https://github.com/python/cpython
Tip revision: 74f4bd53e03ded8408bcc2de67cf0f5a4ac5b1a1 authored by Barry Warsaw on 23 February 2012, 15:59:38 UTC
Bump some more copyright years (as per PEP 101), since this is the first
Bump some more copyright years (as per PEP 101), since this is the first
Tip revision: 74f4bd5
mystrtoul.c
#include "Python.h"
#if defined(__sgi) && defined(WITH_THREAD) && !defined(_SGI_MP_SOURCE)
#define _SGI_MP_SOURCE
#endif
/* strtol and strtoul, renamed to avoid conflicts */
#include <ctype.h>
#ifdef HAVE_ERRNO_H
#include <errno.h>
#endif
/* Static overflow check values for bases 2 through 36.
* smallmax[base] is the largest unsigned long i such that
* i * base doesn't overflow unsigned long.
*/
static unsigned long smallmax[] = {
0, /* bases 0 and 1 are invalid */
0,
ULONG_MAX / 2,
ULONG_MAX / 3,
ULONG_MAX / 4,
ULONG_MAX / 5,
ULONG_MAX / 6,
ULONG_MAX / 7,
ULONG_MAX / 8,
ULONG_MAX / 9,
ULONG_MAX / 10,
ULONG_MAX / 11,
ULONG_MAX / 12,
ULONG_MAX / 13,
ULONG_MAX / 14,
ULONG_MAX / 15,
ULONG_MAX / 16,
ULONG_MAX / 17,
ULONG_MAX / 18,
ULONG_MAX / 19,
ULONG_MAX / 20,
ULONG_MAX / 21,
ULONG_MAX / 22,
ULONG_MAX / 23,
ULONG_MAX / 24,
ULONG_MAX / 25,
ULONG_MAX / 26,
ULONG_MAX / 27,
ULONG_MAX / 28,
ULONG_MAX / 29,
ULONG_MAX / 30,
ULONG_MAX / 31,
ULONG_MAX / 32,
ULONG_MAX / 33,
ULONG_MAX / 34,
ULONG_MAX / 35,
ULONG_MAX / 36,
};
/* maximum digits that can't ever overflow for bases 2 through 36,
* calculated by [int(math.floor(math.log(2**32, i))) for i in range(2, 37)].
* Note that this is pessimistic if sizeof(long) > 4.
*/
#if SIZEOF_LONG == 4
static int digitlimit[] = {
0, 0, 32, 20, 16, 13, 12, 11, 10, 10, /* 0 - 9 */
9, 9, 8, 8, 8, 8, 8, 7, 7, 7, /* 10 - 19 */
7, 7, 7, 7, 6, 6, 6, 6, 6, 6, /* 20 - 29 */
6, 6, 6, 6, 6, 6, 6}; /* 30 - 36 */
#elif SIZEOF_LONG == 8
/* [int(math.floor(math.log(2**64, i))) for i in range(2, 37)] */
static int digitlimit[] = {
0, 0, 64, 40, 32, 27, 24, 22, 21, 20, /* 0 - 9 */
19, 18, 17, 17, 16, 16, 16, 15, 15, 15, /* 10 - 19 */
14, 14, 14, 14, 13, 13, 13, 13, 13, 13, /* 20 - 29 */
13, 12, 12, 12, 12, 12, 12}; /* 30 - 36 */
#else
#error "Need table for SIZEOF_LONG"
