include/linux/string.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef _LINUX_STRING_H_
   3 #define _LINUX_STRING_H_
   4
   5 #include <linux/args.h>
   6 #include <linux/array_size.h>
   7 #include <linux/compiler.h>     /* for inline */
   8 #include <linux/types.h>        /* for size_t */
   9 #include <linux/stddef.h>       /* for NULL */
  10 #include <linux/err.h>          /* for ERR_PTR() */
  11 #include <linux/errno.h>        /* for E2BIG */
  12 #include <linux/overflow.h>     /* for check_mul_overflow() */
  13 #include <linux/stdarg.h>
  14 #include <uapi/linux/string.h>
  15
  16 extern char *strndup_user(const char __user *, long);
  17 extern void *memdup_user(const void __user *, size_t) __realloc_size(2);
  18 extern void *vmemdup_user(const void __user *, size_t) __realloc_size(2);
  19 extern void *memdup_user_nul(const void __user *, size_t);
  20
  21 /**
  22  * memdup_array_user - duplicate array from user space
  23  * @src: source address in user space
  24  * @n: number of array members to copy
  25  * @size: size of one array member
  26  *
  27  * Return: an ERR_PTR() on failure. Result is physically
  28  * contiguous, to be freed by kfree().
  29  */
  30 static inline __realloc_size(2, 3)
  31 void *memdup_array_user(const void __user *src, size_t n, size_t size)
  32 {
  33         size_t nbytes;
  34
  35         if (check_mul_overflow(n, size, &nbytes))
  36                 return ERR_PTR(-EOVERFLOW);
  37
  38         return memdup_user(src, nbytes);
  39 }
  40
  41 /**
  42  * vmemdup_array_user - duplicate array from user space
  43  * @src: source address in user space
  44  * @n: number of array members to copy
  45  * @size: size of one array member
  46  *
  47  * Return: an ERR_PTR() on failure. Result may be not
  48  * physically contiguous. Use kvfree() to free.
  49  */
  50 static inline __realloc_size(2, 3)
  51 void *vmemdup_array_user(const void __user *src, size_t n, size_t size)
  52 {
  53         size_t nbytes;
  54
  55         if (check_mul_overflow(n, size, &nbytes))
  56                 return ERR_PTR(-EOVERFLOW);
  57
  58         return vmemdup_user(src, nbytes);
  59 }
  60
  61 /*
  62  * Include machine specific inline routines
  63  */
  64 #include <asm/string.h>
  65
  66 #ifndef __HAVE_ARCH_STRCPY
  67 extern char * strcpy(char *,const char *);
  68 #endif
  69 #ifndef __HAVE_ARCH_STRNCPY
  70 extern char * strncpy(char *,const char *, __kernel_size_t);
  71 #endif
  72 ssize_t sized_strscpy(char *, const char *, size_t);
  73
  74 /*
  75  * The 2 argument style can only be used when dst is an array with a
  76  * known size.
  77  */
  78 #define __strscpy0(dst, src, ...)       \
  79         sized_strscpy(dst, src, sizeof(dst) + __must_be_array(dst) +    \
  80                                 __must_be_cstr(dst) + __must_be_cstr(src))
  81 #define __strscpy1(dst, src, size)      \
  82         sized_strscpy(dst, src, size + __must_be_cstr(dst) + __must_be_cstr(src))
  83
  84 #define __strscpy_pad0(dst, src, ...)   \
  85         sized_strscpy_pad(dst, src, sizeof(dst) + __must_be_array(dst) +        \
  86                                     __must_be_cstr(dst) + __must_be_cstr(src))
  87 #define __strscpy_pad1(dst, src, size)  \
  88         sized_strscpy_pad(dst, src, size + __must_be_cstr(dst) + __must_be_cstr(src))
  89
  90 /**
  91  * strscpy - Copy a C-string into a sized buffer
  92  * @dst: Where to copy the string to
  93  * @src: Where to copy the string from
  94  * @...: Size of destination buffer (optional)
  95  *
  96  * Copy the source string @src, or as much of it as fits, into the
  97  * destination @dst buffer. The behavior is undefined if the string
  98  * buffers overlap. The destination @dst buffer is always NUL terminated,
  99  * unless it's zero-sized.
