/*-
 * SPDX-License-Identifier: BSD-3-Clause AND BSD-2-Clause
 *
 * Copyright (c) 2002-2010 M. Warner Losh <imp@FreeBSD.org>
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * my_system is a variation on lib/libc/stdlib/system.c:
 *
 * Copyright (c) 1988, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

/*
 * DEVD control daemon.
 */

// TODO list:
//      o devd.conf and devd man pages need a lot of help:
//        - devd needs to document the unix domain socket
//        - devd.conf needs more details on the supported statements.

#include <sys/param.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/sysctl.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <sys/un.h>

#include <cctype>
#include <cerrno>
#include <cstdlib>
#include <cstdio>
#include <csignal>
#include <cstring>
#include <cstdarg>

#include <dirent.h>
#include <err.h>
#include <fcntl.h>
#include <libutil.h>
#include <paths.h>
#include <poll.h>
#include <regex.h>
#include <syslog.h>
#include <unistd.h>

#include <algorithm>
#include <map>
#include <string>
#include <list>
#include <stdexcept>
#include <vector>

#include "devd.h"               /* C compatible definitions */
#include "devd.hh"              /* C++ class definitions */

#define STREAMPIPE "/var/run/devd.pipe"
#define SEQPACKETPIPE "/var/run/devd.seqpacket.pipe"
#define CF "/etc/devd.conf"
#define SYSCTL "hw.bus.devctl_queue"

/*
 * Since the client socket is nonblocking, we must increase its send buffer to
 * handle brief event storms.  On FreeBSD, AF_UNIX sockets don't have a receive
 * buffer, so the client can't increase the buffersize by itself.
 *
 * For example, when creating a ZFS pool, devd emits one 165 character
 * resource.fs.zfs.statechange message for each vdev in the pool.  The kernel
 * allocates a 4608B mbuf for each message.  Modern technology places a limit of
 * roughly 450 drives/rack, and it's unlikely that a zpool will ever be larger
 * than that.
 *
 * 450 drives * 165 bytes / drive = 74250B of data in the sockbuf
 * 450 drives * 4608B / drive = 2073600B of mbufs in the sockbuf
 *
 * We can't directly set the sockbuf's mbuf limit, but we can do it indirectly.
 * The kernel sets it to the minimum of a hard-coded maximum value and sbcc *
 * kern.ipc.sockbuf_waste_factor, where sbcc is the socket buffer size set by
 * the user.  The default value of kern.ipc.sockbuf_waste_factor is 8.  If we
 * set the bufsize to 256k and use the kern.ipc.sockbuf_waste_factor, then the
 * kernel will set the mbuf limit to 2MB, which is just large enough for 450
 * drives.  It also happens to be the same as the hardcoded maximum value.
 */
#define CLIENT_BUFSIZE 262144

using namespace std;

typedef struct client {
        int fd;
        int socktype;
} client_t;

extern FILE *yyin;

static const char notify = '!';
static const char nomatch = '?';
static const char attach = '+';
static const char detach = '-';

static struct pidfh *pfh;

static int no_daemon = 0;
static int daemonize_quick = 0;
static int quiet_mode = 0;
static unsigned total_events = 0;
static volatile sig_atomic_t got_siginfo = 0;
static volatile sig_atomic_t romeo_must_die = 0;

static const char *configfile = CF;

static  char    vm_guest[80];

static void devdlog(int priority, const char* message, ...)
        __printflike(2, 3);
static void event_loop(void);
static void usage(void) __dead2;

template <class T> void
delete_and_clear(vector<T *> &v)
{
        typename vector<T *>::const_iterator i;

        for (i = v.begin(); i != v.end(); ++i)
                delete *i;
        v.clear();
}

static config cfg;

static const char *curr_cf = NULL;

event_proc::event_proc() : _prio(-1)
{
        _epsvec.reserve(4);
}

event_proc::~event_proc()
{
        delete_and_clear(_epsvec);
}

void
event_proc::add(eps *eps)
{
        _epsvec.push_back(eps);
}

bool
event_proc::matches(config &c) const
{
        vector<eps *>::const_iterator i;

        for (i = _epsvec.begin(); i != _epsvec.end(); ++i)
                if (!(*i)->do_match(c))
                        return (false);
        return (true);
}

bool
event_proc::run(config &c) const
{
        vector<eps *>::const_iterator i;

        for (i = _epsvec.begin(); i != _epsvec.end(); ++i)
                if (!(*i)->do_action(c))
                        return (false);
        return (true);
}

action::action(const char *cmd)
        : _cmd(cmd)
{
        // nothing
}

action::~action()
{
        // nothing
}

static int
my_system(const char *command)
{
        pid_t pid, savedpid;
        int pstat;
        struct sigaction ign, intact, quitact;
        sigset_t newsigblock, oldsigblock;

        if (!command)           /* just checking... */
                return (1);

