/src/cpython/Python/mystrtoul.c

Source
// strtol() and strtoul(), renamed to avoid conflicts.
//
// API:
//
// - PyOS_strtol(): convert string to C long integer.
// - PyOS_strtoul(): convert string to C unsigned long integer.

#include "Python.h"
#include "pycore_long.h"          // _PyLong_DigitValue

/* strtol and strtoul, renamed to avoid conflicts */


#ifdef HAVE_ERRNO_H
#  include <errno.h>              // errno
#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 const 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 const 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 const 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 0b, 0o 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(const char *str, char **ptr, int base)
{
    unsigned long result = 0; /* return value of the function */
    int c;             /* current input character */
    int ovlimit;       /* required digits to overflow */

    /* skip leading white space */
    while (*str && Py_ISSPACE(*str))
        ++str;

    /* check for leading 0b, 0o or 0x for auto-base or base 16 */
    switch (base) {
    case 0:             /* look for leading 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 = (char *)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 = (char *)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 = (char *)str;
                    return 0;
                }
                ++str;
                base = 2;
            } else {
                /* skip all zeroes... */
                while (*str == '0')
                    ++str;
                while (Py_ISSPACE(*str))
                    ++str;
                if (ptr)
                    *ptr = (char *)str;
                return 0;
            }
        }
        else
            base = 10;
        break;

    /* even with explicit base, skip leading 0? prefix */
    case 16:
        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 = (char *)str;
                    return 0;
                }
                ++str;
            }
        }
        break;
    case 8:
        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 = (char *)str;
                    return 0;
                }
                ++str;
            }
        }
        break;
    case 2:
        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 = (char *)str;
                    return 0;
                }
                ++str;
            }
        }
        break;
    }

    /* catch silly bases */
    if (base < 2 || base > 36) {
        if (ptr)
            *ptr = (char *)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 */
            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 = (char *)str;

    return result;

overflowed:
    if (ptr) {
        /* spool through remaining digit characters */
        while (_PyLong_DigitValue[Py_CHARMASK(*str)] < base)
            ++str;
        *ptr = (char *)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(const char *str, char **ptr, int base)
{
    long result;
    unsigned long uresult;
    char sign;

    while (*str && Py_ISSPACE(*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;
}

