Improved strncpy for Snort...

[Bill Parker <wp02855 () gmail com>]

Hello All,

    I was wondering if improvements to strncpy() would have any impact on
snort performance, and here is a function (also implemented as a macro)
which can cut down on use of strncpy:

int Snort_Strrncmp(char *, char *, int);    /* function prototype  */

/*  This function implements a faster version of the C library  */
/*  function 'strncmp', by comparing the first character of     */
/*  each string, and if a MATCH is found, then call 'strncmp'   */
/*  to make a more exact comparison.  The expected speed up by  */
/*  using this routine is approximately 15 to 1 (given the      */
/*  distribution of letters in the alphabet                     */

int Snort_Strncmp(const char *str1, const char *str2, int n)
{
    if (*str1 != *str2)
        return (int) ((unsigned char) *(str1) -(unsigned char) *(str2));
    else
        return strncmp(str1, str2, n);
}

Here is the above function as a #define macro:

#define Snort_Strncmp(a,b,c)    (*(a) != *(b) ? \
                                (int) ((unsigned char) *(a) - \
                                (unsigned char) *(b)) : \
                                strncmp((a), (b), (c)))

Comments anyone?

Bill

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