[v9,3/6] iotests: add testenv.py

diff --git a/tests/qemu-iotests/testenv.py b/tests/qemu-iotests/testenv.py
new file mode 100644
index 0000000000..ca9cab531b
--- /dev/null
+++ b/tests/qemu-iotests/testenv.py
@@ -0,0 +1,279 @@ 
+# TestEnv class to manage test environment variables.
+#
+# Copyright (c) 2020-2021 Virtuozzo International GmbH
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+#
+
+import os
+import sys
+import tempfile
+from pathlib import Path
+import shutil
+import collections
+import random
+import subprocess
+import glob
+from contextlib import AbstractContextManager
+from typing import Dict, Any, Optional
+
+
+def isxfile(path: str) -> bool:
+    return os.path.isfile(path) and os.access(path, os.X_OK)
+
+
+def get_default_machine(qemu_prog: str) -> str:
+    outp = subprocess.run([qemu_prog, '-machine', 'help'], check=True,
+                          universal_newlines=True,
+                          stdout=subprocess.PIPE).stdout
+
+    machines = outp.split('\n')
+    default_machine = next(m for m in machines if m.endswith(' (default)'))
+    default_machine = default_machine.split(' ', 1)[0]
+
+    alias_suf = ' (alias of {})'.format(default_machine)
+    alias = next((m for m in machines if m.endswith(alias_suf)), None)
+    if alias is not None:
+        default_machine = alias.split(' ', 1)[0]
+
+    return default_machine
+
+
+class TestEnv(AbstractContextManager['TestEnv']):
+    """
+    Manage system environment for running tests
+
+    The following variables are supported/provided. They are represented by
+    lower-cased TestEnv attributes.
+    """
+
+    # We store environment variables as instance attributes, and there are a
+    # lot of them. Silence pylint:
+    # pylint: disable=too-many-instance-attributes
+
+    env_variables = ['PYTHONPATH', 'TEST_DIR', 'SOCK_DIR', 'SAMPLE_IMG_DIR',
+                     'OUTPUT_DIR', 'PYTHON', 'QEMU_PROG', 'QEMU_IMG_PROG',
+                     'QEMU_IO_PROG', 'QEMU_NBD_PROG', 'QSD_PROG',
+                     'SOCKET_SCM_HELPER', 'QEMU_OPTIONS', 'QEMU_IMG_OPTIONS',
+                     'QEMU_IO_OPTIONS', 'QEMU_IO_OPTIONS_NO_FMT',
+                     'QEMU_NBD_OPTIONS', 'IMGOPTS', 'IMGFMT', 'IMGPROTO',
+                     'AIOMODE', 'CACHEMODE', 'VALGRIND_QEMU',
+                     'CACHEMODE_IS_DEFAULT', 'IMGFMT_GENERIC', 'IMGOPTSSYNTAX',
+                     'IMGKEYSECRET', 'QEMU_DEFAULT_MACHINE', 'MALLOC_PERTURB_']
+
+    def get_env(self) -> Dict[str, str]:
+        env = {}
+        for v in self.env_variables:
+            val = getattr(self, v.lower(), None)
+            if val is not None:
+                env[v] = val
+
+        return env
+
+    def init_directories(self):
+        """Init directory variables:
+             PYTHONPATH
+             TEST_DIR
+             SOCK_DIR
+             SAMPLE_IMG_DIR
+             OUTPUT_DIR
+        """
+        self.pythonpath = os.getenv('PYTHONPATH')
+        if self.pythonpath:
+            self.pythonpath = self.source_iotests + os.pathsep + \
+                self.pythonpath
+        else:
+            self.pythonpath = self.source_iotests
+
+        self.test_dir = os.getenv('TEST_DIR',
+                                  os.path.join(os.getcwd(), 'scratch'))
+        Path(self.test_dir).mkdir(parents=True, exist_ok=True)
+
+        self.sock_dir = os.getenv('SOCK_DIR')
+        self.tmp_sock_dir = False
+        if self.sock_dir:
+            Path(self.test_dir).mkdir(parents=True, exist_ok=True)
+        else:
+            self.sock_dir = tempfile.mkdtemp()
+            self.tmp_sock_dir = True
+
+        self.sample_img_dir = os.getenv('SAMPLE_IMG_DIR',
+                                        os.path.join(self.source_iotests,
+                                                     'sample_images'))
+
+        self.output_dir = os.getcwd()  # OUTPUT_DIR
+
+    def init_binaries(self):
+        """Init binary path variables:
+             PYTHON (for bash tests)
+             QEMU_PROG, QEMU_IMG_PROG, QEMU_IO_PROG, QEMU_NBD_PROG, QSD_PROG
+             SOCKET_SCM_HELPER
+        """
+        self.python = sys.executable
+
+        def root(*names):
+            return os.path.join(self.build_root, *names)
+
+        arch = os.uname().machine
+        if 'ppc64' in arch:
+            arch = 'ppc64'
+
+        self.qemu_prog = os.getenv('QEMU_PROG', root(f'qemu-system-{arch}'))
+        if not os.path.exists(self.qemu_prog):
+            pattern = root('qemu-system-*')
+            try:
+                progs = glob.iglob(pattern)
+                self.qemu_prog = next(p for p in progs if isxfile(p))
+            except StopIteration:
+                sys.exit("Not found any Qemu executable binary by pattern "
+                         f"'{pattern}'")
+
+        self.qemu_img_prog = os.getenv('QEMU_IMG_PROG', root('qemu-img'))
+        self.qemu_io_prog = os.getenv('QEMU_IO_PROG', root('qemu-io'))
+        self.qemu_nbd_prog = os.getenv('QEMU_NBD_PROG', root('qemu-nbd'))
+        self.qsd_prog = os.getenv('QSD_PROG', root('storage-daemon',
+                                                   'qemu-storage-daemon'))
+
+        for b in [self.qemu_img_prog, self.qemu_io_prog, self.qemu_nbd_prog,
+                  self.qemu_prog, self.qsd_prog]:
+            if not os.path.exists(b):
+                sys.exit('No such file: ' + b)
+            if not isxfile(b):
+                sys.exit('Not executable: ' + b)
+
+        helper_path = os.path.join(self.build_iotests, 'socket_scm_helper')
+        if isxfile(helper_path):
+            self.socket_scm_helper = helper_path  # SOCKET_SCM_HELPER
+
+    def __init__(self, imgfmt: str, imgproto: str, aiomode: str,
+                 cachemode: Optional[str] = None,
+                 imgopts: Optional[str] = None,
+                 misalign: bool = False,
+                 debug: bool = False,
+                 valgrind: bool = False) -> None:
+        self.imgfmt = imgfmt
+        self.imgproto = imgproto
+        self.aiomode = aiomode
+        self.imgopts = imgopts
+        self.misalign = misalign
+        self.debug = debug
+
+        if valgrind:
+            self.valgrind_qemu = 'y'
+
+        if cachemode is None:
+            self.cachemode_is_default = 'true'
+            self.cachemode = 'writeback'
+        else:
+            self.cachemode_is_default = 'false'
+            self.cachemode = cachemode
+
+        # Initialize generic paths: build_root, build_iotests, source_iotests,
+        # which are needed to initialize some environment variables. They are
+        # used by init_*() functions as well.
