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Handle subprocess disallowing preexec during shutdown #4879

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merged 4 commits into from
Jul 13, 2023
Merged

Handle subprocess disallowing preexec during shutdown #4879

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6f14a16
Handle subprocess disallowing preexec during shutdown
AdamWill Jul 5, 2023
9efd336
Add do_preexec propagation also to execWithCapture and shutdownServer
VladimirSlavik Jul 12, 2023
0fd50ca
Change startProgram preexec check to early exit style
VladimirSlavik Jul 12, 2023
7f30721
Fix and add tests for the preexec changes
VladimirSlavik Jul 12, 2023
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8 changes: 4 additions & 4 deletions anaconda.py
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Original file line number Diff line number Diff line change
Expand Up @@ -89,15 +89,15 @@ def exitHandler(rebootData):
util.dracut_eject(device_path)

if flags.kexec:
util.execWithRedirect("systemctl", ["--no-wall", "kexec"])
util.execWithRedirect("systemctl", ["--no-wall", "kexec"], do_preexec=False)
while True:
time.sleep(10000)
elif rebootData.action == KS_SHUTDOWN:
util.execWithRedirect("systemctl", ["--no-wall", "poweroff"])
util.execWithRedirect("systemctl", ["--no-wall", "poweroff"], do_preexec=False)
elif rebootData.action == KS_WAIT:
util.execWithRedirect("systemctl", ["--no-wall", "halt"])
util.execWithRedirect("systemctl", ["--no-wall", "halt"], do_preexec=False)
else: # reboot action is KS_REBOOT or None
util.execWithRedirect("systemctl", ["--no-wall", "reboot"])
util.execWithRedirect("systemctl", ["--no-wall", "reboot"], do_preexec=False)


def parse_arguments(argv=None, boot_cmdline=None):
Expand Down
76 changes: 42 additions & 34 deletions pyanaconda/core/util.py
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Original file line number Diff line number Diff line change
Expand Up @@ -76,7 +76,8 @@ def augmentEnv():


def startProgram(argv, root='/', stdin=None, stdout=subprocess.PIPE, stderr=subprocess.STDOUT,
env_prune=None, env_add=None, reset_handlers=True, reset_lang=True, **kwargs):
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
Expand All @@ -93,6 +94,7 @@ def startProgram(argv, root='/', stdin=None, stdout=subprocess.PIPE, stderr=subp
: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.
"""
Expand All @@ -105,32 +107,11 @@ def startProgram(argv, root='/', stdin=None, stdout=subprocess.PIPE, stderr=subp
if target_root == conf.target.physical_root:
target_root = conf.target.system_root

# Check for and save a preexec_fn argument
preexec_fn = kwargs.pop("preexec_fn", None)

# 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

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()

with program_log_lock:
if target_root != '/':
program_log.info("Running in chroot '%s'... %s", target_root, " ".join(argv))
Expand All @@ -148,13 +129,38 @@ def preexec():
env.update(env_add)

# pylint: disable=subprocess-popen-preexec-fn
return subprocess.Popen(argv,
stdin=stdin,
stdout=stdout,
stderr=stderr,
close_fds=True,
restore_signals=restore_signals,
preexec_fn=preexec, cwd=root, env=env, **kwargs)
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 do_preexec:
# 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)
return partsubp()


class X11Status:
Expand Down Expand Up @@ -253,7 +259,7 @@ def sigusr1_preexec():


def _run_program(argv, root='/', stdin=None, stdout=None, env_prune=None, log_output=True,
binary_output=False, filter_stderr=False):
binary_output=False, filter_stderr=False, do_preexec=True):
""" 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
Expand All @@ -267,6 +273,7 @@ def _run_program(argv, root='/', stdin=None, stdout=None, env_prune=None, log_ou
: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
:return: The return code of the command and the output
"""
try:
Expand All @@ -276,7 +283,7 @@ def _run_program(argv, root='/', stdin=None, stdout=None, env_prune=None, log_ou
stderr = subprocess.STDOUT

proc = startProgram(argv, root=root, stdin=stdin, stdout=subprocess.PIPE, stderr=stderr,
env_prune=env_prune)
env_prune=env_prune, do_preexec=do_preexec)

(output_string, err_string) = proc.communicate()
if not binary_output:
Expand Down Expand Up @@ -322,8 +329,8 @@ def _run_program(argv, root='/', stdin=None, stdout=None, env_prune=None, log_ou
return (proc.returncode, output_string)


def execWithRedirect(command, argv, stdin=None, stdout=None,
root='/', env_prune=None, log_output=True, binary_output=False):
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
Expand All @@ -334,11 +341,12 @@ def execWithRedirect(command, argv, stdin=None, stdout=None,
: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)[0]
log_output=log_output, binary_output=binary_output, do_preexec=do_preexec)[0]


def execWithCapture(command, argv, stdin=None, root='/', log_output=True, filter_stderr=False):
Expand Down