/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "unixd.h"
#include "ap_mpm.h"
#include "apr_thread_proc.h"
#include "apr_strings.h"
#include "apr_queue.h"
#include "apr_global_mutex.h"
#include "apr_version.h"
#if APR_MAJOR_VERSION < 2
#include "apr_support.h"
#endif
#include "http_config.h"
#include "fcgid_pm.h"
#include "fcgid_pm_main.h"
#include "fcgid_conf.h"
#include "fcgid_proctbl.h"
#include "fcgid_spawn_ctl.h"
#include "fcgid_mutex.h"
#include <unistd.h>

#if MODULE_MAGIC_NUMBER_MAJOR >= 20090209
#include "mod_unixd.h"
#endif

#if MODULE_MAGIC_NUMBER_MAJOR < 20081201
#define ap_unixd_config unixd_config
#define ap_unixd_setup_child unixd_setup_child
#endif

/* The APR other-child API doesn't tell us how the daemon exited
 * (SIGSEGV vs. exit(1)).  The other-child maintenance function
 * needs to decide whether to restart the daemon after a failure
 * based on whether or not it exited due to a fatal startup error
 * or something that happened at steady-state.  This exit status
 * is unlikely to collide with exit signals.
 */
#define DAEMON_STARTUP_ERROR 254

static apr_status_t create_process_manager(server_rec * main_server,
                                           apr_pool_t * configpool);

static int g_wakeup_timeout = 0;
static apr_proc_t *g_process_manager = NULL;
static apr_file_t *g_pm_read_pipe = NULL;
static apr_file_t *g_pm_write_pipe = NULL;
static apr_file_t *g_ap_write_pipe = NULL;
static apr_file_t *g_ap_read_pipe = NULL;
static apr_global_mutex_t *g_pipelock = NULL;
static const char *g_pipelock_name;
static const char *g_pipelock_mutex_type = "fcgid-pipe";

static int volatile g_caughtSigTerm = 0;
static pid_t g_pm_pid;
static void signal_handler(int signo)
{
    /* Sanity check, Make sure I am not the subprocess. A subprocess may
       get signale after fork() and before execve() */
    if (getpid() != g_pm_pid) {
        exit(0);
        return;
    }

    if ((signo == SIGTERM) || (signo == SIGUSR1) || (signo == SIGHUP)) {
        g_caughtSigTerm = 1;
        /* Tell the world it's time to die */
        proctable_get_globalshare()->must_exit = 1;
    }
}

static apr_status_t init_signal(server_rec * main_server)
{
    struct sigaction sa;

    /* Setup handlers */
    sa.sa_handler = signal_handler;
    sigemptyset(&sa.sa_mask);
    sa.sa_flags = 0;

    if (sigaction(SIGTERM, &sa, NULL) < 0) {
        ap_log_error(APLOG_MARK, APLOG_ERR, errno, main_server,
                     "mod_fcgid: Can't install SIGTERM handler");
        return APR_EGENERAL;
    }

    /* Httpd restart */
    if (sigaction(SIGHUP, &sa, NULL) < 0) {
        ap_log_error(APLOG_MARK, APLOG_ERR, errno, main_server,
                     "mod_fcgid: Can't install SIGHUP handler");
        return APR_EGENERAL;
    }

    /* Httpd graceful restart */
    if (sigaction(SIGUSR1, &sa, NULL) < 0) {
        ap_log_error(APLOG_MARK, APLOG_ERR, errno, main_server,
                     "mod_fcgid: Can't install SIGUSR1 handler");
        return APR_EGENERAL;
    }

