Couple of thoughts

[sheredom]

Couple of thoughts

[mlabbe]

Here is my safer strncpy, verbatim paste from my core lib. If you want to adapt or use any part of this, I release it under the public domain.

The FTG_ATTRIBUTES() thing is a macro that generates a compiler warning if the truncation bit is ignored. Since it is a potential security risk if a string is truncated, I force a check. This is appropriate for my code. (I wish I could conditionally avoid this warning if *src was a literal).

/* Fill up to max_copy characters in dst, including null.  Unlike strncpy(), a null
   terminating character is guaranteed to be appended, EVEN if it overwrites
   the last character in the string.

   Only appends a single NULL character instead of NULL filling the string.  The 
   trailing bytes are left uninitialized.

   No bytes are written if max_copy is 0, and FTG_ASSERT is thrown.

   \return 1 on truncation or max_copy==0, zero otherwise.
                                                                                   */
FTG_ATTRIBUTES(FTG_EXT_warn_unused_result) int
ftg_strncpy(char *ftg_restrict dst, const char *ftg_restrict src, size_t max_copy)
{
    size_t n;
    char *d;

    FTG_ASSERT(dst);
    FTG_ASSERT(src);
    FTG_ASSERT(max_copy > 0);

    if (max_copy == 0)
        return 1;

    n = max_copy;
    d = dst;
    while ( n > 0 && *src != '\0' )    
    {
        *d++ = *src++;
        --n;
    }

    /* Truncation case -
       terminate string and return true */
    if ( n == 0 )
    {
        dst[max_copy-1] = '\0';
        return 1;
    }

    /* No truncation.  Append a single NULL and return. */
    *d = '\0';
    return 0;
}

[sheredom]

I'll take your comments on restrict on board for sure - I'm not certain I like the assert myself personally (but I'm willing to spend some brain cycles on the thought before I commit one way or the other!)

Thanks for the input though - all comments are good comments 😄

[sheredom]

Just for clarity - I've decided against adding the assert, but I have done the restrict change. Thanks again for spending time reviewing my lib!