<?php declare(strict_types=1);
/*
* This file is part of the Monolog package.
*
* (c) Jordi Boggiano <[email protected]>
*
* For the full copyright and license information, please view the LICENSE
* file that was distributed with this source code.
*/
namespace Monolog\Handler;
use Monolog\Logger;
/**
* Stores to STDIN of any process, specified by a command.
*
* Usage example:
* <pre>
* $log = new Logger('myLogger');
* $log->pushHandler(new ProcessHandler('/usr/bin/php /var/www/monolog/someScript.php'));
* </pre>
*
* @author Kolja Zuelsdorf <[email protected]>
*/
class ProcessHandler extends AbstractProcessingHandler
{
/**
* Holds the process to receive data on its STDIN.
*
* @var resource|bool|null
*/
private $process;
/**
* @var string
*/
private $command;
/**
* @var string|null
*/
private $cwd;
/**
* @var array
*/
private $pipes = [];
/**
* @var array
*/
protected const DESCRIPTOR_SPEC = [
0 => ['pipe', 'r'], // STDIN is a pipe that the child will read from
1 => ['pipe', 'w'], // STDOUT is a pipe that the child will write to
2 => ['pipe', 'w'], // STDERR is a pipe to catch the any errors
];
/**
* @param string $command Command for the process to start. Absolute paths are recommended,
* especially if you do not use the $cwd parameter.
* @param string|int $level The minimum logging level at which this handler will be triggered.
* @param bool $bubble Whether the messages that are handled can bubble up the stack or not.
* @param string|null $cwd "Current working directory" (CWD) for the process to be executed in.
* @throws \InvalidArgumentException
*/
public function __construct(string $command, $level = Logger::DEBUG, bool $bubble = true, ?string $cwd = null)
{
if ($command === '') {
throw new \InvalidArgumentException('The command argument must be a non-empty string.');
}
if ($cwd === '') {
throw new \InvalidArgumentException('The optional CWD argument must be a non-empty string or null.');
}
parent::__construct($level, $bubble);
$this->command = $command;
$this->cwd = $cwd;
}
/**
* Writes the record down to the log of the implementing handler
*
* @throws \UnexpectedValueException
*/
protected function write(array $record): void
{
$this->ensureProcessIsStarted();
$this->writeProcessInput($record['formatted']);
$errors = $this->readProcessErrors();
if (empty($errors) === false) {
throw new \UnexpectedValueException(sprintf('Errors while writing to process: %s', $errors));
}
}
/**
* Makes sure that the process is actually started, and if not, starts it,
* assigns the stream pipes, and handles startup errors, if any.
*/
private function ensureProcessIsStarted(): void
{
if (is_resource($this->process) === false) {
$this->startProcess();
$this->handleStartupErrors();
}
}
/**
* Starts the actual process and sets all streams to non-blocking.
*/
private function startProcess(): void
{
$this->process = proc_open($this->command, static::DESCRIPTOR_SPEC, $this->pipes, $this->cwd);
foreach ($this->pipes as $pipe) {
stream_set_blocking($pipe, false);
}
}
/**
* Selects the STDERR stream, handles upcoming startup errors, and throws an exception, if any.
*
* @throws \UnexpectedValueException
*/
private function handleStartupErrors(): void
{
$selected = $this->selectErrorStream();
if (false === $selected) {
throw new \UnexpectedValueException('Something went wrong while selecting a stream.');
}
$errors = $this->readProcessErrors();
if (is_resource($this->process) === false || empty($errors) === false) {
throw new \UnexpectedValueException(
sprintf('The process "%s" could not be opened: ' . $errors, $this->command)
);
}
}
/**
* Selects the STDERR stream.
*
* @return int|bool
*/
protected function selectErrorStream()
{
$empty = [];
$errorPipes = [$this->pipes[2]];
return stream_select($errorPipes, $empty, $empty, 1);
}
/**
* Reads the errors of the process, if there are any.
*
* @codeCoverageIgnore
* @return string Empty string if there are no errors.
*/
protected function readProcessErrors(): string
{
return stream_get_contents($this->pipes[2]);
}
/**
* Writes to the input stream of the opened process.
*
* @codeCoverageIgnore
*/
protected function writeProcessInput(string $string): void
{
fwrite($this->pipes[0], $string);
}
/**
* {@inheritdoc}
*/
public function close(): void
{
if (is_resource($this->process)) {
foreach ($this->pipes as $pipe) {
fclose($pipe);
}
proc_close($this->process);
$this->process = null;
}
}
}