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         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
 107 /**
 108  * kstrtoull - convert a string to an unsigned long long
 109  * @s: The start of the string. The string must be null-terminated, and may also
 110  *  include a single newline before its terminating null. The first character
 111  *  may also be a plus sign, but not a minus sign.
 112  * @base: The number base to use. The maximum supported base is 16. If base is
 113  *  given as 0, then the base of the string is automatically detected with the
 114  *  conventional semantics - If it begins with 0x the number will be parsed as a
 115  *  hexadecimal (case insensitive), if it otherwise begins with 0, it will be
 116  *  parsed as an octal number. Otherwise it will be parsed as a decimal.
 117  * @res: Where to write the result of the conversion on success.
 118  *
 119  * Returns 0 on success, -ERANGE on overflow and -EINVAL on parsing error.
 120  * Used as a replacement for the obsolete simple_strtoull. Return code must
 121  * be checked.
 122  */
 123 int kstrtoull(const char *s, unsigned int base, unsigned long long *res)
 124 {
 125         if (s[0] == '+')
 126                 s++;
 127         return _kstrtoull(s, base, res);
 128 }
 129 EXPORT_SYMBOL(kstrtoull);
 130
 131 /**
 132  * kstrtoll - convert a string to a long long
 133  * @s: The start of the string. The string must be null-terminated, and may also
 134  *  include a single newline before its terminating null. The first character
 135  *  may also be a plus sign or a minus sign.
 136  * @base: The number base to use. The maximum supported base is 16. If base is
 137  *  given as 0, then the base of the string is automatically detected with the
 138  *  conventional semantics - If it begins with 0x the number will be parsed as a
 139  *  hexadecimal (case insensitive), if it otherwise begins with 0, it will be
 140  *  parsed as an octal number. Otherwise it will be parsed as a decimal.
 141  * @res: Where to write the result of the conversion on success.
 142  *
 143  * Returns 0 on success, -ERANGE on overflow and -EINVAL on parsing error.
 144  * Used as a replacement for the obsolete simple_strtoull. Return code must
 145  * be checked.
 146  */
 147 int kstrtoll(const char *s, unsigned int base, long long *res)
 148 {
 149         unsigned long long tmp;
 150         int rv;
 151
 152         if (s[0] == '-') {
 153                 rv = _kstrtoull(s + 1, base, &tmp);
 154                 if (rv < 0)
 155                         return rv;
 156                 if ((long long)(-tmp) >= 0)
 157                         return -ERANGE;
 158                 *res = -tmp;
 159         } else {
 160                 rv = kstrtoull(s, base, &tmp);
 161                 if (rv < 0)
 162                         return rv;
 163                 if ((long long)tmp < 0)
 164                         return -ERANGE;
 165                 *res = tmp;
 166         }
 167         return 0;
 168 }
 169 EXPORT_SYMBOL(kstrtoll);
 170
 171 /* Internal, do not use. */
 172 int _kstrtoul(const char *s, unsigned int base, unsigned long *res)
 173 {
 174         unsigned long long tmp;
 175         int rv;
 176
 177         rv = kstrtoull(s, base, &tmp);
 178         if (rv < 0)
 179                 return rv;
 180         if (tmp != (unsigned long long)(unsigned long)tmp)
 181                 return -ERANGE;
 182         *res = tmp;
 183         return 0;
 184 }
 185 EXPORT_SYMBOL(_kstrtoul);
 186
 187 /* Internal, do not use. */
 188 int _kstrtol(const char *s, unsigned int base, long *res)
 189 {
 190         long long tmp;
 191         int rv;
 192
 193         rv = kstrtoll(s, base, &tmp);
 194         if (rv < 0)
 195                 return rv;
 196         if (tmp != (long long)(long)tmp)
 197                 return -ERANGE;
 198         *res = tmp;
 199         return 0;
 200 }
 201 EXPORT_SYMBOL(_kstrtol);
 202
 203 /**
 204  * kstrtouint - convert a string to an unsigned int
 205  * @s: The start of the string. The string must be null-terminated, and may also
 206  *  include a single newline before its terminating null. The first character
 207  *  may also be a plus sign, but not a minus sign.
 208  * @base: The number base to use. The maximum supported base is 16. If base is
 209  *  given as 0, then the base of the string is automatically detected with the
 210  *  conventional semantics - If it begins with 0x the number will be parsed as a
 211  *  hexadecimal (case insensitive), if it otherwise begins with 0, it will be
 212  *  parsed as an octal number. Otherwise it will be parsed as a decimal.
 213  * @res: Where to write the result of the conversion on success.
 214  *
 215  * Returns 0 on success, -ERANGE on overflow and -EINVAL on parsing error.
 216  * Used as a replacement for the obsolete simple_strtoull. Return code must
 217  * be checked.
