lib/kstrtox.c

   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/export.h>
  19 #include <linux/types.h>
  20 #include <asm/uaccess.h>
  21 #include "kstrtox.h"
  22
  23 const 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  */
  47 unsigned 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
  86 static 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         if (rv == 0)
  96                 return -EINVAL;
  97         s += rv;
  98         if (*s == '\n')
  99                 s++;
 100         if (*s)
 101                 return -EINVAL;
 102         *res = _res;
 103         return 0;
 104 }
 105
 106 /**
 107  * kstrtoull - convert a string to an unsigned long long
 108  * @s: The start of the string. The string must be null-terminated, and may also
 109  *  include a single newline before its terminating null. The first character
 110  *  may also be a plus sign, but not a minus sign.
 111  * @base: The number base to use. The maximum supported base is 16. If base is
 112  *  given as 0, then the base of the string is automatically detected with the
 113  *  conventional semantics - If it begins with 0x the number will be parsed as a
 114  *  hexadecimal (case insensitive), if it otherwise begins with 0, it will be
 115  *  parsed as an octal number. Otherwise it will be parsed as a decimal.
 116  * @res: Where to write the result of the conversion on success.
 117  *
 118  * Returns 0 on success, -ERANGE on overflow and -EINVAL on parsing error.
 119  * Used as a replacement for the obsolete simple_strtoull. Return code must
 120  * be checked.
 121  */
 122 int kstrtoull(const char *s, unsigned int base, unsigned long long *res)
 123 {
 124         if (s[0] == '+')
 125                 s++;
 126         return _kstrtoull(s, base, res);
 127 }
 128 EXPORT_SYMBOL(kstrtoull);
 129
 130 /**
 131  * kstrtoll - convert a string to a long long
 132  * @s: The start of the string. The string must be null-terminated, and may also
 133  *  include a single newline before its terminating null. The first character
 134  *  may also be a plus sign or a minus sign.
 135  * @base: The number base to use. The maximum supported base is 16. If base is
 136  *  given as 0, then the base of the string is automatically detected with the
 137  *  conventional semantics - If it begins with 0x the number will be parsed as a
 138  *  hexadecimal (case insensitive), if it otherwise begins with 0, it will be
 139  *  parsed as an octal number. Otherwise it will be parsed as a decimal.
 140  * @res: Where to write the result of the conversion on success.
 141  *
 142  * Returns 0 on success, -ERANGE on overflow and -EINVAL on parsing error.
 143  * Used as a replacement for the obsolete simple_strtoull. Return code must
 144  * be checked.
 145  */
 146 int kstrtoll(const char *s, unsigned int base, long long *res)
 147 {
 148         unsigned long long tmp;
 149         int rv;
 150
 151         if (s[0] == '-') {
 152                 rv = _kstrtoull(s + 1, base, &tmp);
 153                 if (rv < 0)
 154                         return rv;
 155                 if ((long long)(-tmp) >= 0)
 156                         return -ERANGE;
 157                 *res = -tmp;
 158         } else {
 159                 rv = kstrtoull(s, base, &tmp);
 160                 if (rv < 0)
 161                         return rv;
 162                 if ((long long)tmp < 0)
 163                         return -ERANGE;
 164                 *res = tmp;
 165         }
 166         return 0;
 167 }
 168 EXPORT_SYMBOL(kstrtoll);
 169
 170 /* Internal, do not use. */
 171 int _kstrtoul(const char *s, unsigned int base, unsigned long *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 long)tmp)
 180                 return -ERANGE;
 181         *res = tmp;
 182         return 0;
 183 }
 184 EXPORT_SYMBOL(_kstrtoul);
 185
 186 /* Internal, do not use. */
 187 int _kstrtol(const char *s, unsigned int base, long *res)
 188 {
 189         long long tmp;
 190         int rv;
 191
 192         rv = kstrtoll(s, base, &tmp);
 193         if (rv < 0)
 194                 return rv;
 195         if (tmp != (long long)(long)tmp)
 196                 return -ERANGE;
 197         *res = tmp;
 198         return 0;
 199 }
 200 EXPORT_SYMBOL(_kstrtol);
 201
 202 /**
 203  * kstrtouint - convert a string to an unsigned int
 204  * @s: The start of the string. The string must be null-terminated, and may also
 205  *  include a single newline before its terminating null. The first character
 206  *  may also be a plus sign, but not a minus sign.
 207  * @base: The number base to use. The maximum supported base is 16. If base is
 208  *  given as 0, then the base of the string is automatically detected with the
 209  *  conventional semantics - If it begins with 0x the number will be parsed as a
 210  *  hexadecimal (case insensitive), if it otherwise begins with 0, it will be
 211  *  parsed as an octal number. Otherwise it will be parsed as a decimal.
 212  * @res: Where to write the result of the conversion on success.
 213  *
 214  * Returns 0 on success, -ERANGE on overflow and -EINVAL on parsing error.
 215  * Used as a replacement for the obsolete simple_strtoull. Return code must
 216  * be checked.
