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 #endif
  79
  80 #ifndef __HAVE_ARCH_STRNCPY
  81 /**
  82  * strncpy - Copy a length-limited, %NUL-terminated string
  83  * @dest: Where to copy the string to
  84  * @src: Where to copy the string from
  85  * @count: The maximum number of bytes to copy
  86  *
  87  * The result is not %NUL-terminated if the source exceeds
  88  * @count bytes.
  89  */
  90 char * strncpy(char * dest,const char *src,size_t count)
  91 {
  92         char *tmp = dest;
  93
  94         while (count) {
  95                 if ((*tmp = *src) != 0) src++;
  96                 tmp++;
  97                 count--;
  98         }
  99         return dest;
 100 }
 101 #endif
 102
 103 #ifndef __HAVE_ARCH_STRLCPY
 104 /**
 105  * strlcpy - Copy a %NUL terminated string into a sized buffer
 106  * @dest: Where to copy the string to
 107  * @src: Where to copy the string from
 108  * @size: size of destination buffer
 109  *
 110  * Compatible with *BSD: the result is always a valid
 111  * NUL-terminated string that fits in the buffer (unless,
 112  * of course, the buffer size is zero). It does not pad
 113  * out the result like strncpy() does.
 114  */
 115 size_t strlcpy(char *dest, const char *src, size_t size)
 116 {
 117         size_t ret = strlen(src);
 118
 119         if (size) {
 120                 size_t len = (ret >= size) ? size-1 : ret;
 121                 memcpy(dest, src, len);
 122                 dest[len] = '\0';
 123         }
 124         return ret;
 125 }
 126 EXPORT_SYMBOL(strlcpy);
 127 #endif
 128
 129 #ifndef __HAVE_ARCH_STRCAT
 130 /**
 131  * strcat - Append one %NUL-terminated string to another
 132  * @dest: The string to be appended to
 133  * @src: The string to append to it
 134  */
 135 char * strcat(char * dest, const char * src)
 136 {
 137         char *tmp = dest;
 138
 139         while (*dest)
 140                 dest++;
 141         while ((*dest++ = *src++) != '\0')
 142                 ;
 143
 144         return tmp;
 145 }
 146 #endif
 147
 148 #ifndef __HAVE_ARCH_STRNCAT
 149 /**
 150  * strncat - Append a length-limited, %NUL-terminated string to another
 151  * @dest: The string to be appended to
 152  * @src: The string to append to it
 153  * @count: The maximum numbers of bytes to copy
 154  *
 155  * Note that in contrast to strncpy, strncat ensures the result is
 156  * terminated.
 157  */
 158 char * strncat(char *dest, const char *src, size_t count)
 159 {
 160         char *tmp = dest;
 161
 162         if (count) {
 163                 while (*dest)
 164                         dest++;
 165                 while ((*dest++ = *src++)) {
 166                         if (--count == 0) {
 167                                 *dest = '\0';
 168                                 break;
 169                         }
 170                 }
 171         }
 172
 173         return tmp;
 174 }
 175 #endif
 176
 177 #ifndef __HAVE_ARCH_STRLCAT
 178 /**
 179  * strlcat - Append a length-limited, %NUL-terminated string to another
 180  * @dest: The string to be appended to
 181  * @src: The string to append to it
 182  * @count: The size of the destination buffer.
