> The snprintf function returns the number of characters that would have been written had n been sufficiently large, not counting the terminating null character, or a negative value if an encoding error occurred.
In essence it needs to return strlen of huge_string even though very little of it was actually written.
Well that's pretty fucked up. I note that the GNU C library docs say this:
> Attention: In versions of the GNU C Library prior to 2.1 the return value is the number of characters stored, not including the terminating null; unless there was not enough space in s to store the result in which case -1 is returned. This was changed in order to comply with the ISO C99 standard.
ISO C99 needs a kick in the head. Yes, there is a use case for this return value (buffer wasn't large enough, reallocate and try it again). But wow, own goal team!
Thanks for this. I had no idea that C99 had defined this so stupidly. I do see that in 2004, the linux kernel added replacements (scnprintf() which behave as the pre-C99 versions of snprintf generally did). There's a good discussion of this here: https://lwn.net/Articles/69419/
