The examples provided are some of the more complex cases that let you do advanced things.

You can shrink the amount of code required if you limit it to more simple cases as those shown in the slides.

For example, as derived from the OpenBSD presentation:

  if (pledge("stdio fattr", NULL) == -1):
     err(1, "pledge");

A similar (not completely equivalent, since OpenBSD chose some "interesting" definitions for their privileges, and is admittedly untested) example for Solaris might be:

  priv_set_t *tmp = priv_str_to_set(
     "PRIV_FILE_READ PRIV_FILE_WRITE PRIV_FILE_CHOWN_SELF",
     " ", NULL);

  /* Assert required privileges. */
  if (setppriv(PRIV_ON, PRIV_PERMITTED, tmp) == -1)
    err(1, "setppriv permitted");
  if (setppriv(PRIV_ON, PRIV_EFFECTIVE, tmp) == -1)
    err(1, "setppriv effective");

  priv_inverse(tmp);

  /* Drop all privileges not required. */
  (void) setppriv(PRIV_OFF, PRIV_PERMITTED, tmp);

The big difference, I think, between the Solaris interfaces and the OpenBSD ones are that Solaris allows the process to temporarily drop privileges and then add them back, or permanently drop them. From the proposed OpenBSD interfaces, it looks they only allow the permanent drop model.

There are a few convenience wrappers that might simplify the above further, but the real point is not to compare efficiency of interfaces, but capability.

Also, Solaris offers the ability to restrict privileges of programs without source code modification (imagine a program you don't quite trust and don't have the source code to). I didn't see that in the OpenBSD presentation.

In their defense, they're also clearly still working on these interfaces, so there can't yet be a fair comparison. Solaris has had privilege interfaces for over a decade, so the model presented is a bit more mature obviously.

The only thing I'd mention is that Solaris tries to provide a default set of privileges that represent things closer to administrative boundaries, rather then implementation-specific ones, as implementation can change, but the basic high-level operations do not.

For example, Solaris has a file read/write privilege, but doesn't bother letting you restrict the ability to set file timestamps separately because that doesn't seem like a useful thing to do. It does however, provide separate privilege(s) for manipulating ownership of files, since that's clearly a different category of operations. OpenBSD currently seems to be focused on the implementation instead of the administrative-level operations being performed.