 217  */
 218 int kstrtouint(const char *s, unsigned int base, unsigned int *res)
 219 {
 220         unsigned long long tmp;
 221         int rv;
 222
 223         rv = kstrtoull(s, base, &tmp);
 224         if (rv < 0)
 225                 return rv;
 226         if (tmp != (unsigned long long)(unsigned int)tmp)
 227                 return -ERANGE;
 228         *res = tmp;
 229         return 0;
 230 }
 231 EXPORT_SYMBOL(kstrtouint);
 232
 233 /**
 234  * kstrtoint - convert a string to an int
 235  * @s: The start of the string. The string must be null-terminated, and may also
 236  *  include a single newline before its terminating null. The first character
 237  *  may also be a plus sign or a minus sign.
 238  * @base: The number base to use. The maximum supported base is 16. If base is
 239  *  given as 0, then the base of the string is automatically detected with the
 240  *  conventional semantics - If it begins with 0x the number will be parsed as a
 241  *  hexadecimal (case insensitive), if it otherwise begins with 0, it will be
 242  *  parsed as an octal number. Otherwise it will be parsed as a decimal.
 243  * @res: Where to write the result of the conversion on success.
 244  *
 245  * Returns 0 on success, -ERANGE on overflow and -EINVAL on parsing error.
 246  * Used as a replacement for the obsolete simple_strtoull. Return code must
 247  * be checked.
 248  */
 249 int kstrtoint(const char *s, unsigned int base, int *res)
 250 {
 251         long long tmp;
 252         int rv;
 253
 254         rv = kstrtoll(s, base, &tmp);
 255         if (rv < 0)
 256                 return rv;
 257         if (tmp != (long long)(int)tmp)
 258                 return -ERANGE;
 259         *res = tmp;
 260         return 0;
 261 }
 262 EXPORT_SYMBOL(kstrtoint);
 263
 264 int kstrtou16(const char *s, unsigned int base, u16 *res)
 265 {
 266         unsigned long long tmp;
 267         int rv;
 268
 269         rv = kstrtoull(s, base, &tmp);
 270         if (rv < 0)
 271                 return rv;
 272         if (tmp != (unsigned long long)(u16)tmp)
 273                 return -ERANGE;
 274         *res = tmp;
 275         return 0;
 276 }
 277 EXPORT_SYMBOL(kstrtou16);
 278
 279 int kstrtos16(const char *s, unsigned int base, s16 *res)
 280 {
 281         long long tmp;
 282         int rv;
 283
 284         rv = kstrtoll(s, base, &tmp);
 285         if (rv < 0)
 286                 return rv;
 287         if (tmp != (long long)(s16)tmp)
 288                 return -ERANGE;
 289         *res = tmp;
 290         return 0;
 291 }
 292 EXPORT_SYMBOL(kstrtos16);
 293
 294 int kstrtou8(const char *s, unsigned int base, u8 *res)
 295 {
 296         unsigned long long tmp;
 297         int rv;
 298
 299         rv = kstrtoull(s, base, &tmp);
 300         if (rv < 0)
 301                 return rv;
 302         if (tmp != (unsigned long long)(u8)tmp)
 303                 return -ERANGE;
 304         *res = tmp;
 305         return 0;
 306 }
 307 EXPORT_SYMBOL(kstrtou8);
 308
 309 int kstrtos8(const char *s, unsigned int base, s8 *res)
 310 {
 311         long long tmp;
 312         int rv;
 313
 314         rv = kstrtoll(s, base, &tmp);
 315         if (rv < 0)
 316                 return rv;
 317         if (tmp != (long long)(s8)tmp)
 318                 return -ERANGE;
 319         *res = tmp;
 320         return 0;
 321 }
 322 EXPORT_SYMBOL(kstrtos8);
 323
 324 #define kstrto_from_user(f, g, type)                                    \
 325 int f(const char __user *s, size_t count, unsigned int base, type *res) \
 326 {                                                                       \
 327         /* sign, base 2 representation, newline, terminator */          \
 328         char buf[1 + sizeof(type) * 8 + 1 + 1];                         \
 329                                                                         \
 330         count = min(count, sizeof(buf) - 1);                            \
 331         if (copy_from_user(buf, s, count))                              \
 332                 return -EFAULT;                                         \
 333         buf[count] = '\0';                                              \
 334         return g(buf, base, res);                                       \
 335 }                                                                       \
 336 EXPORT_SYMBOL(f)
 337
 338 kstrto_from_user(kstrtoull_from_user,   kstrtoull,      unsigned long long);
 339 kstrto_from_user(kstrtoll_from_user,    kstrtoll,       long long);
 340 kstrto_from_user(kstrtoul_from_user,    kstrtoul,       unsigned long);
 341 kstrto_from_user(kstrtol_from_user,     kstrtol,        long);
 342 kstrto_from_user(kstrtouint_from_user,  kstrtouint,     unsigned int);
 343 kstrto_from_user(kstrtoint_from_user,   kstrtoint,      int);
 344 kstrto_from_user(kstrtou16_from_user,   kstrtou16,      u16);
 345 kstrto_from_user(kstrtos16_from_user,   kstrtos16,      s16);
 346 kstrto_from_user(kstrtou8_from_user,    kstrtou8,       u8);
 347 kstrto_from_user(kstrtos8_from_user,    kstrtos8,       s8);