1 /* 2 * linux/lib/string.c 3 * 4 * Copyright (C) 1991, 1992 Linus Torvalds 5 */ 6 7 /* 8 * stupid library routines.. The optimized versions should generally be found 9 * as inline code in <asm-xx/string.h> 10 * 11 * These are buggy as well.. 12 * 13 * * Fri Jun 25 1999, Ingo Oeser <ioe@informatik.tu-chemnitz.de> 14 * - Added strsep() which will replace strtok() soon (because strsep() is 15 * reentrant and should be faster). Use only strsep() in new code, please. 16 * 17 * * Sat Feb 09 2002, Jason Thomas <jason@topic.com.au>, 18 * Matthew Hawkins <matt@mh.dropbear.id.au> 19 * - Kissed strtok() goodbye 20 */ 21 22 #include <linux/types.h> 23 #include <linux/string.h> 24 #include <linux/ctype.h> 25 #include <linux/kernel.h> 26 #include <linux/export.h> 27 #include <linux/bug.h> 28 #include <linux/errno.h> 29 30 #ifndef __HAVE_ARCH_STRNICMP 31 /** 32 * strnicmp - Case insensitive, length-limited string comparison 33 * @s1: One string 34 * @s2: The other string 35 * @len: the maximum number of characters to compare 36 */ 37 int strnicmp(const char *s1, const char *s2, size_t len) 38 { 39 /* Yes, Virginia, it had better be unsigned */ 40 unsigned char c1, c2; 41 42 if (!len) 43 return 0; 44 45 do { 46 c1 = *s1++; 47 c2 = *s2++; 48 if (!c1 || !c2) 49 break; 50 if (c1 == c2) 51 continue; 52 c1 = tolower(c1); 53 c2 = tolower(c2); 54 if (c1 != c2) 55 break; 56 } while (--len); 57 return (int)c1 - (int)c2; 58 } 59 EXPORT_SYMBOL(strnicmp); 60 #endif 61 62 #ifndef __HAVE_ARCH_STRCASECMP 63 int strcasecmp(const char *s1, const char *s2) 64 { 65 int c1, c2; 66 67 do { 68 c1 = tolower(*s1++); 69 c2 = tolower(*s2++); 70 } while (c1 == c2 && c1 != 0); 71 return c1 - c2; 72 } 73 EXPORT_SYMBOL(strcasecmp); 74 #endif 75 76 #ifndef __HAVE_ARCH_STRNCASECMP 77 int strncasecmp(const char *s1, const char *s2, size_t n) 78 { 79 int c1, c2; 80 81 do { 82 c1 = tolower(*s1++); 83 c2 = tolower(*s2++); 84 } while ((--n > 0) && c1 == c2 && c1 != 0); 85 return c1 - c2; 86 } 87 EXPORT_SYMBOL(strncasecmp); 88 #endif 89 90 #ifndef __HAVE_ARCH_STRCPY 91 /** 92 * strcpy - Copy a %NUL terminated string 93 * @dest: Where to copy the string to 94 * @src: Where to copy the string from 95 */ 96 #undef strcpy 97 char *strcpy(char *dest, const char *src) 98 { 99 char *tmp = dest; 100 101 while ((*dest++ = *src++) != '\0') 102 /* nothing */; 103 return tmp; 104 } 105 EXPORT_SYMBOL(strcpy); 106 #endif 107 108 #ifndef __HAVE_ARCH_STRNCPY 109 /** 110 * strncpy - Copy a length-limited, C-string 111 * @dest: Where to copy the string to 112 * @src: Where to copy the string from 113 * @count: The maximum number of bytes to copy 114 * 115 * The result is not %NUL-terminated if the source exceeds 116 * @count bytes. 117 * 118 * In the case where the length of @src is less than that of 119 * count, the remainder of @dest will be padded with %NUL. 120 * 121 */ 122 char *strncpy(char *dest, const char *src, size_t count) 123 { 124 char *tmp = dest; 125 126 while (count) { 127 if ((*tmp = *src) != 0) 128 src++; 129 tmp++; 130 count--; 131 } 132 return dest; 133 } 134 EXPORT_SYMBOL(strncpy); 135 #endif 136 137 #ifndef __HAVE_ARCH_STRLCPY 138 /** 139 * strlcpy - Copy a C-string into a sized buffer 140 * @dest: Where to copy the string to 141 * @src: Where to copy the string from 142 * @size: size of destination buffer 143 * 144 * Compatible with *BSD: the result is always a valid 145 * NUL-terminated string that fits in the buffer (unless, 146 * of course, the buffer size is zero). It does not pad 147 * out the result like strncpy() does. 148 */ 149 size_t strlcpy(char *dest, const char *src, size_t size) 150 { 151 size_t ret = strlen(src); 152 153 if (size) { 154 size_t len = (ret >= size) ? size - 1 : ret; 155 memcpy(dest, src, len); 156 dest[len] = '\0'; 157 } 158 return ret; 159 } 160 EXPORT_SYMBOL(strlcpy); 161 #endif 162 163 #ifndef __HAVE_ARCH_STRCAT 164 /** 165 * strcat - Append one %NUL-terminated string to another 166 * @dest: The string to be appended to 167 * @src: The string to append to it 168 */ 169 #undef strcat 170 char *strcat(char *dest, const char *src) 171 { 172 char *tmp = dest; 173 174 while (*dest) 175 dest++; 176 while ((*dest++ = *src++) != '\0') 177 ; 178 return tmp; 179 } 180 EXPORT_SYMBOL(strcat); 181 #endif 182 183 #ifndef __HAVE_ARCH_STRNCAT 184 /** 185 * strncat - Append a length-limited, C-string to another 186 * @dest: The string to be appended to 187 * @src: The string to append to it 188 * @count: The maximum numbers of bytes to copy 189 * 190 * Note that in contrast to strncpy(), strncat() ensures the result is 191 * terminated. 192 */ 193 char *strncat(char *dest, const char *src, size_t count) 194 { 195 char *tmp = dest; 196 197 if (count) { 198 while (*dest) 199 dest++; 200 while ((*dest++ = *src++) != 0) { 201 if (--count == 0) { 202 *dest = '\0'; 203 break; 204 } 205 } 206 } 207 return tmp; 208 } 209 EXPORT_SYMBOL(strncat); 210 #endif 211 212 #ifndef __HAVE_ARCH_STRLCAT 213 /** 214 * strlcat - Append a length-limited, C-string to another 215 * @dest: The string to be appended to 216 * @src: The string to append to it 217 * @count: The size of the destination buffer. 218 */ 219 size_t strlcat(char *dest, const char *src, size_t count) 220 { 221 size_t dsize = strlen(dest); 222 size_t len = strlen(src); 223 size_t res = dsize + len; 224 225 /* This would be a bug */ 226 BUG_ON(dsize >= count); 227 228 dest += dsize; 229 count -= dsize; 230 if (len >= count) 231 len = count-1; 232 memcpy(dest, src, len); 233 dest[len] = 0; 234 return res; 235 } 236 EXPORT_SYMBOL(strlcat); 237 #endif 238 239 #ifndef __HAVE_ARCH_STRCMP 240 /** 241 * strcmp - Compare two strings 242 * @cs: One string 243 * @ct: Another string 244 */ 245 #undef strcmp 246 int strcmp(const char *cs, const char *ct) 247 { 248 unsigned char c1, c2; 249 250 while (1) { 251 c1 = *cs++; 252 c2 = *ct++; 253 if (c1 != c2) 254 return c1 < c2 ? -1 : 1; 255 if (!c1) 256 break; 257 } 258 return 0; 259 } 260 EXPORT_SYMBOL(strcmp); 261 #endif 262 263 #ifndef __HAVE_ARCH_STRNCMP 264 /** 265 * strncmp - Compare two length-limited strings 266 * @cs: One string 267 * @ct: Another string 268 * @count: The maximum number of bytes to compare 269 */ 270 int strncmp(const char *cs, const char *ct, size_t count) 271 { 272 unsigned char c1, c2; 273 274 while (count) { 275 c1 = *cs++; 276 c2 = *ct++; 277 if (c1 != c2) 278 return c1 < c2 ? -1 : 1; 279 if (!c1) 280 break; 281 count--; 282 } 283 return 0; 284 } 285 EXPORT_SYMBOL(strncmp); 286 #endif 