audiod: Skip NULL pointer check in compute_time_diff().

[paraslash.git] / audiod.c

/*
 * Copyright (C) 2005-2014 Andre Noll <maan@systemlinux.org>
 *
 * Licensed under the GPL v2. For licencing details see COPYING.
 */

/** \file audiod.c The paraslash's audio daemon. */
#include <regex.h>
#include <sys/types.h>
#include <signal.h>

#include "para.h"
#include "error.h"
#include "crypt.h"
#include "audiod.cmdline.h"
#include "list.h"
#include "sched.h"
#include "ggo.h"
#include "buffer_tree.h"
#include "recv.h"
#include "filter.h"
#include "grab_client.h"
#include "client.cmdline.h"
#include "client.h"
#include "audiod.h"
#include "net.h"
#include "daemon.h"
#include "string.h"
#include "fd.h"
#include "write.h"
#include "write_common.h"
#include "signal.h"
#include "version.h"

__printf_2_3 void (*para_log)(int, const char*, ...) = daemon_log;
/** define the array of error lists needed by para_audiod */
INIT_AUDIOD_ERRLISTS;
/** define the array containing all supported audio formats */
const char *audio_formats[] = {AUDIOD_AUDIO_FORMAT_ARRAY NULL};

DEFINE_RECEIVER_ARRAY;

/** Defines how audiod handles one supported audio format. */
struct audio_format_info {
        /** pointer to the receiver for this audio format */
        struct receiver *receiver;
        /** the receiver configuration */
        void *receiver_conf;
        /** the number of filters that should be activated for this audio format */
        unsigned int num_filters;
        /** Array of filter numbers to be activated. */
        unsigned *filter_nums;
        /** Pointer to the array of filter configurations. */
        void **filter_conf;
        /** the number of filters that should be activated for this audio format */
        unsigned int num_writers;
        /** Array of writer numbers to be activated. */
        int *writer_nums;
        /** pointer to the array of writer configurations */
        void **writer_conf;
        /** do not start receiver/filters/writer before this time */
        struct timeval restart_barrier;
};

/**
 * para_audiod uses \p MAX_STREAM_SLOTS different slots, each of which may
 * be associated with a receiver/filter/writer triple. This array holds all
 * information on the status of these slots.
 *
 * \sa struct slot_info
 * */
struct slot_info slot[MAX_STREAM_SLOTS];

/** The vss status flags audiod is interested in. */
enum vss_status_flags {
        /** Whether the 'N' flag is set. */
        VSS_STATUS_FLAG_NEXT = 1,
        /** The 'P' flag is set. */
        VSS_STATUS_FLAG_PLAYING = 2,
};

/**
 * The scheduler instance of para_audiod.
 *
 * This is needed also in audiod_command.c (for the tasks command), so it can
 * not be made static.
 */
struct sched sched = {.max_fileno = 0};

/**
 * The task for obtaining para_server's status (para_client stat).
 *
 * \sa struct task, struct sched.
 */
struct status_task {
        /** The associated task structure of audiod. */
        struct task task;
        /** Client data associated with the stat task. */
        struct client_task *ct;
        /** Do not restart client command until this time. */
        struct timeval restart_barrier;
        /** Last time we received status data from para_server. */
        struct timeval last_status_read;
        size_t min_iqs;
        /** The offset value announced by para_server. */
        int offset_seconds;
        /** The length of the current audio file as announced by para_server. */
        int length_seconds;
        /** The start of the current stream from the view of para_server. */
        struct timeval server_stream_start;
        /** The average time deviation between para_server and para_audiod. */
        struct timeval sa_time_diff;
        /** Whether client time is ahead of server time. */
        int sa_time_diff_sign;
        /** The 'P' and the 'N' flags as announced by para_server. */
        enum vss_status_flags vss_status;
        /** Number of times the clock difference is to be checked. */
        unsigned clock_diff_count;
        /** When to start the next check for clock difference. */
        struct timeval clock_diff_barrier;
        /** Number of the audio format as announced by para_server. */
        int current_audio_format_num;
        /* The status task btrn is the child of the client task. */
        struct btr_node *btrn;
};

/** The array of status items sent by para_server. */
char *stat_item_values[NUM_STAT_ITEMS] = {NULL};

/**
 * the current mode of operation of which can be changed by the on/off/cycle
 * commands. It is either, AUDIOD_OFF, AUDIOD_ON or AUDIOD_STANDBY.
 */
int audiod_status = AUDIOD_ON;

/**
 * the gengetopt args_info struct that holds information on all command line
 * arguments
 */
struct audiod_args_info conf;

static char *socket_name;
static struct audio_format_info afi[NUM_AUDIO_FORMATS];

static struct signal_task signal_task_struct, *sig_task = &signal_task_struct;

static struct status_task status_task_struct;

/**
 * the task that calls the status command of para_server
 *
 * \sa struct status_task
 */
static struct status_task *stat_task = &status_task_struct;

/**
 * the task for handling audiod commands
 *
 * \sa struct task, struct sched
 */
struct command_task {
        /** the local listening socket */
        int fd;
        /** the associated task structure */
        struct task task;
};

/** iterate over all supported audio formats */
#define FOR_EACH_AUDIO_FORMAT(af) for (af = 0; af < NUM_AUDIO_FORMATS; af++)

