lib/string.c

   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 #define IN_STRING_C 1
  23
  24 #include <linux/types.h>
  25 #include <linux/string.h>
  26 #include <linux/ctype.h>
  27 #include <linux/module.h>
  28
  29 #ifndef __HAVE_ARCH_STRNICMP
  30 /**
  31  * strnicmp - Case insensitive, length-limited string comparison
  32  * @s1: One string
  33  * @s2: The other string
  34  * @len: the maximum number of characters to compare
  35  */
  36 int strnicmp(const char *s1, const char *s2, size_t len)
  37 {
  38         /* Yes, Virginia, it had better be unsigned */
  39         unsigned char c1, c2;
  40
  41         c1 = 0; c2 = 0;
  42         if (len) {
  43                 do {
  44                         c1 = *s1; c2 = *s2;
  45                         s1++; s2++;
  46                         if (!c1)
  47                                 break;
  48                         if (!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         }
  58         return (int)c1 - (int)c2;
  59 }
  60
  61 EXPORT_SYMBOL(strnicmp);
  62 #endif
  63
  64 #ifndef __HAVE_ARCH_STRCPY
  65 /**
  66  * strcpy - Copy a %NUL terminated string
  67  * @dest: Where to copy the string to
  68  * @src: Where to copy the string from
  69  */
  70 char * strcpy(char * dest,const char *src)
  71 {
  72         char *tmp = dest;
  73
  74         while ((*dest++ = *src++) != '\0')
  75                 /* nothing */;
  76         return tmp;
  77 }
  78 EXPORT_SYMBOL(strcpy);
  79 #endif
  80
  81 #ifndef __HAVE_ARCH_STRNCPY
  82 /**
  83  * strncpy - Copy a length-limited, %NUL-terminated string
  84  * @dest: Where to copy the string to
  85  * @src: Where to copy the string from
  86  * @count: The maximum number of bytes to copy
  87  *
  88  * The result is not %NUL-terminated if the source exceeds
  89  * @count bytes.
  90  */
  91 char * strncpy(char * dest,const char *src,size_t count)
  92 {
  93         char *tmp = dest;
  94
  95         while (count) {
  96                 if ((*tmp = *src) != 0) src++;
  97                 tmp++;
  98                 count--;
  99         }
 100         return dest;
 101 }
 102 EXPORT_SYMBOL(strncpy);
 103 #endif
 104
 105 #ifndef __HAVE_ARCH_STRLCPY
 106 /**
 107  * strlcpy - Copy a %NUL terminated 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 EXPORT_SYMBOL(strlcpy);
 129 #endif
 130
 131 #ifndef __HAVE_ARCH_STRCAT
 132 /**
 133  * strcat - Append one %NUL-terminated string to another
 134  * @dest: The string to be appended to
 135  * @src: The string to append to it
 136  */
 137 char * strcat(char * dest, const char * src)
 138 {
 139         char *tmp = dest;
 140
 141         while (*dest)
 142                 dest++;
 143         while ((*dest++ = *src++) != '\0')
 144                 ;
 145
 146         return tmp;
 147 }
 148 EXPORT_SYMBOL(strcat);
 149 #endif
 150
 151 #ifndef __HAVE_ARCH_STRNCAT
 152 /**
 153  * strncat - Append a length-limited, %NUL-terminated string to another
 154  * @dest: The string to be appended to
 155  * @src: The string to append to it
 156  * @count: The maximum numbers of bytes to copy
 157  *
 158  * Note that in contrast to strncpy, strncat ensures the result is
 159  * terminated.
 160  */
 161 char * strncat(char *dest, const char *src, size_t count)
 162 {
 163         char *tmp = dest;
 164
 165         if (count) {
 166                 while (*dest)
 167                         dest++;
 168                 while ((*dest++ = *src++) != 0) {
 169                         if (--count == 0) {
 170                                 *dest = '\0';
 171                                 break;
 172                         }
 173                 }
 174         }
 175
 176         return tmp;
 177 }
 178 EXPORT_SYMBOL(strncat);
 179 #endif
 180
 181 #ifndef __HAVE_ARCH_STRLCAT
 182 /**
 183  * strlcat - Append a length-limited, %NUL-terminated string to another
 184  * @dest: The string to be appended to
 185  * @src: The string to append to it
 186  * @count: The size of the destination buffer.