287 288 #ifndef __HAVE_ARCH_STRCHR 289 /** 290 * strchr - Find the first occurrence of a character in a string 291 * @s: The string to be searched 292 * @c: The character to search for 293 */ 294 char *strchr(const char *s, int c) 295 { 296 for (; *s != (char)c; ++s) 297 if (*s == '\0') 298 return NULL; 299 return (char *)s; 300 } 301 EXPORT_SYMBOL(strchr); 302 #endif 303 304 #ifndef __HAVE_ARCH_STRCHRNUL 305 /** 306 * strchrnul - Find and return a character in a string, or end of string 307 * @s: The string to be searched 308 * @c: The character to search for 309 * 310 * Returns pointer to first occurrence of 'c' in s. If c is not found, then 311 * return a pointer to the null byte at the end of s. 312 */ 313 char *strchrnul(const char *s, int c) 314 { 315 while (*s && *s != (char)c) 316 s++; 317 return (char *)s; 318 } 319 EXPORT_SYMBOL(strchrnul); 320 #endif 321 322 #ifndef __HAVE_ARCH_STRRCHR 323 /** 324 * strrchr - Find the last occurrence of a character in a string 325 * @s: The string to be searched 326 * @c: The character to search for 327 */ 328 char *strrchr(const char *s, int c) 329 { 330 const char *p = s + strlen(s); 331 do { 332 if (*p == (char)c) 333 return (char *)p; 334 } while (--p >= s); 335 return NULL; 336 } 337 EXPORT_SYMBOL(strrchr); 338 #endif 339 340 #ifndef __HAVE_ARCH_STRNCHR 341 /** 342 * strnchr - Find a character in a length limited string 343 * @s: The string to be searched 344 * @count: The number of characters to be searched 345 * @c: The character to search for 346 */ 347 char *strnchr(const char *s, size_t count, int c) 348 { 349 for (; count-- && *s != '\0'; ++s) 350 if (*s == (char)c) 351 return (char *)s; 352 return NULL; 353 } 354 EXPORT_SYMBOL(strnchr); 355 #endif 356 357 /** 358 * skip_spaces - Removes leading whitespace from @str. 359 * @str: The string to be stripped. 360 * 361 * Returns a pointer to the first non-whitespace character in @str. 362 */ 363 char *skip_spaces(const char *str) 364 { 365 while (isspace(*str)) 366 ++str; 367 return (char *)str; 368 } 369 EXPORT_SYMBOL(skip_spaces); 370 371 /** 372 * strim - Removes leading and trailing whitespace from @s. 373 * @s: The string to be stripped. 374 * 375 * Note that the first trailing whitespace is replaced with a %NUL-terminator 376 * in the given string @s. Returns a pointer to the first non-whitespace 377 * character in @s. 378 */ 379 char *strim(char *s) 380 { 381 size_t size; 382 char *end; 383 384 size = strlen(s); 385 if (!size) 386 return s; 387 388 end = s + size - 1; 389 while (end >= s && isspace(*end)) 390 end--; 391 *(end + 1) = '\0'; 392 393 return skip_spaces(s); 394 } 395 EXPORT_SYMBOL(strim); 396 397 #ifndef __HAVE_ARCH_STRLEN 398 /** 399 * strlen - Find the length of a string 400 * @s: The string to be sized 401 */ 402 size_t strlen(const char *s) 403 { 404 const char *sc; 405 406 for (sc = s; *sc != '\0'; ++sc) 407 /* nothing */; 408 return sc - s; 409 } 410 EXPORT_SYMBOL(strlen); 411 #endif 412 413 #ifndef __HAVE_ARCH_STRNLEN 414 /** 415 * strnlen - Find the length of a length-limited string 416 * @s: The string to be sized 417 * @count: The maximum number of bytes to search 418 */ 419 size_t strnlen(const char *s, size_t count) 420 { 421 const char *sc; 422 