anaconda/anaconda-40.22.3.13/pyanaconda/core/util.py
2024-11-14 21:39:56 -08:00

908 lines
33 KiB
Python

#
# util.py - generic install utility functions
#
# Copyright (C) 1999-2014
# Red Hat, Inc. All rights reserved.
#
# 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 os.path
import subprocess
# Used for ascii_lowercase, ascii_uppercase constants
import tempfile
import re
import signal
import sys
import types
import inspect
import functools
import importlib.util
import importlib.machinery
import requests
from requests_file import FileAdapter
from requests_ftp import FTPAdapter
from pyanaconda.core.configuration.anaconda import conf
from pyanaconda.core.path import make_directories, open_with_perm, join_paths
from pyanaconda.core.constants import DRACUT_SHUTDOWN_EJECT, \
IPMI_ABORTED, PACKAGES_LIST_FILE
from pyanaconda.core.live_user import get_live_user
from pyanaconda.errors import RemovedModuleError
from pyanaconda.anaconda_logging import program_log_lock
from pyanaconda.anaconda_loggers import get_module_logger, get_program_logger
log = get_module_logger(__name__)
program_log = get_program_logger()
from pykickstart.constants import KS_SCRIPT_ONERROR
_child_env = {}
def setenv(name, value):
""" Set an environment variable to be used by child processes.
This method does not modify os.environ for the running process, which
is not thread-safe. If setenv has already been called for a particular
variable name, the old value is overwritten.
:param str name: The name of the environment variable
:param str value: The value of the environment variable
"""
_child_env[name] = value
def augmentEnv():
env = os.environ.copy()
# FIXME: Remove the support for the ANA_INSTALL_PATH variable.
env.update({"ANA_INSTALL_PATH": conf.target.system_root})
env.update(_child_env)
return env
def startProgram(argv, root='/', stdin=None, stdout=subprocess.PIPE, stderr=subprocess.STDOUT,
env_prune=None, env_add=None, reset_handlers=True, reset_lang=True,
do_preexec=True, **kwargs):
""" Start an external program and return the Popen object.
The root and reset_handlers arguments are handled by passing a
preexec_fn argument to subprocess.Popen, but an additional preexec_fn
can still be specified and will be run. The user preexec_fn will be run
last.
:param argv: The command to run and argument
:param root: The directory to chroot to before running command.
:param stdin: The file object to read stdin from.
:param stdout: The file object to write stdout to.
:param stderr: The file object to write stderr to.
:param env_prune: environment variables to remove before execution
:param env_add: environment variables to add before execution
:param reset_handlers: whether to reset to SIG_DFL any signal handlers set to SIG_IGN
:param reset_lang: whether to set the locale of the child process to C
:param do_preexec: whether to use the preexec function
:param kwargs: Additional parameters to pass to subprocess.Popen
:return: A Popen object for the running command.
"""
if env_prune is None:
env_prune = []
# Transparently redirect callers requesting root=_root_path to the
# configured system root.
target_root = root
if target_root == conf.target.physical_root:
target_root = conf.target.system_root
# Map reset_handlers to the restore_signals Popen argument.
# restore_signals handles SIGPIPE, and preexec below handles any additional
# signals ignored by anaconda.
restore_signals = reset_handlers
with program_log_lock:
if target_root != '/':
program_log.info("Running in chroot '%s'... %s", target_root, " ".join(argv))
else:
program_log.info("Running... %s", " ".join(argv))
env = augmentEnv()
for var in env_prune:
env.pop(var, None)
if reset_lang:
env.update({"LC_ALL": "C"})
if env_add:
env.update(env_add)
# pylint: disable=subprocess-popen-preexec-fn
partsubp = functools.partial(subprocess.Popen,
argv,
stdin=stdin,
stdout=stdout,
stderr=stderr,
close_fds=True,
restore_signals=restore_signals,
cwd=root, env=env, **kwargs)
if not do_preexec:
return partsubp()
# Check for and save a preexec_fn argument
preexec_fn = kwargs.pop("preexec_fn", None)
def preexec():
# If a target root was specificed, chroot into it
if target_root and target_root != '/':
os.chroot(target_root)
os.chdir("/")