 187  */
 188 size_t strlcat(char *dest, const char *src, size_t count)
 189 {
 190         size_t dsize = strlen(dest);
 191         size_t len = strlen(src);
 192         size_t res = dsize + len;
 193
 194         /* This would be a bug */
 195         BUG_ON(dsize >= count);
 196
 197         dest += dsize;
 198         count -= dsize;
 199         if (len >= count)
 200                 len = count-1;
 201         memcpy(dest, src, len);
 202         dest[len] = 0;
 203         return res;
 204 }
 205 EXPORT_SYMBOL(strlcat);
 206 #endif
 207
 208 #ifndef __HAVE_ARCH_STRCMP
 209 /**
 210  * strcmp - Compare two strings
 211  * @cs: One string
 212  * @ct: Another string
 213  */
 214 int strcmp(const char * cs,const char * ct)
 215 {
 216         register signed char __res;
 217
 218         while (1) {
 219                 if ((__res = *cs - *ct++) != 0 || !*cs++)
 220                         break;
 221         }
 222
 223         return __res;
 224 }
 225 EXPORT_SYMBOL(strcmp);
 226 #endif
 227
 228 #ifndef __HAVE_ARCH_STRNCMP
 229 /**
 230  * strncmp - Compare two length-limited strings
 231  * @cs: One string
 232  * @ct: Another string
 233  * @count: The maximum number of bytes to compare
 234  */
 235 int strncmp(const char * cs,const char * ct,size_t count)
 236 {
 237         register signed char __res = 0;
 238
 239         while (count) {
 240                 if ((__res = *cs - *ct++) != 0 || !*cs++)
 241                         break;
 242                 count--;
 243         }
 244
 245         return __res;
 246 }
 247 EXPORT_SYMBOL(strncmp);
 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  */
 256 char * 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 EXPORT_SYMBOL(strchr);
 264 #endif
 265
 266 #ifndef __HAVE_ARCH_STRRCHR
 267 /**
 268  * strrchr - Find the last occurrence of a character in a string
 269  * @s: The string to be searched
 270  * @c: The character to search for
 271  */
 272 char * strrchr(const char * s, int c)
 273 {
 274        const char *p = s + strlen(s);
 275        do {
 276            if (*p == (char)c)
 277                return (char *)p;
 278        } while (--p >= s);
 279        return NULL;
 280 }
 281 EXPORT_SYMBOL(strrchr);
 282 #endif
 283
 284 #ifndef __HAVE_ARCH_STRNCHR
 285 /**
 286  * strnchr - Find a character in a length limited string
 287  * @s: The string to be searched
 288  * @count: The number of characters to be searched
 289  * @c: The character to search for
 290  */
 291 char *strnchr(const char *s, size_t count, int c)
 292 {
 293         for (; count-- && *s != '\0'; ++s)
 294                 if (*s == (char) c)
 295                         return (char *) s;
 296         return NULL;
 297 }
 298 EXPORT_SYMBOL(strnchr);
 299 #endif
 300
 301 #ifndef __HAVE_ARCH_STRLEN
 302 /**
 303  * strlen - Find the length of a string
 304  * @s: The string to be sized
 305  */
 306 size_t strlen(const char * s)
 307 {
 308         const char *sc;
 309
 310         for (sc = s; *sc != '\0'; ++sc)
 311                 /* nothing */;
 312         return sc - s;
 313 }
 314 EXPORT_SYMBOL(strlen);
 315 #endif
 316
 317 #ifndef __HAVE_ARCH_STRNLEN
 318 /**
 319  * strnlen - Find the length of a length-limited string
 320  * @s: The string to be sized
 321  * @count: The maximum number of bytes to search
 322  */
 323 size_t strnlen(const char * s, size_t count)
 324 {
 325         const char *sc;
 326
 327         for (sc = s; count-- && *sc != '\0'; ++sc)
 328                 /* nothing */;
 329         return sc - s;
 330 }
 331 EXPORT_SYMBOL(strnlen);
 332 #endif
 333
 334 #ifndef __HAVE_ARCH_STRSPN
 335 /**
 336  * strspn - Calculate the length of the initial substring of @s which only
 337  *      contain letters in @accept
 338  * @s: The string to be searched
 339  * @accept: The string to search for
 340  */
 341 size_t strspn(const char *s, const char *accept)
 342 {
 343         const char *p;
 344         const char *a;
 345         size_t count = 0;
 346
 347         for (p = s; *p != '\0'; ++p) {