 100  *
 101  * The size argument @... is only required when @dst is not an array, or
 102  * when the copy needs to be smaller than sizeof(@dst).
 103  *
 104  * Preferred to strncpy() since it always returns a valid string, and
 105  * doesn't unnecessarily force the tail of the destination buffer to be
 106  * zero padded. If padding is desired please use strscpy_pad().
 107  *
 108  * Returns the number of characters copied in @dst (not including the
 109  * trailing %NUL) or -E2BIG if @size is 0 or the copy from @src was
 110  * truncated.
 111  */
 112 #define strscpy(dst, src, ...)  \
 113         CONCATENATE(__strscpy, COUNT_ARGS(__VA_ARGS__))(dst, src, __VA_ARGS__)
 114
 115 #define sized_strscpy_pad(dest, src, count)     ({                      \
 116         char *__dst = (dest);                                           \
 117         const char *__src = (src);                                      \
 118         const size_t __count = (count);                                 \
 119         ssize_t __wrote;                                                \
 120                                                                         \
 121         __wrote = sized_strscpy(__dst, __src, __count);                 \
 122         if (__wrote >= 0 && __wrote < __count)                          \
 123                 memset(__dst + __wrote + 1, 0, __count - __wrote - 1);  \
 124         __wrote;                                                        \
 125 })
 126
 127 /**
 128  * strscpy_pad() - Copy a C-string into a sized buffer
 129  * @dst: Where to copy the string to
 130  * @src: Where to copy the string from
 131  * @...: Size of destination buffer
 132  *
 133  * Copy the string, or as much of it as fits, into the dest buffer. The
 134  * behavior is undefined if the string buffers overlap. The destination
 135  * buffer is always %NUL terminated, unless it's zero-sized.
 136  *
 137  * If the source string is shorter than the destination buffer, the
 138  * remaining bytes in the buffer will be filled with %NUL bytes.
 139  *
 140  * For full explanation of why you may want to consider using the
 141  * 'strscpy' functions please see the function docstring for strscpy().
 142  *
 143  * Returns:
 144  * * The number of characters copied (not including the trailing %NULs)
 145  * * -E2BIG if count is 0 or @src was truncated.
 146  */
 147 #define strscpy_pad(dst, src, ...)      \
 148         CONCATENATE(__strscpy_pad, COUNT_ARGS(__VA_ARGS__))(dst, src, __VA_ARGS__)
 149
 150 #ifndef __HAVE_ARCH_STRCAT
 151 extern char * strcat(char *, const char *);
 152 #endif
 153 #ifndef __HAVE_ARCH_STRNCAT
 154 extern char * strncat(char *, const char *, __kernel_size_t);
 155 #endif
 156 #ifndef __HAVE_ARCH_STRLCAT
 157 extern size_t strlcat(char *, const char *, __kernel_size_t);
 158 #endif
 159 #ifndef __HAVE_ARCH_STRCMP
 160 extern int strcmp(const char *,const char *);
 161 #endif
 162 #ifndef __HAVE_ARCH_STRNCMP
 163 extern int strncmp(const char *,const char *,__kernel_size_t);
 164 #endif
 165 #ifndef __HAVE_ARCH_STRCASECMP
 166 extern int strcasecmp(const char *s1, const char *s2);
 167 #endif
 168 #ifndef __HAVE_ARCH_STRNCASECMP
 169 extern int strncasecmp(const char *s1, const char *s2, size_t n);
 170 #endif
 171 #ifndef __HAVE_ARCH_STRCHR
 172 extern char * strchr(const char *,int);
 173 #endif
 174 #ifndef __HAVE_ARCH_STRCHRNUL
 175 extern char * strchrnul(const char *,int);
 176 #endif
 177 extern char * strnchrnul(const char *, size_t, int);
 178 #ifndef __HAVE_ARCH_STRNCHR