    /* Ignore SIGPIPE */
    sa.sa_handler = SIG_IGN;
    if (sigaction(SIGPIPE, &sa, NULL) < 0) {
        ap_log_error(APLOG_MARK, APLOG_ERR, errno, main_server,
                     "mod_fcgid: Can't install SIGPIPE handler");
        return APR_EGENERAL;
    }

    return APR_SUCCESS;
}

static void fcgid_maint(int reason, void *data, apr_wait_t status)
{
    apr_proc_t *proc = data;
    int mpm_state;

    switch (reason) {
    case APR_OC_REASON_DEATH:
        apr_proc_other_child_unregister(data);
        if (ap_mpm_query(AP_MPMQ_MPM_STATE, &mpm_state) == APR_SUCCESS
            && mpm_state != AP_MPMQ_STOPPING) {
            if (status == DAEMON_STARTUP_ERROR) {
                ap_log_error(APLOG_MARK, APLOG_CRIT, 0, NULL,
                             "mod_fcgid: fcgid process manager failed to initialize; "
                             "stopping httpd");
                /* mod_fcgid requests will hang due to lack of a process manager;
                 * try to terminate httpd
                 */
                kill(getpid(), SIGTERM);

            }
            else {
                ap_log_error(APLOG_MARK, APLOG_ERR, 0, NULL,
                             "mod_fcgid: fcgid process manager died, restarting the server");

                /* HACK: I can't just call create_process_manager() to
                   restart a process manager, because it will use the dirty
                   share memory, I have to kill myself a SIGHUP, to make
                   a clean restart */
                /* FIXME: This is the httpd parent; mod_fcgid is doing a hard
                 * restart of the server!
                 */
                if (kill(getpid(), SIGHUP) < 0) {
                    ap_log_error(APLOG_MARK, APLOG_EMERG,
                                 apr_get_os_error(), NULL,
                                 "mod_fcgid: can't send SIGHUP to self");
                    exit(0);
                }
            }
        }
        break;
    case APR_OC_REASON_RESTART:
        apr_proc_other_child_unregister(data);
        break;
    case APR_OC_REASON_LOST:
        apr_proc_other_child_unregister(data);
        /* It hack here too, a note above */
        /* FIXME: This is the httpd parent; mod_fcgid is doing a hard
         * restart of the server!
         */
        if (kill(getpid(), SIGHUP) < 0) {
            ap_log_error(APLOG_MARK, APLOG_EMERG,
                         apr_get_os_error(), NULL,
                         "mod_fcgid: can't send SIGHUP to self");
            exit(0);
        }
        break;
    case APR_OC_REASON_UNREGISTER:
        /* I don't think it's going to happen */
        kill(proc->pid, SIGHUP);
        break;
    }
}

static int set_group_privs(void)
{
    if (!geteuid()) {
        const char *name;


        /* Get username if passed as a uid */
        if (ap_unixd_config.user_name[0] == '#') {
            struct passwd *ent;

            uid_t uid = atoi(&ap_unixd_config.user_name[1]);

            if ((ent = getpwuid(uid)) == NULL) {
                ap_log_error(APLOG_MARK, APLOG_ALERT, errno, NULL,
                             "getpwuid: couldn't determine user name from uid %u, "
                             "you probably need to modify the User directive",
                             (unsigned) uid);
                return -1;
            }
            name = ent->pw_name;
        }

        else
            name = ap_unixd_config.user_name;

#if !defined(OS2) && !defined(TPF)
        /* OS/2 and TPF don't support groups. */

        /*
         * Set the GID before initgroups(), since on some platforms
         * setgid() is known to zap the group list.
         */
        if (setgid(ap_unixd_config.group_id) == -1) {
            ap_log_error(APLOG_MARK, APLOG_ALERT, errno, NULL,
                         "setgid: unable to set group id to Group %u",
                         (unsigned) ap_unixd_config.group_id);
            return -1;
        }

        /* Reset `groups' attributes. */
        if (initgroups(name, ap_unixd_config.group_id) == -1) {
            ap_log_error(APLOG_MARK, APLOG_ALERT, errno, NULL,
                         "initgroups: unable to set groups for User %s "
                         "and Group %u", name,
                         (unsigned) ap_unixd_config.group_id);
            return -1;
        }
#endif                          /* !defined(OS2) && !defined(TPF) */
    }
    return 0;
}


