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 <linux/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
  52         res = 0;
  53         rv = 0;
  54         while (1) {
  55                 unsigned int c = *s;
  56                 unsigned int lc = c | 0x20; /* don't tolower() this line */
  57                 unsigned int val;
  58
  59                 if ('0' <= c && c <= '9')
  60                         val = c - '0';
  61                 else if ('a' <= lc && lc <= 'f')
  62                         val = lc - '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                                 rv |= KSTRTOX_OVERFLOW;
  75                 }
  76                 res = res * base + val;
  77                 rv++;
  78                 s++;
  79         }
  80         *p = res;
  81         return rv;
  82 }
  83
  84 static int _kstrtoull(const char *s, unsigned int base, unsigned long long *res)
  85 {
  86         unsigned long long _res;
  87         unsigned int rv;
  88
  89         s = _parse_integer_fixup_radix(s, &base);
  90         rv = _parse_integer(s, base, &_res);
  91         if (rv & KSTRTOX_OVERFLOW)
  92                 return -ERANGE;
  93         if (rv == 0)
  94                 return -EINVAL;
  95         s += rv;
  96         if (*s == '\n')
  97                 s++;
  98         if (*s)
  99                 return -EINVAL;
 100         *res = _res;
 101         return 0;
 102 }
 103
 104 /**
 105  * kstrtoull - convert a string to an unsigned long long
 106  * @s: The start of the string. The string must be null-terminated, and may also
 107  *  include a single newline before its terminating null. The first character
 108  *  may also be a plus sign, but not a minus sign.
 109  * @base: The number base to use. The maximum supported base is 16. If base is
 110  *  given as 0, then the base of the string is automatically detected with the
 111  *  conventional semantics - If it begins with 0x the number will be parsed as a
 112  *  hexadecimal (case insensitive), if it otherwise begins with 0, it will be
 113  *  parsed as an octal number. Otherwise it will be parsed as a decimal.
 114  * @res: Where to write the result of the conversion on success.
 115  *
 116  * Returns 0 on success, -ERANGE on overflow and -EINVAL on parsing error.
 117  * Used as a replacement for the obsolete simple_strtoull. Return code must
 118  * be checked.
 119  */
 120 int kstrtoull(const char *s, unsigned int base, unsigned long long *res)
 121 {
 122         if (s[0] == '+')
 123                 s++;
 124         return _kstrtoull(s, base, res);
 125 }
 126 EXPORT_SYMBOL(kstrtoull);
 127
 128 /**
 129  * kstrtoll - convert a string to a long long
 130  * @s: The start of the string. The string must be null-terminated, and may also
 131  *  include a single newline before its terminating null. The first character
 132  *  may also be a plus sign or a minus sign.
 133  * @base: The number base to use. The maximum supported base is 16. If base is
 134  *  given as 0, then the base of the string is automatically detected with the
 135  *  conventional semantics - If it begins with 0x the number will be parsed as a
 136  *  hexadecimal (case insensitive), if it otherwise begins with 0, it will be
 137  *  parsed as an octal number. Otherwise it will be parsed as a decimal.
 138  * @res: Where to write the result of the conversion on success.
 139  *
 140  * Returns 0 on success, -ERANGE on overflow and -EINVAL on parsing error.
 141  * Used as a replacement for the obsolete simple_strtoull. Return code must
 142  * be checked.
 143  */
 144 int kstrtoll(const char *s, unsigned int base, long long *res)
 145 {
 146         unsigned long long tmp;
 147         int rv;
 148
 149         if (s[0] == '-') {
 150                 rv = _kstrtoull(s + 1, base, &tmp);
 151                 if (rv < 0)
 152                         return rv;
 153                 if ((long long)-tmp > 0)
 154                         return -ERANGE;
 155                 *res = -tmp;
 156         } else {
 157                 rv = kstrtoull(s, base, &tmp);
 158                 if (rv < 0)
 159                         return rv;
 160                 if ((long long)tmp < 0)
 161                         return -ERANGE;
 162                 *res = tmp;
 163         }
 164         return 0;
 165 }
 166 EXPORT_SYMBOL(kstrtoll);
 167
 168 /* Internal, do not use. */
 169 int _kstrtoul(const char *s, unsigned int base, unsigned long *res)
 170 {
 171         unsigned long long tmp;
 172         int rv;
 173
 174         rv = kstrtoull(s, base, &tmp);
 175         if (rv < 0)
 176                 return rv;
 177         if (tmp != (unsigned long long)(unsigned long)tmp)
 178                 return -ERANGE;
 179         *res = tmp;
 180         return 0;
 181 }
 182 EXPORT_SYMBOL(_kstrtoul);
 183
 184 /* Internal, do not use. */
 185 int _kstrtol(const char *s, unsigned int base, long *res)
 186 {
 187         long long tmp;
 188         int rv;
 189
 190         rv = kstrtoll(s, base, &tmp);
 191         if (rv < 0)
 192                 return rv;
 193         if (tmp != (long long)(long)tmp)
 194                 return -ERANGE;
 195         *res = tmp;
 196         return 0;
 197 }
 198 EXPORT_SYMBOL(_kstrtol);
 199
 200 /**
 201  * kstrtouint - convert a string to an unsigned int
 202  * @s: The start of the string. The string must be null-terminated, and may also
 203  *  include a single newline before its terminating null. The first character
 204  *  may also be a plus sign, but not a minus sign.
