Note that unfreed results of strdupa(), despite having "dup" in the name, does not result in memory leaks. The "a" in the name means it uses alloca(), thus the memory comes from the stack and it's properly released on function return. It's also probably slightly faster than malloc() since it just moves the stack pointer.

Before jumping to conclusions, please verify what the code really does. C is a complex beast and what's "obvious" may not be such.

Relying on such niceties (as weird as it may seem, to a C programmer those are niceties) is what you gain if you are willing to trade them for portability (strndupa() is a GNU extension).