# Signal handlers set to SIG_IGN persist across exec. Reset
# these to SIG_DFL if requested. In particular this will include the
# SIGPIPE handler set by python.
if reset_handlers:
for signum in range(1, signal.NSIG):
if signal.getsignal(signum) == signal.SIG_IGN:
signal.signal(signum, signal.SIG_DFL)
# If the user specified an additional preexec_fn argument, run it
if preexec_fn is not None:
preexec_fn()
return partsubp(preexec_fn=preexec)
def _run_program(argv, root='/', stdin=None, stdout=None, env_prune=None,
log_output=True, binary_output=False, filter_stderr=False,
do_preexec=True, env_add=None, user=None):
""" Run an external program, log the output and return it to the caller
NOTE/WARNING: UnicodeDecodeError will be raised if the output of the of the
external command can't be decoded as UTF-8.
:param argv: The command to run and argument
:param root: The directory to chroot to before running command.
:param stdin: The file object to read stdin from.
:param stdout: Optional file object to write the output to.
:param env_prune: environment variable to remove before execution
:param log_output: whether to log the output of command
:param binary_output: whether to treat the output of command as binary data
:param filter_stderr: whether to exclude the contents of stderr from the returned output
:param do_preexec: whether to use a preexec_fn for subprocess.Popen
:param env_add: environment variables added for the execution
:param user: Specify user UID under which the command will be executed
:return: The return code of the command and the output
"""
try:
if filter_stderr:
stderr = subprocess.PIPE
else:
stderr = subprocess.STDOUT
proc = startProgram(argv, root=root, stdin=stdin, stdout=subprocess.PIPE, stderr=stderr,
env_prune=env_prune, env_add=env_add, do_preexec=do_preexec, user=user)
(output_string, err_string) = proc.communicate()
if not binary_output:
output_string = output_string.decode("utf-8")
if output_string and output_string[-1] != "\n":
output_string = output_string + "\n"
if log_output:
with program_log_lock:
if binary_output:
# try to decode as utf-8 and replace all undecodable data by
# "safe" printable representations when logging binary output
decoded_output_lines = output_string.decode("utf-8", "replace")
else:
# output_string should already be a Unicode string
decoded_output_lines = output_string.splitlines(True)
for line in decoded_output_lines:
program_log.info(line.strip())
if stdout:
stdout.write(output_string)
# If stderr was filtered, log it separately
if filter_stderr and err_string and log_output:
# try to decode as utf-8 and replace all undecodable data by
# "safe" printable representations when logging binary output
decoded_err_string = err_string.decode("utf-8", "replace")
err_lines = decoded_err_string.splitlines(True)
with program_log_lock:
for line in err_lines:
program_log.info(line.strip())
except OSError as e:
with program_log_lock:
program_log.error("Error running %s: %s", argv[0], e.strerror)
raise
with program_log_lock:
program_log.debug("Return code: %d", proc.returncode)
return (proc.returncode, output_string)
def execWithRedirect(command, argv, stdin=None, stdout=None, root='/', env_prune=None,
log_output=True, binary_output=False, do_preexec=True):
""" Run an external program and redirect the output to a file.
:param command: The command to run
:param argv: The argument list
:param stdin: The file object to read stdin from.
:param stdout: Optional file object to redirect stdout and stderr to.
:param root: The directory to chroot to before running command.
:param env_prune: environment variable to remove before execution
:param log_output: whether to log the output of command
:param binary_output: whether to treat the output of command as binary data
:param do_preexec: whether to use a preexec_fn for subprocess.Popen
:return: The return code of the command
"""
argv = [command] + argv
return _run_program(argv, stdin=stdin, stdout=stdout, root=root, env_prune=env_prune,
log_output=log_output, binary_output=binary_output, do_preexec=do_preexec)[0]
def execWithCapture(command, argv, stdin=None, root='/', env_prune=None, env_add=None,
log_output=True, filter_stderr=False, do_preexec=True):
""" Run an external program and capture standard out and err.
:param command: The command to run
:param argv: The argument list
:param stdin: The file object to read stdin from.
:param root: The directory to chroot to before running command.