 205  * @base: The number base to use. The maximum supported base is 16. If base is
 206  *  given as 0, then the base of the string is automatically detected with the
 207  *  conventional semantics - If it begins with 0x the number will be parsed as a
 208  *  hexadecimal (case insensitive), if it otherwise begins with 0, it will be
 209  *  parsed as an octal number. Otherwise it will be parsed as a decimal.
 210  * @res: Where to write the result of the conversion on success.
 211  *
 212  * Returns 0 on success, -ERANGE on overflow and -EINVAL on parsing error.
 213  * Used as a replacement for the obsolete simple_strtoull. Return code must
 214  * be checked.
 215  */
 216 int kstrtouint(const char *s, unsigned int base, unsigned int *res)
 217 {
 218         unsigned long long tmp;
 219         int rv;
 220
 221         rv = kstrtoull(s, base, &tmp);
 222         if (rv < 0)
 223                 return rv;
 224         if (tmp != (unsigned long long)(unsigned int)tmp)
 225                 return -ERANGE;
 226         *res = tmp;
 227         return 0;
 228 }
 229 EXPORT_SYMBOL(kstrtouint);
 230
 231 /**
 232  * kstrtoint - convert a string to an int
 233  * @s: The start of the string. The string must be null-terminated, and may also
 234  *  include a single newline before its terminating null. The first character
 235  *  may also be a plus sign or a minus sign.
 236  * @base: The number base to use. The maximum supported base is 16. If base is
 237  *  given as 0, then the base of the string is automatically detected with the
 238  *  conventional semantics - If it begins with 0x the number will be parsed as a
 239  *  hexadecimal (case insensitive), if it otherwise begins with 0, it will be
 240  *  parsed as an octal number. Otherwise it will be parsed as a decimal.
 241  * @res: Where to write the result of the conversion on success.
 242  *
 243  * Returns 0 on success, -ERANGE on overflow and -EINVAL on parsing error.
 244  * Used as a replacement for the obsolete simple_strtoull. Return code must
 245  * be checked.
 246  */
 247 int kstrtoint(const char *s, unsigned int base, int *res)
 248 {
 249         long long tmp;
 250         int rv;
 251
 252         rv = kstrtoll(s, base, &tmp);
 253         if (rv < 0)
 254                 return rv;
 255         if (tmp != (long long)(int)tmp)
 256                 return -ERANGE;
 257         *res = tmp;
 258         return 0;
 259 }
 260 EXPORT_SYMBOL(kstrtoint);
 261
 262 int kstrtou16(const char *s, unsigned int base, u16 *res)
 263 {
 264         unsigned long long tmp;
 265         int rv;
 266
 267         rv = kstrtoull(s, base, &tmp);
 268         if (rv < 0)
 269                 return rv;
 270         if (tmp != (unsigned long long)(u16)tmp)
 271                 return -ERANGE;
 272         *res = tmp;
 273         return 0;
 274 }
 275 EXPORT_SYMBOL(kstrtou16);
 276
 277 int kstrtos16(const char *s, unsigned int base, s16 *res)
 278 {
 279         long long tmp;
 280         int rv;
 281
 282         rv = kstrtoll(s, base, &tmp);
 283         if (rv < 0)
 284                 return rv;
 285         if (tmp != (long long)(s16)tmp)
 286                 return -ERANGE;
 287         *res = tmp;
 288         return 0;
 289 }
 290 EXPORT_SYMBOL(kstrtos16);
 291
 292 int kstrtou8(const char *s, unsigned int base, u8 *res)
 293 {
 294         unsigned long long tmp;
 295         int rv;
 296
 297         rv = kstrtoull(s, base, &tmp);
 298         if (rv < 0)
 299                 return rv;
 300         if (tmp != (unsigned long long)(u8)tmp)
 301                 return -ERANGE;
 302         *res = tmp;
 303         return 0;
 304 }
 305 EXPORT_SYMBOL(kstrtou8);
 306
 307 int kstrtos8(const char *s, unsigned int base, s8 *res)
 308 {
 309         long long tmp;
 310         int rv;
 311
 312         rv = kstrtoll(s, base, &tmp);
 313         if (rv < 0)
 314                 return rv;
 315         if (tmp != (long long)(s8)tmp)
 316                 return -ERANGE;
 317         *res = tmp;
 318         return 0;
 319 }
 320 EXPORT_SYMBOL(kstrtos8);
 321
 322 /**
 323  * kstrtobool - convert common user inputs into boolean values
 324  * @s: input string
 325  * @res: result
 326  *
 327  * This routine returns 0 iff the first character is one of 'Yy1Nn0', or
 328  * [oO][NnFf] for "on" and "off". Otherwise it will return -EINVAL.  Value
 329  * pointed to by res is updated upon finding a match.
