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phorge-phorge/scripts/ssh/ssh-connect.php
epriestley f56f1b05c0 Install a SIGTERM handler in ssh-connect
Summary:
Ref T10547. This has been around for a while but I was never able to reproduce it. I caught a repro case in the cluster recently and I think this is the right fix.

We tell Subversion to run `ssh-connect` instead of `ssh` so we can provide options and credentials, by using `SVN_SSH` in the environment. Subversion will sometimes kill the SSH tunnel subprocess aggressively with SIGTERM -- as of writing, you can search for `SIGTERM` in `make_tunnel()` here:

http://svn.apache.org/repos/asf/subversion/trunk/subversion/libsvn_ra_svn/client.c

By default, when a PHP process gets SIGTERM it just exits immediately, without running destructors or shutdown functions. Since destructors/shutdown functions don't run, `TempFile` doesn't get a chance to remove the file.

I don't have a clear picture of //when// Subversion sends SIGTERM to the child process. I can't really get this to trigger locally via `svn`, although I was able to get it to trigger explicitly. So I'm only about 95% sure this fixes it, but it seems likely.

Test Plan:
Locally, I couldn't get this to reproduce "normally" even knowing the cause (maybe Subversion doesn't do the SIGTERM stuff on OSX?) but I was able to get it to reproduce reliabily by adding `posix_kill(getmypid(), SIGTERM);` to the body of the script.

With that added, running the script with `PHABRICATOR_CREDENTIAL=PHID-CDTL-...` in the environment reliably left straggler temporary files.

Adding `declare()` and a signal handler fixed this: the script now runs the `TempFile` destructor and longer leaves the stragglers around.

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T10547

Differential Revision: https://secure.phabricator.com/D16102
2016-06-13 10:05:46 -07:00

111 lines
2.9 KiB
PHP
Executable file

#!/usr/bin/env php
<?php
// This is a wrapper script for Git, Mercurial, and Subversion. It primarily
// serves to inject "-o StrictHostKeyChecking=no" into the SSH arguments.
// In some cases, Subversion sends us SIGTERM. If we don't catch the signal and
// react to it, we won't run object destructors by default and thus won't clean
// up temporary files. Declare ticks so we can install a signal handler.
declare(ticks=1);
$root = dirname(dirname(dirname(__FILE__)));
require_once $root.'/scripts/__init_script__.php';
// Contrary to the documentation, Git may pass a "-p" flag. If it does, respect
// it and move it before the "--" argument.
$args = new PhutilArgumentParser($argv);
$args->parsePartial(
array(
array(
'name' => 'port',
'short' => 'p',
'param' => pht('port'),
'help' => pht('Port number to connect to.'),
),
));
$unconsumed_argv = $args->getUnconsumedArgumentVector();
if (function_exists('pcntl_signal')) {
pcntl_signal(SIGTERM, 'ssh_connect_signal');
}
function ssh_connect_signal($signo) {
// This is just letting destructors fire. In particular, we want to clean
// up any temporary files we wrote. See T10547.
exit(128 + $signo);
}
$pattern = array();
$arguments = array();
$pattern[] = 'ssh';
$pattern[] = '-o';
$pattern[] = 'StrictHostKeyChecking=no';
// This prevents "known host" failures, and covers for issues where HOME is set
// to something unusual.
$pattern[] = '-o';
$pattern[] = 'UserKnownHostsFile=/dev/null';
$as_device = getenv('PHABRICATOR_AS_DEVICE');
$credential_phid = getenv('PHABRICATOR_CREDENTIAL');
if ($as_device) {
$device = AlmanacKeys::getLiveDevice();
if (!$device) {
throw new Exception(
pht(
'Attempting to create an SSH connection that authenticates with '.
'the current device, but this host is not configured as a cluster '.
'device.'));
}
if ($credential_phid) {
throw new Exception(
pht(
'Attempting to proxy an SSH connection that authenticates with '.
'both the current device and a specific credential. These options '.
'are mutually exclusive.'));
}
}
if ($credential_phid) {
$viewer = PhabricatorUser::getOmnipotentUser();
$key = PassphraseSSHKey::loadFromPHID($credential_phid, $viewer);
$pattern[] = '-l %P';
$arguments[] = $key->getUsernameEnvelope();
$pattern[] = '-i %P';
$arguments[] = $key->getKeyfileEnvelope();
}
if ($as_device) {
$pattern[] = '-l %R';
$arguments[] = AlmanacKeys::getClusterSSHUser();
$pattern[] = '-i %R';
$arguments[] = AlmanacKeys::getKeyPath('device.key');
}
$port = $args->getArg('port');
if ($port) {
$pattern[] = '-p %d';
$arguments[] = $port;
}
$pattern[] = '--';
$passthru_args = $unconsumed_argv;
foreach ($passthru_args as $passthru_arg) {
$pattern[] = '%s';
$arguments[] = $passthru_arg;
}
$pattern = implode(' ', $pattern);
array_unshift($arguments, $pattern);
$err = newv('PhutilExecPassthru', $arguments)
->execute();
exit($err);