        /*
         * Ignore SIGINT and SIGQUIT, block SIGCHLD. Remember to save
         * existing signal dispositions.
         */
        ign.sa_handler = SIG_IGN;
        ::sigemptyset(&ign.sa_mask);
        ign.sa_flags = 0;
        ::sigaction(SIGINT, &ign, &intact);
        ::sigaction(SIGQUIT, &ign, &quitact);
        ::sigemptyset(&newsigblock);
        ::sigaddset(&newsigblock, SIGCHLD);
        ::sigprocmask(SIG_BLOCK, &newsigblock, &oldsigblock);
        switch (pid = ::fork()) {
        case -1:                        /* error */
                break;
        case 0:                         /* child */
                /*
                 * Restore original signal dispositions and exec the command.
                 */
                ::sigaction(SIGINT, &intact, NULL);
                ::sigaction(SIGQUIT,  &quitact, NULL);
                ::sigprocmask(SIG_SETMASK, &oldsigblock, NULL);
                /*
                 * Close the PID file, and all other open descriptors.
                 * Inherit std{in,out,err} only.
                 */
                cfg.close_pidfile();
                ::closefrom(3);
                ::execl(_PATH_BSHELL, "sh", "-c", command, (char *)NULL);
                ::_exit(127);
        default:                        /* parent */
                savedpid = pid;
                do {
                        pid = ::wait4(savedpid, &pstat, 0, (struct rusage *)0);
                } while (pid == -1 && errno == EINTR);
                break;
        }
        ::sigaction(SIGINT, &intact, NULL);
        ::sigaction(SIGQUIT,  &quitact, NULL);
        ::sigprocmask(SIG_SETMASK, &oldsigblock, NULL);
        return (pid == -1 ? -1 : pstat);
}

bool
action::do_action(config &c)
{
        string s = c.expand_string(_cmd.c_str());
        devdlog(LOG_INFO, "Executing '%s'\n", s.c_str());
        my_system(s.c_str());
        return (true);
}

match::match(config &c, const char *var, const char *re) :
        _inv(re[0] == '!'),
        _var(var),
        _re(c.expand_string(_inv ? re + 1 : re, "^", "$"))
{
        regcomp(&_regex, _re.c_str(), REG_EXTENDED | REG_NOSUB | REG_ICASE);
}

match::~match()
{
        regfree(&_regex);
}

bool
match::do_match(config &c)
{
        const string &value = c.get_variable(_var);
        bool retval;

        /*
         * This function gets called WAY too often to justify calling syslog()
         * each time, even at LOG_DEBUG.  Because if syslogd isn't running, it
         * can consume excessive amounts of systime inside of connect().  Only
         * log when we're in -d mode.
         */
        if (no_daemon) {
                devdlog(LOG_DEBUG, "Testing %s=%s against %s, invert=%d\n",
                    _var.c_str(), value.c_str(), _re.c_str(), _inv);
        }

        retval = (regexec(&_regex, value.c_str(), 0, NULL, 0) == 0);
        if (_inv == 1)
                retval = (retval == 0) ? 1 : 0;

        return (retval);
}

#include <sys/sockio.h>
#include <net/if.h>
#include <net/if_media.h>

media::media(config &, const char *var, const char *type)
        : _var(var), _type(-1)
{
        static struct ifmedia_description media_types[] = {
                { IFM_ETHER,            "Ethernet" },
                { IFM_IEEE80211,        "802.11" },
                { IFM_ATM,              "ATM" },
                { -1,                   "unknown" },
                { 0, NULL },
        };
        for (int i = 0; media_types[i].ifmt_string != NULL; ++i)
                if (strcasecmp(type, media_types[i].ifmt_string) == 0) {
                        _type = media_types[i].ifmt_word;
                        break;
                }
}

media::~media()
{
}

bool
media::do_match(config &c)
{
        string value;
        struct ifmediareq ifmr;
        bool retval;
        int s;