:param log_output: Whether to log the output of command
:param filter_stderr: Whether stderr should be excluded from the returned output
:param do_preexec: whether to use the preexec function
:return: The output of the command
"""
argv = [command] + argv
return _run_program(argv, stdin=stdin, root=root, log_output=log_output, env_prune=env_prune,
env_add=env_add, filter_stderr=filter_stderr, do_preexec=do_preexec)[1]
def execWithCaptureAsLiveUser(command, argv, stdin=None, root='/', log_output=True,
filter_stderr=False, do_preexec=True):
""" Run an external program and capture standard out and err as liveuser user.
The liveuser user account is used on Fedora live media. If we need to read values from the
running live system we might need to run the commands under the liveuser account.
:param command: The command to run
:param argv: The argument list
:param stdin: The file object to read stdin from.
:param root: The directory to chroot to before running command.
:param log_output: Whether to log the output of command
:param filter_stderr: Whether stderr should be excluded from the returned output
:param do_preexec: whether to use the preexec function
:return: The output of the command
"""
argv = [command] + argv
user = get_live_user()
if user is None:
raise OSError("Live user is requested to run command but can't be found")
return _run_program(argv, stdin=stdin, root=root, log_output=log_output,
filter_stderr=filter_stderr, do_preexec=do_preexec,
user=user.uid, env_add=user.env_add, env_prune=user.env_prune)[1]
def execReadlines(command, argv, stdin=None, root='/', env_prune=None, filter_stderr=False,
raise_on_nozero=True):
""" Execute an external command and return the line output of the command
in real-time.
This method assumes that there is a reasonably low delay between the
end of output and the process exiting. If the child process closes
stdout and then keeps on truckin' there will be problems.
NOTE/WARNING: UnicodeDecodeError will be raised if the output of the
external command can't be decoded as UTF-8.
:param command: The command to run
:param argv: The argument list
:param stdin: The file object to read stdin from.
:param stdout: Optional file object to redirect stdout and stderr to.
:param root: The directory to chroot to before running command.
:param env_prune: environment variable to remove before execution
:param filter_stderr: Whether stderr should be excluded from the returned output
:param raise_on_nozero: Whether a nonzero exit status of the tool should cause an exception
Output from the file is not logged to program.log
This returns an iterator with the lines from the command until it has finished
"""
class ExecLineReader(object):
"""Iterator class for returning lines from a process and cleaning
up the process when the output is no longer needed.
"""
def __init__(self, proc, argv, raise_on_nozero):
self._proc = proc
self._argv = argv
self._raise_on_nozero = raise_on_nozero
def __iter__(self):
return self
def __del__(self):
# See if the process is still running
if self._proc.poll() is None:
# Stop the process and ignore any problems that might arise
try:
self._proc.terminate()
except OSError:
pass
def __next__(self):
# Read the next line, blocking if a line is not yet available
line = self._proc.stdout.readline().decode("utf-8")
if line == '':
# Output finished, wait for the process to end
self._proc.communicate()
# If we don't care about return codes, just finish
if not self._raise_on_nozero:
raise StopIteration
# Check for successful exit
if self._proc.returncode < 0:
raise OSError("process '%s' was killed by signal %s" %
(self._argv, -self._proc.returncode))
elif self._proc.returncode > 0:
raise OSError("process '%s' exited with status %s" %
(self._argv, self._proc.returncode))
raise StopIteration
return line.strip()
@property
def rc(self):
return self._proc.returncode
argv = [command] + argv
if filter_stderr:
stderr = subprocess.DEVNULL
else:
stderr = subprocess.STDOUT
try:
proc = startProgram(argv, root=root, stdin=stdin, stderr=stderr, env_prune=env_prune)
except OSError as e:
with program_log_lock:
program_log.error("Error running %s: %s", argv[0], e.strerror)
raise
return ExecLineReader(proc, argv, raise_on_nozero)
## Run a shell.
def execConsole():
try:
proc = startProgram(["/bin/bash"], stdout=None, stderr=None, reset_lang=False)
proc.wait()
except OSError as e:
raise RuntimeError("Error running /bin/bash: " + e.strerror) from e
def get_active_console(dev="console"):
"""Find the active console device.
Some tty devices (/dev/console, /dev/tty0) aren't actual devices;
they just redirect input and output to the real console device(s).
These 'fake' ttys have an 'active' sysfs attribute, which lists the real
console device(s). (If there's more than one, the *last* one in the list
is the primary console.)
