mirror of
https://github.com/brain-hackers/u-boot-brain
synced 2024-09-09 06:13:21 +09:00
![Stephen Warren](/assets/img/avatar_default.png)
u_boot_console.exec_attach.get_spawn() performs two steps: 1) Spawn a process to communicate with the serial console. 2) Reset the board so that U-Boot starts running from scratch. Currently, if an exception happens in step (2), no cleanup is performed on the process created in step (1). That process stays running and may e.g. hold serial port locks, or simply continue to read data from the serial port, thus preventing it from reaching any other process that attempts to read from the same serial port later. While there is error cleanup code in u_boot_console_base.ensure_spawned(), this is not triggered since the exception prevents assignment to self.p there, and hence the exception handler has no object to operate upon in cleanup_spawn(). Solve this by enhancing u_boot_console.exec_attach.get_spawn() to clean up any objects it has created. In theory, u_boot_spawn.Spawn's constructor has a similar issue, so fix this too. Signed-off-by: Stephen Warren <swarren@nvidia.com> Acked-by: Simon Glass <sjg@chromium.org>
192 lines
5.4 KiB
Python
192 lines
5.4 KiB
Python
# Copyright (c) 2015-2016, NVIDIA CORPORATION. All rights reserved.
|
|
#
|
|
# SPDX-License-Identifier: GPL-2.0
|
|
|
|
# Logic to spawn a sub-process and interact with its stdio.
|
|
|
|
import os
|
|
import re
|
|
import pty
|
|
import signal
|
|
import select
|
|
import time
|
|
|
|
class Timeout(Exception):
|
|
"""An exception sub-class that indicates that a timeout occurred."""
|
|
pass
|
|
|
|
class Spawn(object):
|
|
"""Represents the stdio of a freshly created sub-process. Commands may be
|
|
sent to the process, and responses waited for.
|
|
"""
|
|
|
|
def __init__(self, args, cwd=None):
|
|
"""Spawn (fork/exec) the sub-process.
|
|
|
|
Args:
|
|
args: array of processs arguments. argv[0] is the command to
|
|
execute.
|
|
cwd: the directory to run the process in, or None for no change.
|
|
|
|
Returns:
|
|
Nothing.
|
|
"""
|
|
|
|
self.waited = False
|
|
self.buf = ''
|
|
self.logfile_read = None
|
|
self.before = ''
|
|
self.after = ''
|
|
self.timeout = None
|
|
|
|
(self.pid, self.fd) = pty.fork()
|
|
if self.pid == 0:
|
|
try:
|
|
# For some reason, SIGHUP is set to SIG_IGN at this point when
|
|
# run under "go" (www.go.cd). Perhaps this happens under any
|
|
# background (non-interactive) system?
|
|
signal.signal(signal.SIGHUP, signal.SIG_DFL)
|
|
if cwd:
|
|
os.chdir(cwd)
|
|
os.execvp(args[0], args)
|
|
except:
|
|
print 'CHILD EXECEPTION:'
|
|
import traceback
|
|
traceback.print_exc()
|
|
finally:
|
|
os._exit(255)
|
|
|
|
try:
|
|
self.poll = select.poll()
|
|
self.poll.register(self.fd, select.POLLIN | select.POLLPRI | select.POLLERR | select.POLLHUP | select.POLLNVAL)
|
|
except:
|
|
self.close()
|
|
raise
|
|
|
|
def kill(self, sig):
|
|
"""Send unix signal "sig" to the child process.
|
|
|
|
Args:
|
|
sig: The signal number to send.
|
|
|
|
Returns:
|
|
Nothing.
|
|
"""
|
|
|
|
os.kill(self.pid, sig)
|
|
|
|
def isalive(self):
|
|
"""Determine whether the child process is still running.
|
|
|
|
Args:
|
|
None.
|
|
|
|
Returns:
|
|
Boolean indicating whether process is alive.
|
|
"""
|
|
|
|
if self.waited:
|
|
return False
|
|
|
|
w = os.waitpid(self.pid, os.WNOHANG)
|
|
if w[0] == 0:
|
|
return True
|
|
|
|
self.waited = True
|
|
return False
|
|
|
|
def send(self, data):
|
|
"""Send data to the sub-process's stdin.
|
|
|
|
Args:
|
|
data: The data to send to the process.
|
|
|
|
Returns:
|
|
Nothing.
|
|
"""
|
|
|
|
os.write(self.fd, data)
|
|
|
|
def expect(self, patterns):
|
|
"""Wait for the sub-process to emit specific data.
|
|
|
|
This function waits for the process to emit one pattern from the
|
|
supplied list of patterns, or for a timeout to occur.
|
|
|
|
Args:
|
|
patterns: A list of strings or regex objects that we expect to
|
|
see in the sub-process' stdout.
|
|
|
|
Returns:
|
|
The index within the patterns array of the pattern the process
|
|
emitted.
|
|
|
|
Notable exceptions:
|
|
Timeout, if the process did not emit any of the patterns within
|
|
the expected time.
|
|
"""
|
|
|
|
for pi in xrange(len(patterns)):
|
|
if type(patterns[pi]) == type(''):
|
|
patterns[pi] = re.compile(patterns[pi])
|
|
|
|
tstart_s = time.time()
|
|
try:
|
|
while True:
|
|
earliest_m = None
|
|
earliest_pi = None
|
|
for pi in xrange(len(patterns)):
|
|
pattern = patterns[pi]
|
|
m = pattern.search(self.buf)
|
|
if not m:
|
|
continue
|
|
if earliest_m and m.start() >= earliest_m.start():
|
|
continue
|
|
earliest_m = m
|
|
earliest_pi = pi
|
|
if earliest_m:
|
|
pos = earliest_m.start()
|
|
posafter = earliest_m.end()
|
|
self.before = self.buf[:pos]
|
|
self.after = self.buf[pos:posafter]
|
|
self.buf = self.buf[posafter:]
|
|
return earliest_pi
|
|
tnow_s = time.time()
|
|
if self.timeout:
|
|
tdelta_ms = (tnow_s - tstart_s) * 1000
|
|
poll_maxwait = self.timeout - tdelta_ms
|
|
if tdelta_ms > self.timeout:
|
|
raise Timeout()
|
|
else:
|
|
poll_maxwait = None
|
|
events = self.poll.poll(poll_maxwait)
|
|
if not events:
|
|
raise Timeout()
|
|
c = os.read(self.fd, 1024)
|
|
if not c:
|
|
raise EOFError()
|
|
if self.logfile_read:
|
|
self.logfile_read.write(c)
|
|
self.buf += c
|
|
finally:
|
|
if self.logfile_read:
|
|
self.logfile_read.flush()
|
|
|
|
def close(self):
|
|
"""Close the stdio connection to the sub-process.
|
|
|
|
This also waits a reasonable time for the sub-process to stop running.
|
|
|
|
Args:
|
|
None.
|
|
|
|
Returns:
|
|
Nothing.
|
|
"""
|
|
|
|
os.close(self.fd)
|
|
for i in xrange(100):
|
|
if not self.isalive():
|
|
break
|
|
time.sleep(0.1)
|