/**
 * Get the audio format number.
 *
 * \param name The name of the audio format.
 *
 * \return The audio format number on success, -E_UNSUPPORTED_AUDIO_FORMAT if
 * \a name is not a supported audio format.
 */
static int get_audio_format_num(const char *name)
{
        int i;

        while (para_isspace(*name))
                name++;
        FOR_EACH_AUDIO_FORMAT(i)
                if (!strcmp(name, audio_formats[i]))
                        return i;
        return -E_UNSUPPORTED_AUDIO_FORMAT;
}

static int get_matching_audio_format_nums(const char *re)
{
        int i, ret;
        regex_t preg;

        ret = para_regcomp(&preg, re, REG_EXTENDED | REG_NOSUB);
        if (ret < 0)
                return ret;
        ret = 0;
        FOR_EACH_AUDIO_FORMAT(i)
                if (regexec(&preg, audio_formats[i], 0, NULL, 0) != REG_NOMATCH)
                        ret |= (1 << i);
        regfree(&preg);
        return ret;
}

/**
 * Compute the play time based on information of the given slot.
 *
 * \param slot_num The slot number (negative means: no slot).
 *
 * This computes a string of the form "0:07 [3:33] (3%/3:40)" using information
 * from the status items received from para_server and the start time of the
 * (first) writer of the given slot.
 *
 * It has to take into account that the stream was probably not started at
 * the beginning of the file, that the clock between the server and the client
 * host may differ and that playback of the stream was delayed, e.g. because
 * the prebuffer filter is used in the filter configuration of the given slot.
 *
 * If no writer is active in the given slot, or \a slot_num is negative
 * (indicating that para_audiod runs in standby mode), an approximation based
 * only on the status items is computed and the returned string is prefixed
 * with "~".
 *
 * \return A string that must be freed by the caller.
 */
char *get_time_string(int slot_num)
{
        int ret, seconds = 0, length;
        struct timeval *tmp, sum, sss, /* server stream start */
                rstime, /* receiver start time */
                wstime, /* writer start time */
                wtime, /* now - writer start */
                rskip; /* receiver start - sss */
        struct slot_info *s = slot_num < 0? NULL : &slot[slot_num];
        char *msg;

        if (audiod_status == AUDIOD_OFF)
                goto empty;
        if (!(stat_task->vss_status & VSS_STATUS_FLAG_PLAYING)) {
                if (stat_task->length_seconds) /* paused */
                        return NULL;
                goto empty; /* stopped */
        }
        if (audiod_status == AUDIOD_ON && !s)
                goto empty;
        /*
         * Valid status items and playing, set length and tmp to the stream
         * start. We use the slot info and fall back to the info from current
         * status items if no slot info is available.
         */
        length = stat_task->length_seconds;
        tmp = &stat_task->server_stream_start;
        if (s && s->wns && s->wns[0].btrn) { /* writer active in this slot */
                btr_get_node_start(s->wns[0].btrn, &wstime);
                if (wstime.tv_sec != 0) { /* writer wrote something */
                        if (s->server_stream_start.tv_sec == 0) {
                                /* copy status info to slot */
                                s->server_stream_start = stat_task->server_stream_start;
                                s->offset_seconds = stat_task->offset_seconds;
                                s->seconds_total = stat_task->length_seconds;
                        }
                        length = s->seconds_total;
                        tmp = &s->server_stream_start;
                }
        }
        if (stat_task->sa_time_diff_sign > 0)
                tv_diff(tmp, &stat_task->sa_time_diff, &sss);
        else
                tv_add(tmp, &stat_task->sa_time_diff, &sss);
        if (!s || !s->wns || !s->wns[0].btrn) {
                struct timeval diff;
                tv_diff(now, &sss, &diff);
                seconds = diff.tv_sec + stat_task->offset_seconds;
                goto out;
        }
        tv_diff(now, &wstime, &wtime);
        //PARA_CRIT_LOG("offset %d\n", s->offset_seconds);
        seconds = s->offset_seconds;
        if (s->receiver_node->btrn) {
                btr_get_node_start(s->receiver_node->btrn, &rstime);
                ret = tv_diff(&rstime, &sss, &rskip);
                if (ret > 0) { /* audiod was started in the middle of the stream */
                        tv_add(&wtime, &rskip, &sum);
                        seconds += sum.tv_sec;
                } else
                        seconds += wtime.tv_sec;
        } else
                seconds += wtime.tv_sec;
out:
        seconds = PARA_MIN(seconds, length);
        seconds = PARA_MAX(seconds, 0);
        msg = make_message(
                "%s%d:%02d [%d:%02d] (%d%%/%d:%02d)",
                s? "" : "~",
                seconds / 60,
                seconds % 60,
                (length - seconds) / 60,
                (length - seconds) % 60,
                length? (seconds * 100 + length / 2) / length : 0,
                length / 60,
                length % 60
        );
        //PARA_DEBUG_LOG("slot %d: %s\n", slot_num, msg);
        return msg;
empty:
        return para_strdup(NULL);
}

static int want_colors(void)
{
        if (conf.color_arg == color_arg_no)
                return 0;
        if (conf.color_arg == color_arg_yes)
                return 1;
        if (conf.logfile_given)
                return 0;
        return isatty(STDERR_FILENO);
}

static void parse_config_or_die(void)
{
        int ret;
        char *config_file;
        struct audiod_cmdline_parser_params params = {
                .override = 0,
                .initialize = 0,
                .check_required = 1,
                .check_ambiguity = 0,
                .print_errors = 1
        };

        if (conf.config_file_given)
                config_file = para_strdup(conf.config_file_arg);
        else {
                char *home = para_homedir();
                config_file = make_message("%s/.paraslash/audiod.conf", home);
                free(home);
        }
        ret = file_exists(config_file);
        if (conf.config_file_given && !ret) {
                PARA_EMERG_LOG("can not read config file %s\n", config_file);
                goto err;
        }
        if (ret) {
                audiod_cmdline_parser_config_file(config_file, &conf, &params);
                daemon_set_loglevel(conf.loglevel_arg);
        }
        free(config_file);
        return;
err:
        free(config_file);
        exit(EXIT_FAILURE);
}

static void setup_signal_handling(void)
{
        sig_task->fd = para_signal_init();
        PARA_INFO_LOG("signal pipe: fd %d\n", sig_task->fd);
        para_install_sighandler(SIGINT);
        para_install_sighandler(SIGTERM);
        para_install_sighandler(SIGHUP);
        para_sigaction(SIGPIPE, SIG_IGN);
}

static void clear_slot(int slot_num)
{
        struct slot_info *s = &slot[slot_num];