423 for (sc = s; count-- && *sc != '\0'; ++sc) 424 /* nothing */; 425 return sc - s; 426 } 427 EXPORT_SYMBOL(strnlen); 428 #endif 429 430 #ifndef __HAVE_ARCH_STRSPN 431 /** 432 * strspn - Calculate the length of the initial substring of @s which only contain letters in @accept 433 * @s: The string to be searched 434 * @accept: The string to search for 435 */ 436 size_t strspn(const char *s, const char *accept) 437 { 438 const char *p; 439 const char *a; 440 size_t count = 0; 441 442 for (p = s; *p != '\0'; ++p) { 443 for (a = accept; *a != '\0'; ++a) { 444 if (*p == *a) 445 break; 446 } 447 if (*a == '\0') 448 return count; 449 ++count; 450 } 451 return count; 452 } 453 454 EXPORT_SYMBOL(strspn); 455 #endif 456 457 #ifndef __HAVE_ARCH_STRCSPN 458 /** 459 * strcspn - Calculate the length of the initial substring of @s which does not contain letters in @reject 460 * @s: The string to be searched 461 * @reject: The string to avoid 462 */ 463 size_t strcspn(const char *s, const char *reject) 464 { 465 const char *p; 466 const char *r; 467 size_t count = 0; 468 469 for (p = s; *p != '\0'; ++p) { 470 for (r = reject; *r != '\0'; ++r) { 471 if (*p == *r) 472 return count; 473 } 474 ++count; 475 } 476 return count; 477 } 478 EXPORT_SYMBOL(strcspn); 479 #endif 480 481 #ifndef __HAVE_ARCH_STRPBRK 482 /** 483 * strpbrk - Find the first occurrence of a set of characters 484 * @cs: The string to be searched 485 * @ct: The characters to search for 486 */ 487 char *strpbrk(const char *cs, const char *ct) 488 { 489 const char *sc1, *sc2; 490 491 for (sc1 = cs; *sc1 != '\0'; ++sc1) { 492 for (sc2 = ct; *sc2 != '\0'; ++sc2) { 493 if (*sc1 == *sc2) 494 return (char *)sc1; 495 } 496 } 497 return NULL; 498 } 499 EXPORT_SYMBOL(strpbrk); 500 #endif 501 502 #ifndef __HAVE_ARCH_STRSEP 503 /** 504 * strsep - Split a string into tokens 505 * @s: The string to be searched 506 * @ct: The characters to search for 507 * 508 * strsep() updates @s to point after the token, ready for the next call. 509 * 510 * It returns empty tokens, too, behaving exactly like the libc function 511 * of that name. In fact, it was stolen from glibc2 and de-fancy-fied. 512 * Same semantics, slimmer shape. ;) 513 */ 514 char *strsep(char **s, const char *ct) 515 { 516 char *sbegin = *s; 517 char *end; 518 519 if (sbegin == NULL) 520 return NULL; 521 522 end = strpbrk(sbegin, ct); 523 if (end) 524 *end++ = '\0'; 525 *s = end; 526 return sbegin; 527 } 528 EXPORT_SYMBOL(strsep); 529 #endif 530 531 /** 532 * sysfs_streq - return true if strings are equal, modulo trailing newline 533 * @s1: one string 534 * @s2: another string 535 * 536 * This routine returns true iff two strings are equal, treating both 537 * NUL and newline-then-NUL as equivalent string terminations. It's 538 * geared for use with sysfs input strings, which generally terminate 539 * with newlines but are compared against values without newlines. 540 */ 541 bool sysfs_streq(const char *s1, const char *s2) 542 { 543 while (*s1 && *s1 == *s2) { 544 s1++; 545 s2++; 546 } 547 548 if (*s1 == *s2) 549 return true; 550 if (!*s1 && *s2 == '\n' && !s2[1]) 551 return true; 552 if (*s1 == '\n' && !s1[1] && !