16) && c == '0') {
c = *(p++);
if ((c | 32) == 'x') {
*base = 16;
} else if (*base == 0 && (c | 32) == 'o') {
*base = 8;
} else if (*base == 0 && (c | 32) == 'b') {
*base = 2;
} else {
if (*base == 0) {
*base = 10;
}
p -= 2;
}
} else if (*base == 8 && c == '0') {
c = *(p++);
if ((c | 32) != 'o') {
p -= 2;
}
} else if (*base == 2 && c == '0') {
c = *(p++);
if ((c | 32) != 'b') {
p -= 2;
}
} else {
if (*base == 0) {
*base = 10;
}
p--;
}
return p - (const byte*)str;
}