        PARA_INFO_LOG("clearing slot %d\n", slot_num);
        memset(s, 0, sizeof(struct slot_info));
        s->format = -1;
}

static void close_receiver(int slot_num)
{
        struct slot_info *s = &slot[slot_num];
        struct audio_format_info *a;

        if (s->format < 0 || !s->receiver_node)
                return;
        a = &afi[s->format];
        PARA_NOTICE_LOG("closing %s receiver in slot %d\n",
                audio_formats[s->format], slot_num);
        a->receiver->close(s->receiver_node);
        btr_remove_node(&s->receiver_node->btrn);
        free(s->receiver_node);
        s->receiver_node = NULL;
        tv_add(now, &(struct timeval)EMBRACE(0, 200 * 1000),
                &a->restart_barrier);
}

static void writer_cleanup(struct writer_node *wn)
{
        struct writer *w;

        if (!wn)
                return;
        w = writers + wn->writer_num;
        PARA_INFO_LOG("closing %s\n", writer_names[wn->writer_num]);
        w->close(wn);
        btr_remove_node(&wn->btrn);
}

static void close_writers(struct slot_info *s)
{
        struct audio_format_info *a;
        int i;

        if (s->format < 0)
                return;
        assert(s->wns);
        a = afi + s->format;
        if (a->num_writers == 0)
                writer_cleanup(s->wns);
        else {
                for (i = 0; i < a->num_writers; i++)
                        writer_cleanup(s->wns + i);
        }
        free(s->wns);
        s->wns = NULL;
}

static void close_filters(struct slot_info *s)
{
        int i;
        struct audio_format_info *a = afi + s->format;
        if (a->num_filters == 0)
                return;
        for (i = a->num_filters - 1; i >= 0; i--) {
                struct filter_node *fn = s->fns + i;
                struct filter *f;

                if (!fn)
                        continue;
                f = filters + fn->filter_num;
                if (f->close)
                        f->close(fn);
                btr_remove_node(&fn->btrn);
        }
        free(s->fns);
        s->fns = NULL;
}

static void notify_receivers(int error)
{
        int i;

        FOR_EACH_SLOT(i) {
                struct slot_info *s = slot + i;
                if (s->format < 0)
                        continue;
                if (!s->receiver_node)
                        continue;
                task_notify(&s->receiver_node->task, error);
        }
}

static int get_empty_slot(void)
{
        int i;
        struct slot_info *s;

        FOR_EACH_SLOT(i) {
                s = &slot[i];
                if (s->format < 0) {
                        clear_slot(i);
                        return i;
                }
                if (s->wns || s->receiver_node || s->fns)
                        continue;
                clear_slot(i);
                return i;
        }
        return -E_NO_MORE_SLOTS;
}

static void open_filters(struct slot_info *s)
{
        struct audio_format_info *a = afi + s->format;
        struct filter_node *fn;
        int nf = a->num_filters;
        struct btr_node *parent;
        int i;

        if (nf == 0)
                return;
        PARA_INFO_LOG("opening %s filters\n", audio_formats[s->format]);
        assert(s->fns == NULL);
        s->fns = para_calloc(nf * sizeof(struct filter_node));
        parent = s->receiver_node->btrn;
        for (i = 0; i < nf; i++) {
                struct filter *f = filters + a->filter_nums[i];
                fn = s->fns + i;
                fn->filter_num = a->filter_nums[i];
                fn->conf = a->filter_conf[i];
                fn->task.pre_select = f->pre_select;
                fn->task.post_select = f->post_select;
                fn->btrn = btr_new_node(&(struct btr_node_description)
                        EMBRACE(.name = f->name, .parent = parent,
                                .handler = f->execute, .context = fn));

                f->open(fn);
                register_task(&sched, &fn->task);
                parent = fn->btrn;
                PARA_NOTICE_LOG("%s filter %d/%d (%s) started in slot %d\n",
                        audio_formats[s->format], i,  nf, f->name, (int)(s - slot));
                sprintf(fn->task.status, "%s (slot %d)", f->name, (int)(s - slot));
        }
}

static void open_writers(struct slot_info *s)
{
        int i;
        struct audio_format_info *a = afi + s->format;
        struct writer_node *wn;
        struct btr_node *parent = s->fns[a->num_filters - 1].btrn;

        assert(s->wns == NULL);
        s->wns = para_calloc(PARA_MAX(1U, a->num_writers)
                * sizeof(struct writer_node));
        for (i = 0; i < a->num_writers; i++) {
                wn = s->wns + i;
                wn->conf = a->writer_conf[i];
                wn->writer_num = a->writer_nums[i];
                register_writer_node(wn, parent, &sched);
                PARA_NOTICE_LOG("%s writer started in slot %d\n",
                        writer_names[a->writer_nums[i]], (int)(s - slot));
        }
}