"""
# If there's an 'active' attribute, this is a fake console..
while os.path.exists("/sys/class/tty/%s/active" % dev):
# So read the name of the real, primary console out of the file.
console_path = "/sys/class/tty/%s/active" % dev
active = open(console_path, "rt").read()
if active.split():
# the active attribute seems to be pointing to another console
dev = active.split()[-1]
else:
# At least some consoles on PPC have the "active" attribute, but it is empty.
# (see rhbz#1569045 for more details)
log.warning("%s is empty while console name is expected", console_path)
# We can't continue to a next console if active is empty, so set dev to ""
# and break the search loop.
dev = ""
break
return dev
def isConsoleOnVirtualTerminal(dev="console"):
console = get_active_console(dev) # e.g. 'tty1', 'ttyS0', 'hvc1'
consoletype = console.rstrip('0123456789') # remove the number
return consoletype == 'tty'
def reIPL(ipldev):
try:
rc = execWithRedirect("chreipl", ["node", "/dev/" + ipldev])
except RuntimeError as e:
rc = True
log.info("Unable to set reIPL device to %s: %s",
ipldev, e)
if rc:
log.info("reIPL configuration failed")
else:
log.info("reIPL configuration successful")
def dracut_eject(device):
"""
Use dracut shutdown hook to eject media after the system is shutdown.
This is needed because we are running from the squashfs.img on the media
so ejecting too early will crash the installer.
"""
if not device:
return
try:
if not os.path.exists(DRACUT_SHUTDOWN_EJECT):
make_directories(os.path.dirname(DRACUT_SHUTDOWN_EJECT))
f = open_with_perm(DRACUT_SHUTDOWN_EJECT, "w", 0o755)
f.write("#!/bin/sh\n")
f.write("# Created by Anaconda\n")
else:
f = open(DRACUT_SHUTDOWN_EJECT, "a")
f.write("eject %s\n" % (device,))
f.close()
log.info("Wrote dracut shutdown eject hook for %s", device)
except OSError as e:
log.error("Error writing dracut shutdown eject hook for %s: %s", device, e)
def vtActivate(num):
"""
Try to switch to tty number $num.
:type num: int
:return: whether the switch was successful or not
:rtype: bool
"""
try:
ret = execWithRedirect("chvt", [str(num)], do_preexec=False)
except OSError as oserr:
ret = -1
log.error("Failed to run chvt: %s", oserr.strerror)
if ret != 0:
log.error("Failed to switch to tty%d", num)
return ret == 0
def xprogressive_delay():
""" A delay generator, the delay starts short and gets longer
as the internal counter increases.
For example for 10 retries, the delay will increases from
0.5 to 256 seconds.
:returns float: time to wait in seconds
"""
counter = 1
while True:
yield 0.25 * (2 ** counter)
counter += 1
def persistent_root_image():
""":returns: whether we are running from a persistent (not in RAM) root.img"""
for line in execReadlines("losetup", ["--list"]):
# if there is an active loop device for a curl-fetched file that has
# been deleted, it means we run from a non-persistent root image
# EXAMPLE line:
# /dev/loop0 0 0 0 1 /tmp/curl_fetch_url0/my_comps_squashfs.img (deleted)
if re.match(r'.*curl_fetch_url.*\(deleted\)\s*$', line):
return False
return True
_supports_ipmi = None
def ipmi_report(event):
log.info("Reporting the IPMI event: %s", event)
global _supports_ipmi
if _supports_ipmi is None:
_supports_ipmi = os.path.exists("/dev/ipmi0") and os.path.exists("/usr/bin/ipmitool")
if not _supports_ipmi:
return
(fd, path) = tempfile.mkstemp()
# EVM revision - always 0x4
# Sensor type - always 0x1F for Base OS Boot/Installation Status
# Sensor num - always 0x0 for us
# Event dir & type - always 0x6f for us
# Event data 1 - the event code passed in
# Event data 2 & 3 - always 0x0 for us
event_string = "0x4 0x1F 0x0 0x6f %#x 0x0 0x0\n" % event
os.write(fd, event_string.encode("utf-8"))
os.close(fd)
execWithCapture("ipmitool", ["event", "file", path])
os.remove(path)
def ipmi_abort(scripts=None):
ipmi_report(IPMI_ABORTED)
runOnErrorScripts(scripts)
def runOnErrorScripts(scripts):
if not scripts:
return
log.info("Running kickstart %%onerror script(s)")
for script in filter(lambda s: s.type == KS_SCRIPT_ONERROR, scripts):
script.run("/")
log.info("All kickstart %%onerror script(s) have been run")
def requests_session():
"""Return a requests.Session object with file and ftp support."""
session = requests.Session()
session.mount("file://", FileAdapter())
session.mount("ftp://", FTPAdapter())
return session
def collect(module_pattern, path, pred):
"""Traverse the directory (given by path), import all files as a module
module_pattern % filename and find all classes within that match
the given predicate. This is then returned as a list of classes.