*s2) 553 return true; 554 return false; 555 } 556 EXPORT_SYMBOL(sysfs_streq); 557 558 /** 559 * strtobool - convert common user inputs into boolean values 560 * @s: input string 561 * @res: result 562 * 563 * This routine returns 0 iff the first character is one of 'Yy1Nn0'. 564 * Otherwise it will return -EINVAL. Value pointed to by res is 565 * updated upon finding a match. 566 */ 567 int strtobool(const char *s, bool *res) 568 { 569 switch (s[0]) { 570 case 'y': 571 case 'Y': 572 case '1': 573 *res = true; 574 break; 575 case 'n': 576 case 'N': 577 case '0': 578 *res = false; 579 break; 580 default: 581 return -EINVAL; 582 } 583 return 0; 584 } 585 EXPORT_SYMBOL(strtobool); 586 587 #ifndef __HAVE_ARCH_MEMSET 588 /** 589 * memset - Fill a region of memory with the given value 590 * @s: Pointer to the start of the area. 591 * @c: The byte to fill the area with 592 * @count: The size of the area. 593 * 594 * Do not use memset() to access IO space, use memset_io() instead. 595 */ 596 void *memset(void *s, int c, size_t count) 597 { 598 char *xs = s; 599 600 while (count--) 601 *xs++ = c; 602 return s; 603 } 604 EXPORT_SYMBOL(memset); 605 #endif 606 607 #ifndef __HAVE_ARCH_MEMCPY 608 /** 609 * memcpy - Copy one area of memory to another 610 * @dest: Where to copy to 611 * @src: Where to copy from 612 * @count: The size of the area. 613 * 614 * You should not use this function to access IO space, use memcpy_toio() 615 * or memcpy_fromio() instead. 616 */ 617 void *memcpy(void *dest, const void *src, size_t count) 618 { 619 char *tmp = dest; 620 const char *s = src; 621 622 while (count--) 623 *tmp++ = *s++; 624 return dest; 625 } 626 EXPORT_SYMBOL(memcpy); 627 #endif 628 629 #ifndef __HAVE_ARCH_MEMMOVE 630 /** 631 * memmove - Copy one area of memory to another 632 * @dest: Where to copy to 633 * @src: Where to copy from 634 * @count: The size of the area. 635 * 636 * Unlike memcpy(), memmove() copes with overlapping areas. 637 */ 638 void *memmove(void *dest, const void *src, size_t count) 639 { 640 char *tmp; 641 const char *s; 642 643 if (dest <= src) { 644 tmp = dest; 645 s = src; 646 while (count--) 647 *tmp++ = *s++; 648 } else { 649 tmp = dest; 650 tmp += count; 651 s = src; 652 s += count; 653 while (count--) 654 *--tmp = *--s; 655 } 656 return dest; 657 } 658 EXPORT_SYMBOL(memmove); 659 #endif 660 661 #ifndef __HAVE_ARCH_MEMCMP 662 /** 663 * memcmp - Compare two areas of memory 664 * @cs: One area of memory 665 * @ct: Another area of memory 666 * @count: The size of the area. 667 */ 668 #undef memcmp 669 __visible int memcmp(const void *cs, const void *ct, size_t count) 670 { 671 const unsigned char *su1, *su2; 672 int res = 0; 673 674 for (su1 = cs, su2 = ct; 0 < count; ++su1, ++su2, count--) 675 if ((res = *su1 - *su2) != 0) 676 break; 677 return res; 678 } 679 EXPORT_SYMBOL(memcmp); 680 #endif 681 682 #ifndef __HAVE_ARCH_MEMSCAN 683 /** 684 * memscan - Find a character in an area of memory. 