 330  */
 331 int kstrtobool(const char *s, bool *res)
 332 {
 333         if (!s)
 334                 return -EINVAL;
 335
 336         switch (s[0]) {
 337         case 'y':
 338         case 'Y':
 339         case '1':
 340                 *res = true;
 341                 return 0;
 342         case 'n':
 343         case 'N':
 344         case '0':
 345                 *res = false;
 346                 return 0;
 347         case 'o':
 348         case 'O':
 349                 switch (s[1]) {
 350                 case 'n':
 351                 case 'N':
 352                         *res = true;
 353                         return 0;
 354                 case 'f':
 355                 case 'F':
 356                         *res = false;
 357                         return 0;
 358                 default:
 359                         break;
 360                 }
 361         default:
 362                 break;
 363         }
 364
 365         return -EINVAL;
 366 }
 367 EXPORT_SYMBOL(kstrtobool);
 368
 369 /*
 370  * Since "base" would be a nonsense argument, this open-codes the
 371  * _from_user helper instead of using the helper macro below.
 372  */
 373 int kstrtobool_from_user(const char __user *s, size_t count, bool *res)
 374 {
 375         /* Longest string needed to differentiate, newline, terminator */
 376         char buf[4];
 377
 378         count = min(count, sizeof(buf) - 1);
 379         if (copy_from_user(buf, s, count))
 380                 return -EFAULT;
 381         buf[count] = '\0';
 382         return kstrtobool(buf, res);
 383 }
 384 EXPORT_SYMBOL(kstrtobool_from_user);
 385
 386 #define kstrto_from_user(f, g, type)                                    \
 387 int f(const char __user *s, size_t count, unsigned int base, type *res) \
 388 {                                                                       \
 389         /* sign, base 2 representation, newline, terminator */          \
 390         char buf[1 + sizeof(type) * 8 + 1 + 1];                         \
 391                                                                         \
 392         count = min(count, sizeof(buf) - 1);                            \
 393         if (copy_from_user(buf, s, count))                              \
 394                 return -EFAULT;                                         \
 395         buf[count] = '\0';                                              \
 396         return g(buf, base, res);                                       \
 397 }                                                                       \
 398 EXPORT_SYMBOL(f)
 399
 400 kstrto_from_user(kstrtoull_from_user,   kstrtoull,      unsigned long long);
 401 kstrto_from_user(kstrtoll_from_user,    kstrtoll,       long long);
 402 kstrto_from_user(kstrtoul_from_user,    kstrtoul,       unsigned long);
 403 kstrto_from_user(kstrtol_from_user,     kstrtol,        long);
 404 kstrto_from_user(kstrtouint_from_user,  kstrtouint,     unsigned int);
 405 kstrto_from_user(kstrtoint_from_user,   kstrtoint,      int);
 406 kstrto_from_user(kstrtou16_from_user,   kstrtou16,      u16);
 407 kstrto_from_user(kstrtos16_from_user,   kstrtos16,      s16);
 408 kstrto_from_user(kstrtou8_from_user,    kstrtou8,       u8);
 409 kstrto_from_user(kstrtos8_from_user,    kstrtos8,       s8);