It is suggested you use collect_categories or collect_spokes instead of
this lower-level method.
:param module_pattern: the full name pattern (pyanaconda.ui.gui.spokes.%s)
we want to assign to imported modules
:type module_pattern: string
:param path: the directory we are picking up modules from
:type path: string
:param pred: function which marks classes as good to import
:type pred: function with one argument returning True or False
"""
retval = []
try:
contents = os.listdir(path)
# when the directory "path" does not exist
except OSError:
return []
for module_file in contents:
if (not module_file.endswith(".py")) and \
(not module_file.endswith(".so")):
continue
if module_file == "__init__.py":
continue
try:
mod_name = module_file[:module_file.rindex(".")]
except ValueError:
mod_name = module_file
module = None
module_path = None
try:
# see what can be found
spec = importlib.machinery.PathFinder.find_spec(mod_name, [path])
module_path = spec.origin
candidate_name, dot, found_ext = module_path.rpartition(".")
if not dot:
continue
found_ext = dot + found_ext
# see what is already loaded
module = sys.modules.get(module_pattern % mod_name)
# do not load module if any module with the same name
# is already imported
if not module:
# try importing the module the standard way first
# uses sys.path and the module's full name!
try:
__import__(module_pattern % mod_name)
module = sys.modules[module_pattern % mod_name]
# if it fails (package-less addon?) try importing single file
# and filling up the package structure voids
except ImportError:
# prepare dummy modules to prevent RuntimeWarnings
module_parts = (module_pattern % mod_name).split(".")
# remove the last name as it will be inserted by the import
module_parts.pop()
# make sure all "parent" modules are in sys.modules
for ind in range(len(module_parts)):
module_part_name = ".".join(module_parts[:ind + 1])
if module_part_name not in sys.modules:
module_part = types.ModuleType(module_part_name)
module_part.__path__ = [path]
sys.modules[module_part_name] = module_part
# load the collected module
module = importlib.util.module_from_spec(spec)
sys.modules[mod_name] = module
spec.loader.exec_module(module)
# get the filenames without the extensions so we can compare those
# with the .py[co]? equivalence in mind
# - we do not have to care about files without extension as the
# condition at the beginning of the for loop filters out those
# - found_ext contains the extension of the module importlib found
loaded_name, loaded_ext = module.__file__.rsplit(".", 1)
# restore the extension dot eaten by split
loaded_ext = "." + loaded_ext
# do not collect classes when the module is already imported
# from different path than we are traversing
# this condition checks the module name without file extension
if candidate_name != loaded_name:
continue
# if the candidate file is .py[co]? and the loaded is not (.so)
# skip the file as well
if found_ext.startswith(".py") and not loaded_ext.startswith(".py"):
continue
# if the candidate file is not .py[co]? and the loaded is
# skip the file as well
if not found_ext.startswith(".py") and loaded_ext.startswith(".py"):
continue
except RemovedModuleError:
# collected some removed module
continue
except ImportError as imperr:
# pylint: disable=unsupported-membership-test
if module_path and "pyanaconda" in module_path:
# failure when importing our own module:
raise
log.error("Failed to import module %s from path %s in collect: %s", mod_name, module_path, imperr)
continue
p = lambda obj: inspect.isclass(obj) and pred(obj)
# if __all__ is defined in the module, use it
if not hasattr(module, "__all__"):
members = inspect.getmembers(module, p)
else:
members = [(name, getattr(module, name))
for name in module.__all__
if p(getattr(module, name))]
for (_name, val) in members:
retval.append(val)
return retval
def item_counter(item_count):
"""A generator for easy counting of items.
:param int item_count: number of items
The general idea is to initialize the generator with the number
of items and then activating it every time an item is being
processed.