/* returns slot num on success */
static int open_receiver(int format)
{
        struct audio_format_info *a = &afi[format];
        struct slot_info *s;
        int ret, slot_num;
        struct receiver *r = a->receiver;
        struct receiver_node *rn;

        tv_add(now, &(struct timeval)EMBRACE(2, 0), &a->restart_barrier);
        ret = get_empty_slot();
        if (ret < 0)
                return ret;
        slot_num = ret;
        rn = para_calloc(sizeof(*rn));
        rn->receiver = r;
        rn->conf = a->receiver_conf;
        rn->btrn = btr_new_node(&(struct btr_node_description)
                EMBRACE(.name = r->name, .context = rn));
        ret = r->open(rn);
        if (ret < 0) {
                btr_remove_node(&rn->btrn);
                free(rn);
                return ret;
        }
        s = &slot[slot_num];
        s->format = format;
        s->receiver_node = rn;
        PARA_NOTICE_LOG("started %s: %s receiver in slot %d\n",
                audio_formats[format], r->name, slot_num);
        rn->task.pre_select = r->pre_select;
        rn->task.post_select = r->post_select;
        sprintf(rn->task.status, "%s receiver node", r->name);
        register_task(&sched, &rn->task);
        return slot_num;
}

static bool receiver_running(void)
{
        int i;
        long unsigned ss1 = stat_task->server_stream_start.tv_sec;

        FOR_EACH_SLOT(i) {
                struct slot_info *s = &slot[i];
                long unsigned ss2 = s->server_stream_start.tv_sec;

                if (!s->receiver_node)
                        continue;
                if (s->receiver_node->task.error >= 0)
                        return true;
                if (ss1 == ss2)
                        return true;
        }
        return false;
}

/**
 * Return the root node of the current buffer tree.
 *
 * This is only used for stream grabbing.
 *
 * \return \p NULL if no slot is currently active. If more than one buffer tree
 * exists, the node corresponding to the most recently started receiver is
 * returned.
 */
struct btr_node *audiod_get_btr_root(void)
{
        int i, newest_slot = -1;
        struct timeval newest_rstime = {0, 0};

        FOR_EACH_SLOT(i) {
                struct slot_info *s = &slot[i];
                struct timeval rstime;
                if (!s->receiver_node)
                        continue;
                if (s->receiver_node->task.error < 0)
                        continue;
                btr_get_node_start(s->receiver_node->btrn, &rstime);
                if (newest_slot >= 0 && tv_diff(&rstime, &newest_rstime, NULL) < 0)
                        continue;
                newest_rstime = rstime;
                newest_slot = i;
        }
        if (newest_slot == -1)
                return NULL;
        return slot[newest_slot].receiver_node->btrn;
}

/* whether a new instance of a decoder should be started. */
static bool must_start_decoder(void)
{
        int cafn = stat_task->current_audio_format_num;
        unsigned vs = stat_task->vss_status;

        if (audiod_status != AUDIOD_ON)
                return false;
        if (cafn < 0)
                return false;
        if (!stat_task->ct)
                return false;
        if (vs & VSS_STATUS_FLAG_NEXT)
                return false;
        if (!(vs & VSS_STATUS_FLAG_PLAYING))
                return false;
        if (receiver_running())
                return false;
        if (tv_diff(now, &afi[cafn].restart_barrier, NULL) < 0)
                return false;
        return true;
}

static void compute_time_diff(const struct timeval *status_time)
{
        struct timeval tmp, diff;
        static unsigned count;
        int sign, sa_time_diff_sign = stat_task->sa_time_diff_sign;
        const struct timeval max_deviation = {0, 500 * 1000};
        const int time_smooth = 5;

        sign = tv_diff(status_time, now, &diff);
//              PARA_NOTICE_LOG("%s: sign = %i, sa_time_diff_sign = %i\n", __func__,
//                      sign, sa_time_diff_sign);
        if (!count) {
                sa_time_diff_sign = sign;
                stat_task->sa_time_diff = diff;
                count++;
                goto out;
        }
        if (count > 5) {
                int s = tv_diff(&diff, &stat_task->sa_time_diff, &tmp);
                if (tv_diff(&max_deviation, &tmp, NULL) < 0)
                        PARA_WARNING_LOG("time diff jump: %lims\n",
                                s * tv2ms(&tmp));
        }
        count++;
        sa_time_diff_sign = tv_convex_combination(
                sa_time_diff_sign * time_smooth, &stat_task->sa_time_diff,
                count > 10? sign : sign * time_smooth, &diff,
                &tmp);
        stat_task->sa_time_diff = tmp;
        PARA_INFO_LOG("time diff (cur/avg): %s%lums/%s%lums\n",
                sign < 0? "-" : "+",
                tv2ms(&diff),
                sa_time_diff_sign < 0? "-" : "+",
                tv2ms(&stat_task->sa_time_diff)
        );
out:
        stat_task->sa_time_diff_sign = sa_time_diff_sign;
}

static int update_item(int itemnum, char *buf)
{
        long unsigned sec, usec;

        if (stat_task->clock_diff_count && itemnum != SI_CURRENT_TIME)
                return 1;
        free(stat_item_values[itemnum]);
        stat_item_values[itemnum] = para_strdup(buf);
        stat_client_write_item(itemnum);
        switch (itemnum) {
        case SI_STATUS_FLAGS:
                stat_task->vss_status = 0;
                if (strchr(buf, 'N'))
                        stat_task->vss_status |= VSS_STATUS_FLAG_NEXT;
                if (strchr(buf, 'P'))
                        stat_task->vss_status |= VSS_STATUS_FLAG_PLAYING;
                break;
        case SI_OFFSET:
                stat_task->offset_seconds = atoi(buf);
                break;
        case SI_SECONDS_TOTAL:
                stat_task->length_seconds = atoi(buf);
                break;
        case SI_STREAM_START:
                if (sscanf(buf, "%lu.%lu", &sec, &usec) == 2) {
                        stat_task->server_stream_start.tv_sec = sec;
                        stat_task->server_stream_start.tv_usec = usec;
                }
                break;
        case SI_CURRENT_TIME:
                if (sscanf(buf, "%lu.%lu", &sec, &usec) == 2) {
                        struct timeval tv = {sec, usec};
                        compute_time_diff(&tv);
                }
                break;
        case SI_FORMAT:
                stat_task->current_audio_format_num
                        = get_audio_format_num(buf);
        }
        return 1;
}