 179 extern char * strnchr(const char *, size_t, int);
 180 #endif
 181 #ifndef __HAVE_ARCH_STRRCHR
 182 extern char * strrchr(const char *,int);
 183 #endif
 184 extern char * __must_check skip_spaces(const char *);
 185
 186 extern char *strim(char *);
 187
 188 static inline __must_check char *strstrip(char *str)
 189 {
 190         return strim(str);
 191 }
 192
 193 #ifndef __HAVE_ARCH_STRSTR
 194 extern char * strstr(const char *, const char *);
 195 #endif
 196 #ifndef __HAVE_ARCH_STRNSTR
 197 extern char * strnstr(const char *, const char *, size_t);
 198 #endif
 199 #ifndef __HAVE_ARCH_STRLEN
 200 extern __kernel_size_t strlen(const char *);
 201 #endif
 202 #ifndef __HAVE_ARCH_STRNLEN
 203 extern __kernel_size_t strnlen(const char *,__kernel_size_t);
 204 #endif
 205 #ifndef __HAVE_ARCH_STRPBRK
 206 extern char * strpbrk(const char *,const char *);
 207 #endif
 208 #ifndef __HAVE_ARCH_STRSEP
 209 extern char * strsep(char **,const char *);
 210 #endif
 211 #ifndef __HAVE_ARCH_STRSPN
 212 extern __kernel_size_t strspn(const char *,const char *);
 213 #endif
 214 #ifndef __HAVE_ARCH_STRCSPN
 215 extern __kernel_size_t strcspn(const char *,const char *);
 216 #endif
 217
 218 #ifndef __HAVE_ARCH_MEMSET
 219 extern void * memset(void *,int,__kernel_size_t);
 220 #endif
 221
 222 #ifndef __HAVE_ARCH_MEMSET16
 223 extern void *memset16(uint16_t *, uint16_t, __kernel_size_t);
 224 #endif
 225
 226 #ifndef __HAVE_ARCH_MEMSET32
 227 extern void *memset32(uint32_t *, uint32_t, __kernel_size_t);
 228 #endif
 229
 230 #ifndef __HAVE_ARCH_MEMSET64
 231 extern void *memset64(uint64_t *, uint64_t, __kernel_size_t);
 232 #endif
 233
 234 static inline void *memset_l(unsigned long *p, unsigned long v,
 235                 __kernel_size_t n)
 236 {
 237         if (BITS_PER_LONG == 32)
 238                 return memset32((uint32_t *)p, v, n);
 239         else
 240                 return memset64((uint64_t *)p, v, n);
 241 }
 242
 243 static inline void *memset_p(void **p, void *v, __kernel_size_t n)
 244 {
 245         if (BITS_PER_LONG == 32)
 246                 return memset32((uint32_t *)p, (uintptr_t)v, n);
 247         else
 248                 return memset64((uint64_t *)p, (uintptr_t)v, n);
 249 }
 250
 251 extern void **__memcat_p(void **a, void **b);
 252 #define memcat_p(a, b) ({                                       \
 253         BUILD_BUG_ON_MSG(!__same_type(*(a), *(b)),              \
 254                          "type mismatch in memcat_p()");        \
 255         (typeof(*a) *)__memcat_p((void **)(a), (void **)(b));   \
 256 })
 257
 258 #ifndef __HAVE_ARCH_MEMCPY
 259 extern void * memcpy(void *,const void *,__kernel_size_t);
 260 #endif
 261 #ifndef __HAVE_ARCH_MEMMOVE
 262 extern void * memmove(void *,const void *,__kernel_size_t);
 263 #endif
 264 #ifndef __HAVE_ARCH_MEMSCAN
 265 extern void * memscan(void *,int,__kernel_size_t);
 266 #endif
 267 #ifndef __HAVE_ARCH_MEMCMP
 268 extern int memcmp(const void *,const void *,__kernel_size_t);
 269 #endif
 270 #ifndef __HAVE_ARCH_BCMP
 271 extern int bcmp(const void *,const void *,__kernel_size_t);
 272 #endif
 273 #ifndef __HAVE_ARCH_MEMCHR
 274 extern void * memchr(const void *,int,__kernel_size_t);
 275 #endif
 276 #ifndef __HAVE_ARCH_MEMCPY_FLUSHCACHE
 277 static inline void memcpy_flushcache(void *dst, const void *src, size_t cnt)
 278 {
 279         memcpy(dst, src, cnt);
 280 }
 281 #endif
 282
 283 void *memchr_inv(const void *s, int c, size_t n);
 284 char *strreplace(char *str, char old, char new);
 285
 286 /**
 287  * mem_is_zero - Check if an area of memory is all 0's.