        // Since we can be called from both a device attach/detach
        // context where device-name is defined and what we want,
        // as well as from a link status context, where subsystem is
        // the name of interest, first try device-name and fall back
        // to subsystem if none exists.
        value = c.get_variable("device-name");
        if (value.empty())
                value = c.get_variable("subsystem");
        devdlog(LOG_DEBUG, "Testing media type of %s against 0x%x\n",
                    value.c_str(), _type);

        retval = false;

        s = socket(PF_INET, SOCK_DGRAM, 0);
        if (s >= 0) {
                memset(&ifmr, 0, sizeof(ifmr));
                strlcpy(ifmr.ifm_name, value.c_str(), sizeof(ifmr.ifm_name));

                if (ioctl(s, SIOCGIFMEDIA, (caddr_t)&ifmr) >= 0 &&
                    ifmr.ifm_status & IFM_AVALID) {
                        devdlog(LOG_DEBUG, "%s has media type 0x%x\n",
                                    value.c_str(), IFM_TYPE(ifmr.ifm_active));
                        retval = (IFM_TYPE(ifmr.ifm_active) == _type);
                } else if (_type == -1) {
                        devdlog(LOG_DEBUG, "%s has unknown media type\n",
                                    value.c_str());
                        retval = true;
                }
                close(s);
        }

        return (retval);
}

const string var_list::bogus = "_$_$_$_$_B_O_G_U_S_$_$_$_$_";
const string var_list::nothing = "";

const string &
var_list::get_variable(const string &var) const
{
        map<string, string>::const_iterator i;

        i = _vars.find(var);
        if (i == _vars.end())
                return (var_list::bogus);
        return (i->second);
}

bool
var_list::is_set(const string &var) const
{
        return (_vars.find(var) != _vars.end());
}

/** fix_value
 *
 * Removes quoted characters that have made it this far. \" are
 * converted to ". For all other characters, both \ and following
 * character. So the string 'fre\:\"' is translated to 'fred\:"'.
 */
std::string
var_list::fix_value(const std::string &val) const
{
        std::string rv(val);
        std::string::size_type pos(0);

        while ((pos = rv.find("\\\"", pos)) != rv.npos) {
                rv.erase(pos, 1);
        }
        return (rv);
}

void
var_list::set_variable(const string &var, const string &val)
{
        /*
         * This function gets called WAY too often to justify calling syslog()
         * each time, even at LOG_DEBUG.  Because if syslogd isn't running, it
         * can consume excessive amounts of systime inside of connect().  Only
         * log when we're in -d mode.
         */
        _vars[var] = fix_value(val);
        if (no_daemon)
                devdlog(LOG_DEBUG, "setting %s=%s\n", var.c_str(), val.c_str());
}

void
config::reset(void)
{
        _dir_list.clear();
        delete_and_clear(_var_list_table);
        delete_and_clear(_attach_list);
        delete_and_clear(_detach_list);
        delete_and_clear(_nomatch_list);
        delete_and_clear(_notify_list);
}

/*
 * Called recursively as new files are included, so current stack of old names
 * saved in each instance of 'old' on the call stack. Called single threaded
 * so global varaibles curr_cf and lineno (and all of yacc's parser state)
 * are safe to access w/o a lock.
 */
void
config::parse_one_file(const char *fn)
{
        const char *old;

        devdlog(LOG_DEBUG, "Parsing %s\n", fn);
        yyin = fopen(fn, "r");
        old = curr_cf;
        curr_cf = fn;
        if (yyin == NULL)
                err(1, "Cannot open config file %s", fn);
        lineno = 1;
        if (yyparse() != 0)
                errx(1, "Cannot parse %s at line %d", fn, lineno);
        fclose(yyin);
        curr_cf = old;
}

void
config::parse_files_in_dir(const char *dirname)
{
        DIR *dirp;
        struct dirent *dp;
        char path[PATH_MAX];

        devdlog(LOG_DEBUG, "Parsing files in %s\n", dirname);
        dirp = opendir(dirname);
        if (dirp == NULL)
                return;
        readdir(dirp);          /* Skip . */
        readdir(dirp);          /* Skip .. */
        while ((dp = readdir(dirp)) != NULL) {
                if (strcmp(dp->d_name + dp->d_namlen - 5, ".conf") == 0) {
                        snprintf(path, sizeof(path), "%s/%s",
                            dirname, dp->d_name);
                        parse_one_file(path);
                }
        }
        closedir(dirp);
}

