strdup(null) dumps core.
Tried in on ubuntu and freeBSD both.
why? Shouldn't it return null?
char *b = NULL;
a = strdup(b);
This will dump core on strdup call.
That's quite ok.
The documentation implies that its argument must be a string. If it's something else, such as a null pointer, it's anyone's guess what'll happen. In essence, you get undefined behavior when passing a NULL pointer to strdup.
It's quite normal for functions to yield undefined behavior if you pass them something you're not supposed to. Many standard C functions such as strcpy and strlen do not accept null pointers either.