```   1/*
2 * Convert integer string representation to an integer.
3 * If an integer doesn't fit into specified type, -E is returned.
4 *
5 * Integer starts with optional sign.
6 * kstrtou*() functions do not accept sign "-".
7 *
8 * Radix 0 means autodetection: leading "0x" implies radix 16,
9 * leading "0" implies radix 8, otherwise radix is 10.
10 * Autodetection hints work after optional sign, but not before.
11 *
12 * If -E is returned, result is not touched.
13 */
14#include <linux/ctype.h>
15#include <linux/errno.h>
16#include <linux/kernel.h>
17#include <linux/math64.h>
18#include <linux/module.h>
19#include <linux/types.h>
20#include <asm/uaccess.h>
21#include "kstrtox.h"
22
23const char *_parse_integer_fixup_radix(const char *s, unsigned int *base)
24{
25        if (*base == 0) {
26                if (s[0] == '0') {
27                        if (_tolower(s[1]) == 'x' && isxdigit(s[2]))
28                                *base = 16;
29                        else
30                                *base = 8;
31                } else
32                        *base = 10;
33        }
34        if (*base == 16 && s[0] == '0' && _tolower(s[1]) == 'x')
35                s += 2;
36        return s;
37}
38
39/*
40 * Convert non-negative integer string representation in explicitly given radix
41 * to an integer.
42 * Return number of characters consumed maybe or-ed with overflow bit.
43 * If overflow occurs, result integer (incorrect) is still returned.
44 *
45 * Don't you dare use this function.
46 */
47unsigned int _parse_integer(const char *s, unsigned int base, unsigned long long *p)
48{
49        unsigned long long res;
50        unsigned int rv;
51        int overflow;
52
53        res = 0;
54        rv = 0;
55        overflow = 0;
56        while (*s) {
57                unsigned int val;
58
59                if ('0' <= *s && *s <= '9')
60                        val = *s - '0';
61                else if ('a' <= _tolower(*s) && _tolower(*s) <= 'f')
62                        val = _tolower(*s) - 'a' + 10;
63                else
64                        break;
65
66                if (val >= base)
67                        break;
68                /*
69                 * Check for overflow only if we are within range of
70                 * it in the max base we support (16)
71                 */
72                if (unlikely(res & (~0ull << 60))) {
73                        if (res > div_u64(ULLONG_MAX - val, base))
74                                overflow = 1;
75                }
76                res = res * base + val;
77                rv++;
78                s++;
79        }
80        *p = res;
81        if (overflow)
82                rv |= KSTRTOX_OVERFLOW;
83        return rv;
84}
85
86static int _kstrtoull(const char *s, unsigned int base, unsigned long long *res)
87{
88        unsigned long long _res;
89        unsigned int rv;
90
91        s = _parse_integer_fixup_radix(s, &base);
92        rv = _parse_integer(s, base, &_res);
93        if (rv & KSTRTOX_OVERFLOW)
94                return -ERANGE;
95        rv &= ~KSTRTOX_OVERFLOW;
96        if (rv == 0)
97                return -EINVAL;
98        s += rv;
99        if (*s == '\n')
100                s++;
101        if (*s)
102                return -EINVAL;
103        *res = _res;
104        return 0;
105}
106
107int kstrtoull(const char *s, unsigned int base, unsigned long long *res)
108{
109        if (s[0] == '+')
110                s++;
111        return _kstrtoull(s, base, res);
112}
113EXPORT_SYMBOL(kstrtoull);
114
115int kstrtoll(const char *s, unsigned int base, long long *res)
116{
117        unsigned long long tmp;
118        int rv;
119
120        if (s[0] == '-') {
121                rv = _kstrtoull(s + 1, base, &tmp);
122                if (rv < 0)
123                        return rv;
124                if ((long long)(-tmp) >= 0)
125                        return -ERANGE;
126                *res = -tmp;
127        } else {
128                rv = kstrtoull(s, base, &tmp);
129                if (rv < 0)
130                        return rv;
131                if ((long long)tmp < 0)
132                        return -ERANGE;
133                *res = tmp;
134        }
135        return 0;
136}
137EXPORT_SYMBOL(kstrtoll);
138
139/* Internal, do not use. */
140int _kstrtoul(const char *s, unsigned int base, unsigned long *res)
141{
142        unsigned long long tmp;
143        int rv;
144
145        rv = kstrtoull(s, base, &tmp);
146        if (rv < 0)
147                return rv;