#endif
/*
** strtoul
** This is a general purpose routine for converting
** an ascii string to an integer in an arbitrary base.
** Leading white space is ignored. If 'base' is zero
** it looks for a leading 0, 0b, 0B, 0o, 0O, 0x or 0X
** to tell which base. If these are absent it defaults
** to 10. Base must be 0 or between 2 and 36 (inclusive).
** If 'ptr' is non-NULL it will contain a pointer to
** the end of the scan.
** Errors due to bad pointers will probably result in
** exceptions - we don't check for them.
*/
unsigned long
PyOS_strtoul(register char *str, char **ptr, int base)
{
register unsigned long result = 0; /* return value of the function */
register int c; /* current input character */
register int ovlimit; /* required digits to overflow */
/* skip leading white space */
while (*str && isspace(Py_CHARMASK(*str)))
++str;
/* check for leading 0 or 0x for auto-base or base 16 */
switch (base) {
case 0: /* look for leading 0, 0b, 0o or 0x */
if (*str == '0') {
++str;
if (*str == 'x' || *str == 'X') {
/* there must be at least one digit after 0x */
if (_PyLong_DigitValue[Py_CHARMASK(str[1])] >= 16) {
if (ptr)
*ptr = str;
return 0;
}
++str;
base = 16;
} else if (*str == 'o' || *str == 'O') {
/* there must be at least one digit after 0o */
if (_PyLong_DigitValue[Py_CHARMASK(str[1])] >= 8) {
if (ptr)
*ptr = str;
return 0;
}
++str;
base = 8;
} else if (*str == 'b' || *str == 'B') {
/* there must be at least one digit after 0b */
if (_PyLong_DigitValue[Py_CHARMASK(str[1])] >= 2) {
if (ptr)
*ptr = str;
return 0;
}
++str;
base = 2;
} else {
base = 8;
}
}
else
base = 10;
break;
case 2: /* skip leading 0b or 0B */
if (*str == '0') {
++str;
if (*str == 'b' || *str == 'B') {
/* there must be at least one digit after 0b */
if (_PyLong_DigitValue[Py_CHARMASK(str[1])] >= 2) {
if (ptr)
*ptr = str;
return 0;
}
++str;
}
}
break;
case 8: /* skip leading 0o or 0O */
if (*str == '0') {
++str;
if (*str == 'o' || *str == 'O') {
/* there must be at least one digit after 0o */
if (_PyLong_DigitValue[Py_CHARMASK(str[1])] >= 8) {
if (ptr)
*ptr = str;
return 0;
}
++str;
}
}
break;
case 16: /* skip leading 0x or 0X */
if (*str == '0') {
++str;
if (*str == 'x' || *str == 'X') {
/* there must be at least one digit after 0x */
if (_PyLong_DigitValue[Py_CHARMASK(str[1])] >= 16) {
if (ptr)
*ptr = str;
return 0;
}
++str;
}
}
break;
}
/* catch silly bases */
if (base < 2 || base > 36) {
if (ptr)
*ptr = str;
return 0;
}
/* skip leading zeroes */
while (*str == '0')
++str;
/* base is guaranteed to be in [2, 36] at this point */
ovlimit = digitlimit[base];
/* do the conversion until non-digit character encountered */
while ((c = _PyLong_DigitValue[Py_CHARMASK(*str)]) < base) {
if (ovlimit > 0) /* no overflow check required */
result = result * base + c;
else { /* requires overflow check */
register unsigned long temp_result;
if (ovlimit < 0) /* guaranteed overflow */
goto overflowed;
/* there could be an overflow */
/* check overflow just from shifting */
if (result > smallmax[base])
goto overflowed;
result *= base;
/* check overflow from the digit's value */
temp_result = result + c;
if (temp_result < result)
goto overflowed;
result = temp_result;
}
++str;
--ovlimit;
}
/* set pointer to point to the last character scanned */
if (ptr)
*ptr = str;
return result;
overflowed:
if (ptr) {
/* spool through remaining digit characters */
while (_PyLong_DigitValue[Py_CHARMASK(*str)] < base)
++str;
*ptr = str;
}
errno = ERANGE;
return (unsigned long)-1;
}
/* Checking for overflow in PyOS_strtol is a PITA; see comments
* about PY_ABS_LONG_MIN in longobject.c.
*/
#define PY_ABS_LONG_MIN (0-(unsigned long)LONG_MIN)
long
PyOS_strtol(char *str, char **ptr, int base)
{
long result;
unsigned long uresult;
char sign;
while (*str && isspace(Py_CHARMASK(*str)))
str++;
sign = *str;
if (sign == '+' || sign == '-')
str++;
uresult = PyOS_strtoul(str, ptr, base);
if (uresult <= (unsigned long)LONG_MAX) {
result = (long)uresult;
if (sign == '-')
result = -result;
}
else if (sign == '-' && uresult == PY_ABS_LONG_MIN) {
result = LONG_MIN;
}
else {
errno = ERANGE;
result = LONG_MAX;
}
return result;
}