The generator produces strings in the <index>/<item count> format,
for example:
1/20
2/20
3/20
And so on.
Such strings can be easily used to add a current/total counter
to log messages when tasks and task queues are processed.
"""
if item_count < 0:
raise ValueError("Item count can't be negative.")
index = 1
while index <= item_count:
yield "%d/%d" % (index, item_count)
index += 1
def synchronized(wrapped):
"""A locking decorator for methods.
The decorator is only intended for methods and the class providing
the method also needs to have a Lock/RLock instantiated in self._lock.
The decorator prevents the wrapped method from being executed until
self._lock can be acquired. Once available, it acquires the lock and
prevents other decorated methods & other users of self._lock from
executing until the wrapped method finishes running.
"""
@functools.wraps(wrapped)
def _wrapper(self, *args, **kwargs):
with self._lock:
return wrapped(self, *args, **kwargs)
return _wrapper
def get_anaconda_version_string(build_time_version=False):
"""Return a string describing current Anaconda version.
If the current version can't be determined the string
"unknown" will be returned.
:param bool build_time_version: return build time version
Build time version is set at package build time and will
in most cases be identified by a build number or other identifier
appended to the upstream tarball version.
:returns: string describing Anaconda version
:rtype: str
"""
# Ignore pylint not finding the version module, since thanks to automake
# there's a good chance that version.py is not in the same directory as
# the rest of pyanaconda.
try:
from pyanaconda import version # pylint: disable=no-name-in-module
if build_time_version:
return version.__build_time_version__
else:
return version.__version__
except (ImportError, AttributeError):
# there is a slight chance version.py might be generated incorrectly
# during build, so don't crash in that case
return "unknown"
class LazyObject(object):
"""The lazy object."""
def __init__(self, getter):
"""Create a proxy of an object.
The object might not exist until we call the given
function. The function is called only when we try
to access the attributes of the object.
The returned object is not cached in this class.
We call the function every time.
:param getter: a function that returns the object
"""
self._getter = getter
@property
def _object(self):
return self._getter()
def __eq__(self, other):
return self._object == other
def __hash__(self):
return self._object.__hash__()
def __getattr__(self, name):
return getattr(self._object, name)
def __setattr__(self, name, value):
if name in ("_getter", ):
return super().__setattr__(name, value)
return setattr(self._object, name, value)
def get_os_release_value(name, sysroot="/"):
"""Read os-release files and return a value of the specified parameter.
:param name: a name of the parameter (for example, "VERSION_ID")
:param sysroot: a path to the system root
:return: a string with the value of None if nothing found
"""
# Match the variable assignment (for example, "VERSION_ID=").
name += "="
# Search all os-release files in the system root.
paths = ("/etc/os-release", "/usr/lib/os-release")
for path in paths:
try:
with open(join_paths(sysroot, path), "r") as f:
for line in f:
# Match the current line.
if not line.startswith(name):
continue
# Get the value.
value = line[len(name):]
# Strip spaces and then quotes.
value = value.strip().strip("\"'")
return value
except FileNotFoundError:
pass
# No value found.
log.debug("%s not found in os-release files", name[:-1])
return None
def restorecon(paths, root, skip_nonexistent=False):
"""Try to restore contexts for a list of paths.
Do not fail if the program does not exist because it was not in the payload, just say so.
:param [str] paths: list of paths to restore
:param str root: root to run in; mandatory because we restore contexts only on the new system
:param bool skip_nonexistent: optionally, do not fail if some of the paths do not exist
:return bool: did anything run at all
"""
if skip_nonexistent:
opts = ["-ir"]
else:
opts = ["-r"]
try:
execWithRedirect("restorecon", opts + paths, root=root)
except FileNotFoundError:
return False
else:
return True
def get_image_packages_info(max_string_chars=0):
"""List of strings containing versions of installer image packages.
The package version specifications are space separated in the strings.
:param int max_string_chars: maximum number of character in a string
:return [str]
"""
info_lines = []
if os.path.exists(PACKAGES_LIST_FILE):
with open(PACKAGES_LIST_FILE) as f:
while True:
lines = f.readlines(max_string_chars)
if not lines:
break
info_lines.append(' '.join(line.strip() for line in lines))
return info_lines