Coverage Report

Created: 2026-10-31 06:21

Line	Count	Source
1		// strtol() and strtoul(), renamed to avoid conflicts.
2		//
3		// API:
4		//
5		// - PyOS_strtol(): convert string to C long integer.
6		// - PyOS_strtoul(): convert string to C unsigned long integer.
7
8		#include "Python.h"
9		#include "pycore_long.h" // _PyLong_DigitValue
10
11		/* strtol and strtoul, renamed to avoid conflicts */
12
13
14		#ifdef HAVE_ERRNO_H
15		# include <errno.h> // errno
16		#endif
17
18		/* Static overflow check values for bases 2 through 36.
19		* smallmax[base] is the largest unsigned long i such that
20		* i * base doesn't overflow unsigned long.
21		*/
22		static const unsigned long smallmax[] = {
23		0, /* bases 0 and 1 are invalid */
24		0,
25		ULONG_MAX / 2,
26		ULONG_MAX / 3,
27		ULONG_MAX / 4,
28		ULONG_MAX / 5,
29		ULONG_MAX / 6,
30		ULONG_MAX / 7,
31		ULONG_MAX / 8,
32		ULONG_MAX / 9,
33		ULONG_MAX / 10,
34		ULONG_MAX / 11,
35		ULONG_MAX / 12,
36		ULONG_MAX / 13,
37		ULONG_MAX / 14,
38		ULONG_MAX / 15,
39		ULONG_MAX / 16,
40		ULONG_MAX / 17,
41		ULONG_MAX / 18,
42		ULONG_MAX / 19,
43		ULONG_MAX / 20,
44		ULONG_MAX / 21,
45		ULONG_MAX / 22,
46		ULONG_MAX / 23,
47		ULONG_MAX / 24,
48		ULONG_MAX / 25,
49		ULONG_MAX / 26,
50		ULONG_MAX / 27,
51		ULONG_MAX / 28,
52		ULONG_MAX / 29,
53		ULONG_MAX / 30,
54		ULONG_MAX / 31,
55		ULONG_MAX / 32,
56		ULONG_MAX / 33,
57		ULONG_MAX / 34,
58		ULONG_MAX / 35,
59		ULONG_MAX / 36,
60		};
61
62		/* maximum digits that can't ever overflow for bases 2 through 36,
63		* calculated by [int(math.floor(math.log(2**32, i))) for i in range(2, 37)].
64		* Note that this is pessimistic if sizeof(long) > 4.
65		*/
66		#if SIZEOF_LONG == 4
67		static const int digitlimit[] = {
68		0, 0, 32, 20, 16, 13, 12, 11, 10, 10, /* 0 - 9 */
69		9, 9, 8, 8, 8, 8, 8, 7, 7, 7, /* 10 - 19 */
70		7, 7, 7, 7, 6, 6, 6, 6, 6, 6, /* 20 - 29 */
71		6, 6, 6, 6, 6, 6, 6}; /* 30 - 36 */
72		#elif SIZEOF_LONG == 8
73		/* [int(math.floor(math.log(2*64, i))) for i in range(2, 37)] /
74		static const int digitlimit[] = {
75		0, 0, 64, 40, 32, 27, 24, 22, 21, 20, /* 0 - 9 */
76		19, 18, 17, 17, 16, 16, 16, 15, 15, 15, /* 10 - 19 */
77		14, 14, 14, 14, 13, 13, 13, 13, 13, 13, /* 20 - 29 */
78		13, 12, 12, 12, 12, 12, 12}; /* 30 - 36 */
79		#else
80		# error "Need table for SIZEOF_LONG"
81		#endif
82
83		/*
84		** strtoul
85		** This is a general purpose routine for converting
86		** an ascii string to an integer in an arbitrary base.
87		** Leading white space is ignored. If 'base' is zero
88		** it looks for a leading 0b, 0o or 0x to tell which
89		** base. If these are absent it defaults to 10.
90		** Base must be 0 or between 2 and 36 (inclusive).
91		** If 'ptr' is non-NULL it will contain a pointer to
92		** the end of the scan.
93		** Errors due to bad pointers will probably result in
94		** exceptions - we don't check for them.
95		*/
96		unsigned long
97		PyOS_strtoul(const char str, char *ptr, int base)
98	133k	{
99	133k	unsigned long result = 0; /* return value of the function */
100	133k	int c; /* current input character */
101	133k	int ovlimit; /* required digits to overflow */
102
103		/* skip leading white space */
104	133k	while (str && Py_ISSPACE(str))
105	0	++str;
106
107		/* check for leading 0b, 0o or 0x for auto-base or base 16 */
108	133k	switch (base) {
109	133k	case 0: /* look for leading 0b, 0o or 0x */
110	133k	if (*str == '0') {
111	36.7k	++str;
112	36.7k	if (str == 'x' \|\| str == 'X') {
113		/* there must be at least one digit after 0x */
114	16.1k	if (_PyLong_DigitValue[Py_CHARMASK(str[1])] >= 16) {
115	0	if (ptr)
116	0	ptr = (char )str;
117	0	return 0;
118	0	}
119	16.1k	++str;
120	16.1k	base = 16;
121	20.6k	} else if (str == 'o' \|\| str == 'O') {
122		/* there must be at least one digit after 0o */
123	1.98k	if (_PyLong_DigitValue[Py_CHARMASK(str[1])] >= 8) {
124	0	if (ptr)
125	0	ptr = (char )str;
126	0	return 0;
127	0	}
128	1.98k	++str;
129	1.98k	base = 8;
130	18.6k	} else if (str == 'b' \|\| str == 'B') {
