Adopt pyzfs from ClusterHQ

This commit introduces several changes:

 * Update LICENSE and project information

 * Give a good PEP8 talk to existing Python source code

 * Add RPM/DEB packaging for pyzfs

 * Fix some outstanding issues with the existing pyzfs code caused by
   changes in the ABI since the last time the code was updated

 * Integrate pyzfs Python unittest with the ZFS Test Suite

 * Add missing libzfs_core functions: lzc_change_key,
   lzc_channel_program, lzc_channel_program_nosync, lzc_load_key,
   lzc_receive_one, lzc_receive_resumable, lzc_receive_with_cmdprops,
   lzc_receive_with_header, lzc_reopen, lzc_send_resume, lzc_sync,
   lzc_unload_key, lzc_remap

Note: this commit slightly changes zfs_ioc_unload_key() ABI. This allow
to differentiate the case where we tried to unload a key on a
non-existing dataset (ENOENT) from the situation where a dataset has
no key loaded: this is consistent with the "change" case where trying
to zfs_ioc_change_key() from a dataset with no key results in EACCES.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: loli10K <ezomori.nozomu@gmail.com>
Closes #7230

tests/zfs-tests/tests/functional/Makefile.am

@@ -31,6 +31,7 @@ SUBDIRS = \
 	large_files \
 	largest_pool \
 	libzfs \
+	pyzfs \
 	link_count \
 	migration \
 	mmap \

tests/zfs-tests/tests/functional/pyzfs/Makefile.am

@@ -0,0 +1,4 @@
+pkgdatadir = $(datadir)/@PACKAGE@/zfs-tests/tests/functional/pyzfs
+
+dist_pkgdata_SCRIPTS = \
+	pyzfs_unittest.ksh

tests/zfs-tests/tests/functional/pyzfs/pyzfs_unittest.ksh

@@ -0,0 +1,52 @@
+#!/bin/ksh -p
+#
+# This file and its contents are supplied under the terms of the
+# Common Development and Distribution License ("CDDL"), version 1.0.
+# You may only use this file in accordance with the terms of version
+# 1.0 of the CDDL.
+#
+# A full copy of the text of the CDDL should have accompanied this
+# source.  A copy of the CDDL is also available via the Internet at
+# http://www.illumos.org/license/CDDL.
+#
+
+#
+# Copyright 2018, loli10K <ezomori.nozomu@gmail.com>. All rights reserved.
+#
+
+. $STF_SUITE/include/libtest.shlib
+
+#
+# DESCRIPTION:
+#	Verify the libzfs_core Python test suite can be run successfully
+#
+# STRATEGY:
+#	1. Run the nvlist and libzfs_core Python unittest
+#	2. Verify the exit code is 0 (no errors)
+#
+
+verify_runnable "global"
+
+# We don't just try to "import libzfs_core" because we want to skip these tests
+# only if pyzfs was not installed due to missing, build-time, dependencies; if
+# we cannot load "libzfs_core" due to other reasons, for instance an API/ABI
+# mismatch, we want to report it.
+python -c '
+import pkgutil, sys
+sys.exit(pkgutil.find_loader("libzfs_core") is None)'
+if [ $? -eq 1 ]
+then
+	log_unsupported "libzfs_core not found by Python"
+fi
+
+log_assert "Verify the nvlist and libzfs_core Python unittest run successfully"
+
+# NOTE: don't use log_must() here because it makes output unreadable
+python -m unittest --verbose \
+	libzfs_core.test.test_nvlist.TestNVList \
+	libzfs_core.test.test_libzfs_core.ZFSTest
+if [ $? -ne 0 ]; then
+	log_fail "Python unittest completed with errors"
+fi
+
+log_pass "Python unittest completed without errors"