class epv_greater {
public:
        int operator()(event_proc *const&l1, event_proc *const&l2) const
        {
                return (l1->get_priority() > l2->get_priority());
        }
};

void
config::sort_vector(vector<event_proc *> &v)
{
        stable_sort(v.begin(), v.end(), epv_greater());
}

void
config::parse(void)
{
        vector<string>::const_iterator i;

        parse_one_file(configfile);
        for (i = _dir_list.begin(); i != _dir_list.end(); ++i)
                parse_files_in_dir((*i).c_str());
        sort_vector(_attach_list);
        sort_vector(_detach_list);
        sort_vector(_nomatch_list);
        sort_vector(_notify_list);
}

void
config::open_pidfile()
{
        pid_t otherpid;

        if (_pidfile.empty())
                return;
        pfh = pidfile_open(_pidfile.c_str(), 0600, &otherpid);
        if (pfh == NULL) {
                if (errno == EEXIST)
                        errx(1, "devd already running, pid: %d", (int)otherpid);
                warn("cannot open pid file");
        }
}

void
config::write_pidfile()
{

        pidfile_write(pfh);
}

void
config::close_pidfile()
{

        pidfile_close(pfh);
}

void
config::remove_pidfile()
{

        pidfile_remove(pfh);
}

void
config::add_attach(int prio, event_proc *p)
{
        p->set_priority(prio);
        _attach_list.push_back(p);
}

void
config::add_detach(int prio, event_proc *p)
{
        p->set_priority(prio);
        _detach_list.push_back(p);
}

void
config::add_directory(const char *dir)
{
        _dir_list.push_back(string(dir));
}

void
config::add_nomatch(int prio, event_proc *p)
{
        p->set_priority(prio);
        _nomatch_list.push_back(p);
}

void
config::add_notify(int prio, event_proc *p)
{
        p->set_priority(prio);
        _notify_list.push_back(p);
}

void
config::set_pidfile(const char *fn)
{
        _pidfile = fn;
}

void
config::push_var_table()
{
        var_list *vl;

        vl = new var_list();
        _var_list_table.push_back(vl);
        devdlog(LOG_DEBUG, "Pushing table\n");
}

void
config::pop_var_table()
{
        delete _var_list_table.back();
        _var_list_table.pop_back();
        devdlog(LOG_DEBUG, "Popping table\n");
}

void
config::set_variable(const char *var, const char *val)
{
        _var_list_table.back()->set_variable(var, val);
}

const string &
config::get_variable(const string &var)
{
        vector<var_list *>::reverse_iterator i;

        for (i = _var_list_table.rbegin(); i != _var_list_table.rend(); ++i) {
                if ((*i)->is_set(var))
                        return ((*i)->get_variable(var));
        }
        return (var_list::nothing);
}

bool
config::is_id_char(char ch) const
{
        return (ch != '\0' && (isalpha(ch) || isdigit(ch) || ch == '_' ||
            ch == '-'));
}

string
config::shell_quote(const string &s)
{
        string buffer;
        const char *cs, *ce;
        char c;

        /*
         * Enclose the string in $' ' with escapes for ' and / characters making
         * it one argument and ensuring the shell won't be affected by its
         * usual list of candidates.
         */
        buffer.reserve(s.length() * 3 / 2);
        buffer += '$';
        buffer += '\'';
        cs = s.c_str();
        ce = cs + strlen(cs);
        for (; cs < ce; cs++) {
                c = *cs;
                if (c == '\'' || c == '\\') {
                        buffer += '\\';
                }
                buffer += c;
        }
        buffer += '\'';

        return buffer;
}

void
config::expand_one(const char *&src, string &dst, bool is_shell)
{
        int count;
        string buffer;

        src++;
        // $$ -> $
        if (*src == '$') {
                dst += *src++;
                return;
        }

        // $(foo) -> $(foo)
        // This is the escape hatch for passing down shell subcommands
        if (*src == '(') {
                dst += '$';
                count = 0;
                /* If the string ends before ) is matched , return. */
                do {
                        if (*src == ')')
                                count--;
                        else if (*src == '(')
                                count++;
                        dst += *src++;
                } while (count > 0 && *src);
                return;
        }

