cpython/Python/mystrtoul.c

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#include "Python.h"
#if defined(__sgi) && defined(WITH_THREAD) && !defined(_SGI_MP_SOURCE)
#define _SGI_MP_SOURCE
#endif
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/* Convert a possibly signed character to a nonnegative int */
/* XXX This assumes characters are 8 bits wide */
#ifdef __CHAR_UNSIGNED__
#define Py_CHARMASK(c) (c)
#else
#define Py_CHARMASK(c) ((c) & 0xff)
#endif
/* strtol and strtoul, renamed to avoid conflicts */
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/*
** 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, 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.
*/
#include <ctype.h>
#ifndef DONT_HAVE_ERRNO_H
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#include <errno.h>
#endif
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unsigned long
PyOS_strtoul(register char *str, char **ptr, int base)
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{
register unsigned long result; /* return value of the function */
register int c; /* current input character */
register unsigned long temp; /* used in overflow testing */
int ovf; /* true if overflow occurred */
result = 0;
ovf = 0;
/* catch silly bases */
if (base != 0 && (base < 2 || base > 36))
{
if (ptr)
*ptr = str;
return 0;
}
/* skip leading white space */
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while (*str && isspace(Py_CHARMASK(*str)))
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str++;
/* check for leading 0 or 0x for auto-base or base 16 */
switch (base)
{
case 0: /* look for leading 0, 0x or 0X */
if (*str == '0')
{
str++;
if (*str == 'x' || *str == 'X')
{
str++;
base = 16;
}
else
base = 8;
}
else
base = 10;
break;
case 16: /* skip leading 0x or 0X */
if (*str == '0' && (*(str+1) == 'x' || *(str+1) == 'X'))
str += 2;
break;
}
/* do the conversion */
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while ((c = Py_CHARMASK(*str)) != '\0')
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{
if (isdigit(c) && c - '0' < base)
c -= '0';
else
{
if (isupper(c))
c = tolower(c);
if (c >= 'a' && c <= 'z')
c -= 'a' - 10;
else /* non-"digit" character */
break;
if (c >= base) /* non-"digit" character */
break;
}
temp = result;
result = result * base + c;
if(base == 10) {
if(((long)(result - c) / base != (long)temp)) /* overflow */
ovf = 1;
}
else {
if ((result - c) / base != temp) /* overflow */
ovf = 1;
}
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str++;
}
/* set pointer to point to the last character scanned */
if (ptr)
*ptr = str;
if (ovf)
{
result = (unsigned long) ~0L;
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errno = ERANGE;
}
return result;
}
long
PyOS_strtol(char *str, char **ptr, int base)
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{
long result;
char sign;
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while (*str && isspace(Py_CHARMASK(*str)))
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str++;
sign = *str;
if (sign == '+' || sign == '-')
str++;
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result = (long) PyOS_strtoul(str, ptr, base);
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/* Signal overflow if the result appears negative,
except for the largest negative integer */
if (result < 0 && !(sign == '-' && result == -result)) {
errno = ERANGE;
result = 0x7fffffff;
}
if (sign == '-')
result = -result;
return result;
}