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Code Issues Releases Wiki Activity

utils/ssh: Implement work around for issue in pexpect

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As detailed in https://github.com/pexpect/pexpect/issues/552 when
sending a command with exactly the length of the prompt less than the
window width, an extra prompt is introduced into the returned data
causing the matching to fail and only return part of the commands
output. To workaround this check the length of the command to be
submitted and if of the specific length add an additional whitespace
character to the end of the command to prevent this behaviour.
This commit is contained in:
Marc Bonnici 2019-01-21 18:01:20 +00:00 committed by setrofim
parent cc0679e40f
commit 911a9f2ef4
1 changed files with 21 additions and 5 deletions
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26
devlib/utils/ssh.py
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@ -41,7 +41,8 @@ from pexpect import EOF, TIMEOUT, spawn
# pylint: disable=redefined-builtin,wrong-import-position # pylint: disable=redefined-builtin,wrong-import-position
from devlib.exception import (HostError, TargetStableError, TargetNotRespondingError, from devlib.exception import (HostError, TargetStableError, TargetNotRespondingError,
TimeoutError, TargetTransientError) TimeoutError, TargetTransientError)
from devlib.utils.misc import which, strip_bash_colors, check_output, sanitize_cmd_template from devlib.utils.misc import (which, strip_bash_colors, check_output,
sanitize_cmd_template, memoized)
from devlib.utils.types import boolean from devlib.utils.types import boolean
@ -253,7 +254,7 @@ class SshConnection(object):
# simulate impatiently hitting ^C until command prompt appears # simulate impatiently hitting ^C until command prompt appears
logger.debug('Sending ^C') logger.debug('Sending ^C')
for _ in range(self.max_cancel_attempts): for _ in range(self.max_cancel_attempts):
self.conn.sendline(chr(3)) self._sendline(chr(3))
if self.conn.prompt(0.1): if self.conn.prompt(0.1):
return True return True
return False return False
@ -267,15 +268,15 @@ class SshConnection(object):
command = self.sudo_cmd.format(quote(command)) command = self.sudo_cmd.format(quote(command))
if log: if log:
logger.debug(command) logger.debug(command)
self.conn.sendline(command) self._sendline(command)
if self.password: if self.password:
index = self.conn.expect_exact([self.password_prompt, TIMEOUT], timeout=0.5) index = self.conn.expect_exact([self.password_prompt, TIMEOUT], timeout=0.5)
if index == 0: if index == 0:
self.conn.sendline(self.password) self._sendline(self.password)
else: # not as_root else: # not as_root
if log: if log:
logger.debug(command) logger.debug(command)
self.conn.sendline(command) self._sendline(command)
timed_out = self._wait_for_prompt(timeout) timed_out = self._wait_for_prompt(timeout)
# the regex removes line breaks potential introduced when writing # the regex removes line breaks potential introduced when writing
# command to shell. # command to shell.
@ -321,6 +322,21 @@ class SshConnection(object):
except TimeoutError as e: except TimeoutError as e:
raise TimeoutError(command_redacted, e.output) raise TimeoutError(command_redacted, e.output)
def _sendline(self, command):
# Workaround for https://github.com/pexpect/pexpect/issues/552
if len(command) == self._get_window_size()[1] - self._get_prompt_length():
command += ' '
self.conn.sendline(command)
@memoized
def _get_prompt_length(self):
self.conn.sendline()
self.conn.prompt()
return len(self.conn.after)
@memoized
def _get_window_size(self):
return self.conn.getwinsize()
class TelnetConnection(SshConnection): class TelnetConnection(SshConnection):