/* Base on ap_unixd_setup_child() */
static int suexec_setup_child(void)
{
    if (set_group_privs()) {
        exit(-1);
    }

    /* Only try to switch if we're running as root */
    if (!geteuid() && (seteuid(ap_unixd_config.user_id) == -1)) {
        ap_log_error(APLOG_MARK, APLOG_ALERT, errno, NULL,
                     "seteuid: unable to change to uid %ld",
                     (long) ap_unixd_config.user_id);
        exit(-1);
    }
    return 0;
}

static apr_status_t
create_process_manager(server_rec * main_server, apr_pool_t * configpool)
{
    apr_status_t rv;

    g_process_manager =
        (apr_proc_t *) apr_pcalloc(configpool, sizeof(*g_process_manager));
    rv = apr_proc_fork(g_process_manager, configpool);
    if (rv == APR_INCHILD) {
        /* I am the child */
        g_pm_pid = getpid();
        ap_log_error(APLOG_MARK, APLOG_INFO, 0, main_server,
                     "mod_fcgid: Process manager %" APR_PID_T_FMT  " started", getpid());

        if ((rv = init_signal(main_server)) != APR_SUCCESS) {
            ap_log_error(APLOG_MARK, APLOG_EMERG, rv, main_server,
                         "mod_fcgid: can't install signal handler, exiting now");
            exit(DAEMON_STARTUP_ERROR);
        }

        /* If running as root, switch to configured user.
         *
         * When running children via suexec, only the effective uid is
         * switched, so that the PM can return to euid 0 to kill child
         * processes.
         *
         * When running children as the configured user, the real uid
         * is switched.
         */
        if (ap_unixd_config.suexec_enabled) {
            if (getuid() != 0) {
                ap_log_error(APLOG_MARK, APLOG_EMERG, 0, main_server,
                             "mod_fcgid: current user is not root while suexec is enabled, exiting now");
                exit(DAEMON_STARTUP_ERROR);
            }
            suexec_setup_child();
        } else
            ap_unixd_setup_child();
        apr_file_pipe_timeout_set(g_pm_read_pipe,
                                  apr_time_from_sec(g_wakeup_timeout));
        apr_file_close(g_ap_write_pipe);
        apr_file_close(g_ap_read_pipe);

        /* Initialize spawn controler */
        spawn_control_init(main_server, configpool);

        pm_main(main_server, configpool);

        ap_log_error(APLOG_MARK, APLOG_INFO, 0, main_server,
                     "mod_fcgid: Process manager %" APR_PID_T_FMT " stopped", getpid());
        exit(0);
    } else if (rv != APR_INPARENT) {
        ap_log_error(APLOG_MARK, APLOG_EMERG, rv, main_server,
                     "mod_fcgid: Create process manager error");
        exit(1);
    }

    /* I am the parent
       I will send the stop signal in procmgr_stop_procmgr() */
    apr_pool_note_subprocess(configpool, g_process_manager,
                             APR_KILL_ONLY_ONCE);
    apr_proc_other_child_register(g_process_manager, fcgid_maint,
                                  g_process_manager, NULL, configpool);

    return APR_SUCCESS;
}

apr_status_t
procmgr_child_init(server_rec * main_server, apr_pool_t * configpool)
{
    apr_status_t rv;

    if ((rv = apr_global_mutex_child_init(&g_pipelock,
                                          g_pipelock_name,
                                          main_server->process->pconf)) !=
        APR_SUCCESS) {
        ap_log_error(APLOG_MARK, APLOG_EMERG, rv, main_server,
                     "mod_fcgid: apr_global_mutex_child_init error for pipe mutex");
        exit(1);
    }

    return APR_SUCCESS;
}

apr_status_t procmgr_pre_config(apr_pool_t *p, apr_pool_t *plog,
                                apr_pool_t *ptemp)
{
    return fcgid_mutex_register(g_pipelock_mutex_type, p);
}

apr_status_t
procmgr_post_config(server_rec * main_server, apr_pool_t * configpool)
{
    apr_status_t rv;
    apr_finfo_t finfo;
    fcgid_server_conf *sconf = ap_get_module_config(main_server->module_config,
                                                    &fcgid_module);