 288  * @s: The memory area
 289  * @n: The size of the area
 290  *
 291  * Return: True if the area of memory is all 0's.
 292  */
 293 static inline bool mem_is_zero(const void *s, size_t n)
 294 {
 295         return !memchr_inv(s, 0, n);
 296 }
 297
 298 extern void kfree_const(const void *x);
 299
 300 extern char *kstrdup(const char *s, gfp_t gfp) __malloc;
 301 extern const char *kstrdup_const(const char *s, gfp_t gfp);
 302 extern char *kstrndup(const char *s, size_t len, gfp_t gfp);
 303 extern void *kmemdup_noprof(const void *src, size_t len, gfp_t gfp) __realloc_size(2);
 304 #define kmemdup(...)    alloc_hooks(kmemdup_noprof(__VA_ARGS__))
 305
 306 extern void *kvmemdup(const void *src, size_t len, gfp_t gfp) __realloc_size(2);
 307 extern char *kmemdup_nul(const char *s, size_t len, gfp_t gfp);
 308 extern void *kmemdup_array(const void *src, size_t count, size_t element_size, gfp_t gfp)
 309                 __realloc_size(2, 3);
 310
 311 /* lib/argv_split.c */
 312 extern char **argv_split(gfp_t gfp, const char *str, int *argcp);
 313 extern void argv_free(char **argv);
 314
 315 /* lib/cmdline.c */
 316 extern int get_option(char **str, int *pint);
 317 extern char *get_options(const char *str, int nints, int *ints);
 318 extern unsigned long long memparse(const char *ptr, char **retptr);
 319 extern bool parse_option_str(const char *str, const char *option);
 320 extern char *next_arg(char *args, char **param, char **val);
 321
 322 extern bool sysfs_streq(const char *s1, const char *s2);
 323 int match_string(const char * const *array, size_t n, const char *string);
 324 int __sysfs_match_string(const char * const *array, size_t n, const char *s);
 325
 326 /**
 327  * sysfs_match_string - matches given string in an array
 328  * @_a: array of strings
 329  * @_s: string to match with
 330  *
 331  * Helper for __sysfs_match_string(). Calculates the size of @a automatically.
 332  */
 333 #define sysfs_match_string(_a, _s) __sysfs_match_string(_a, ARRAY_SIZE(_a), _s)
 334
 335 #ifdef CONFIG_BINARY_PRINTF
 336 int vbin_printf(u32 *bin_buf, size_t size, const char *fmt, va_list args);
 337 int bstr_printf(char *buf, size_t size, const char *fmt, const u32 *bin_buf);
 338 #endif
 339
 340 extern ssize_t memory_read_from_buffer(void *to, size_t count, loff_t *ppos,
 341                                        const void *from, size_t available);
 342
 343 int ptr_to_hashval(const void *ptr, unsigned long *hashval_out);
 344
 345 /**
 346  * strstarts - does @str start with @prefix?
 347  * @str: string to examine
 348  * @prefix: prefix to look for.
 349  */
 350 static inline bool strstarts(const char *str, const char *prefix)
 351 {
 352         return strncmp(str, prefix, strlen(prefix)) == 0;
 353 }
 354
 355 size_t memweight(const void *ptr, size_t bytes);
 356
 357 /**
 358  * memzero_explicit - Fill a region of memory (e.g. sensitive
 359  *                    keying data) with 0s.
 360  * @s: Pointer to the start of the area.
 361  * @count: The size of the area.
 362  *
 363  * Note: usually using memset() is just fine (!), but in cases
 364  * where clearing out _local_ data at the end of a scope is
 365  * necessary, memzero_explicit() should be used instead in
 366  * order to prevent the compiler from optimising away zeroing.
 367  *
 368  * memzero_explicit() doesn't need an arch-specific version as
 369  * it just invokes the one of memset() implicitly.
