Add tests for pipe(2) and POSIX standardized IPC syscalls

[aniketp]

Summary

This revision introduces test cases for following set of syscalls within inter-process
communication audit class.

• shm_open(2)
• shm_unlink(2)
• posix_openpt(2)
• pipe(2)

Test Plan

Execute make && make install from test/sys/audit.
Execute kyua test from /usr/tests/sys/audit. All testcases should succeed.

[asomers]

Do these complete the IPC set?

tests/sys/audit/inter-process.c

1416

New code should use strlcat instead of strncat.

1422

shared memory segments are actually persistent. So the unlink steps needs to go in the cleanup function. However, if you create the object with SHM_ANON for path, then it will be automatically destroyed.

1510

The file descriptors are outputs from pipe(2), not inputs to it. Don't initialize them with open.

1542

I'm surprised this doesn't segfault. Better to use NULL. Or, just use pipe2 with invalid flags. pipe(2) is actually a wrapper around pipe2(2). If you really want to test the pipe(2) syscall, you'll have to do it the same way you tested open(2), but using syscall(2). However, pipe and pipe2 both have the same audit event, AUE_PIPE.

[aniketp]

Changes as suggested in the inline comments

[asomers]

tests/sys/audit/inter-process.c

1461

No need for the -1.

[aniketp]

Remove -1 from strlcat() in shm_inlink_success test case