| # SPDX-License-Identifier: GPL-2.0 | |
| # Copyright (c) 2015-2016, NVIDIA CORPORATION. All rights reserved. | |
| """ | |
| Logic to spawn a sub-process and interact with its stdio. | |
| """ | |
| import os | |
| import re | |
| import pty | |
| import signal | |
| import select | |
| import time | |
| import traceback | |
| class Timeout(Exception): | |
| """An exception sub-class that indicates that a timeout occurred.""" | |
| class Spawn: | |
| """Represents the stdio of a freshly created sub-process. Commands may be | |
| sent to the process, and responses waited for. | |
| Members: | |
| output: accumulated output from expect() | |
| """ | |
| 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.exit_code = 0 | |
| self.exit_info = '' | |
| self.buf = '' | |
| self.output = '' | |
| self.logfile_read = None | |
| self.before = '' | |
| self.after = '' | |
| self.timeout = None | |
| # http://stackoverflow.com/questions/7857352/python-regex-to-match-vt100-escape-sequences | |
| self.re_vt100 = re.compile(r'(\x1b\[|\x9b)[^@-_]*[@-_]|\x1b[@-_]', re.I) | |
| (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:') | |
| 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 checkalive(self): | |
| """Determine whether the child process is still running. | |
| Returns: | |
| tuple: | |
| True if process is alive, else False | |
| 0 if process is alive, else exit code of process | |
| string describing what happened ('' or 'status/signal n') | |
| """ | |
| if self.waited: | |
| return False, self.exit_code, self.exit_info | |
| w = os.waitpid(self.pid, os.WNOHANG) | |
| if w[0] == 0: | |
| return True, 0, 'running' | |
| status = w[1] | |
| if os.WIFEXITED(status): | |
| self.exit_code = os.WEXITSTATUS(status) | |
| self.exit_info = 'status %d' % self.exit_code | |
| elif os.WIFSIGNALED(status): | |
| signum = os.WTERMSIG(status) | |
| self.exit_code = -signum | |
| self.exit_info = 'signal %d (%s)' % (signum, signal.Signals(signum).name) | |
| self.waited = True | |
| return False, self.exit_code, self.exit_info | |
| def isalive(self): | |
| """Determine whether the child process is still running. | |
| Args: | |
| None. | |
| Returns: | |
| Boolean indicating whether process is alive. | |
| """ | |
| return self.checkalive()[0] | |
| 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.encode(errors='replace')) | |
| 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 range(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 range(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.output += self.buf[: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() | |
| try: | |
| c = os.read(self.fd, 1024).decode(errors='replace') | |
| except OSError as err: | |
| # With sandbox, try to detect when U-Boot exits when it | |
| # shouldn't and explain why. This is much more friendly than | |
| # just dying with an I/O error | |
| if err.errno == 5: # Input/output error | |
| alive, _, info = self.checkalive() | |
| if alive: | |
| raise err | |
| raise ValueError('U-Boot exited with %s' % info) | |
| raise err | |
| if self.logfile_read: | |
| self.logfile_read.write(c) | |
| self.buf += c | |
| # count=0 is supposed to be the default, which indicates | |
| # unlimited substitutions, but in practice the version of | |
| # Python in Ubuntu 14.04 appears to default to count=2! | |
| self.buf = self.re_vt100.sub('', self.buf, count=1000000) | |
| 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 _ in range(100): | |
| if not self.isalive(): | |
| break | |
| time.sleep(0.1) | |
| def get_expect_output(self): | |
| """Return the output read by expect() | |
| Returns: | |
| The output processed by expect(), as a string. | |
| """ | |
| return self.output |