static int parse_stream_command(const char *txt, char **cmd)
{
        int ret, len;
        char *re, *p = strchr(txt, ':');

        if (!p)
                return -E_MISSING_COLON;
        *cmd = p + 1;
        len = p - txt;
        re = malloc(len + 1);
        strncpy(re, txt, len);
        re[len] = '\0';
        ret = get_matching_audio_format_nums(re);
        free(re);
        return ret;
}

static int add_filter(int format, char *cmdline)
{
        struct audio_format_info *a = &afi[format];
        int filter_num, nf = a->num_filters;
        void *cfg;

        filter_num = check_filter_arg(cmdline, &cfg);
        if (filter_num < 0)
                return filter_num;
        a->filter_conf = para_realloc(a->filter_conf,
                (nf + 1) * sizeof(void *));
        a->filter_nums = para_realloc(a->filter_nums,
                (nf + 1) * sizeof(unsigned));
        a->filter_nums[nf] = filter_num;
        a->filter_conf[nf] = cfg;
        a->num_filters++;
        PARA_INFO_LOG("%s filter %d: %s\n", audio_formats[format], nf,
                filters[filter_num].name);
        return filter_num;
}

static int parse_writer_args(void)
{
        int i, ret;
        char *cmd;
        struct audio_format_info *a;

        for (i = 0; i < conf.writer_given; i++) {
                void *wconf;
                int j, nw, writer_num, af_mask;

                ret = parse_stream_command(conf.writer_arg[i], &cmd);
                if (ret < 0)
                        return ret;
                af_mask = ret;
                FOR_EACH_AUDIO_FORMAT(j) {
                        a = afi + j;
                        if ((af_mask & (1 << j)) == 0) /* no match */
                                continue;
                        wconf = check_writer_arg_or_die(cmd, &writer_num);
                        nw = a->num_writers;
                        a->writer_nums = para_realloc(a->writer_nums, (nw + 1) * sizeof(int));
                        a->writer_conf = para_realloc(a->writer_conf, (nw + 1) * sizeof(void *));
                        a->writer_nums[nw] = writer_num;
                        a->writer_conf[nw] = wconf;
                        PARA_INFO_LOG("%s writer #%d: %s\n", audio_formats[j],
                                nw, writer_names[writer_num]);
                        a->num_writers++;
                }
        }
        /* Use default writer for audio formats which are not yet set up. */
        FOR_EACH_AUDIO_FORMAT(i) {
                void *writer_conf;
                int writer_num;
                a = afi + i;
                if (a->num_writers > 0)
                        continue; /* already set up */
                writer_conf = check_writer_arg_or_die(NULL, &writer_num);
                a->writer_nums = para_malloc(sizeof(int));
                a->writer_nums[0] = writer_num;
                a->writer_conf = para_malloc(sizeof(void *));
                a->writer_conf[0] = writer_conf;
                a->num_writers = 1;
                PARA_INFO_LOG("%s writer: %s (default)\n", audio_formats[i],
                        writer_names[writer_num]);
        }
        return 1;
}

static int parse_receiver_args(void)
{
        int i, ret, receiver_num;
        char *cmd = NULL;
        struct audio_format_info *a;

        for (i = conf.receiver_given - 1; i >= 0; i--) {
                char *arg;
                int j, af_mask;

                ret = parse_stream_command(conf.receiver_arg[i], &arg);
                if (ret < 0)
                        goto out;
                af_mask = ret;
                FOR_EACH_AUDIO_FORMAT(j) {
                        a = afi + j;
                        if ((af_mask & (1 << j)) == 0) /* no match */
                                continue;
                        /*
                         * If multiple receivers are given for this audio format, the
                         * last one wins and we have to free the previous receiver
                         * config here. Since we are iterating backwards, the winning
                         * receiver arg is in fact the first one given.
                         */
                        if (a->receiver_conf)
                                a->receiver->free_config(a->receiver_conf);
                        a->receiver_conf = check_receiver_arg(arg, &receiver_num);
                        ret = -E_RECV_SYNTAX;
                        if (!a->receiver_conf)
                                goto out;
                        a->receiver = receivers + receiver_num;
                }
        }
        /*
         * Use the first available receiver with no arguments for those audio
         * formats for which no receiver was specified.
         */
        cmd = para_strdup(receivers[0].name);
        FOR_EACH_AUDIO_FORMAT(i) {
                a = &afi[i];
                if (a->receiver_conf)
                        continue;
                a->receiver_conf = check_receiver_arg(cmd, &receiver_num);
                if (!a->receiver_conf)
                        return -E_RECV_SYNTAX;
                a->receiver = &receivers[receiver_num];
        }
        FOR_EACH_AUDIO_FORMAT(i) {
                a = afi + i;
                PARA_INFO_LOG("receiving %s streams via %s receiver\n",
                        audio_formats[i], a->receiver->name);
        }
        ret = 1;
out:
        free(cmd);
        return ret;
}

static int init_default_filters(void)
{
        int i, ret = 1;

