libc/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
  18 #include "config.h"
  19 #include "libc/string.h"
  20 #include "libc/stdlib.h"
  21
  22 /**
  23  * strnicmp - Case insensitive, length-limited string comparison
  24  * @s1: One string
  25  * @s2: The other string
  26  * @len: the maximum number of characters to compare
  27  */
  28 int strnicmp(const char *s1, const char *s2, size_t len)
  29 {
  30         /* Yes, Virginia, it had better be unsigned */
  31         unsigned char c1, c2;
  32
  33         c1 = 0; c2 = 0;
  34         if (len) {
  35                 do {
  36                         c1 = *s1; c2 = *s2;
  37                         s1++; s2++;
  38                         if (!c1)
  39                                 break;
  40                         if (!c2)
  41                                 break;
  42                         if (c1 == c2)
  43                                 continue;
  44                         c1 = tolower(c1);
  45                         c2 = tolower(c2);
  46                         if (c1 != c2)
  47                                 break;
  48                 } while (--len);
  49         }
  50         return (int)c1 - (int)c2;
  51 }
  52
  53 /**
  54  * strcpy - Copy a %NUL terminated string
  55  * @dest: Where to copy the string to
  56  * @src: Where to copy the string from
  57  */
  58 char * strcpy(char * dest,const char *src)
  59 {
  60         char *tmp = dest;
  61
  62         while ((*dest++ = *src++) != '\0')
  63                 /* nothing */;
  64         return tmp;
  65 }
  66
  67 /**
  68  * strncpy - Copy a length-limited, %NUL-terminated string
  69  * @dest: Where to copy the string to
  70  * @src: Where to copy the string from
  71  * @count: The maximum number of bytes to copy
  72  *
  73  * Note that unlike userspace strncpy, this does not %NUL-pad the buffer.
  74  * However, the result is not %NUL-terminated if the source exceeds
  75  * @count bytes.
  76  */
  77 char * strncpy(char * dest,const char *src,size_t count)
  78 {
  79         char *tmp = dest;
  80
  81         while (count-- && (*dest++ = *src++) != '\0')
  82                 /* nothing */;
  83
  84         return tmp;
  85 }
  86
  87 /**
  88  * strcat - Append one %NUL-terminated string to another
  89  * @dest: The string to be appended to
  90  * @src: The string to append to it
  91  */
  92 char * strcat(char * dest, const char * src)
  93 {
  94         char *tmp = dest;
  95
  96         while (*dest)
  97                 dest++;
  98         while ((*dest++ = *src++) != '\0')
  99                 ;
 100
 101         return tmp;
 102 }
 103
 104 /**
 105  * strncat - Append a length-limited, %NUL-terminated string to another
 106  * @dest: The string to be appended to
 107  * @src: The string to append to it
 108  * @count: The maximum numbers of bytes to copy
 109  *
 110  * Note that in contrast to strncpy, strncat ensures the result is
 111  * terminated.
 112  */
 113 char * strncat(char *dest, const char *src, size_t count)
 114 {
 115         char *tmp = dest;
 116
 117         if (count) {
 118                 while (*dest)
 119                         dest++;
 120                 while ((*dest++ = *src++)) {
 121                         if (--count == 0) {
 122                                 *dest = '\0';
 123                                 break;
 124                         }
 125                 }
 126         }
 127
 128         return tmp;
 129 }
 130
 131 /**
 132  * strcmp - Compare two strings
 133  * @cs: One string
 134  * @ct: Another string
 135  */
 136 int strcmp(const char * cs,const char * ct)
 137 {
 138         register signed char __res;
 139
 140         while (1) {
 141                 if ((__res = *cs - *ct++) != 0 || !*cs++)
 142                         break;
 143         }
 144
 145         return __res;
 146 }
 147
 148 /**
 149  * strncmp - Compare two length-limited strings
 150  * @cs: One string
 151  * @ct: Another string
 152  * @count: The maximum number of bytes to compare
 153  */
 154 int strncmp(const char * cs,const char * ct,size_t count)
 155 {
 156         register signed char __res = 0;
 157
 158         while (count) {
 159                 if ((__res = *cs - *ct++) != 0 || !*cs++)
 160                         break;
 161                 count--;
 162         }
 163
 164         return __res;
 165 }
 166
 167
 168 /**
 169  * strchr - Find the first occurrence of a character in a string
 170  * @s: The string to be searched
 171  * @c: The character to search for
 172  */
 173 char * strchr(const char * s, int c)
 174 {
 175         for(; *s != (char) c; ++s)
 176                 if (*s == '\0')
 177                         return NULL;
 178         return (char *) s;
 179 }
 180
 181 /**
 182  * strrchr - Find the last occurrence of a character in a string
 183  * @s: The string to be searched
 184  * @c: The character to search for
 185  */
 186 char * strrchr(const char * s, int c)
 187 {
 188        const char *p = s + strlen(s);
 189        do {
 190            if (*p == (char)c)
 191                return (char *)p;
 192        } while (--p >= s);
 193        return NULL;
 194 }
 195
 196 /**
 197  * strlen - Find the length of a string
 198  * @s: The string to be sized
 199  */
 200 size_t strlen(const char * s)
 201 {
 202         const char *sc;
 203
 204         for (sc = s; *sc != '\0'; ++sc)
 205                 /* nothing */;
 206         return sc - s;
 207 }
 208
 209 /**
 210  * strnlen - Find the length of a length-limited string
 211  * @s: The string to be sized
 212  * @count: The maximum number of bytes to search
 213  */
 214 size_t strnlen(const char * s, size_t count)
 215 {
 216         const char *sc;
 217
 218         for (sc = s; count-- && *sc != '\0'; ++sc)
 219                 /* nothing */;
 220         return sc - s;
 221 }
 222
 223 /**
 224  * strpbrk - Find the first occurrence of a set of characters
 225  * @cs: The string to be searched
 226  * @ct: The characters to search for
 227  */
 228 char * strpbrk(const char * cs,const char * ct)
 229 {
 230         const char *sc1,*sc2;
 231
 232         for( sc1 = cs; *sc1 != '\0'; ++sc1) {
 233                 for( sc2 = ct; *sc2 != '\0'; ++sc2) {
 234                         if (*sc1 == *sc2)
 235                                 return (char *) sc1;
 236                 }
 237         }
 238         return NULL;
 239 }
 240
 241 /**
 242  * strsep - Split a string into tokens
 243  * @s: The string to be searched
 244  * @ct: The characters to search for
 245  *
 246  * strsep() updates @s to point after the token, ready for the next call.
