FreeBSD/Linux Kernel Cross Reference
sys/lib/string.c

     /*
      *  linux/lib/string.c
      *
      *  Copyright (C) 1991, 1992  Linus Torvalds
      */
     
     /*
      * stupid library routines.. The optimized versions should generally be found
      * as inline code in <asm-xx/string.h>
     *
     * These are buggy as well..
     *
     * * Fri Jun 25 1999, Ingo Oeser <ioe@informatik.tu-chemnitz.de>
     * -  Added strsep() which will replace strtok() soon (because strsep() is
     *    reentrant and should be faster). Use only strsep() in new code, please.
     */
     
    #include <linux/types.h>
    #include <linux/string.h>
    #include <linux/ctype.h>
    
    #ifndef __HAVE_ARCH_STRNICMP
    /**
     * strnicmp - Case insensitive, length-limited string comparison
     * @s1: One string
     * @s2: The other string
     * @len: the maximum number of characters to compare
     */
    int strnicmp(const char *s1, const char *s2, size_t len)
    {
            /* Yes, Virginia, it had better be unsigned */
            unsigned char c1, c2;
    
            c1 = 0; c2 = 0;
            if (len) {
                    do {
                            c1 = *s1; c2 = *s2;
                            s1++; s2++;
                            if (!c1)
                                    break;
                            if (!c2)
                                    break;
                            if (c1 == c2)
                                    continue;
                            c1 = tolower(c1);
                            c2 = tolower(c2);
                            if (c1 != c2)
                                    break;
                    } while (--len);
            }
            return (int)c1 - (int)c2;
    }
    #endif
    
    char * ___strtok;
    
    #ifndef __HAVE_ARCH_STRCPY
    /**
     * strcpy - Copy a %NUL terminated string
     * @dest: Where to copy the string to
     * @src: Where to copy the string from
     */
    char * strcpy(char * dest,const char *src)
    {
            char *tmp = dest;
    
            while ((*dest++ = *src++) != '\0')
                    /* nothing */;
            return tmp;
    }
    #endif
    
    #ifndef __HAVE_ARCH_STRNCPY
    /**
     * strncpy - Copy a length-limited, %NUL-terminated string
     * @dest: Where to copy the string to
     * @src: Where to copy the string from
     * @count: The maximum number of bytes to copy
     *
     * Note that unlike userspace strncpy, this does not %NUL-pad the buffer.
     * However, the result is not %NUL-terminated if the source exceeds
     * @count bytes.
     */
    char * strncpy(char * dest,const char *src,size_t count)
    {
            char *tmp = dest;
    
            while (count-- && (*dest++ = *src++) != '\0')
                    /* nothing */;
    
            return tmp;
    }
    #endif
    
    #ifndef __HAVE_ARCH_STRCAT
    /**
     * strcat - Append one %NUL-terminated string to another
     * @dest: The string to be appended to
     * @src: The string to append to it
    */
   char * strcat(char * dest, const char * src)
   {
           char *tmp = dest;
   
           while (*dest)
                   dest++;
           while ((*dest++ = *src++) != '\0')
                   ;
   
           return tmp;
   }
   #endif
   
   #ifndef __HAVE_ARCH_STRNCAT
   /**
    * strncat - Append a length-limited, %NUL-terminated string to another
    * @dest: The string to be appended to
    * @src: The string to append to it
    * @count: The maximum numbers of bytes to copy
    *
    * Note that in contrast to strncpy, strncat ensures the result is
    * terminated.
    */
   char * strncat(char *dest, const char *src, size_t count)
   {
           char *tmp = dest;
   
           if (count) {
                   while (*dest)
                           dest++;
                   while ((*dest++ = *src++)) {
                           if (--count == 0) {
                                   *dest = '\0';
                                   break;
                           }
                   }
           }
   
           return tmp;
   }
   #endif
   
   #ifndef __HAVE_ARCH_STRCMP
   /**
    * strcmp - Compare two strings
    * @cs: One string
    * @ct: Another string
    */
   int strcmp(const char * cs,const char * ct)
   {
           register signed char __res;
   
           while (1) {
                   if ((__res = *cs - *ct++) != 0 || !*cs++)
                           break;
           }
   
           return __res;
   }
   #endif
   
   #ifndef __HAVE_ARCH_STRNCMP
   /**
    * strncmp - Compare two length-limited strings
    * @cs: One string
    * @ct: Another string
    * @count: The maximum number of bytes to compare
    */
   int strncmp(const char * cs,const char * ct,size_t count)
   {
           register signed char __res = 0;
   
           while (count) {
                   if ((__res = *cs - *ct++) != 0 || !*cs++)
                           break;
                   count--;
           }
   
           return __res;
   }
   #endif
   
   #ifndef __HAVE_ARCH_STRCHR
   /**
    * strchr - Find the first occurrence of a character in a string
    * @s: The string to be searched
    * @c: The character to search for
    */
   char * strchr(const char * s, int c)
   {
           for(; *s != (char) c; ++s)
                   if (*s == '\0')
                           return NULL;
           return (char *) s;
   }
   #endif
   