        FOR_EACH_AUDIO_FORMAT(i) {
                struct audio_format_info *a = &afi[i];
                char *tmp;
                int j;

                if (a->num_filters)
                        continue; /* no default -- nothing to to */
                /*
                 * udp and dccp streams are fec-encoded, so add fecdec as the
                 * first filter.
                 */
                if (strcmp(afi[i].receiver->name, "udp") == 0 ||
                                strcmp(afi[i].receiver->name, "dccp") == 0) {
                        tmp = para_strdup("fecdec");
                        add_filter(i, tmp);
                        free(tmp);
                        if (ret < 0)
                                goto out;
                }
                /* add "dec" to audio format name */
                tmp = make_message("%sdec", audio_formats[i]);
                for (j = 0; filters[j].name; j++)
                        if (!strcmp(tmp, filters[j].name))
                                break;
                free(tmp);
                ret = -E_UNSUPPORTED_FILTER;
                if (!filters[j].name)
                        goto out;
                tmp = para_strdup(filters[j].name);
                ret = add_filter(i, tmp);
                free(tmp);
                if (ret < 0)
                        goto out;
                PARA_INFO_LOG("%s -> default filter: %s\n", audio_formats[i],
                        filters[j].name);
        }
out:
        return ret;
}

static int parse_filter_args(void)
{
        int i, j, ret, af_mask, num_matches;

        for (i = 0; i < conf.filter_given; i++) {
                char *arg;
                ret = parse_stream_command(conf.filter_arg[i], &arg);
                if (ret < 0)
                        goto out;
                af_mask = ret;
                num_matches = 0;
                FOR_EACH_AUDIO_FORMAT(j) {
                        if ((af_mask & (1 << j)) == 0) /* no match */
                                continue;
                        ret = add_filter(j, arg);
                        if (ret < 0)
                                goto out;
                        num_matches++;
                }
                if (num_matches == 0)
                        PARA_WARNING_LOG("ignoring filter spec: %s\n",
                                conf.filter_arg[i]);
        }
        ret = init_default_filters(); /* use default values for the rest */
out:
        return ret;
}

static int parse_stream_args(void)
{
        int ret;

        ret = parse_receiver_args();
        if (ret < 0)
                return ret;
        ret = parse_filter_args();
        if (ret < 0)
                return ret;
        ret = parse_writer_args();
        if (ret < 0)
                return ret;
        return 1;
}

/* does not unlink socket on errors */
static int audiod_get_socket(void)
{
        struct sockaddr_un unix_addr;
        int ret, fd;

        if (conf.socket_given)
                socket_name = para_strdup(conf.socket_arg);
        else {
                char *hn = para_hostname();
                socket_name = make_message("/var/paraslash/audiod_socket.%s",
                        hn);
                free(hn);
        }
        PARA_NOTICE_LOG("local socket: %s\n", socket_name);
        if (conf.force_given)
                unlink(socket_name);
        ret = create_local_socket(socket_name, &unix_addr,
                S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IWOTH);
        if (ret < 0)
                goto err;
        fd = ret;
        if (listen(fd , 5) < 0) {
                ret = -ERRNO_TO_PARA_ERROR(errno);
                goto err;
        }
        ret = mark_fd_nonblocking(fd);
        if (ret < 0)
                goto err;
        return fd;
err:
        PARA_EMERG_LOG("%s\n", para_strerror(-ret));
        exit(EXIT_FAILURE);
}

static void signal_pre_select(struct sched *s, struct task *t)
{
        struct signal_task *st = container_of(t, struct signal_task, task);
        para_fd_set(st->fd, &s->rfds, &s->max_fileno);
}

static int signal_post_select(struct sched *s, __a_unused struct task *t)
{
        int signum;

        signum = para_next_signal(&s->rfds);
        switch (signum) {
        case SIGINT:
        case SIGTERM:
        case SIGHUP:
                PARA_NOTICE_LOG("received signal %d\n", signum);
                clean_exit(EXIT_FAILURE, "caught deadly signal");
        }
        return 0;
}

static void signal_setup_default(struct signal_task *st)
{
        st->task.pre_select = signal_pre_select;
        st->task.post_select = signal_post_select;
        sprintf(st->task.status, "signal task");
}

static void command_pre_select(struct sched *s, struct task *t)
{
        struct command_task *ct = container_of(t, struct command_task, task);
        para_fd_set(ct->fd, &s->rfds, &s->max_fileno);
}

static int command_post_select(struct sched *s, struct task *t)
{
        int ret;
        struct command_task *ct = container_of(t, struct command_task, task);
        static struct timeval last_status_dump;
        struct timeval tmp, delay;
        bool force = true;

        ret = handle_connect(ct->fd, &s->rfds);
        if (ret < 0)
                PARA_ERROR_LOG("%s\n", para_strerror(-ret));
        else if (ret > 0)
                goto dump;

        /* if last status dump was less than 500ms ago, do nothing */
        delay.tv_sec = 0;
        delay.tv_usec = 500 * 1000;
        tv_add(&last_status_dump, &delay, &tmp);
        if (tv_diff(now, &tmp, NULL) < 0)
                return 0;

        /*
         * If last status dump was more than 5s ago, force update. Otherwise,
         * update only those items that have changed.
         */
        delay.tv_sec = 5;
        delay.tv_usec = 0;
        tv_add(&last_status_dump, &delay, &tmp);
        if (tv_diff(now, &tmp, NULL) < 0)
                force = false;
dump:
        audiod_status_dump(force);
        last_status_dump = *now;
        return 1;
}

static void init_command_task(struct command_task *ct)
{
        ct->task.pre_select = command_pre_select;
        ct->task.post_select = command_post_select;
        ct->task.error = 0;
        ct->fd = audiod_get_socket(); /* doesn't return on errors */
        sprintf(ct->task.status, "command task");
}

static void close_stat_pipe(void)
{
        if (!stat_task->ct)
                return;
        client_close(stat_task->ct);
        stat_task->ct = NULL;
        clear_and_dump_items();
        stat_task->length_seconds = 0;
        stat_task->offset_seconds = 0;
        stat_task->vss_status = 0;
        stat_task->current_audio_format_num = -1;
        audiod_status_dump(true);
}