+
+        if os.path.islink(sys.argv[0]):
+            # called from the build tree
+            self.source_iotests = os.path.dirname(os.readlink(sys.argv[0]))
+            self.build_iotests = os.path.dirname(os.path.abspath(sys.argv[0]))
+        else:
+            # called from the source tree
+            self.source_iotests = os.getcwd()
+            self.build_iotests = self.source_iotests
+
+        self.build_root = os.path.join(self.build_iotests, '..', '..')
+
+        self.init_directories()
+        self.init_binaries()
+
+        self.malloc_perturb_ = os.getenv('MALLOC_PERTURB_',
+                                         str(random.randrange(1, 255)))
+
+        # QEMU_OPTIONS
+        self.qemu_options = '-nodefaults -display none -accel qtest'
+        machine_map = (
+            ('arm', 'virt'),
+            ('aarch64', 'virt'),
+            ('avr', 'mega2560'),
+            ('rx', 'gdbsim-r5f562n8'),
+            ('tricore', 'tricore_testboard')
+        )
+        for suffix, machine in machine_map:
+            if self.qemu_prog.endswith(f'qemu-system-{suffix}'):
+                self.qemu_options += f' -machine {machine}'
+
+        # QEMU_DEFAULT_MACHINE
+        self.qemu_default_machine = get_default_machine(self.qemu_prog)
+
+        self.qemu_img_options = os.getenv('QEMU_IMG_OPTIONS')
+        self.qemu_nbd_options = os.getenv('QEMU_NBD_OPTIONS')
+
+        is_generic = self.imgfmt not in ['bochs', 'cloop', 'dmg']
+        self.imgfmt_generic = 'true' if is_generic else 'false'
+
+        self.qemu_io_options = f'--cache {self.cachemode} --aio {self.aiomode}'
+        if self.misalign:
+            self.qemu_io_options += ' --misalign'
+
+        self.qemu_io_options_no_fmt = self.qemu_io_options
+
+        if self.imgfmt == 'luks':
+            self.imgoptssyntax = 'true'
+            self.imgkeysecret = '123456'
+            if not self.imgopts:
+                self.imgopts = 'iter-time=10'
+            elif 'iter-time=' not in self.imgopts:
+                self.imgopts += ',iter-time=10'
+        else:
+            self.imgoptssyntax = 'false'
+            self.qemu_io_options += ' -f ' + self.imgfmt
+
+        if self.imgfmt == 'vmdk':
+            if not self.imgopts:
+                self.imgopts = 'zeroed_grain=on'
+            elif 'zeroed_grain=' not in self.imgopts:
+                self.imgopts += ',zeroed_grain=on'
+
+    def close(self) -> None:
+        if self.tmp_sock_dir:
+            shutil.rmtree(self.sock_dir)
+
+    def __enter__(self) -> 'TestEnv':
+        return self
+
+    def __exit__(self, exc_type: Any, exc_value: Any, traceback: Any) -> None:
+        self.close()
+
+    def print_env(self) -> None:
+        template = """\
+QEMU          -- "{QEMU_PROG}" {QEMU_OPTIONS}
+QEMU_IMG      -- "{QEMU_IMG_PROG}" {QEMU_IMG_OPTIONS}
+QEMU_IO       -- "{QEMU_IO_PROG}" {QEMU_IO_OPTIONS}
+QEMU_NBD      -- "{QEMU_NBD_PROG}" {QEMU_NBD_OPTIONS}
+IMGFMT        -- {IMGFMT}{imgopts}
+IMGPROTO      -- {IMGPROTO}
+PLATFORM      -- {platform}
+TEST_DIR      -- {TEST_DIR}
+SOCK_DIR      -- {SOCK_DIR}
+SOCKET_SCM_HELPER -- {SOCKET_SCM_HELPER}"""
+
+        args = collections.defaultdict(str, self.get_env())
+
+        if 'IMGOPTS' in args:
+            args['imgopts'] = f" ({args['IMGOPTS']})"
+
+        u = os.uname()
+        args['platform'] = f'{u.sysname}/{u.machine} {u.nodename} {u.release}'
+
+        print(template.format_map(args))