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 18#include <config.h> 19#include <linux/compiler.h> 20#include <linux/types.h> 21#include <linux/string.h> 22#include <linux/ctype.h> 23#include <malloc.h> 24 25 26/** 27 * strncasecmp - Case insensitive, length-limited string comparison 28 * @s1: One string 29 * @s2: The other string 30 * @len: the maximum number of characters to compare 31 */ 32int strncasecmp(const char *s1, const char *s2, size_t len) 33{ 34 /* Yes, Virginia, it had better be unsigned */ 35 unsigned char c1, c2; 36 37 c1 = 0; c2 = 0; 38 if (len) { 39 do { 40 c1 = *s1; c2 = *s2; 41 s1++; s2++; 42 if (!c1) 43 break; 44 if (!c2) 45 break; 46 if (c1 == c2) 47 continue; 48 c1 = tolower(c1); 49 c2 = tolower(c2); 50 if (c1 != c2) 51 break; 52 } while (--len); 53 } 54 return (int)c1 - (int)c2; 55} 56 57/** 58 * strcasecmp - Case insensitive string comparison 59 * @s1: One string 60 * @s2: The other string 61 */ 62int strcasecmp(const char *s1, const char *s2) 63{ 64 return strncasecmp(s1, s2, -1U); 65} 66 67char * ___strtok; 68 69#ifndef __HAVE_ARCH_STRCPY 70/** 71 * strcpy - Copy a %NUL terminated string 72 * @dest: Where to copy the string to 73 * @src: Where to copy the string from 74 */ 75char * strcpy(char * dest,const char *src) 76{ 77 char *tmp = dest; 78 79 while ((*dest++ = *src++) != '\0') 80 /* nothing */; 81 return tmp; 82} 83#endif 84 85#ifndef __HAVE_ARCH_STRNCPY 86/** 87 * strncpy - Copy a length-limited, %NUL-terminated string 88 * @dest: Where to copy the string to 89 * @src: Where to copy the string from 90 * @count: The maximum number of bytes to copy 91 * 92 * Note that unlike userspace strncpy, this does not %NUL-pad the buffer. 93 * However, the result is not %NUL-terminated if the source exceeds 94 * @count bytes. 95 */ 96char * strncpy(char * dest,const char *src,size_t count) 97{ 98 char *tmp = dest; 99 100 while (count-- && (*dest++ = *src++) != '\0') 101 /* nothing */; 102 103 return tmp; 104} 105#endif 106 107#ifndef __HAVE_ARCH_STRLCPY 108/** 109 * strlcpy - Copy a C-string into a sized buffer 110 * @dest: Where to copy the string to 111 * @src: Where to copy the string from 112 * @size: size of destination buffer 113 * 114 * Compatible with *BSD: the result is always a valid 115 * NUL-terminated string that fits in the buffer (unless, 116 * of course, the buffer size is zero). It does not pad 117 * out the result like strncpy() does. 118 * 119 * Return: strlen(src) 120 */ 121size_t strlcpy(char *dest, const char *src, size_t size) 122{ 123 size_t ret = strlen(src); 124 125 if (size) { 126 size_t len = (ret >= size) ? size - 1 : ret; 127 memcpy(dest, src, len); 128 dest[len] = '\0'; 129 } 130 return ret; 131} 132#endif 133 134#ifndef __HAVE_ARCH_STRCAT 135/** 136 * strcat - Append one %NUL-terminated string to another 137 * @dest: The string to be appended to 138 * @src: The string to append to it 139 */ 140char * strcat(char * dest, const char * src) 141{ 142 char *tmp = dest; 143 144 while (*dest) 145 dest++; 146 while ((*dest++ = *src++) != '\0') 147 ; 148 149 return tmp; 150} 151#endif 152 153#ifndef __HAVE_ARCH_STRNCAT 154/** 155 * strncat - Append a length-limited, %NUL-terminated string to another 156 * @dest: The string to be appended to 157 * @src: The string to append to it 158 * @count: The maximum numbers of bytes to copy 159 * 160 * Note that in contrast to strncpy, strncat ensures the result is 161 * terminated. 