> What is the maximum number of caracters on a file 
name 
> that HHtrack can support ?
512 bytes.

see in htsglobal.h to increase it (can not be done 
using an option):
#define HTS_URLMAXSIZE 512

Longer (>512 bytes) URLs are not supported (by 
default), even if RFC2616 does not set any limit - but 
I had to set a default one during the development, 
which is equal to 512.