 348                 for (a = accept; *a != '\0'; ++a) {
 349                         if (*p == *a)
 350                                 break;
 351                 }
 352                 if (*a == '\0')
 353                         return count;
 354                 ++count;
 355         }
 356
 357         return count;
 358 }
 359
 360 EXPORT_SYMBOL(strspn);
 361 #endif
 362
 363 /**
 364  * strcspn - Calculate the length of the initial substring of @s which does
 365  *      not contain letters in @reject
 366  * @s: The string to be searched
 367  * @reject: The string to avoid
 368  */
 369 size_t strcspn(const char *s, const char *reject)
 370 {
 371         const char *p;
 372         const char *r;
 373         size_t count = 0;
 374
 375         for (p = s; *p != '\0'; ++p) {
 376                 for (r = reject; *r != '\0'; ++r) {
 377                         if (*p == *r)
 378                                 return count;
 379                 }
 380                 ++count;
 381         }
 382
 383         return count;
 384 }
 385 EXPORT_SYMBOL(strcspn);
 386
 387 #ifndef __HAVE_ARCH_STRPBRK
 388 /**
 389  * strpbrk - Find the first occurrence of a set of characters
 390  * @cs: The string to be searched
 391  * @ct: The characters to search for
 392  */
 393 char * strpbrk(const char * cs,const char * ct)
 394 {
 395         const char *sc1,*sc2;
 396
 397         for( sc1 = cs; *sc1 != '\0'; ++sc1) {
 398                 for( sc2 = ct; *sc2 != '\0'; ++sc2) {
 399                         if (*sc1 == *sc2)
 400                                 return (char *) sc1;
 401                 }
 402         }
 403         return NULL;
 404 }
 405 EXPORT_SYMBOL(strpbrk);
 406 #endif
 407
 408 #ifndef __HAVE_ARCH_STRSEP
 409 /**
 410  * strsep - Split a string into tokens
 411  * @s: The string to be searched
 412  * @ct: The characters to search for
 413  *
 414  * strsep() updates @s to point after the token, ready for the next call.
 415  *
 416  * It returns empty tokens, too, behaving exactly like the libc function
 417  * of that name. In fact, it was stolen from glibc2 and de-fancy-fied.
 418  * Same semantics, slimmer shape. ;)
 419  */
 420 char * strsep(char **s, const char *ct)
 421 {
 422         char *sbegin = *s, *end;
 423
 424         if (sbegin == NULL)
 425                 return NULL;
 426
 427         end = strpbrk(sbegin, ct);
 428         if (end)
 429                 *end++ = '\0';
 430         *s = end;
 431
 432         return sbegin;
 433 }
 434
 435 EXPORT_SYMBOL(strsep);
 436 #endif
 437
 438 #ifndef __HAVE_ARCH_MEMSET
 439 /**
 440  * memset - Fill a region of memory with the given value
 441  * @s: Pointer to the start of the area.
 442  * @c: The byte to fill the area with
 443  * @count: The size of the area.
 444  *
 445  * Do not use memset() to access IO space, use memset_io() instead.
 446  */
 447 void * memset(void * s,int c,size_t count)
 448 {
 449         char *xs = (char *) s;
 450
 451         while (count--)
 452                 *xs++ = c;
 453
 454         return s;
 455 }
 456 EXPORT_SYMBOL(memset);
 457 #endif
 458
 459 #ifndef __HAVE_ARCH_BCOPY
 460 /**
 461  * bcopy - Copy one area of memory to another
 462  * @srcp: Where to copy from
 463  * @destp: Where to copy to
 464  * @count: The size of the area.
 465  *
 466  * Note that this is the same as memcpy(), with the arguments reversed.
 467  * memcpy() is the standard, bcopy() is a legacy BSD function.
 468  *
 469  * You should not use this function to access IO space, use memcpy_toio()
 470  * or memcpy_fromio() instead.
 471  */
 472 void bcopy(const void * srcp, void * destp, size_t count)
 473 {
 474         const char *src = srcp;
 475         char *dest = destp;
 476
 477         while (count--)
 478                 *dest++ = *src++;
 479 }
 480 EXPORT_SYMBOL(bcopy);
 481 #endif
 482
 483 #ifndef __HAVE_ARCH_MEMCPY
 484 /**
 485  * memcpy - Copy one area of memory to another
 486  * @dest: Where to copy to
 487  * @src: Where to copy from
 488  * @count: The size of the area.