 183  */
 184 size_t strlcat(char *dest, const char *src, size_t count)
 185 {
 186         size_t dsize = strlen(dest);
 187         size_t len = strlen(src);
 188         size_t res = dsize + len;
 189
 190         /* This would be a bug */
 191         BUG_ON(dsize >= count);
 192
 193         dest += dsize;
 194         count -= dsize;
 195         if (len >= count)
 196                 len = count-1;
 197         memcpy(dest, src, len);
 198         dest[len] = 0;
 199         return res;
 200 }
 201 EXPORT_SYMBOL(strlcat);
 202 #endif
 203
 204 #ifndef __HAVE_ARCH_STRCMP
 205 /**
 206  * strcmp - Compare two strings
 207  * @cs: One string
 208  * @ct: Another string
 209  */
 210 int strcmp(const char * cs,const char * ct)
 211 {
 212         register signed char __res;
 213
 214         while (1) {
 215                 if ((__res = *cs - *ct++) != 0 || !*cs++)
 216                         break;
 217         }
 218
 219         return __res;
 220 }
 221 #endif
 222
 223 #ifndef __HAVE_ARCH_STRNCMP
 224 /**
 225  * strncmp - Compare two length-limited strings
 226  * @cs: One string
 227  * @ct: Another string
 228  * @count: The maximum number of bytes to compare
 229  */
 230 int strncmp(const char * cs,const char * ct,size_t count)
 231 {
 232         register signed char __res = 0;
 233
 234         while (count) {
 235                 if ((__res = *cs - *ct++) != 0 || !*cs++)
 236                         break;
 237                 count--;
 238         }
 239
 240         return __res;
 241 }
 242 #endif
 243
 244 #ifndef __HAVE_ARCH_STRCHR
 245 /**
 246  * strchr - Find the first occurrence of a character in a string
 247  * @s: The string to be searched
 248  * @c: The character to search for
 249  */
 250 char * strchr(const char * s, int c)
 251 {
 252         for(; *s != (char) c; ++s)
 253                 if (*s == '\0')
 254                         return NULL;
 255         return (char *) s;
 256 }
 257 #endif
 258
 259 #ifndef __HAVE_ARCH_STRRCHR
 260 /**
 261  * strrchr - Find the last occurrence of a character in a string
 262  * @s: The string to be searched
 263  * @c: The character to search for
 264  */
 265 char * strrchr(const char * s, int c)
 266 {
 267        const char *p = s + strlen(s);
 268        do {
 269            if (*p == (char)c)
 270                return (char *)p;
 271        } while (--p >= s);
 272        return NULL;
 273 }
 274 #endif
 275
 276 #ifndef __HAVE_ARCH_STRNCHR
 277 /**
 278  * strnchr - Find a character in a length limited string
 279  * @s: The string to be searched
 280  * @count: The number of characters to be searched
 281  * @c: The character to search for
 282  */
 283 char *strnchr(const char *s, size_t count, int c)
 284 {
 285         for (; count-- && *s != '\0'; ++s)
 286                 if (*s == (char) c)
 287                         return (char *) s;
 288         return NULL;
 289 }
 290 #endif
 291
 292 #ifndef __HAVE_ARCH_STRLEN
 293 /**
 294  * strlen - Find the length of a string
 295  * @s: The string to be sized
 296  */
 297 size_t strlen(const char * s)
 298 {
 299         const char *sc;
 300
 301         for (sc = s; *sc != '\0'; ++sc)
 302                 /* nothing */;
 303         return sc - s;
 304 }
 305 #endif
 306
 307 #ifndef __HAVE_ARCH_STRNLEN
 308 /**
 309  * strnlen - Find the length of a length-limited string
 310  * @s: The string to be sized
 311  * @count: The maximum number of bytes to search
 312  */
 313 size_t strnlen(const char * s, size_t count)
 314 {
 315         const char *sc;
 316
 317         for (sc = s; count-- && *sc != '\0'; ++sc)
 318                 /* nothing */;
 319         return sc - s;
 320 }
 321 #endif
 322
 323 #ifndef __HAVE_ARCH_STRSPN
 324 /**
 325  * strspn - Calculate the length of the initial substring of @s which only
 326  *      contain letters in @accept
 327  * @s: The string to be searched
 328  * @accept: The string to search for
 329  */
 330 size_t strspn(const char *s, const char *accept)
 331 {
 332         const char *p;
