sendmail, 4th Edition

Milter smfi_getpriv()

Fetch private data pointer All sendmail versions

The smfi_setpriv() routine (Milter smfi_setpriv() on page 1199) allows you to set aside and save private data on a per-context basis. From inside any of the xxfi_ routines you write, you may call smfi_getpriv() to fetch a pointer to the private data you earlier saved. You fetch private data like this:

dataptr = (type *)smfi_getpriv(ctx);

The smfi_getpriv() routine’s only argument is the common context pointer ctx passed to the xxfi_ function you write. The value returned (and here stored in dataptr) is a pointer. The smfi_getpriv() routine is of type void *, so you need to cast the return value to a type that matches your saved datatype. If you failed to first set aside a pointer with the smfi_setpriv() routine, smfi_getpriv() will return NULL.

Be very careful with your use of saved data. Milters are multi-threaded and any shared data should be protected with mutexes. If you allocate and free data, be careful to always test the retuned value for NULL to avoid dereferencing a zero address.

Note too that each private data is bound to a single context (the ctx pointer) that is instantiated when each connection starts. Thus, it is best to think of such private data as per-connection private data.