162 */ 163char * strncat(char *dest, const char *src, size_t count) 164{ 165 char *tmp = dest; 166 167 if (count) { 168 while (*dest) 169 dest++; 170 while ((*dest++ = *src++)) { 171 if (--count == 0) { 172 *dest = '\0'; 173 break; 174 } 175 } 176 } 177 178 return tmp; 179} 180#endif 181 182#ifndef __HAVE_ARCH_STRLCAT 183/** 184 * strlcat - Append a length-limited, %NUL-terminated string to another 185 * @dest: The string to be appended to 186 * @src: The string to append to it 187 * @size: The size of @dest 188 * 189 * Compatible with *BSD: the result is always a valid NUL-terminated string that 190 * fits in the buffer (unless, of course, the buffer size is zero). It does not 191 * write past @size like strncat() does. 192 * 193 * Return: min(strlen(dest), size) + strlen(src) 194 */ 195size_t strlcat(char *dest, const char *src, size_t size) 196{ 197 size_t len = strnlen(dest, size); 198 199 return len + strlcpy(dest + len, src, size - len); 200} 201#endif 202 203#ifndef __HAVE_ARCH_STRCMP 204/** 205 * strcmp - Compare two strings 206 * @cs: One string 207 * @ct: Another string 208 */ 209int strcmp(const char *cs, const char *ct) 210{ 211 int ret; 212 213 while (1) { 214 unsigned char a = *cs++; 215 unsigned char b = *ct++; 216 217 ret = a - b; 218 if (ret || !b) 219 break; 220 } 221 222 return ret; 223} 224#endif 225 226#ifndef __HAVE_ARCH_STRNCMP 227/** 228 * strncmp - Compare two length-limited strings 229 * @cs: One string 230 * @ct: Another string 231 * @count: The maximum number of bytes to compare 232 */ 233int strncmp(const char *cs, const char *ct, size_t count) 234{ 235 int ret = 0; 236 237 while (count--) { 238 unsigned char a = *cs++; 239 unsigned char b = *ct++; 240 241 ret = a - b; 242 if (ret || !b) 243 break; 244 } 245 246 return ret; 247} 248#endif 249 250#ifndef __HAVE_ARCH_STRCHR 251/** 252 * strchr - Find the first occurrence of a character in a string 253 * @s: The string to be searched 254 * @c: The character to search for 255 */ 256char * strchr(const char * s, int c) 257{ 258 for(; *s != (char) c; ++s) 259 if (*s == '\0') 260 return NULL; 261 return (char *) s; 262} 263#endif 264 265const char *strchrnul(const char *s, int c) 266{ 267 for (; *s != (char)c; ++s) 268 if (*s == '\0') 269 break; 270 return s; 271} 272 273#ifndef __HAVE_ARCH_STRRCHR 274/** 275 * strrchr - Find the last occurrence of a character in a string 276 * @s: The string to be searched 277 * @c: The character to search for 278 */ 279char * strrchr(const char * s, int c) 280{ 281 const char *p = s + strlen(s); 282 do { 283 if (*p == (char)c) 284 return (char *)p; 285 } while (--p >= s); 286 return NULL; 287} 288#endif 289 290#ifndef __HAVE_ARCH_STRLEN 291/** 292 * strlen - Find the length of a string 293 * @s: The string to be sized 294 */ 295size_t strlen(const char * s) 296{ 297 const char *sc; 298 299 for (sc = s; *sc != '\0'; ++sc) 300 /* nothing */; 301 return sc - s; 302} 303#endif 304 305#ifndef __HAVE_ARCH_STRNLEN 306/** 307 * strnlen - Find the length of a length-limited string 308 * @s: The string to be sized 309 * @count: The maximum number of bytes to search 310 */ 311size_t strnlen(const char * s, size_t count) 312{ 313 const char *sc; 314 315 for (sc = s; count-- && *sc != '\0'; ++sc) 316 /* nothing */; 317 return sc - s; 318} 319#endif 320 321#ifndef __HAVE_ARCH_STRCSPN 322/** 323 * strcspn - Calculate the length of the initial substring of @s which does 324 * not contain letters in @reject 325 * @s: The string to be searched 326 * @reject: The string to avoid 327 */ 328size_t strcspn(const char *s, const char *reject) 329{ 330 const char *p; 331 const char *r; 332 size_t count = 0; 333 334 for (p = s; *p != '\0'; ++p) { 335 for (r = reject; *r != '\0'; ++r) { 336 if (*p == *r) 337 return count; 338 } 339 ++count; 340 } 341 return count; 342} 343#endif 344 345#ifndef __HAVE_ARCH_STRDUP 346char * strdup(const char *s) 347{ 348 char *new; 349 350 if ((s == NULL) || 351 ((new = malloc (strlen(s) + 1)) == NULL) ) { 352 return NULL; 353 } 354 355 strcpy (new, s); 356 return new; 357} 358 359char * strndup(const char *s, size_t n) 360{ 361 size_t len; 362 char *new; 363 364 if (s == NULL) 365 return NULL; 366 367 len = strlen(s); 368 369 if (n < len) 370 len = n; 371 372 new = malloc(len + 1); 373 if (new == NULL) 374 return NULL; 375 376 strncpy(new, s, len); 377 new[len] = '\0'; 378 379 return new; 380} 381#endif 382 383#ifndef __HAVE_ARCH_STRSPN 384/** 385 * strspn - Calculate the length of the initial substring of @s which only 386 * contain letters in @accept 387 * @s: The string to be searched 388 * @accept: The string to search for 389 */ 390size_t strspn(const char *s, const char *accept) 391{ 392 const char *p; 393 const char *a; 394 size_t count = 0; 395 396 for (p = s; *p != '\0'; ++p) { 397 for (a = accept; *a != '\0'; ++a) { 398 if (*p == *a) 399 break; 400 } 401 if (*a == '\0') 402 return count; 403 ++count; 404 } 405 406 return count; 407} 408#endif 409 410#ifndef __HAVE_ARCH_STRPBRK 411/** 412 * strpbrk - Find the first occurrence of a set of characters 413 * @cs: The string to be searched 414 * @ct: The characters to search for 415 */ 416char * strpbrk(const char * cs,const char * ct) 417{ 418 const char *sc1,*sc2; 419 420 for( sc1 = cs; *sc1 != '\0'; ++sc1) { 421 for( sc2 = ct; *sc2 != '\0'; ++sc2) { 422 if (*sc1 == *sc2) 423 return (char *) sc1; 424 } 425 } 426 return NULL; 427} 428#endif 429 430#ifndef __HAVE_ARCH_STRTOK 431/** 432 * strtok - Split a string into tokens 433 * @s: The string to be searched 434 * @ct: The characters to search for 435 * 436 * WARNING: strtok is deprecated, use strsep instead. 437 */ 438char * strtok(char * s,const char * ct) 439{ 440 char *sbegin, *send; 441 442 sbegin = s ? s : ___strtok; 443 if (!sbegin) { 444 return NULL; 445 } 446 sbegin += strspn(sbegin,ct); 447 if (*sbegin == '\0') { 448 ___strtok = NULL; 449 return( NULL ); 450 } 451 send = strpbrk( sbegin, ct); 452 if (send && *send != '\0') 453 *send++ = '\0'; 454 ___strtok = send; 455 return (sbegin); 456} 457#endif 458 459#ifndef __HAVE_ARCH_STRSEP 460/** 461 * strsep - Split a string into tokens 462 * @s: The string to be searched 463 * @ct: The characters to search for 464 * 465 * strsep() updates @s to point after the token, ready for the next call. 466 * 467 * It returns empty tokens, too, behaving exactly like the libc function 468 * of that name. In fact, it was stolen from glibc2 and de-fancy-fied. 469 * Same semantics, slimmer shape. ;) 470 */ 471char * strsep(char **s, const char *ct) 472{ 473 char *sbegin = *s, *end; 474 475 if (sbegin == NULL) 476 return NULL; 477 478 end = strpbrk(sbegin, ct); 479 if (end) 480 *end++ = '\0'; 481 *s = end; 482 483 return sbegin; 484} 485#endif 486 487#ifndef __HAVE_ARCH_STRSWAB 488/** 489 * strswab - swap adjacent even and odd bytes in %NUL-terminated string 490 * s: address of the string 491 * 492 * returns the address of the swapped string or NULL on error. If 493 * string length is odd, last byte is untouched. 