 370  */
 371 static inline void memzero_explicit(void *s, size_t count)
 372 {
 373         memset(s, 0, count);
 374         barrier_data(s);
 375 }
 376
 377 /**
 378  * kbasename - return the last part of a pathname.
 379  *
 380  * @path: path to extract the filename from.
 381  */
 382 static inline const char *kbasename(const char *path)
 383 {
 384         const char *tail = strrchr(path, '/');
 385         return tail ? tail + 1 : path;
 386 }
 387
 388 #if !defined(__NO_FORTIFY) && defined(__OPTIMIZE__) && defined(CONFIG_FORTIFY_SOURCE)
 389 #include <linux/fortify-string.h>
 390 #endif
 391 #ifndef unsafe_memcpy
 392 #define unsafe_memcpy(dst, src, bytes, justification)           \
 393         memcpy(dst, src, bytes)
 394 #endif
 395
 396 void memcpy_and_pad(void *dest, size_t dest_len, const void *src, size_t count,
 397                     int pad);
 398
 399 /**
 400  * strtomem_pad - Copy NUL-terminated string to non-NUL-terminated buffer
 401  *
 402  * @dest: Pointer of destination character array (marked as __nonstring)
 403  * @src: Pointer to NUL-terminated string
 404  * @pad: Padding character to fill any remaining bytes of @dest after copy
 405  *
 406  * This is a replacement for strncpy() uses where the destination is not
 407  * a NUL-terminated string, but with bounds checking on the source size, and
 408  * an explicit padding character. If padding is not required, use strtomem().
 409  *
 410  * Note that the size of @dest is not an argument, as the length of @dest
 411  * must be discoverable by the compiler.
 412  */
 413 #define strtomem_pad(dest, src, pad)    do {                            \
 414         const size_t _dest_len = __builtin_object_size(dest, 1);        \
 415         const size_t _src_len = __builtin_object_size(src, 1);          \
 416                                                                         \
 417         BUILD_BUG_ON(!__builtin_constant_p(_dest_len) ||                \
 418                      _dest_len == (size_t)-1);                          \
 419         memcpy_and_pad(dest, _dest_len, src,                            \
 420                        strnlen(src, min(_src_len, _dest_len)), pad);    \
 421 } while (0)
 422
 423 /**
 424  * strtomem - Copy NUL-terminated string to non-NUL-terminated buffer
 425  *
 426  * @dest: Pointer of destination character array (marked as __nonstring)
 427  * @src: Pointer to NUL-terminated string
 428  *
 429  * This is a replacement for strncpy() uses where the destination is not
 430  * a NUL-terminated string, but with bounds checking on the source size, and
 431  * without trailing padding. If padding is required, use strtomem_pad().
 432  *
 433  * Note that the size of @dest is not an argument, as the length of @dest
 434  * must be discoverable by the compiler.
 435  */
 436 #define strtomem(dest, src)     do {                                    \
 437         const size_t _dest_len = __builtin_object_size(dest, 1);        \
 438         const size_t _src_len = __builtin_object_size(src, 1);          \
 439                                                                         \
 440         BUILD_BUG_ON(!__builtin_constant_p(_dest_len) ||                \
 441                      _dest_len == (size_t)-1);                          \
 442         memcpy(dest, src, strnlen(src, min(_src_len, _dest_len)));      \
 443 } while (0)
 444
 445 /**
 446  * memtostr - Copy a possibly non-NUL-term string to a NUL-term string
 447  * @dest: Pointer to destination NUL-terminates string
 448  * @src: Pointer to character array (likely marked as __nonstring)
 449  *
 450  * This is a replacement for strncpy() uses where the source is not
 451  * a NUL-terminated string.
 452  *
 453  * Note that sizes of @dest and @src must be known at compile-time.