 247  *
 248  * It returns empty tokens, too, behaving exactly like the libc function
 249  * of that name. In fact, it was stolen from glibc2 and de-fancy-fied.
 250  * Same semantics, slimmer shape. ;)
 251  */
 252 char * strsep(char **s, const char *ct)
 253 {
 254         char *sbegin = *s, *end;
 255
 256         if (sbegin == NULL)
 257                 return NULL;
 258
 259         end = strpbrk(sbegin, ct);
 260         if (end)
 261                 *end++ = '\0';
 262         *s = end;
 263
 264         return sbegin;
 265 }
 266
 267 /**
 268  * memset - Fill a region of memory with the given value
 269  * @s: Pointer to the start of the area.
 270  * @c: The byte to fill the area with
 271  * @count: The size of the area.
 272  *
 273  * Do not use memset() to access IO space, use memset_io() instead.
 274  */
 275 void * memset(void * s,int c,size_t count)
 276 {
 277         char *xs = (char *) s;
 278
 279         while (count--)
 280                 *xs++ = c;
 281
 282         return s;
 283 }
 284
 285 /**
 286  * memcpy - Copy one area of memory to another
 287  * @dest: Where to copy to
 288  * @src: Where to copy from
 289  * @count: The size of the area.
 290  *
 291  * You should not use this function to access IO space, use memcpy_toio()
 292  * or memcpy_fromio() instead.
 293  */
 294 void * memcpy(void * dest,const void *src,size_t count)
 295 {
 296         char *tmp = (char *) dest, *s = (char *) src;
 297
 298         while (count--)
 299                 *tmp++ = *s++;
 300
 301         return dest;
 302 }
 303
 304 /**
 305  * memmove - Copy one area of memory to another
 306  * @dest: Where to copy to
 307  * @src: Where to copy from
 308  * @count: The size of the area.
 309  *
 310  * Unlike memcpy(), memmove() copes with overlapping areas.
 311  */
 312 void * memmove(void * dest,const void *src,size_t count)
 313 {
 314         char *tmp, *s;
 315
 316         if (dest <= src) {
 317                 tmp = (char *) dest;
 318                 s = (char *) src;
 319                 while (count--)
 320                         *tmp++ = *s++;
 321                 }
 322         else {
 323                 tmp = (char *) dest + count;
 324                 s = (char *) src + count;
 325                 while (count--)
 326                         *--tmp = *--s;
 327                 }
 328
 329         return dest;
 330 }
 331
 332 /**
 333  * memcmp - Compare two areas of memory
 334  * @cs: One area of memory
 335  * @ct: Another area of memory
 336  * @count: The size of the area.
 337  */
 338 int memcmp(const void * cs,const void * ct,size_t count)
 339 {
 340         const unsigned char *su1, *su2;
 341         int res = 0;
 342
 343         for( su1 = cs, su2 = ct; 0 < count; ++su1, ++su2, count--)
 344                 if ((res = *su1 - *su2) != 0)
 345                         break;
 346         return res;
 347 }
 348
 349 char *
 350 strdup( const char *str )
 351 {
 352         char *p;
 353         if( !str )
 354                 return NULL;
 355         p = malloc( strlen(str) + 1 );
 356         strcpy( p, str );
 357         return p;
 358 }
 359
 360 int
 361 strcasecmp( const char *cs, const char *ct )
 362 {
 363         register signed char __res;
 364
 365         while (1) {
 366                 char ch1 = toupper(*cs), ch2 = toupper(*ct);
 367                 ct++;
 368                 if ((__res = ch1 - ch2) != 0 || !*cs++)
 369                         break;
 370         }
 371         return __res;
 372 }
 373
 374 int
 375 strncasecmp( const char *cs, const char *ct, size_t count )
 376 {
 377         register signed char __res = 0;
 378
 379         while (count--) {
 380                 char ch1 = toupper(*cs), ch2 = toupper(*ct);
 381                 ct++;
 382                 if ((__res = ch1 - ch2) != 0 || !*cs++)
 383                         break;
 384         }
 385         return __res;
 386 }
 387