   #ifndef __HAVE_ARCH_STRRCHR
   /**
    * strrchr - Find the last occurrence of a character in a string
    * @s: The string to be searched
    * @c: The character to search for
    */
   char * strrchr(const char * s, int c)
   {
          const char *p = s + strlen(s);
          do {
              if (*p == (char)c)
                  return (char *)p;
          } while (--p >= s);
          return NULL;
   }
   #endif
   
   #ifndef __HAVE_ARCH_STRLEN
   /**
    * strlen - Find the length of a string
    * @s: The string to be sized
    */
   size_t strlen(const char * s)
   {
           const char *sc;
   
           for (sc = s; *sc != '\0'; ++sc)
                   /* nothing */;
           return sc - s;
   }
   #endif
   
   #ifndef __HAVE_ARCH_STRNLEN
   /**
    * strnlen - Find the length of a length-limited string
    * @s: The string to be sized
    * @count: The maximum number of bytes to search
    */
   size_t strnlen(const char * s, size_t count)
   {
           const char *sc;
   
           for (sc = s; count-- && *sc != '\0'; ++sc)
                   /* nothing */;
           return sc - s;
   }
   #endif
   
   #ifndef __HAVE_ARCH_STRSPN
   /**
    * strspn - Calculate the length of the initial substring of @s which only
    *      contain letters in @accept
    * @s: The string to be searched
    * @accept: The string to search for
    */
   size_t strspn(const char *s, const char *accept)
   {
           const char *p;
           const char *a;
           size_t count = 0;
   
           for (p = s; *p != '\0'; ++p) {
                   for (a = accept; *a != '\0'; ++a) {
                           if (*p == *a)
                                   break;
                   }
                   if (*a == '\0')
                           return count;
                   ++count;
           }
   
           return count;
   }
   #endif
   
   #ifndef __HAVE_ARCH_STRPBRK
   /**
    * strpbrk - Find the first occurrence of a set of characters
    * @cs: The string to be searched
    * @ct: The characters to search for
    */
   char * strpbrk(const char * cs,const char * ct)
   {
           const char *sc1,*sc2;
   
           for( sc1 = cs; *sc1 != '\0'; ++sc1) {
                   for( sc2 = ct; *sc2 != '\0'; ++sc2) {
                           if (*sc1 == *sc2)
                                   return (char *) sc1;
                   }
           }
           return NULL;
   }
   #endif
   
   #ifndef __HAVE_ARCH_STRTOK
   /**
    * strtok - Split a string into tokens
    * @s: The string to be searched
    * @ct: The characters to search for
    *
    * WARNING: strtok is deprecated, use strsep instead.
    */
   char * strtok(char * s,const char * ct)
   {
           char *sbegin, *send;
   
           sbegin  = s ? s : ___strtok;
           if (!sbegin) {
                   return NULL;
           }
           sbegin += strspn(sbegin,ct);
           if (*sbegin == '\0') {
                   ___strtok = NULL;
                   return( NULL );
           }
           send = strpbrk( sbegin, ct);
           if (send && *send != '\0')
                   *send++ = '\0';
           ___strtok = send;
           return (sbegin);
   }
   #endif
   
   #ifndef __HAVE_ARCH_STRSEP
   /**
    * strsep - Split a string into tokens
    * @s: The string to be searched
    * @ct: The characters to search for
    *
    * strsep() updates @s to point after the token, ready for the next call.
    *
    * It returns empty tokens, too, behaving exactly like the libc function
    * of that name. In fact, it was stolen from glibc2 and de-fancy-fied.
    * Same semantics, slimmer shape. ;)
    */
   char * strsep(char **s, const char *ct)
   {
           char *sbegin = *s, *end;
   
           if (sbegin == NULL)
                   return NULL;
   
           end = strpbrk(sbegin, ct);
           if (end)
                   *end++ = '\0';
           *s = end;
   