        // $[^-A-Za-z_*] -> $\1
        if (!isalpha(*src) && *src != '_' && *src != '-' && *src != '*') {
                dst += '$';
                dst += *src++;
                return;
        }

        // $var -> replace with value
        do {
                buffer += *src++;
        } while (is_id_char(*src));
        dst.append(is_shell ? shell_quote(get_variable(buffer)) : get_variable(buffer));
}

const string
config::expand_string(const char *src, const char *prepend, const char *append)
{
        const char *var_at;
        string dst;

        /*
         * 128 bytes is enough for 2427 of 2438 expansions that happen
         * while parsing config files, as tested on 2013-01-30.
         */
        dst.reserve(128);

        if (prepend != NULL)
                dst = prepend;

        for (;;) {
                var_at = strchr(src, '$');
                if (var_at == NULL) {
                        dst.append(src);
                        break;
                }
                dst.append(src, var_at - src);
                src = var_at;
                expand_one(src, dst, prepend == NULL);
        }

        if (append != NULL)
                dst.append(append);

        return (dst);
}

bool
config::chop_var(char *&buffer, char *&lhs, char *&rhs) const
{
        char *walker;

        if (*buffer == '\0')
                return (false);
        walker = lhs = buffer;
        while (is_id_char(*walker))
                walker++;
        if (*walker != '=')
                return (false);
        walker++;               // skip =
        if (*walker == '"') {
                walker++;       // skip "
                rhs = walker;
                while (*walker && *walker != '"') {
                        // Skip \" ... We leave it in the string and strip the \ later.
                        // due to the super simplistic parser that we have here.
                        if (*walker == '\\' && walker[1] == '"')
                                walker++;
                        walker++;
                }
                if (*walker != '"')
                        return (false);
                rhs[-2] = '\0';
                *walker++ = '\0';
        } else {
                rhs = walker;
                while (*walker && !isspace(*walker))
                        walker++;
                if (*walker != '\0')
                        *walker++ = '\0';
                rhs[-1] = '\0';
        }
        while (isspace(*walker))
                walker++;
        buffer = walker;
        return (true);
}


char *
config::set_vars(char *buffer)
{
        char *lhs;
        char *rhs;

        while (1) {
                if (!chop_var(buffer, lhs, rhs))
                        break;
                set_variable(lhs, rhs);
        }
        return (buffer);
}

void
config::find_and_execute(char type)
{
        vector<event_proc *> *l;
        vector<event_proc *>::const_iterator i;
        const char *s;

        switch (type) {
        default:
                return;
        case notify:
                l = &_notify_list;
                s = "notify";
                break;
        case nomatch:
                l = &_nomatch_list;
                s = "nomatch";
                break;
        case attach:
                l = &_attach_list;
                s = "attach";
                break;
        case detach:
                l = &_detach_list;
                s = "detach";
                break;
        }
        devdlog(LOG_DEBUG, "Processing %s event\n", s);
        for (i = l->begin(); i != l->end(); ++i) {
                if ((*i)->matches(*this)) {
                        (*i)->run(*this);
                        break;
                }
        }

}


static void
process_event(char *buffer)
{
        char type;
        char *sp;
        struct timeval tv;
        char *timestr;

        sp = buffer + 1;
        devdlog(LOG_INFO, "Processing event '%s'\n", buffer);
        type = *buffer++;
        cfg.push_var_table();
        // $* is the entire line
        cfg.set_variable("*", buffer - 1);
        // $_ is the entire line without the initial character
        cfg.set_variable("_", buffer);

        // Save the time this happened (as approximated by when we got
        // around to processing it).
        gettimeofday(&tv, NULL);
        asprintf(&timestr, "%jd.%06ld", (uintmax_t)tv.tv_sec, tv.tv_usec);
        cfg.set_variable("timestamp", timestr);
        free(timestr);

        cfg.set_variable("vm_guest", vm_guest);