 454  */
 455 #define memtostr(dest, src)     do {                                    \
 456         const size_t _dest_len = __builtin_object_size(dest, 1);        \
 457         const size_t _src_len = __builtin_object_size(src, 1);          \
 458         const size_t _src_chars = strnlen(src, _src_len);               \
 459         const size_t _copy_len = min(_dest_len - 1, _src_chars);        \
 460                                                                         \
 461         BUILD_BUG_ON(!__builtin_constant_p(_dest_len) ||                \
 462                      !__builtin_constant_p(_src_len) ||                 \
 463                      _dest_len == 0 || _dest_len == (size_t)-1 ||       \
 464                      _src_len == 0 || _src_len == (size_t)-1);          \
 465         memcpy(dest, src, _copy_len);                                   \
 466         dest[_copy_len] = '\0';                                         \
 467 } while (0)
 468
 469 /**
 470  * memtostr_pad - Copy a possibly non-NUL-term string to a NUL-term string
 471  *                with NUL padding in the destination
 472  * @dest: Pointer to destination NUL-terminates string
 473  * @src: Pointer to character array (likely marked as __nonstring)
 474  *
 475  * This is a replacement for strncpy() uses where the source is not
 476  * a NUL-terminated string.
 477  *
 478  * Note that sizes of @dest and @src must be known at compile-time.
 479  */
 480 #define memtostr_pad(dest, src)         do {                            \
 481         const size_t _dest_len = __builtin_object_size(dest, 1);        \
 482         const size_t _src_len = __builtin_object_size(src, 1);          \
 483         const size_t _src_chars = strnlen(src, _src_len);               \
 484         const size_t _copy_len = min(_dest_len - 1, _src_chars);        \
 485                                                                         \
 486         BUILD_BUG_ON(!__builtin_constant_p(_dest_len) ||                \
 487                      !__builtin_constant_p(_src_len) ||                 \
 488                      _dest_len == 0 || _dest_len == (size_t)-1 ||       \
 489                      _src_len == 0 || _src_len == (size_t)-1);          \
 490         memcpy(dest, src, _copy_len);                                   \
 491         memset(&dest[_copy_len], 0, _dest_len - _copy_len);             \
 492 } while (0)
 493
 494 /**
 495  * memset_after - Set a value after a struct member to the end of a struct
 496  *
 497  * @obj: Address of target struct instance
 498  * @v: Byte value to repeatedly write
 499  * @member: after which struct member to start writing bytes
 500  *
 501  * This is good for clearing padding following the given member.
 502  */
 503 #define memset_after(obj, v, member)                                    \
 504 ({                                                                      \
 505         u8 *__ptr = (u8 *)(obj);                                        \
 506         typeof(v) __val = (v);                                          \
 507         memset(__ptr + offsetofend(typeof(*(obj)), member), __val,      \
 508                sizeof(*(obj)) - offsetofend(typeof(*(obj)), member));   \
 509 })
 510
 511 /**
 512  * memset_startat - Set a value starting at a member to the end of a struct
 513  *
 514  * @obj: Address of target struct instance
 515  * @v: Byte value to repeatedly write
 516  * @member: struct member to start writing at
 517  *
 518  * Note that if there is padding between the prior member and the target
 519  * member, memset_after() should be used to clear the prior padding.
 520  */
 521 #define memset_startat(obj, v, member)                                  \
 522 ({                                                                      \
 523         u8 *__ptr = (u8 *)(obj);                                        \
 524         typeof(v) __val = (v);                                          \
 525         memset(__ptr + offsetof(typeof(*(obj)), member), __val,         \
 526                sizeof(*(obj)) - offsetof(typeof(*(obj)), member));      \
 527 })
 528
 529 /**
 530  * str_has_prefix - Test if a string has a given prefix
 531  * @str: The string to test
 532  * @prefix: The string to see if @str starts with
 533  *
 534  * A common way to test a prefix of a string is to do:
 535  *  strncmp(str, prefix, sizeof(prefix) - 1)
 536  *
 537  * But this can lead to bugs due to typos, or if prefix is a pointer
 538  * and not a constant. Instead use str_has_prefix().
 539  *
 540  * Returns:
 541  * * strlen(@prefix) if @str starts with @prefix
 542  * * 0 if @str does not start with @prefix
 543  */
 544 static __always_inline size_t str_has_prefix(const char *str, const char *prefix)
 545 {
 546         size_t len = strlen(prefix);
 547         return strncmp(str, prefix, len) == 0 ? len : 0;
 548 }
 549
 550 #endif /* _LINUX_STRING_H_ */