           return sbegin;
   }
   #endif
   
   #ifndef __HAVE_ARCH_MEMSET
   /**
    * memset - Fill a region of memory with the given value
    * @s: Pointer to the start of the area.
    * @c: The byte to fill the area with
    * @count: The size of the area.
    *
    * Do not use memset() to access IO space, use memset_io() instead.
    */
   void * memset(void * s,int c,size_t count)
   {
           char *xs = (char *) s;
   
           while (count--)
                   *xs++ = c;
   
           return s;
   }
   #endif
   
   #ifndef __HAVE_ARCH_BCOPY
   /**
    * bcopy - Copy one area of memory to another
    * @src: Where to copy from
    * @dest: Where to copy to
    * @count: The size of the area.
    *
    * Note that this is the same as memcpy(), with the arguments reversed.
    * memcpy() is the standard, bcopy() is a legacy BSD function.
    *
    * You should not use this function to access IO space, use memcpy_toio()
    * or memcpy_fromio() instead.
    */
   char * bcopy(const char * src, char * dest, int count)
   {
           char *tmp = dest;
   
           while (count--)
                   *tmp++ = *src++;
   
           return dest;
   }
   #endif
   
   #ifndef __HAVE_ARCH_MEMCPY
   /**
    * memcpy - Copy one area of memory to another
    * @dest: Where to copy to
    * @src: Where to copy from
    * @count: The size of the area.
    *
    * You should not use this function to access IO space, use memcpy_toio()
    * or memcpy_fromio() instead.
    */
   void * memcpy(void * dest,const void *src,size_t count)
   {
           char *tmp = (char *) dest, *s = (char *) src;
   
           while (count--)
                   *tmp++ = *s++;
   
           return dest;
   }
   #endif
   
   #ifndef __HAVE_ARCH_MEMMOVE
   /**
    * memmove - Copy one area of memory to another
    * @dest: Where to copy to
    * @src: Where to copy from
    * @count: The size of the area.
    *
    * Unlike memcpy(), memmove() copes with overlapping areas.
    */
   void * memmove(void * dest,const void *src,size_t count)
   {
           char *tmp, *s;
   
           if (dest <= src) {
                   tmp = (char *) dest;
                   s = (char *) src;
                   while (count--)
                           *tmp++ = *s++;
                   }
           else {
                   tmp = (char *) dest + count;
                   s = (char *) src + count;
                   while (count--)
                           *--tmp = *--s;
                   }
   
           return dest;
   }
   #endif
   
   #ifndef __HAVE_ARCH_MEMCMP
   /**
    * memcmp - Compare two areas of memory
    * @cs: One area of memory
    * @ct: Another area of memory
    * @count: The size of the area.
    */
   int memcmp(const void * cs,const void * ct,size_t count)
   {
           const unsigned char *su1, *su2;
           int res = 0;
   
           for( su1 = cs, su2 = ct; 0 < count; ++su1, ++su2, count--)
                   if ((res = *su1 - *su2) != 0)
                           break;
           return res;
   }
   #endif
   
   #ifndef __HAVE_ARCH_MEMSCAN
   /**
    * memscan - Find a character in an area of memory.
    * @addr: The memory area
    * @c: The byte to search for
    * @size: The size of the area.
    *
    * returns the address of the first occurrence of @c, or 1 byte past
    * the area if @c is not found
    */
   void * memscan(void * addr, int c, size_t size)
   {
           unsigned char * p = (unsigned char *) addr;
   
           while (size) {
                   if (*p == c)
                           return (void *) p;
                   p++;
                   size--;
           }
           return (void *) p;
   }
   #endif
   
   #ifndef __HAVE_ARCH_STRSTR
   /**
    * strstr - Find the first substring in a %NUL terminated string
    * @s1: The string to be searched
    * @s2: The string to search for
    */
   char * strstr(const char * s1,const char * s2)
   {
           int l1, l2;
   
           l2 = strlen(s2);
           if (!l2)
                   return (char *) s1;
           l1 = strlen(s1);
           while (l1 >= l2) {
                   l1--;
                   if (!memcmp(s1,s2,l2))
                           return (char *) s1;
                   s1++;
           }
           return NULL;
   }
   #endif
   
   #ifndef __HAVE_ARCH_MEMCHR
   /**
    * memchr - Find a character in an area of memory.
    * @s: The memory area
    * @c: The byte to search for
    * @n: The size of the area.
    *
    * returns the address of the first occurrence of @c, or %NULL
    * if @c is not found
    */
   void *memchr(const void *s, int c, size_t n)
   {
           const unsigned char *p = s;
           while (n-- != 0) {
                   if ((unsigned char)c == *p++) {
                           return (void *)(p-1);
                   }
           }
           return NULL;
   }
   
   #endif

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