494 */ 495char *strswab(const char *s) 496{ 497 char *p, *q; 498 499 if ((NULL == s) || ('\0' == *s)) { 500 return (NULL); 501 } 502 503 for (p=(char *)s, q=p+1; (*p != '\0') && (*q != '\0'); p+=2, q+=2) { 504 char tmp; 505 506 tmp = *p; 507 *p = *q; 508 *q = tmp; 509 } 510 511 return (char *) s; 512} 513#endif 514 515#ifndef __HAVE_ARCH_MEMSET 516/** 517 * memset - Fill a region of memory with the given value 518 * @s: Pointer to the start of the area. 519 * @c: The byte to fill the area with 520 * @count: The size of the area. 521 * 522 * Do not use memset() to access IO space, use memset_io() instead. 523 */ 524__used void * memset(void * s,int c,size_t count) 525{ 526 unsigned long *sl = (unsigned long *) s; 527 char *s8; 528 529#if !CONFIG_IS_ENABLED(TINY_MEMSET) 530 unsigned long cl = 0; 531 int i; 532 533 /* do it one word at a time (32 bits or 64 bits) while possible */ 534 if ( ((ulong)s & (sizeof(*sl) - 1)) == 0) { 535 for (i = 0; i < sizeof(*sl); i++) { 536 cl <<= 8; 537 cl |= c & 0xff; 538 } 539 while (count >= sizeof(*sl)) { 540 *sl++ = cl; 541 count -= sizeof(*sl); 542 } 543 } 544#endif /* fill 8 bits at a time */ 545 s8 = (char *)sl; 546 while (count--) 547 *s8++ = c; 548 549 return s; 550} 551#endif 552 553#ifndef __HAVE_ARCH_MEMCPY 554/** 555 * memcpy - Copy one area of memory to another 556 * @dest: Where to copy to 557 * @src: Where to copy from 558 * @count: The size of the area. 559 * 560 * You should not use this function to access IO space, use memcpy_toio() 561 * or memcpy_fromio() instead. 562 */ 563__used void * memcpy(void *dest, const void *src, size_t count) 564{ 565 unsigned long *dl = (unsigned long *)dest, *sl = (unsigned long *)src; 566 char *d8, *s8; 567 568 if (src == dest) 569 return dest; 570 571 /* while all data is aligned (common case), copy a word at a time */ 572 if ( (((ulong)dest | (ulong)src) & (sizeof(*dl) - 1)) == 0) { 573 while (count >= sizeof(*dl)) { 574 *dl++ = *sl++; 575 count -= sizeof(*dl); 576 } 577 } 578 /* copy the reset one byte at a time */ 579 d8 = (char *)dl; 580 s8 = (char *)sl; 581 while (count--) 582 *d8++ = *s8++; 583 584 return dest; 585} 586#endif 587 588#ifndef __HAVE_ARCH_MEMMOVE 589/** 590 * memmove - Copy one area of memory to another 591 * @dest: Where to copy to 592 * @src: Where to copy from 593 * @count: The size of the area. 594 * 595 * Unlike memcpy(), memmove() copes with overlapping areas. 596 */ 597__used void * memmove(void * dest,const void *src,size_t count) 598{ 599 char *tmp, *s; 600 601 if (dest <= src || (src + count) <= dest) { 602 /* 603 * Use the fast memcpy implementation (ARCH optimized or lib/string.c) when it is possible: 604 * - when dest is before src (assuming that memcpy is doing forward-copying) 605 * - when destination don't overlap the source buffer (src + count <= dest) 606 * 607 * WARNING: the first optimisation cause an issue, when __HAVE_ARCH_MEMCPY is defined, 608 * __HAVE_ARCH_MEMMOVE is not defined and if the memcpy ARCH-specific 609 * implementation is not doing a forward-copying. 610 * 611 * No issue today because memcpy is doing a forward-copying in lib/string.c and for ARM32 612 * architecture; no other arches use __HAVE_ARCH_MEMCPY without __HAVE_ARCH_MEMMOVE. 