/* avoid busy loop if server is down */
static void set_stat_task_restart_barrier(unsigned seconds)
{
        struct timeval delay = {seconds, 0};
        tv_add(now, &delay, &stat_task->restart_barrier);
}

static bool must_close_slot(int slot_num)
{
        struct slot_info *s = &slot[slot_num];
        struct audio_format_info *a = afi + s->format;
        int i;

        if (s->format < 0)
                return false;
        if (s->receiver_node && s->receiver_node->task.error >= 0)
                return false;
        for (i = 0; i < a->num_filters; i++)
                if (s->fns && s->fns[i].task.error >= 0)
                        return false;
        if (a->num_writers > 0) {
                for (i = 0; i < a->num_writers; i++)
                        if (s->wns && s->wns[i].task.error >= 0)
                                return false;
        } else {
                if (s->wns && s->wns[0].task.error >= 0)
                        return false;
        }
        return true;
}

static void close_slot(int slot_num)
{
        struct slot_info *s = slot + slot_num;

        PARA_INFO_LOG("closing slot %d\n", slot_num);
        close_writers(s);
        close_filters(s);
        close_receiver(slot_num);
        clear_slot(slot_num);
}

static void close_unused_slots(void)
{
        int i;

        FOR_EACH_SLOT(i)
                if (must_close_slot(i))
                        close_slot(i);
}

/**
 * Close the connection to para_server and exit.
 *
 * \param status The exit status which is passed to exit(3).
 * \param msg The log message
 *
 * Log \a msg with loglevel \p EMERG, close the connection to para_server and
 * all slots, and call \p exit(status). \a status should be either EXIT_SUCCESS
 * or EXIT_FAILURE.
 *
 * \sa exit(3).
 */
void __noreturn clean_exit(int status, const char *msg)
{
        int i;

        if (socket_name)
                unlink(socket_name);
        close_stat_pipe();
        FOR_EACH_SLOT(i)
                close_slot(i);
        audiod_cmdline_parser_free(&conf);
        close_stat_clients();
        PARA_EMERG_LOG("%s\n", msg);
        exit(status);
}

/*
 * Check if any receivers/filters/writers need to be started and do so if
 * necessary.
 */
static void start_stop_decoders(void)
{
        int ret;
        struct slot_info *sl;
        struct audio_format_info *a;

        close_unused_slots();
        if (audiod_status != AUDIOD_ON ||
                        !(stat_task->vss_status & VSS_STATUS_FLAG_PLAYING))
                return notify_receivers(E_NOT_PLAYING);
        if (!must_start_decoder())
                return;
        ret = open_receiver(stat_task->current_audio_format_num);
        if (ret < 0) {
                PARA_ERROR_LOG("%s\n", para_strerror(-ret));
                return;
        }
        sl = slot + ret;
        a = afi + sl->format;
        if (a->num_filters)
                open_filters(sl);
        open_writers(sl);
        activate_grab_clients(&sched);
        btr_log_tree(sl->receiver_node->btrn, LL_NOTICE);
}

static void status_pre_select(struct sched *s, struct task *t)
{
        struct status_task *st = container_of(t, struct status_task, task);
        int i, ret, cafn = stat_task->current_audio_format_num;

        if (must_start_decoder())
                goto min_delay;
        FOR_EACH_SLOT(i)
                if (must_close_slot(i))
                        goto min_delay;
        ret = btr_node_status(st->btrn, st->min_iqs, BTR_NT_LEAF);
        if (ret > 0)
                goto min_delay;
        if (st->ct && audiod_status == AUDIOD_OFF)
                goto min_delay;
        if (!st->ct && audiod_status != AUDIOD_OFF)
                sched_request_barrier_or_min_delay(&st->restart_barrier, s);
        if (cafn >= 0)
                sched_request_barrier(&afi[cafn].restart_barrier, s);
        /*
         * If para_server is playing we'd like to have a smooth time display
         * even if we are running in standby mode. So we request a timeout that
         * expires at the next full second.
         */
        if (stat_task->vss_status & VSS_STATUS_FLAG_PLAYING)
                sched_request_timeout_ms(1000 - now->tv_usec / 1000, s);
        return;
min_delay:
        sched_min_delay(s);
}

/* restart the client task if necessary */
static int status_post_select(struct sched *s, struct task *t)
{
        struct status_task *st = container_of(t, struct status_task, task);

        if (audiod_status == AUDIOD_OFF) {
                if (!st->ct)
                        goto out;
                if (st->ct->task.error >= 0) {
                        task_notify(&st->ct->task, E_AUDIOD_OFF);
                        goto out;
                }
                close_stat_pipe();
                st->clock_diff_count = conf.clock_diff_count_arg;
                goto out;
        }
        if (st->ct) {
                char *buf;
                size_t sz;
                int ret;

                ret = btr_node_status(st->btrn, st->min_iqs, BTR_NT_LEAF);
                if (ret < 0) {
                        close_stat_pipe();
                        goto out;
                }
                if (st->ct->status != CL_EXECUTING)
                        goto out;
                if (ret == 0) {
                        struct timeval diff;
                        tv_diff(now, &st->last_status_read, &diff);
                        if (diff.tv_sec > 61)
                                task_notify(&st->ct->task, E_STATUS_TIMEOUT);
                        goto out;
                }
                btr_merge(st->btrn, st->min_iqs);
                sz = btr_next_buffer(st->btrn, &buf);
                ret = for_each_stat_item(buf, sz, update_item);
                if (ret < 0) {
                        task_notify(&st->ct->task, -ret);
                        goto out;
                }
                if (sz != ret) {
                        btr_consume(st->btrn, sz - ret);
                        st->last_status_read = *now;
                        st->min_iqs = 0;
                } else /* current status item crosses buffers */
                        st->min_iqs = sz + 1;
                goto out;
        }
        btr_drain(st->btrn);
        st->current_audio_format_num = -1;
        if (tv_diff(now, &st->restart_barrier, NULL) < 0)
                goto out;
        if (st->clock_diff_count) { /* get status only one time */
                char *argv[] = {"audiod", "--", "stat", "-p", "-n=1", NULL};
                int argc = 5;
                PARA_INFO_LOG("clock diff count: %d\n", st->clock_diff_count);
                st->clock_diff_count--;
                client_open(argc, argv, &st->ct, NULL, NULL, st->btrn, s);
                set_stat_task_restart_barrier(2);

