1 # Copyright (c) 2015-2016, NVIDIA CORPORATION. All rights reserved.
3 # SPDX-License-Identifier: GPL-2.0
5 # Logic to spawn a sub-process and interact with its stdio.
14 class Timeout(Exception):
15 '''An exception sub-class that indicates that a timeout occurred.'''
19 '''Represents the stdio of a freshly created sub-process. Commands may be
20 sent to the process, and responses waited for.
23 def __init__(self, args):
24 '''Spawn (fork/exec) the sub-process.
27 args: array of processs arguments. argv[0] is the command to execute.
35 self.logfile_read = None
40 (self.pid, self.fd) = pty.fork()
43 # For some reason, SIGHUP is set to SIG_IGN at this point when
44 # run under "go" (www.go.cd). Perhaps this happens under any
45 # background (non-interactive) system?
46 signal.signal(signal.SIGHUP, signal.SIG_DFL)
47 os.execvp(args[0], args)
49 print 'CHILD EXECEPTION:'
55 self.poll = select.poll()
56 self.poll.register(self.fd, select.POLLIN | select.POLLPRI | select.POLLERR | select.POLLHUP | select.POLLNVAL)
59 '''Send unix signal "sig" to the child process.
62 sig: The signal number to send.
68 os.kill(self.pid, sig)
71 '''Determine whether the child process is still running.
77 Boolean indicating whether process is alive.
83 w = os.waitpid(self.pid, os.WNOHANG)
91 '''Send data to the sub-process's stdin.
94 data: The data to send to the process.
100 os.write(self.fd, data)
102 def expect(self, patterns):
103 '''Wait for the sub-process to emit specific data.
105 This function waits for the process to emit one pattern from the
106 supplied list of patterns, or for a timeout to occur.
109 patterns: A list of strings or regex objects that we expect to
110 see in the sub-process' stdout.
113 The index within the patterns array of the pattern the process
117 Timeout, if the process did not emit any of the patterns within
121 for pi in xrange(len(patterns)):
122 if type(patterns[pi]) == type(''):
123 patterns[pi] = re.compile(patterns[pi])
129 for pi in xrange(len(patterns)):
130 pattern = patterns[pi]
131 m = pattern.search(self.buf)
134 if earliest_m and m.start() > earliest_m.start():
139 pos = earliest_m.start()
140 posafter = earliest_m.end() + 1
141 self.before = self.buf[:pos]
142 self.after = self.buf[pos:posafter]
143 self.buf = self.buf[posafter:]
145 events = self.poll.poll(self.timeout)
148 c = os.read(self.fd, 1024)
151 if self.logfile_read:
152 self.logfile_read.write(c)
155 if self.logfile_read:
156 self.logfile_read.flush()
159 '''Close the stdio connection to the sub-process.
161 This also waits a reasonable time for the sub-process to stop running.
171 for i in xrange(100):
172 if not self.isalive():