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.
     *
     * * Sat Feb 09 2002, Jason Thomas <jason@topic.com.au>,
     *                    Matthew Hawkins <matt@mh.dropbear.id.au>
     * -  Kissed strtok() goodbye
     */
    
    #include <linux/types.h>
    #include <linux/string.h>
    #include <linux/ctype.h>
    #include <linux/kernel.h>
    #include <linux/export.h>
    #include <linux/bug.h>
    #include <linux/errno.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;
    
            if (!len)
                    return 0;
    
            do {
                    c1 = *s1++;
                    c2 = *s2++;
                    if (!c1 || !c2)
                            break;
                    if (c1 == c2)
                            continue;
                    c1 = tolower(c1);
                    c2 = tolower(c2);
                    if (c1 != c2)
                            break;
            } while (--len);
            return (int)c1 - (int)c2;
    }
    EXPORT_SYMBOL(strnicmp);
    #endif
    
    #ifndef __HAVE_ARCH_STRCASECMP
    int strcasecmp(const char *s1, const char *s2)
    {
            int c1, c2;
    
            do {
                    c1 = tolower(*s1++);
                    c2 = tolower(*s2++);
            } while (c1 == c2 && c1 != 0);
            return c1 - c2;
    }
    EXPORT_SYMBOL(strcasecmp);
    #endif
    
    #ifndef __HAVE_ARCH_STRNCASECMP
    int strncasecmp(const char *s1, const char *s2, size_t n)
    {
            int c1, c2;
    
            do {
                    c1 = tolower(*s1++);
                    c2 = tolower(*s2++);
            } while ((--n > 0) && c1 == c2 && c1 != 0);
            return c1 - c2;
    }
    EXPORT_SYMBOL(strncasecmp);
    #endif
    
    #ifndef __HAVE_ARCH_STRCPY
    /**
     * strcpy - Copy a %NUL terminated string
     * @dest: Where to copy the string to
     * @src: Where to copy the string from
     */
    #undef strcpy
    char *strcpy(char *dest, const char *src)
    {
            char *tmp = dest;
   
           while ((*dest++ = *src++) != '\0')
                   /* nothing */;
           return tmp;
   }
   EXPORT_SYMBOL(strcpy);
   #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
    *
    * The result is not %NUL-terminated if the source exceeds
    * @count bytes.
    *
    * In the case where the length of @src is less than  that  of
    * count, the remainder of @dest will be padded with %NUL.
    *
    */
   char *strncpy(char *dest, const char *src, size_t count)
   {
           char *tmp = dest;
   
           while (count) {
                   if ((*tmp = *src) != 0)
                           src++;
                   tmp++;
                   count--;
           }
           return dest;
   }
   EXPORT_SYMBOL(strncpy);
   #endif
   
   #ifndef __HAVE_ARCH_STRLCPY
   /**
    * strlcpy - Copy a %NUL terminated string into a sized buffer
    * @dest: Where to copy the string to
    * @src: Where to copy the string from
    * @size: size of destination buffer
    *
    * Compatible with *BSD: the result is always a valid
    * NUL-terminated string that fits in the buffer (unless,
    * of course, the buffer size is zero). It does not pad
    * out the result like strncpy() does.
    */
   size_t strlcpy(char *dest, const char *src, size_t size)
   {
           size_t ret = strlen(src);
   
           if (size) {
                   size_t len = (ret >= size) ? size - 1 : ret;
                   memcpy(dest, src, len);
                   dest[len] = '\0';
           }
           return ret;
   }
   EXPORT_SYMBOL(strlcpy);
   #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
    */
   #undef strcat
   char *strcat(char *dest, const char *src)
   {
           char *tmp = dest;
   
           while (*dest)
                   dest++;
           while ((*dest++ = *src++) != '\0')
                   ;
           return tmp;
   }
   EXPORT_SYMBOL(strcat);
   #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++) != 0) {
                           if (--count == 0) {
                                   *dest = '\0';
                                   break;
                           }
                   }
           }
           return tmp;
   }
   EXPORT_SYMBOL(strncat);
   #endif
   
   #ifndef __HAVE_ARCH_STRLCAT
   /**
    * strlcat - 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 size of the destination buffer.
    */
   size_t strlcat(char *dest, const char *src, size_t count)
   {
           size_t dsize = strlen(dest);
           size_t len = strlen(src);
           size_t res = dsize + len;
   
