NetBSD/external/cddl/osnet/sys/sys

# $NetBSD: README,v 1.1 2018/06/03 20:59:49 christos Exp $

General guidelines for system wrapper header maintainance.

There are two kinds of system header files:
        1. "infrastructure" headers that provide base definitions and
           other stuff that other headers use (systm.h)
        2.  "feature" headers that provide a specific feature (proc.h).

The solaris ones generally augment ours; the template should be:

solaris/foo.h:

    #ifndef SOLARIS_SYS_FOO_H
    #define SOLARIS_SYS_FOO_H

    /*
     * This include should not be in #ifdef KERNEL.
     * It is the job of the header itself to protect itself.
     * Unless Solaris exposes this header in userland, where
     * it is probably better to fix our header...
     */
    #include_next <sys/foo.h>

    /* More Solaris-specific definitions */

    #endif /* SOLARIS_SYS_FOO_H */

Now there caaes where the solaris headers expose more stuff than ours,
so we need to include more of our system headers from theirs. When that
happens the rule should be that:

Their infrastructure headers should not include our feature headers,
but can include our infrastructure headers, otherwise we end up with
circular dependencies. Violations to the rule should be kept to a minimum
and tested carefully.

In the general case, if we want the augmented symbols we should include
the solaris ones first in the search path.