148        if (tmp != (unsigned long long)(unsigned long)tmp)
149                return -ERANGE;
150        *res = tmp;
151        return 0;
152}
153EXPORT_SYMBOL(_kstrtoul);
154
155/* Internal, do not use. */
156int _kstrtol(const char *s, unsigned int base, long *res)
157{
158        long long tmp;
159        int rv;
160
161        rv = kstrtoll(s, base, &tmp);
162        if (rv < 0)
163                return rv;
164        if (tmp != (long long)(long)tmp)
165                return -ERANGE;
166        *res = tmp;
167        return 0;
168}
169EXPORT_SYMBOL(_kstrtol);
170
171int kstrtouint(const char *s, unsigned int base, unsigned int *res)
172{
173        unsigned long long tmp;
174        int rv;
175
176        rv = kstrtoull(s, base, &tmp);
177        if (rv < 0)
178                return rv;
179        if (tmp != (unsigned long long)(unsigned int)tmp)
180                return -ERANGE;
181        *res = tmp;
182        return 0;
183}
184EXPORT_SYMBOL(kstrtouint);
185
186int kstrtoint(const char *s, unsigned int base, int *res)
187{
188        long long tmp;
189        int rv;
190
191        rv = kstrtoll(s, base, &tmp);
192        if (rv < 0)
193                return rv;
194        if (tmp != (long long)(int)tmp)
195                return -ERANGE;
196        *res = tmp;
197        return 0;
198}
199EXPORT_SYMBOL(kstrtoint);
200
201int kstrtou16(const char *s, unsigned int base, u16 *res)
202{
203        unsigned long long tmp;
204        int rv;
205
206        rv = kstrtoull(s, base, &tmp);
207        if (rv < 0)
208                return rv;
209        if (tmp != (unsigned long long)(u16)tmp)
210                return -ERANGE;
211        *res = tmp;
212        return 0;
213}
214EXPORT_SYMBOL(kstrtou16);
215
216int kstrtos16(const char *s, unsigned int base, s16 *res)
217{
218        long long tmp;
219        int rv;
220
221        rv = kstrtoll(s, base, &tmp);
222        if (rv < 0)
223                return rv;
224        if (tmp != (long long)(s16)tmp)
225                return -ERANGE;
226        *res = tmp;
227        return 0;
228}
229EXPORT_SYMBOL(kstrtos16);
230
231int kstrtou8(const char *s, unsigned int base, u8 *res)
232{
233        unsigned long long tmp;
234        int rv;
235
236        rv = kstrtoull(s, base, &tmp);
237        if (rv < 0)
238                return rv;
239        if (tmp != (unsigned long long)(u8)tmp)
240                return -ERANGE;
241        *res = tmp;
242        return 0;
243}
244EXPORT_SYMBOL(kstrtou8);
245
246int kstrtos8(const char *s, unsigned int base, s8 *res)
247{
248        long long tmp;
249        int rv;
250
251        rv = kstrtoll(s, base, &tmp);
252        if (rv < 0)
253                return rv;
254        if (tmp != (long long)(s8)tmp)
255                return -ERANGE;
256        *res = tmp;
257        return 0;
258}
259EXPORT_SYMBOL(kstrtos8);
260
261#define kstrto_from_user(f, g, type)                                    \
262int f(const char __user *s, size_t count, unsigned int base, type *res) \
263{                                                                       \
264        /* sign, base 2 representation, newline, terminator */          \
265        char buf[1 + sizeof(type) * 8 + 1 + 1];                         \
266                                                                        \
267        count = min(count, sizeof(buf) - 1);                            \
268        if (copy_from_user(buf, s, count))                              \
269                return -EFAULT;                                         \
270        buf[count] = '\0';                                              \
271        return g(buf, base, res);                                       \
272}                                                                       \
273EXPORT_SYMBOL(f)
274
275kstrto_from_user(kstrtoull_from_user,   kstrtoull,      unsigned long long);
276kstrto_from_user(kstrtoll_from_user,    kstrtoll,       long long);
277kstrto_from_user(kstrtoul_from_user,    kstrtoul,       unsigned long);
278kstrto_from_user(kstrtol_from_user,     kstrtol,        long);
279kstrto_from_user(kstrtouint_from_user,  kstrtouint,     unsigned int);
280kstrto_from_user(kstrtoint_from_user,   kstrtoint,      int);
281kstrto_from_user(kstrtou16_from_user,   kstrtou16,      u16);
282kstrto_from_user(kstrtos16_from_user,   kstrtos16,      s16);
283kstrto_from_user(kstrtou8_from_user,    kstrtou8,       u8);
284kstrto_from_user(kstrtos8_from_user,    kstrtos8,       s8);
285```
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