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    lars at opdenkamp dot eu
    17 years ago
    If you want to make a daemon process that forks on each client connection, you'll find out that there's a bug in PHP. The child processes send SIGCHLD to their parent when they exit but the parent can't handle signals while it's waiting for socket_accept (blocking).

    Here is a piece of code that makes a non-blocking forking server.

    #!/usr/bin/php -q
    <?php
    /**
    * Listens for requests and forks on each connection
    */

    $__server_listening = true;

    error_reporting(E_ALL);
    set_time_limit(0);
    ob_implicit_flush();
    declare(    ticks = 1);

    become_daemon();

    /* nobody/nogroup, change to your host's uid/gid of the non-priv user */
    change_identity(65534, 65534);

    /* handle signals */
    pcntl_signal(SIGTERM, 'sig_handler');
    pcntl_signal(SIGINT, 'sig_handler');
    pcntl_signal(SIGCHLD, 'sig_handler');

    /* change this to your own host / port */
    server_loop("127.0.0.1", 1234);

    /**
    * Change the identity to a non-priv user
    */
    function change_identity( $uid, $gid )
    {
    if( !    posix_setgid( $gid ) )
    {
    print     "Unable to setgid to " . $gid . "!\n";
    exit;
    }

    if( !    posix_setuid( $uid ) )
    {
    print     "Unable to setuid to " . $uid . "!\n";
    exit;
    }
    }

    /**
    * Creates a server socket and listens for incoming client connections
    * @param string $address The address to listen on
    * @param int $port The port to listen on
    */
    function server_loop($address, $port)
    {
    GLOBAL     $__server_listening;

    if((    $sock = socket_create(AF_INET, SOCK_STREAM, 0)) < 0)
    {
    echo     "failed to create socket: ".socket_strerror($sock)."\n";
    exit();
    }

    if((    $ret = socket_bind($sock, $address, $port)) < 0)
    {
    echo     "failed to bind socket: ".socket_strerror($ret)."\n";
    exit();
    }

    if( (     $ret = socket_listen( $sock, 0 ) ) < 0 )
    {
    echo     "failed to listen to socket: ".socket_strerror($ret)."\n";
    exit();
    }

    socket_set_nonblock($sock);

    echo     "waiting for clients to connect\n";

    while (    $__server_listening)
    {
    $connection = @socket_accept($sock);
    if (    $connection === false)
    {
    usleep(100);
    }elseif (    $connection > 0)
    {
    handle_client($sock, $connection);
    }else
    {
    echo     "error: ".socket_strerror($connection);
    die;
    }
    }
    }

    /**
    * Signal handler
    */
    function sig_handler($sig)
    {
    switch(    $sig)
    {
    case     SIGTERM:
    case     SIGINT:
    exit();
    break;

    case     SIGCHLD:
    pcntl_waitpid(-1, $status);
    break;
    }
    }

    /**
    * Handle a new client connection
    */
    function handle_client($ssock, $csock)
    {
    GLOBAL     $__server_listening;

    $pid = pcntl_fork();

    if (    $pid == -1)
    {
    /* fork failed */
    echo "fork failure!\n";
    die;
    }elseif (    $pid == 0)
    {
    /* child process */
    $__server_listening = false;
    socket_close($ssock);
    interact($csock);
    socket_close($csock);
    }else
    {
    socket_close($csock);
    }
    }

    function     interact($socket)
    {
    /* TALK TO YOUR CLIENT */
    }

    /**
    * Become a daemon by forking and closing the parent
    */
    function become_daemon()
    {
    $pid = pcntl_fork();

    if (    $pid == -1)
    {
    /* fork failed */
    echo "fork failure!\n";
    exit();
    }elseif (    $pid)
    {
    /* close the parent */
    exit();
    }else
    {
    /* child becomes our daemon */
    posix_setsid();
    chdir('/');
    umask(0);
    return     posix_getpid();

    }
    }

    ?>

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