        } else {
                char *argv[] = {"audiod", "--", "stat", "-p", NULL};
                int argc = 4;
                client_open(argc, argv, &st->ct, NULL, NULL, st->btrn, s);
                set_stat_task_restart_barrier(5);
        }
        free(stat_item_values[SI_BASENAME]);
        stat_item_values[SI_BASENAME] = para_strdup(
                "no connection to para_server");
        stat_client_write_item(SI_BASENAME);
        st->last_status_read = *now;
out:
        start_stop_decoders();
        return 0;
}

static void init_status_task(struct status_task *st)
{
        memset(st, 0, sizeof(struct status_task));
        st->task.pre_select = status_pre_select;
        st->task.post_select = status_post_select;
        st->sa_time_diff_sign = 1;
        st->clock_diff_count = conf.clock_diff_count_arg;
        st->current_audio_format_num = -1;
        sprintf(st->task.status, "stat");
        st->btrn = btr_new_node(&(struct btr_node_description)
                EMBRACE(.name = "stat"));
}

static void set_initial_status(void)
{
        audiod_status = AUDIOD_ON;
        if (!conf.mode_given)
                return;
        if (!strcmp(conf.mode_arg, "sb")) {
                audiod_status = AUDIOD_STANDBY;
                return;
        }
        if (!strcmp(conf.mode_arg, "off")) {
                audiod_status = AUDIOD_OFF;
                return;
        }
        if (strcmp(conf.mode_arg, "on"))
                PARA_WARNING_LOG("invalid mode\n");
}

__noreturn static void print_help_and_die(void)
{
        struct ggo_help h = DEFINE_GGO_HELP(audiod);
        bool d = conf.detailed_help_given;
        unsigned flags;

        flags = d? GPH_STANDARD_FLAGS_DETAILED : GPH_STANDARD_FLAGS;
        ggo_print_help(&h, flags);

        flags = d? GPH_MODULE_FLAGS_DETAILED : GPH_MODULE_FLAGS;
        print_receiver_helps(flags);
        print_filter_helps(flags);
        print_writer_helps(flags);
        exit(0);
}

static void init_colors_or_die(void)
{
        int i;

        if (!want_colors())
                return;
        daemon_set_default_log_colors();
        daemon_set_flag(DF_COLOR_LOG);
        for (i = 0; i < conf.log_color_given; i++)
                daemon_set_log_color_or_die(conf.log_color_arg[i]);
}

/**
 * the main function of para_audiod
 *
 * \param argc usual argument count
 * \param argv usual argument vector
 *
 * \return EXIT_SUCCESS or EXIT_FAILURE
 *
 * \sa para_audiod(1)
 * */
int main(int argc, char *argv[])
{
        int ret, i;
        struct command_task command_task_struct, *cmd_task = &command_task_struct;
        struct audiod_cmdline_parser_params params = {
                .override = 0,
                .initialize = 1,
                .check_required = 0,
                .check_ambiguity = 0,
                .print_errors = 1
        };

        valid_fd_012();
        audiod_cmdline_parser_ext(argc, argv, &conf, &params);
        daemon_set_loglevel(conf.loglevel_arg);
        version_handle_flag("audiod", conf.version_given);
        /* init receivers/filters/writers early to make help work */
        recv_init();
        filter_init();
        writer_init();
        if (conf.help_given || conf.detailed_help_given)
                print_help_and_die();
        drop_privileges_or_die(conf.user_arg, conf.group_arg);
        parse_config_or_die();
        init_colors_or_die();
        init_random_seed_or_die();
        daemon_set_flag(DF_LOG_TIME);
        daemon_set_flag(DF_LOG_HOSTNAME);
        daemon_set_flag(DF_LOG_LL);
        if (conf.log_timing_given)
                daemon_set_flag(DF_LOG_TIMING);
        if (conf.logfile_given) {
                daemon_set_logfile(conf.logfile_arg);
                daemon_open_log_or_die();
        }
        ret = parse_stream_args();
        if (ret < 0) {
                PARA_EMERG_LOG("%s\n", para_strerror(-ret));
                exit(EXIT_FAILURE);
        }
        log_welcome("para_audiod");
        set_server_start_time(NULL);
        set_initial_status();
        FOR_EACH_SLOT(i)
                clear_slot(i);
        setup_signal_handling();
        signal_setup_default(sig_task);

        init_status_task(stat_task);
        init_command_task(cmd_task);

        if (conf.daemon_given)
                daemonize(false /* parent exits immediately */);

        register_task(&sched, &sig_task->task);
        register_task(&sched, &cmd_task->task);
        register_task(&sched, &stat_task->task);
        sched.default_timeout.tv_sec = 2;
        sched.default_timeout.tv_usec = 999 * 1000;
        ret = schedule(&sched);

        PARA_EMERG_LOG("%s\n", para_strerror(-ret));
        return EXIT_FAILURE;
}