 218  */
 219 int kstrtouint(const char *s, unsigned int base, unsigned int *res)
 220 {
 221         unsigned long long tmp;
 222         int rv;
 223
 224         rv = kstrtoull(s, base, &tmp);
 225         if (rv < 0)
 226                 return rv;
 227         if (tmp != (unsigned long long)(unsigned int)tmp)
 228                 return -ERANGE;
 229         *res = tmp;
 230         return 0;
 231 }
 232 EXPORT_SYMBOL(kstrtouint);
 233
 234 /**
 235  * kstrtoint - convert a string to an int
 236  * @s: The start of the string. The string must be null-terminated, and may also
 237  *  include a single newline before its terminating null. The first character
 238  *  may also be a plus sign or a minus sign.
 239  * @base: The number base to use. The maximum supported base is 16. If base is
 240  *  given as 0, then the base of the string is automatically detected with the
 241  *  conventional semantics - If it begins with 0x the number will be parsed as a
 242  *  hexadecimal (case insensitive), if it otherwise begins with 0, it will be
 243  *  parsed as an octal number. Otherwise it will be parsed as a decimal.
 244  * @res: Where to write the result of the conversion on success.
 245  *
 246  * Returns 0 on success, -ERANGE on overflow and -EINVAL on parsing error.
 247  * Used as a replacement for the obsolete simple_strtoull. Return code must
 248  * be checked.
 249  */
 250 int kstrtoint(const char *s, unsigned int base, int *res)
 251 {
 252         long long tmp;
 253         int rv;
 254
 255         rv = kstrtoll(s, base, &tmp);
 256         if (rv < 0)
 257                 return rv;
 258         if (tmp != (long long)(int)tmp)
 259                 return -ERANGE;
 260         *res = tmp;
 261         return 0;
 262 }
 263 EXPORT_SYMBOL(kstrtoint);
 264
 265 int kstrtou16(const char *s, unsigned int base, u16 *res)
 266 {
 267         unsigned long long tmp;
 268         int rv;
 269
 270         rv = kstrtoull(s, base, &tmp);
 271         if (rv < 0)
 272                 return rv;
 273         if (tmp != (unsigned long long)(u16)tmp)
 274                 return -ERANGE;
 275         *res = tmp;
 276         return 0;
 277 }
 278 EXPORT_SYMBOL(kstrtou16);
 279
 280 int kstrtos16(const char *s, unsigned int base, s16 *res)
 281 {
 282         long long tmp;
 283         int rv;
 284
 285         rv = kstrtoll(s, base, &tmp);
 286         if (rv < 0)
 287                 return rv;
 288         if (tmp != (long long)(s16)tmp)
 289                 return -ERANGE;
 290         *res = tmp;
 291         return 0;
 292 }
 293 EXPORT_SYMBOL(kstrtos16);
 294
 295 int kstrtou8(const char *s, unsigned int base, u8 *res)
 296 {
 297         unsigned long long tmp;
 298         int rv;
 299
 300         rv = kstrtoull(s, base, &tmp);
 301         if (rv < 0)
 302                 return rv;
 303         if (tmp != (unsigned long long)(u8)tmp)
 304                 return -ERANGE;
 305         *res = tmp;
 306         return 0;
 307 }
 308 EXPORT_SYMBOL(kstrtou8);
 309
 310 int kstrtos8(const char *s, unsigned int base, s8 *res)
 311 {
 312         long long tmp;
 313         int rv;
 314
 315         rv = kstrtoll(s, base, &tmp);
 316         if (rv < 0)
 317                 return rv;
 318         if (tmp != (long long)(s8)tmp)
 319                 return -ERANGE;
 320         *res = tmp;
 321         return 0;
 322 }
 323 EXPORT_SYMBOL(kstrtos8);
 324
 325 #define kstrto_from_user(f, g, type)                                    \
 326 int f(const char __user *s, size_t count, unsigned int base, type *res) \
 327 {                                                                       \
 328         /* sign, base 2 representation, newline, terminator */          \
 329         char buf[1 + sizeof(type) * 8 + 1 + 1];                         \
 330                                                                         \
 331         count = min(count, sizeof(buf) - 1);                            \
 332         if (copy_from_user(buf, s, count))                              \
 333                 return -EFAULT;                                         \
 334         buf[count] = '\0';                                              \
 335         return g(buf, base, res);                                       \
 336 }                                                                       \
 337 EXPORT_SYMBOL(f)
 338
 339 kstrto_from_user(kstrtoull_from_user,   kstrtoull,      unsigned long long);
 340 kstrto_from_user(kstrtoll_from_user,    kstrtoll,       long long);
 341 kstrto_from_user(kstrtoul_from_user,    kstrtoul,       unsigned long);
 342 kstrto_from_user(kstrtol_from_user,     kstrtol,        long);
 343 kstrto_from_user(kstrtouint_from_user,  kstrtouint,     unsigned int);
 344 kstrto_from_user(kstrtoint_from_user,   kstrtoint,      int);
 345 kstrto_from_user(kstrtou16_from_user,   kstrtou16,      u16);
 346 kstrto_from_user(kstrtos16_from_user,   kstrtos16,      s16);
 347 kstrto_from_user(kstrtou8_from_user,    kstrtou8,       u8);
 348 kstrto_from_user(kstrtos8_from_user,    kstrtos8,       s8);