    /* Calculate procmgr_peek_cmd wake up interval */
    g_wakeup_timeout = fcgid_min(sconf->error_scan_interval,
                                 sconf->busy_scan_interval);
    g_wakeup_timeout = fcgid_min(sconf->idle_scan_interval,
                                 g_wakeup_timeout);
    if (g_wakeup_timeout == 0)
        g_wakeup_timeout = 1;   /* Make it reasonable */

    rv = apr_stat(&finfo, sconf->sockname_prefix, APR_FINFO_USER,
                  configpool);
    if (rv != APR_SUCCESS) {
        /* Make dir for unix domain socket */
        if ((rv = apr_dir_make_recursive(sconf->sockname_prefix,
                                         APR_UREAD | APR_UWRITE |
                                         APR_UEXECUTE,
                                         configpool)) != APR_SUCCESS) {
            ap_log_error(APLOG_MARK, APLOG_ERR, rv, main_server,
                         "mod_fcgid: Can't create unix socket dir %s",
                         sconf->sockname_prefix);
            exit(1);
        }

        /* Child processes need to be able to create sockets in the unix
         * socket dir.  Change the ownership to the child user only if
         * running as root and we just successfully created the directory
         * (avoiding any concerns about changing the target of a link
         * created by another user).
         *
         * If the directory already existed and was owned by a different user,
         * FastCGI requests will fail at steady state, and manual intervention
         * will be required.
         */

        if (!geteuid()) {
            if (chown(sconf->sockname_prefix,
                      ap_unixd_config.user_id, -1) < 0) {
                ap_log_error(APLOG_MARK, APLOG_ERR, errno, main_server,
                             "mod_fcgid: Can't set ownership of unix socket dir %s",
                             sconf->sockname_prefix);
                exit(1);
            }
        }
    }

    /* Create pipes to communicate between process manager and apache */
    if ((rv = apr_file_pipe_create(&g_pm_read_pipe, &g_ap_write_pipe,
                                   configpool)) != APR_SUCCESS
        || (rv = apr_file_pipe_create(&g_ap_read_pipe, &g_pm_write_pipe,
                                      configpool))) {
        ap_log_error(APLOG_MARK, APLOG_ERR, rv, main_server,
                     "mod_fcgid: Can't create pipe between PM and stub");
        return rv;
    }

    /* Create mutex for pipe reading and writing */
    rv = fcgid_mutex_create(&g_pipelock, &g_pipelock_name,
                            g_pipelock_mutex_type,
                            main_server->process->pconf, main_server);
    if (rv != APR_SUCCESS) {
        exit(1);
    }

    /* Create process manager process */
    return create_process_manager(main_server, configpool);
}

void procmgr_init_spawn_cmd(fcgid_command * command, request_rec * r,
                            fcgid_cmd_conf *cmd_conf)
{
    ap_unix_identity_t *ugid;
    fcgid_server_conf *sconf =
        ap_get_module_config(r->server->module_config, &fcgid_module);

    memset(command, 0, sizeof(*command));

    /* suEXEC check */
    if ((ugid = ap_run_get_suexec_identity(r))) {
        command->uid = ugid->uid;
        command->gid = ugid->gid;
        command->userdir = ugid->userdir;
    } else {
        command->uid = (uid_t) - 1;
        command->gid = (gid_t) - 1;
        command->userdir = 0;
    }