 333         const char *a;
 334         size_t count = 0;
 335
 336         for (p = s; *p != '\0'; ++p) {
 337                 for (a = accept; *a != '\0'; ++a) {
 338                         if (*p == *a)
 339                                 break;
 340                 }
 341                 if (*a == '\0')
 342                         return count;
 343                 ++count;
 344         }
 345
 346         return count;
 347 }
 348
 349 EXPORT_SYMBOL(strspn);
 350 #endif
 351
 352 /**
 353  * strcspn - Calculate the length of the initial substring of @s which does
 354  *      not contain letters in @reject
 355  * @s: The string to be searched
 356  * @reject: The string to avoid
 357  */
 358 size_t strcspn(const char *s, const char *reject)
 359 {
 360         const char *p;
 361         const char *r;
 362         size_t count = 0;
 363
 364         for (p = s; *p != '\0'; ++p) {
 365                 for (r = reject; *r != '\0'; ++r) {
 366                         if (*p == *r)
 367                                 return count;
 368                 }
 369                 ++count;
 370         }
 371
 372         return count;
 373 }
 374
 375 #ifndef __HAVE_ARCH_STRPBRK
 376 /**
 377  * strpbrk - Find the first occurrence of a set of characters
 378  * @cs: The string to be searched
 379  * @ct: The characters to search for
 380  */
 381 char * strpbrk(const char * cs,const char * ct)
 382 {
 383         const char *sc1,*sc2;
 384
 385         for( sc1 = cs; *sc1 != '\0'; ++sc1) {
 386                 for( sc2 = ct; *sc2 != '\0'; ++sc2) {
 387                         if (*sc1 == *sc2)
 388                                 return (char *) sc1;
 389                 }
 390         }
 391         return NULL;
 392 }
 393 #endif
 394
 395 #ifndef __HAVE_ARCH_STRSEP
 396 /**
 397  * strsep - Split a string into tokens
 398  * @s: The string to be searched
 399  * @ct: The characters to search for
 400  *
 401  * strsep() updates @s to point after the token, ready for the next call.
 402  *
 403  * It returns empty tokens, too, behaving exactly like the libc function
 404  * of that name. In fact, it was stolen from glibc2 and de-fancy-fied.
 405  * Same semantics, slimmer shape. ;)
 406  */
 407 char * strsep(char **s, const char *ct)
 408 {
 409         char *sbegin = *s, *end;
 410
 411         if (sbegin == NULL)
 412                 return NULL;
 413
 414         end = strpbrk(sbegin, ct);
 415         if (end)
 416                 *end++ = '\0';
 417         *s = end;
 418
 419         return sbegin;
 420 }
 421
 422 EXPORT_SYMBOL(strsep);
 423 #endif
 424
 425 #ifndef __HAVE_ARCH_MEMSET
 426 /**
 427  * memset - Fill a region of memory with the given value
 428  * @s: Pointer to the start of the area.
 429  * @c: The byte to fill the area with
 430  * @count: The size of the area.
 431  *
 432  * Do not use memset() to access IO space, use memset_io() instead.
 433  */
 434 void * memset(void * s,int c,size_t count)
 435 {
 436         char *xs = (char *) s;
 437
 438         while (count--)
 439                 *xs++ = c;
 440
 441         return s;
 442 }
 443 #endif
 444
 445 #ifndef __HAVE_ARCH_BCOPY
 446 /**
 447  * bcopy - Copy one area of memory to another
 448  * @src: Where to copy from
 449  * @dest: Where to copy to
 450  * @count: The size of the area.
 451  *
 452  * Note that this is the same as memcpy(), with the arguments reversed.
 453  * memcpy() is the standard, bcopy() is a legacy BSD function.
 454  *
 455  * You should not use this function to access IO space, use memcpy_toio()
 456  * or memcpy_fromio() instead.
 457  */
 458 void bcopy(const void * srcp, void * destp, size_t count)
 459 {
 460         const char *src = srcp;
 461         char *dest = destp;
 462
 463         while (count--)
 464                 *dest++ = *src++;
 465 }
 466 #endif
 467
 468 #ifndef __HAVE_ARCH_MEMCPY
 469 /**
 470  * memcpy - Copy one area of memory to another
 471  * @dest: Where to copy to
 472  * @src: Where to copy from
 473  * @count: The size of the area.
