Comment 2 for bug 1062167

The real case how I stumbled over it:
* my PHP application calls geoip_record_by_name with NULL as argument (although it expects a string)
* the PHP GeoIP module converts NULL into an allocated empty string
* libGeoIP is called with "" as hostname. Sometimes, the byte directly preceding the empty string is the dot (.). Must be related to how PHP allocates memory.
* libGeoIP calls the gethostbyname_r function or similar which in turn calls above broken function.
* strncpy overwrites my call stack, making debugging complicated, and then segfaults :-(

I can't think of any common real world example where it might trigger, and my situation is my own fault :-)

It's probably not too easy to trigger it in other situations. One way would be a program which stores the hostname on the stack and e.g. the port number directly before. Or maybe a Big Endian machine using malloc. I think the bytes before the then-empty string are not zeros as on my amd64.
In such a situation, $ program "" 11822 might result in a segfault.