    /* no truncation should ever occur */
    AP_DEBUG_ASSERT(sizeof command->cgipath > strlen(cmd_conf->cgipath));
    apr_cpystrn(command->cgipath, cmd_conf->cgipath, sizeof command->cgipath);
    AP_DEBUG_ASSERT(sizeof command->cmdline > strlen(cmd_conf->cmdline));
    apr_cpystrn(command->cmdline, cmd_conf->cmdline, sizeof command->cmdline);

    command->deviceid = cmd_conf->deviceid;
    command->inode = cmd_conf->inode;
    command->vhost_id = sconf->vhost_id;
    if (r->server->server_hostname) {
        apr_cpystrn(command->server_hostname, r->server->server_hostname,
                    sizeof command->server_hostname);
    }

    get_cmd_options(r, command->cgipath, &command->cmdopts, &command->cmdenv);
}

apr_status_t procmgr_post_spawn_cmd(fcgid_command * command,
                                    request_rec * r)
{
    apr_status_t rv;
    char notifybyte;
    apr_size_t nbytes = sizeof(*command);

    /* Get the global mutex before posting the request */
    if ((rv = apr_global_mutex_lock(g_pipelock)) != APR_SUCCESS) {
        ap_log_rerror(APLOG_MARK, APLOG_EMERG, rv, r,
                      "mod_fcgid: can't get pipe mutex");
        exit(0);
    }

    if ((rv =
         apr_file_write_full(g_ap_write_pipe, command, nbytes,
                             NULL)) != APR_SUCCESS) {
        /* Just print some error log and fall through */
        ap_log_rerror(APLOG_MARK, APLOG_WARNING, rv, r,
                      "mod_fcgid: can't write spawn command");
    } else {
        /* Wait the finish notify while send the request successfully */
        nbytes = sizeof(notifybyte);
        if ((rv =
             apr_file_read(g_ap_read_pipe, &notifybyte,
                           &nbytes)) != APR_SUCCESS) {
            ap_log_rerror(APLOG_MARK, APLOG_WARNING, rv, r,
                          "mod_fcgid: can't get notify from process manager");
        }
    }

    /* Release the lock */
    if ((rv = apr_global_mutex_unlock(g_pipelock)) != APR_SUCCESS) {
        ap_log_rerror(APLOG_MARK, APLOG_EMERG, rv, r,
                      "mod_fcgid: can't release pipe mutex");
        exit(0);
    }

    return APR_SUCCESS;
}

apr_status_t procmgr_finish_notify(server_rec * main_server)
{
    apr_status_t rv;
    char notifybyte = 'p';
    apr_size_t nbytes = sizeof(notifybyte);

    if ((rv =
         apr_file_write(g_pm_write_pipe, &notifybyte,
                        &nbytes)) != APR_SUCCESS) {
        ap_log_error(APLOG_MARK, APLOG_WARNING, rv, main_server,
                     "mod_fcgid: can't send notify from process manager");
    }

    return rv;
}

#define FOR_READ 1
apr_status_t procmgr_peek_cmd(fcgid_command * command,
                              server_rec * main_server)
{
    apr_status_t rv;

    /* Sanity check */
    if (!g_pm_read_pipe)
        return APR_EPIPE;

    /* Wait for next command */
#if APR_MAJOR_VERSION < 2
    rv = apr_wait_for_io_or_timeout(g_pm_read_pipe, NULL, FOR_READ);
#else
    rv = apr_file_pipe_wait(g_pm_read_pipe, APR_WAIT_READ);
#endif

    /* Log any unexpect result */
    if (rv != APR_SUCCESS && !APR_STATUS_IS_TIMEUP(rv)) {
        ap_log_error(APLOG_MARK, APLOG_WARNING, rv, main_server,
                     "mod_fcgid: error while waiting for message from pipe");
        return rv;
    }

    /* Timeout */
    if (rv != APR_SUCCESS)
        return rv;

    return apr_file_read_full(g_pm_read_pipe, command, sizeof(*command),
                              NULL);
}

int procmgr_must_exit()
{
    return g_caughtSigTerm;
}

apr_status_t procmgr_stop_procmgr(void *server)
{
    return APR_SUCCESS;
}