131		/* there must be at least one digit after 0b */
132	586	if (_PyLong_DigitValue[Py_CHARMASK(str[1])] >= 2) {
133	0	if (ptr)
134	0	ptr = (char )str;
135	0	return 0;
136	0	}
137	586	++str;
138	586	base = 2;
139	18.0k	} else {
140		/* skip all zeroes... */
141	20.5k	while (*str == '0')
142	2.47k	++str;
143	18.0k	while (Py_ISSPACE(*str))
144	0	++str;
145	18.0k	if (ptr)
146	18.0k	ptr = (char )str;
147	18.0k	return 0;
148	18.0k	}
149	36.7k	}
150	96.7k	else
151	96.7k	base = 10;
152	115k	break;
153
154		/* even with explicit base, skip leading 0? prefix */
155	115k	case 16:
156	0	if (*str == '0') {
157	0	++str;
158	0	if (str == 'x' \|\| str == 'X') {
159		/* there must be at least one digit after 0x */
160	0	if (_PyLong_DigitValue[Py_CHARMASK(str[1])] >= 16) {
161	0	if (ptr)
162	0	ptr = (char )str;
163	0	return 0;
164	0	}
165	0	++str;
166	0	}
167	0	}
168	0	break;
169	0	case 8:
170	0	if (*str == '0') {
171	0	++str;
172	0	if (str == 'o' \|\| str == 'O') {
173		/* there must be at least one digit after 0o */
174	0	if (_PyLong_DigitValue[Py_CHARMASK(str[1])] >= 8) {
175	0	if (ptr)
176	0	ptr = (char )str;
177	0	return 0;
178	0	}
179	0	++str;
180	0	}
181	0	}
182	0	break;
183	0	case 2:
184	0	if(*str == '0') {
185	0	++str;
186	0	if (str == 'b' \|\| str == 'B') {
187		/* there must be at least one digit after 0b */
188	0	if (_PyLong_DigitValue[Py_CHARMASK(str[1])] >= 2) {
189	0	if (ptr)
190	0	ptr = (char )str;
191	0	return 0;
192	0	}
193	0	++str;
194	0	}
195	0	}
196	0	break;
197	133k	}
198
199		/* catch silly bases */
200	115k	if (base < 2 \|\| base > 36) {
201	0	if (ptr)
202	0	ptr = (char )str;
203	0	return 0;
204	0	}
205
206		/* skip leading zeroes */
207	142k	while (*str == '0')
208	27.3k	++str;
209
210		/* base is guaranteed to be in [2, 36] at this point */
211	115k	ovlimit = digitlimit[base];
212
213		/* do the conversion until non-digit character encountered */
214	469k	while ((c = _PyLong_DigitValue[Py_CHARMASK(*str)]) < base) {
215	358k	if (ovlimit > 0) /* no overflow check required */
216	351k	result = result * base + c;
217	6.75k	else { /* requires overflow check */
218	6.75k	unsigned long temp_result;
219
220	6.75k	if (ovlimit < 0) /* guaranteed overflow */
221	1.84k	goto overflowed;
222
223		/* there could be an overflow */
224		/* check overflow just from shifting */
225	4.91k	if (result > smallmax[base])
226	1.95k	goto overflowed;
227
228	2.95k	result *= base;
229
230		/* check overflow from the digit's value */
231	2.95k	temp_result = result + c;
232	2.95k	if (temp_result < result)
233	401	goto overflowed;
234
235	2.55k	result = temp_result;
236	2.55k	}
237
238	354k	++str;
239	354k	--ovlimit;
240	354k	}
241
242		/* set pointer to point to the last character scanned */
243	111k	if (ptr)
244	111k	ptr = (char )str;
245
246	111k	return result;
247
248	4.20k	overflowed:
249	4.20k	if (ptr) {
250		/* spool through remaining digit characters */
251	103k	while (_PyLong_DigitValue[Py_CHARMASK(*str)] < base)
252	98.9k	++str;
253	4.20k	ptr = (char )str;
254	4.20k	}
255	4.20k	errno = ERANGE;
256	4.20k	return (unsigned long)-1;
257	115k	}
258
259		/* Checking for overflow in PyOS_strtol is a PITA; see comments
260		* about PY_ABS_LONG_MIN in longobject.c.
261		*/
262	0	#define PY_ABS_LONG_MIN (0-(unsigned long)LONG_MIN)
263
264		long
265		PyOS_strtol(const char str, char *ptr, int base)
266	96.7k	{
267	96.7k	long result;
268	96.7k	unsigned long uresult;
269	96.7k	char sign;
270
271	96.7k	while (str && Py_ISSPACE(str))
272	0	str++;
273
274	96.7k	sign = *str;
275	96.7k	if (sign == '+' \|\| sign == '-')
276	0	str++;
277
278	96.7k	uresult = PyOS_strtoul(str, ptr, base);
279
280	96.7k	if (uresult <= (unsigned long)LONG_MAX) {
281	93.2k	result = (long)uresult;
282	93.2k	if (sign == '-')
283	0	result = -result;
284	93.2k	}
285	3.50k	else if (sign == '-' && uresult == PY_ABS_LONG_MIN) {
286	0	result = LONG_MIN;
287	0	}
288	3.50k	else {
289	3.50k	errno = ERANGE;
290		result = LONG_MAX;
291	3.50k	}
292	96.7k	return result;
293	96.7k	}