[abadidea]

If by "he" you mean the person who drew the picture:

First, I absolutely LOVE it when people assume I'm a dude. Plot twist: no I don't. If you don't know someone's gender, getting it wrong with an assumption is a good way to hack them off.

Second: the function is explicitly prototyped as returning bool (I highlighted this in neon green) which means caller expects true or false. It returns a negative value that is not intended to represent either true or false but a detailed error code. THAT IS THE BUG.

If bools don't exist in C then neither does strlen, gahh.