        // Match doesn't have a device, and the format is a little
        // different, so handle it separately.
        switch (type) {
        case notify:
                //! (k=v)*
                sp = cfg.set_vars(sp);
                break;
        case nomatch:
                //? at location pnp-info on bus
                sp = strchr(sp, ' ');
                if (sp == NULL)
                        return; /* Can't happen? */
                *sp++ = '\0';
                while (isspace(*sp))
                        sp++;
                if (strncmp(sp, "at ", 3) == 0)
                        sp += 3;
                sp = cfg.set_vars(sp);
                while (isspace(*sp))
                        sp++;
                if (strncmp(sp, "on ", 3) == 0)
                        cfg.set_variable("bus", sp + 3);
                break;
        case attach:    /*FALLTHROUGH*/
        case detach:
                sp = strchr(sp, ' ');
                if (sp == NULL)
                        return; /* Can't happen? */
                *sp++ = '\0';
                cfg.set_variable("device-name", buffer);
                while (isspace(*sp))
                        sp++;
                if (strncmp(sp, "at ", 3) == 0)
                        sp += 3;
                sp = cfg.set_vars(sp);
                while (isspace(*sp))
                        sp++;
                if (strncmp(sp, "on ", 3) == 0)
                        cfg.set_variable("bus", sp + 3);
                break;
        }

        cfg.find_and_execute(type);
        cfg.pop_var_table();
}

static int
create_socket(const char *name, int socktype)
{
        int fd, slen;
        struct sockaddr_un sun;

        if ((fd = socket(PF_LOCAL, socktype, 0)) < 0)
                err(1, "socket");
        bzero(&sun, sizeof(sun));
        sun.sun_family = AF_UNIX;
        strlcpy(sun.sun_path, name, sizeof(sun.sun_path));
        slen = SUN_LEN(&sun);
        unlink(name);
        if (fcntl(fd, F_SETFL, O_NONBLOCK) < 0)
                err(1, "fcntl");
        if (::bind(fd, (struct sockaddr *) & sun, slen) < 0)
                err(1, "bind");
        listen(fd, 4);
        if (chown(name, 0, 0))  /* XXX - root.wheel */
                err(1, "chown");
        if (chmod(name, 0666))
                err(1, "chmod");
        return (fd);
}

static unsigned int max_clients = 50;   /* Default, can be overridden on cmdline. */
static unsigned int num_clients;

static list<client_t> clients;

static void
notify_clients(const char *data, int len)
{
        list<client_t>::iterator i;

        /*
         * Deliver the data to all clients.  Throw clients overboard at the
         * first sign of trouble.  This reaps clients who've died or closed
         * their sockets, and also clients who are alive but failing to keep up
         * (or who are maliciously not reading, to consume buffer space in
         * kernel memory or tie up the limited number of available connections).
         */
        for (i = clients.begin(); i != clients.end(); ) {
                int flags;
                if (i->socktype == SOCK_SEQPACKET)
                        flags = MSG_EOR;
                else
                        flags = 0;

                if (send(i->fd, data, len, flags) != len) {
                        --num_clients;
                        close(i->fd);
                        i = clients.erase(i);
                        devdlog(LOG_WARNING, "notify_clients: send() failed; "
                            "dropping unresponsive client\n");
                } else
                        ++i;
        }
}

static void
check_clients(void)
{
        int s;
        struct pollfd pfd;
        list<client_t>::iterator i;

        /*
         * Check all existing clients to see if any of them have disappeared.
         * Normally we reap clients when we get an error trying to send them an
         * event.  This check eliminates the problem of an ever-growing list of
         * zombie clients because we're never writing to them on a system
         * without frequent device-change activity.
         */
        pfd.events = 0;
        for (i = clients.begin(); i != clients.end(); ) {
                pfd.fd = i->fd;
                s = poll(&pfd, 1, 0);
                if ((s < 0 && s != EINTR ) ||
                    (s > 0 && (pfd.revents & POLLHUP))) {
                        --num_clients;
                        close(i->fd);
                        i = clients.erase(i);
                        devdlog(LOG_NOTICE, "check_clients:  "
                            "dropping disconnected client\n");
                } else
                        ++i;
        }
}

static void
new_client(int fd, int socktype)
{
        client_t s;
        int sndbuf_size;