613 */ 614 memcpy(dest, src, count); 615 } else { 616 tmp = (char *) dest + count; 617 s = (char *) src + count; 618 while (count--) 619 *--tmp = *--s; 620 } 621 622 return dest; 623} 624#endif 625 626#ifndef __HAVE_ARCH_MEMCMP 627/** 628 * memcmp - Compare two areas of memory 629 * @cs: One area of memory 630 * @ct: Another area of memory 631 * @count: The size of the area. 632 */ 633__used int memcmp(const void * cs,const void * ct,size_t count) 634{ 635 const unsigned char *su1, *su2; 636 int res = 0; 637 638 for( su1 = cs, su2 = ct; 0 < count; ++su1, ++su2, count--) 639 if ((res = *su1 - *su2) != 0) 640 break; 641 return res; 642} 643#endif 644 645#ifndef __HAVE_ARCH_MEMSCAN 646/** 647 * memscan - Find a character in an area of memory. 648 * @addr: The memory area 649 * @c: The byte to search for 650 * @size: The size of the area. 651 * 652 * returns the address of the first occurrence of @c, or 1 byte past 653 * the area if @c is not found 654 */ 655void * memscan(void * addr, int c, size_t size) 656{ 657 unsigned char * p = (unsigned char *) addr; 658 659 while (size) { 660 if (*p == c) 661 return (void *) p; 662 p++; 663 size--; 664 } 665 return (void *) p; 666} 667#endif 668 669char *memdup(const void *src, size_t len) 670{ 671 char *p; 672 673 p = malloc(len); 674 if (!p) 675 return NULL; 676 677 memcpy(p, src, len); 678 679 return p; 680} 681 682#ifndef __HAVE_ARCH_STRSTR 683/** 684 * strstr - Find the first substring in a %NUL terminated string 685 * @s1: The string to be searched 686 * @s2: The string to search for 687 */ 688char * strstr(const char * s1,const char * s2) 689{ 690 int l1, l2; 691 692 l2 = strlen(s2); 693 if (!l2) 694 return (char *) s1; 695 l1 = strlen(s1); 696 while (l1 >= l2) { 697 l1--; 698 if (!memcmp(s1,s2,l2)) 699 return (char *) s1; 700 s1++; 701 } 702 return NULL; 703} 704#endif 705 706#ifndef __HAVE_ARCH_MEMCHR 707/** 708 * memchr - Find a character in an area of memory. 709 * @s: The memory area 710 * @c: The byte to search for 711 * @n: The size of the area. 712 * 713 * returns the address of the first occurrence of @c, or %NULL 714 * if @c is not found 715 */ 716void *memchr(const void *s, int c, size_t n) 717{ 718 const unsigned char *p = s; 719 while (n-- != 0) { 720 if ((unsigned char)c == *p++) { 721 return (void *)(p-1); 722 } 723 } 724 return NULL; 725} 726 727#endif 728#ifndef __HAVE_ARCH_MEMCHR_INV 729static void *check_bytes8(const u8 *start, u8 value, unsigned int bytes) 730{ 731 while (bytes) { 732 if (*start != value) 733 return (void *)start; 734 start++; 735 bytes--; 736 } 737 return NULL; 738} 739/** 740 * memchr_inv - Find an unmatching character in an area of memory. 741 * @start: The memory area 742 * @c: Find a character other than c 743 * @bytes: The size of the area. 744 * 745 * returns the address of the first character other than @c, or %NULL 746 * if the whole buffer contains just @c. 747 */ 748void *memchr_inv(const void *start, int c, size_t bytes) 749{ 750 u8 value = c; 751 u64 value64; 752 unsigned int words, prefix; 753 754 if (bytes <= 16) 755 return check_bytes8(start, value, bytes); 756 757 value64 = value; 758 value64 |= value64 << 8; 759 value64 |= value64 << 16; 760 value64 |= value64 << 32; 761 762 prefix = (unsigned long)start % 8; 763 if (prefix) { 764 u8 *r; 765 766 prefix = 8 - prefix; 767 r = check_bytes8(start, value, prefix); 768 if (r) 769 return r; 770 start += prefix; 771 bytes -= prefix; 772 } 773 774 words = bytes / 8; 775 776 while (words) { 777 if (*(u64 *)start != value64) 778 return check_bytes8(start, value, 8); 779 start += 8; 780 words--; 781 } 782 783 return check_bytes8(start, value, bytes % 8); 784} 785#endif 786