 474  *
 475  * You should not use this function to access IO space, use memcpy_toio()
 476  * or memcpy_fromio() instead.
 477  */
 478 void * memcpy(void * dest,const void *src,size_t count)
 479 {
 480         char *tmp = (char *) dest, *s = (char *) src;
 481
 482         while (count--)
 483                 *tmp++ = *s++;
 484
 485         return dest;
 486 }
 487 #endif
 488
 489 #ifndef __HAVE_ARCH_MEMMOVE
 490 /**
 491  * memmove - Copy one area of memory to another
 492  * @dest: Where to copy to
 493  * @src: Where to copy from
 494  * @count: The size of the area.
 495  *
 496  * Unlike memcpy(), memmove() copes with overlapping areas.
 497  */
 498 void * memmove(void * dest,const void *src,size_t count)
 499 {
 500         char *tmp, *s;
 501
 502         if (dest <= src) {
 503                 tmp = (char *) dest;
 504                 s = (char *) src;
 505                 while (count--)
 506                         *tmp++ = *s++;
 507                 }
 508         else {
 509                 tmp = (char *) dest + count;
 510                 s = (char *) src + count;
 511                 while (count--)
 512                         *--tmp = *--s;
 513                 }
 514
 515         return dest;
 516 }
 517 #endif
 518
 519 #ifndef __HAVE_ARCH_MEMCMP
 520 /**
 521  * memcmp - Compare two areas of memory
 522  * @cs: One area of memory
 523  * @ct: Another area of memory
 524  * @count: The size of the area.
 525  */
 526 int memcmp(const void * cs,const void * ct,size_t count)
 527 {
 528         const unsigned char *su1, *su2;
 529         int res = 0;
 530
 531         for( su1 = cs, su2 = ct; 0 < count; ++su1, ++su2, count--)
 532                 if ((res = *su1 - *su2) != 0)
 533                         break;
 534         return res;
 535 }
 536 #endif
 537
 538 #ifndef __HAVE_ARCH_MEMSCAN
 539 /**
 540  * memscan - Find a character in an area of memory.
 541  * @addr: The memory area
 542  * @c: The byte to search for
 543  * @size: The size of the area.
 544  *
 545  * returns the address of the first occurrence of @c, or 1 byte past
 546  * the area if @c is not found
 547  */
 548 void * memscan(void * addr, int c, size_t size)
 549 {
 550         unsigned char * p = (unsigned char *) addr;
 551
 552         while (size) {
 553                 if (*p == c)
 554                         return (void *) p;
 555                 p++;
 556                 size--;
 557         }
 558         return (void *) p;
 559 }
 560 #endif
 561
 562 #ifndef __HAVE_ARCH_STRSTR
 563 /**
 564  * strstr - Find the first substring in a %NUL terminated string
 565  * @s1: The string to be searched
 566  * @s2: The string to search for
 567  */
 568 char * strstr(const char * s1,const char * s2)
 569 {
 570         int l1, l2;
 571
 572         l2 = strlen(s2);
 573         if (!l2)
 574                 return (char *) s1;
 575         l1 = strlen(s1);
 576         while (l1 >= l2) {
 577                 l1--;
 578                 if (!memcmp(s1,s2,l2))
 579                         return (char *) s1;
 580                 s1++;
 581         }
 582         return NULL;
 583 }
 584 #endif
 585
 586 #ifndef __HAVE_ARCH_MEMCHR
 587 /**
 588  * memchr - Find a character in an area of memory.
 589  * @s: The memory area
 590  * @c: The byte to search for
 591  * @n: The size of the area.
 592  *
 593  * returns the address of the first occurrence of @c, or %NULL
 594  * if @c is not found
 595  */
 596 void *memchr(const void *s, int c, size_t n)
 597 {
 598         const unsigned char *p = s;
 599         while (n-- != 0) {
 600                 if ((unsigned char)c == *p++) {
 601                         return (void *)(p-1);
 602                 }
 603         }
 604         return NULL;
 605 }
 606
 607 #endif