        /*
         * First go reap any zombie clients, then accept the connection, and
         * shut down the read side to stop clients from consuming kernel memory
         * by sending large buffers full of data we'll never read.
         */
        check_clients();
        s.socktype = socktype;
        s.fd = accept(fd, NULL, NULL);
        if (s.fd != -1) {
                sndbuf_size = CLIENT_BUFSIZE;
                if (setsockopt(s.fd, SOL_SOCKET, SO_SNDBUF, &sndbuf_size,
                    sizeof(sndbuf_size)))
                        err(1, "setsockopt");
                shutdown(s.fd, SHUT_RD);
                clients.push_back(s);
                ++num_clients;
        } else
                err(1, "accept");
}

static void
event_loop(void)
{
        int rv;
        int fd;
        char buffer[DEVCTL_MAXBUF];
        int once = 0;
        int stream_fd, seqpacket_fd, max_fd;
        int accepting;
        timeval tv;
        fd_set fds;

        fd = open(PATH_DEVCTL, O_RDONLY | O_CLOEXEC);
        if (fd == -1)
                err(1, "Can't open devctl device %s", PATH_DEVCTL);
        stream_fd = create_socket(STREAMPIPE, SOCK_STREAM);
        seqpacket_fd = create_socket(SEQPACKETPIPE, SOCK_SEQPACKET);
        accepting = 1;
        max_fd = max(fd, max(stream_fd, seqpacket_fd)) + 1;
        while (!romeo_must_die) {
                if (!once && !no_daemon && !daemonize_quick) {
                        // Check to see if we have any events pending.
                        tv.tv_sec = 0;
                        tv.tv_usec = 0;
                        FD_ZERO(&fds);
                        FD_SET(fd, &fds);
                        rv = select(fd + 1, &fds, NULL, NULL, &tv);
                        // No events -> we've processed all pending events
                        if (rv == 0) {
                                devdlog(LOG_DEBUG, "Calling daemon\n");
                                cfg.remove_pidfile();
                                cfg.open_pidfile();
                                daemon(0, 0);
                                cfg.write_pidfile();
                                once++;
                        }
                }
                /*
                 * When we've already got the max number of clients, stop
                 * accepting new connections (don't put the listening sockets in
                 * the set), shrink the accept() queue to reject connections
                 * quickly, and poll the existing clients more often, so that we
                 * notice more quickly when any of them disappear to free up
                 * client slots.
                 */
                FD_ZERO(&fds);
                FD_SET(fd, &fds);
                if (num_clients < max_clients) {
                        if (!accepting) {
                                listen(stream_fd, max_clients);
                                listen(seqpacket_fd, max_clients);
                                accepting = 1;
                        }
                        FD_SET(stream_fd, &fds);
                        FD_SET(seqpacket_fd, &fds);
                        tv.tv_sec = 60;
                        tv.tv_usec = 0;
                } else {
                        if (accepting) {
                                listen(stream_fd, 0);
                                listen(seqpacket_fd, 0);
                                accepting = 0;
                        }
                        tv.tv_sec = 2;
                        tv.tv_usec = 0;
                }
                rv = select(max_fd, &fds, NULL, NULL, &tv);
                if (got_siginfo) {
                        devdlog(LOG_NOTICE, "Events received so far=%u\n",
                            total_events);
                        got_siginfo = 0;
                }
                if (rv == -1) {
                        if (errno == EINTR)
                                continue;
                        err(1, "select");
                } else if (rv == 0)
                        check_clients();
                /*
                 * Aside from the socket type, both sockets use the same
                 * protocol, so we can process clients the same way.
                 */
                if (FD_ISSET(stream_fd, &fds))
                        new_client(stream_fd, SOCK_STREAM);
                if (FD_ISSET(seqpacket_fd, &fds))
                        new_client(seqpacket_fd, SOCK_SEQPACKET);
                if (FD_ISSET(fd, &fds)) {
                        rv = read(fd, buffer, sizeof(buffer) - 1);
                        if (rv > 0) {
                                total_events++;
                                if (rv == sizeof(buffer) - 1) {
                                        devdlog(LOG_WARNING, "Warning: "
                                            "available event data exceeded "
                                            "buffer space\n");
                                }
                                notify_clients(buffer, rv);
                                buffer[rv] = '\0';
                                while (buffer[--rv] == '\n')
                                        buffer[rv] = '\0';
                                try {
                                        process_event(buffer);
                                }
                                catch (const std::length_error& e) {
                                        devdlog(LOG_ERR, "Dropping event %s "
                                            "due to low memory", buffer);
                                }
                        } else if (rv < 0) {
                                if (errno != EINTR)
                                        break;
                        } else {
                                /* EOF */
                                break;
                        }
                }
        }
        cfg.remove_pidfile();
        close(seqpacket_fd);
        close(stream_fd);
        close(fd);
}