685 * @addr: The memory area 686 * @c: The byte to search for 687 * @size: The size of the area. 688 * 689 * returns the address of the first occurrence of @c, or 1 byte past 690 * the area if @c is not found 691 */ 692 void *memscan(void *addr, int c, size_t size) 693 { 694 unsigned char *p = addr; 695 696 while (size) { 697 if (*p == c) 698 return (void *)p; 699 p++; 700 size--; 701 } 702 return (void *)p; 703 } 704 EXPORT_SYMBOL(memscan); 705 #endif 706 707 #ifndef __HAVE_ARCH_STRSTR 708 /** 709 * strstr - Find the first substring in a %NUL terminated string 710 * @s1: The string to be searched 711 * @s2: The string to search for 712 */ 713 char *strstr(const char *s1, const char *s2) 714 { 715 size_t l1, l2; 716 717 l2 = strlen(s2); 718 if (!l2) 719 return (char *)s1; 720 l1 = strlen(s1); 721 while (l1 >= l2) { 722 l1--; 723 if (!memcmp(s1, s2, l2)) 724 return (char *)s1; 725 s1++; 726 } 727 return NULL; 728 } 729 EXPORT_SYMBOL(strstr); 730 #endif 731 732 #ifndef __HAVE_ARCH_STRNSTR 733 /** 734 * strnstr - Find the first substring in a length-limited string 735 * @s1: The string to be searched 736 * @s2: The string to search for 737 * @len: the maximum number of characters to search 738 */ 739 char *strnstr(const char *s1, const char *s2, size_t len) 740 { 741 size_t l2; 742 743 l2 = strlen(s2); 744 if (!l2) 745 return (char *)s1; 746 while (len >= l2) { 747 len--; 748 if (!memcmp(s1, s2, l2)) 749 return (char *)s1; 750 s1++; 751 } 752 return NULL; 753 } 754 EXPORT_SYMBOL(strnstr); 755 #endif 756 757 #ifndef __HAVE_ARCH_MEMCHR 758 /** 759 * memchr - Find a character in an area of memory. 760 * @s: The memory area 761 * @c: The byte to search for 762 * @n: The size of the area. 763 * 764 * returns the address of the first occurrence of @c, or %NULL 765 * if @c is not found 766 */ 767 void *memchr(const void *s, int c, size_t n) 768 { 769 const unsigned char *p = s; 770 while (n-- != 0) { 771 if ((unsigned char)c == *p++) { 772 return (void *)(p - 1); 773 } 774 } 775 return NULL; 776 } 777 EXPORT_SYMBOL(memchr); 778 #endif 779 780 static void *check_bytes8(const u8 *start, u8 value, unsigned int bytes) 781 { 782 while (bytes) { 783 if (*start != value) 784 return (void *)start; 785 start++; 786 bytes--; 787 } 788 return NULL; 789 } 790 791 /** 792 * memchr_inv - Find an unmatching character in an area of memory. 793 * @start: The memory area 794 * @c: Find a character other than c 795 * @bytes: The size of the area. 796 * 797 * returns the address of the first character other than @c, or %NULL 798 * if the whole buffer contains just @c. 799 */ 800 void *memchr_inv(const void *start, int c, size_t bytes) 801 { 802 u8 value = c; 803 u64 value64; 804 unsigned int words, prefix; 805 806 if (bytes <= 16) 807 return check_bytes8(start, value, bytes); 808 809 value64 = value; 810 #if defined(ARCH_HAS_FAST_MULTIPLIER) && BITS_PER_LONG == 64 811 value64 *= 0x0101010101010101; 812 #elif defined(ARCH_HAS_FAST_MULTIPLIER) 813 value64 *= 0x01010101; 814 value64 |= value64 << 32; 815 #else 816 value64 |= value64 << 8; 817 value64 |= value64 << 16; 818 value64 |= value64 << 32; 819 #endif 820 821 prefix = (unsigned long)start % 8; 822 if (prefix) { 823 u8 *r; 824 825 prefix = 8 - prefix; 826 r = check_bytes8(start, value, prefix); 827 if (r) 828 return r; 829 start += prefix; 830 bytes -= prefix; 831 } 832 833 words = bytes / 8; 834 835 while (words) { 836 if (*(u64 *)start != value64) 837 return check_bytes8(start, value, 8); 838 start += 8; 839 words--; 840 } 841 842 return check_bytes8(start, value, bytes % 8); 843 } 844 EXPORT_SYMBOL(memchr_inv); 845