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