 489  *
 490  * You should not use this function to access IO space, use memcpy_toio()
 491  * or memcpy_fromio() instead.
 492  */
 493 void * memcpy(void * dest,const void *src,size_t count)
 494 {
 495         char *tmp = (char *) dest, *s = (char *) src;
 496
 497         while (count--)
 498                 *tmp++ = *s++;
 499
 500         return dest;
 501 }
 502 EXPORT_SYMBOL(memcpy);
 503 #endif
 504
 505 #ifndef __HAVE_ARCH_MEMMOVE
 506 /**
 507  * memmove - Copy one area of memory to another
 508  * @dest: Where to copy to
 509  * @src: Where to copy from
 510  * @count: The size of the area.
 511  *
 512  * Unlike memcpy(), memmove() copes with overlapping areas.
 513  */
 514 void * memmove(void * dest,const void *src,size_t count)
 515 {
 516         char *tmp, *s;
 517
 518         if (dest <= src) {
 519                 tmp = (char *) dest;
 520                 s = (char *) src;
 521                 while (count--)
 522                         *tmp++ = *s++;
 523                 }
 524         else {
 525                 tmp = (char *) dest + count;
 526                 s = (char *) src + count;
 527                 while (count--)
 528                         *--tmp = *--s;
 529                 }
 530
 531         return dest;
 532 }
 533 EXPORT_SYMBOL(memmove);
 534 #endif
 535
 536 #ifndef __HAVE_ARCH_MEMCMP
 537 /**
 538  * memcmp - Compare two areas of memory
 539  * @cs: One area of memory
 540  * @ct: Another area of memory
 541  * @count: The size of the area.
 542  */
 543 int memcmp(const void * cs,const void * ct,size_t count)
 544 {
 545         const unsigned char *su1, *su2;
 546         int res = 0;
 547
 548         for( su1 = cs, su2 = ct; 0 < count; ++su1, ++su2, count--)
 549                 if ((res = *su1 - *su2) != 0)
 550                         break;
 551         return res;
 552 }
 553 EXPORT_SYMBOL(memcmp);
 554 #endif
 555
 556 #ifndef __HAVE_ARCH_MEMSCAN
 557 /**
 558  * memscan - Find a character in an area of memory.
 559  * @addr: The memory area
 560  * @c: The byte to search for
 561  * @size: The size of the area.
 562  *
 563  * returns the address of the first occurrence of @c, or 1 byte past
 564  * the area if @c is not found
 565  */
 566 void * memscan(void * addr, int c, size_t size)
 567 {
 568         unsigned char * p = (unsigned char *) addr;
 569
 570         while (size) {
 571                 if (*p == c)
 572                         return (void *) p;
 573                 p++;
 574                 size--;
 575         }
 576         return (void *) p;
 577 }
 578 EXPORT_SYMBOL(memscan);
 579 #endif
 580
 581 #ifndef __HAVE_ARCH_STRSTR
 582 /**
 583  * strstr - Find the first substring in a %NUL terminated string
 584  * @s1: The string to be searched
 585  * @s2: The string to search for
 586  */
 587 char * strstr(const char * s1,const char * s2)
 588 {
 589         int l1, l2;
 590
 591         l2 = strlen(s2);
 592         if (!l2)
 593                 return (char *) s1;
 594         l1 = strlen(s1);
 595         while (l1 >= l2) {
 596                 l1--;
 597                 if (!memcmp(s1,s2,l2))
 598                         return (char *) s1;
 599                 s1++;
 600         }
 601         return NULL;
 602 }
 603 EXPORT_SYMBOL(strstr);
 604 #endif
 605
 606 #ifndef __HAVE_ARCH_MEMCHR
 607 /**
 608  * memchr - Find a character in an area of memory.
 609  * @s: The memory area
 610  * @c: The byte to search for
 611  * @n: The size of the area.
 612  *
 613  * returns the address of the first occurrence of @c, or %NULL
 614  * if @c is not found
 615  */
 616 void *memchr(const void *s, int c, size_t n)
 617 {
 618         const unsigned char *p = s;
 619         while (n-- != 0) {
 620                 if ((unsigned char)c == *p++) {
 621                         return (void *)(p-1);
 622                 }
 623         }
 624         return NULL;
 625 }
 626 EXPORT_SYMBOL(memchr);
 627 #endif