           /* This would be a bug */
           BUG_ON(dsize >= count);
   
           dest += dsize;
           count -= dsize;
           if (len >= count)
                   len = count-1;
           memcpy(dest, src, len);
           dest[len] = 0;
           return res;
   }
   EXPORT_SYMBOL(strlcat);
   #endif
   
   #ifndef __HAVE_ARCH_STRCMP
   /**
    * strcmp - Compare two strings
    * @cs: One string
    * @ct: Another string
    */
   #undef strcmp
   int strcmp(const char *cs, const char *ct)
   {
           unsigned char c1, c2;
   
           while (1) {
                   c1 = *cs++;
                   c2 = *ct++;
                   if (c1 != c2)
                           return c1 < c2 ? -1 : 1;
                   if (!c1)
                           break;
           }
           return 0;
   }
   EXPORT_SYMBOL(strcmp);
   #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)
   {
           unsigned char c1, c2;
   
           while (count) {
                   c1 = *cs++;
                   c2 = *ct++;
                   if (c1 != c2)
                           return c1 < c2 ? -1 : 1;
                   if (!c1)
                           break;
                   count--;
           }
           return 0;
   }
   EXPORT_SYMBOL(strncmp);
   #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;
   }
   EXPORT_SYMBOL(strchr);
   #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;
   }
   EXPORT_SYMBOL(strrchr);
   #endif
   
   #ifndef __HAVE_ARCH_STRNCHR
   /**
    * strnchr - Find a character in a length limited string
    * @s: The string to be searched
    * @count: The number of characters to be searched
    * @c: The character to search for
    */
   char *strnchr(const char *s, size_t count, int c)
   {
           for (; count-- && *s != '\0'; ++s)
                   if (*s == (char)c)
                           return (char *)s;
           return NULL;
   }
   EXPORT_SYMBOL(strnchr);
   #endif
   
   /**
    * skip_spaces - Removes leading whitespace from @str.
    * @str: The string to be stripped.
    *
    * Returns a pointer to the first non-whitespace character in @str.
    */
   char *skip_spaces(const char *str)
   {
           while (isspace(*str))
                   ++str;
           return (char *)str;
   }
   EXPORT_SYMBOL(skip_spaces);
   
   /**
    * strim - Removes leading and trailing whitespace from @s.
    * @s: The string to be stripped.
    *
    * Note that the first trailing whitespace is replaced with a %NUL-terminator
    * in the given string @s. Returns a pointer to the first non-whitespace
    * character in @s.
    */
   char *strim(char *s)
   {
           size_t size;
           char *end;
   
           size = strlen(s);
           if (!size)
                   return s;
   
           end = s + size - 1;
           while (end >= s && isspace(*end))
                   end--;
           *(end + 1) = '\0';
   
           return skip_spaces(s);
   }
   EXPORT_SYMBOL(strim);
   
   #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;
   }
   EXPORT_SYMBOL(strlen);
   #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;
   }
   EXPORT_SYMBOL(strnlen);
   #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;
   }
   
   EXPORT_SYMBOL(strspn);
   #endif
   
   #ifndef __HAVE_ARCH_STRCSPN
   /**
    * strcspn - Calculate the length of the initial substring of @s which does not contain letters in @reject
    * @s: The string to be searched
    * @reject: The string to avoid
    */
   size_t strcspn(const char *s, const char *reject)
   {
           const char *p;
           const char *r;
           size_t count = 0;
   
           for (p = s; *p != '\0'; ++p) {
                   for (r = reject; *r != '\0'; ++r) {
                           if (*p == *r)
                                   return count;
                   }
                   ++count;
           }
           return count;
   }
   EXPORT_SYMBOL(strcspn);
   #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;
   }
   EXPORT_SYMBOL(strpbrk);
   #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;
           char *end;
   
           if (sbegin == NULL)
                   return NULL;
   
           end = strpbrk(sbegin, ct);
           if (end)
                   *end++ = '\0';
           *s = end;
           return sbegin;
   }
   EXPORT_SYMBOL(strsep);
   #endif
   
   /**
    * sysfs_streq - return true if strings are equal, modulo trailing newline
    * @s1: one string
    * @s2: another string
    *
    * This routine returns true iff two strings are equal, treating both
    * NUL and newline-then-NUL as equivalent string terminations.  It's
    * geared for use with sysfs input strings, which generally terminate
    * with newlines but are compared against values without newlines.
    */
   bool sysfs_streq(const char *s1, const char *s2)
   {
           while (*s1 && *s1 == *s2) {
                   s1++;
                   s2++;
           }
   
           if (*s1 == *s2)
                   return true;
           if (!*s1 && *s2 == '\n' && !s2[1])
                   return true;
           if (*s1 == '\n' && !s1[1] && !*s2)
                   return true;
           return false;
   }
   EXPORT_SYMBOL(sysfs_streq);
   