/*
 * functions that the parser uses.
 */
void
add_attach(int prio, event_proc *p)
{
        cfg.add_attach(prio, p);
}

void
add_detach(int prio, event_proc *p)
{
        cfg.add_detach(prio, p);
}

void
add_directory(const char *dir)
{
        cfg.add_directory(dir);
        free(const_cast<char *>(dir));
}

void
add_nomatch(int prio, event_proc *p)
{
        cfg.add_nomatch(prio, p);
}

void
add_notify(int prio, event_proc *p)
{
        cfg.add_notify(prio, p);
}

event_proc *
add_to_event_proc(event_proc *ep, eps *eps)
{
        if (ep == NULL)
                ep = new event_proc();
        ep->add(eps);
        return (ep);
}

eps *
new_action(const char *cmd)
{
        eps *e = new action(cmd);
        free(const_cast<char *>(cmd));
        return (e);
}

eps *
new_match(const char *var, const char *re)
{
        eps *e = new match(cfg, var, re);
        free(const_cast<char *>(var));
        free(const_cast<char *>(re));
        return (e);
}

eps *
new_media(const char *var, const char *re)
{
        eps *e = new media(cfg, var, re);
        free(const_cast<char *>(var));
        free(const_cast<char *>(re));
        return (e);
}

void
set_pidfile(const char *name)
{
        cfg.set_pidfile(name);
        free(const_cast<char *>(name));
}

void
set_variable(const char *var, const char *val)
{
        cfg.set_variable(var, val);
        free(const_cast<char *>(var));
        free(const_cast<char *>(val));
}



static void
gensighand(int)
{
        romeo_must_die = 1;
}

/*
 * SIGINFO handler.  Will print useful statistics to the syslog or stderr
 * as appropriate
 */
static void
siginfohand(int)
{
        got_siginfo = 1;
}

/*
 * Local logging function.  Prints to syslog if we're daemonized; stderr
 * otherwise.
 */
static void
devdlog(int priority, const char* fmt, ...)
{
        va_list argp;

        va_start(argp, fmt);
        if (no_daemon)
                vfprintf(stderr, fmt, argp);
        else if (quiet_mode == 0 || priority <= LOG_WARNING)
                vsyslog(priority, fmt, argp);
        va_end(argp);
}

static void
usage()
{
        fprintf(stderr, "usage: %s [-dnq] [-l connlimit] [-f file]\n",
            getprogname());
        exit(1);
}

static void
check_devd_enabled()
{
        int val = 0;
        size_t len;

        len = sizeof(val);
        if (sysctlbyname(SYSCTL, &val, &len, NULL, 0) != 0)
                errx(1, "devctl sysctl missing from kernel!");
        if (val == 0) {
                warnx("Setting " SYSCTL " to 1000");
                val = 1000;
                if (sysctlbyname(SYSCTL, NULL, NULL, &val, sizeof(val)))
                        err(1, "sysctlbyname");
        }
}

/*
 * main
 */
int
main(int argc, char **argv)
{
        int ch;
        size_t len;

        check_devd_enabled();
        while ((ch = getopt(argc, argv, "df:l:nq")) != -1) {
                switch (ch) {
                case 'd':
                        no_daemon = 1;
                        break;
                case 'f':
                        configfile = optarg;
                        break;
                case 'l':
                        max_clients = MAX(1, strtoul(optarg, NULL, 0));
                        break;
                case 'n':
                        daemonize_quick = 1;
                        break;
                case 'q':
                        quiet_mode = 1;
                        break;
                default:
                        usage();
                }
        }

        len = sizeof(vm_guest);
        if (sysctlbyname("kern.vm_guest", vm_guest, &len, NULL, 0) < 0) {
                devdlog(LOG_ERR,
                    "sysctlbyname(kern.vm_guest) failed: %d\n", errno);
        }

        cfg.parse();
        if (!no_daemon && daemonize_quick) {
                cfg.open_pidfile();
                daemon(0, 0);
                cfg.write_pidfile();
        }
        signal(SIGPIPE, SIG_IGN);
        signal(SIGHUP, gensighand);
        signal(SIGINT, gensighand);
        signal(SIGTERM, gensighand);
        signal(SIGINFO, siginfohand);
        event_loop();
        return (0);
}