   /**
    * strtobool - convert common user inputs into boolean values
    * @s: input string
    * @res: result
    *
    * This routine returns 0 iff the first character is one of 'Yy1Nn0'.
    * Otherwise it will return -EINVAL.  Value pointed to by res is
    * updated upon finding a match.
    */
   int strtobool(const char *s, bool *res)
   {
           switch (s[0]) {
           case 'y':
           case 'Y':
           case '1':
                   *res = true;
                   break;
           case 'n':
           case 'N':
           case '':
                   *res = false;
                   break;
           default:
                   return -EINVAL;
           }
           return 0;
   }
   EXPORT_SYMBOL(strtobool);
   
   #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 = s;
   
           while (count--)
                   *xs++ = c;
           return s;
   }
   EXPORT_SYMBOL(memset);
   #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 = dest;
           const char *s = src;
   
           while (count--)
                   *tmp++ = *s++;
           return dest;
   }
   EXPORT_SYMBOL(memcpy);
   #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;
           const char *s;
   
           if (dest <= src) {
                   tmp = dest;
                   s = src;
                   while (count--)
                           *tmp++ = *s++;
           } else {
                   tmp = dest;
                   tmp += count;
                   s = src;
                   s += count;
                   while (count--)
                           *--tmp = *--s;
           }
           return dest;
   }
   EXPORT_SYMBOL(memmove);
   #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.
    */
   #undef memcmp
   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;
   }
   EXPORT_SYMBOL(memcmp);
   #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 = addr;
   
           while (size) {
                   if (*p == c)
                           return (void *)p;
                   p++;
                   size--;
           }
           return (void *)p;
   }
   EXPORT_SYMBOL(memscan);
   #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)
   {
           size_t 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;
   }
   EXPORT_SYMBOL(strstr);
   #endif
   
   #ifndef __HAVE_ARCH_STRNSTR
   /**
    * strnstr - Find the first substring in a length-limited string
    * @s1: The string to be searched
    * @s2: The string to search for
    * @len: the maximum number of characters to search
    */
   char *strnstr(const char *s1, const char *s2, size_t len)
   {
           size_t l2;
   
           l2 = strlen(s2);
           if (!l2)
                   return (char *)s1;
           while (len >= l2) {
                   len--;
                   if (!memcmp(s1, s2, l2))
                           return (char *)s1;
                   s1++;
           }
           return NULL;
   }
   EXPORT_SYMBOL(strnstr);
   #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;
   }
   EXPORT_SYMBOL(memchr);
   #endif
   
   static void *check_bytes8(const u8 *start, u8 value, unsigned int bytes)
   {
           while (bytes) {
                   if (*start != value)
                           return (void *)start;
                   start++;
                   bytes--;
           }
           return NULL;
   }
   
   /**
    * memchr_inv - Find an unmatching character in an area of memory.
    * @start: The memory area
    * @c: Find a character other than c
    * @bytes: The size of the area.
    *
    * returns the address of the first character other than @c, or %NULL
    * if the whole buffer contains just @c.
    */
   void *memchr_inv(const void *start, int c, size_t bytes)
   {
           u8 value = c;
           u64 value64;
           unsigned int words, prefix;
   
           if (bytes <= 16)
                   return check_bytes8(start, value, bytes);
   
           value64 = value;
   #if defined(ARCH_HAS_FAST_MULTIPLIER) && BITS_PER_LONG == 64
           value64 *= 0x0101010101010101;
   #elif defined(ARCH_HAS_FAST_MULTIPLIER)
           value64 *= 0x01010101;
           value64 |= value64 << 32;
   #else
           value64 |= value64 << 8;
           value64 |= value64 << 16;
           value64 |= value64 << 32;
   #endif
   
           prefix = (unsigned long)start % 8;
           if (prefix) {
                   u8 *r;
   
                   prefix = 8 - prefix;
                   r = check_bytes8(start, value, prefix);
                   if (r)
                           return r;
                   start += prefix;
                   bytes -= prefix;
           }
   
           words = bytes / 8;
   
           while (words) {
                   if (*(u64 *)start != value64)
                           return check_bytes8(start, value, 8);
                   start += 8;
                   words--;
           }
   
           return check_bytes8(start, value, bytes % 8);
   }
   EXPORT_SYMBOL(memchr_inv);

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