// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *   ALSA sequencer Ports
 *   Copyright (c) 1998 by Frank van de Pol <fvdpol@coil.demon.nl>
 *                         Jaroslav Kysela <perex@perex.cz>
 */

#include <sound/core.h>
#include <linux/slab.h>
#include <linux/module.h>
#include "seq_system.h"
#include "seq_ports.h"
#include "seq_clientmgr.h"

/*

   registration of client ports

 */


/* 

NOTE: the current implementation of the port structure as a linked list is
not optimal for clients that have many ports. For sending messages to all
subscribers of a port we first need to find the address of the port
structure, which means we have to traverse the list. A direct access table
(array) would be better, but big preallocated arrays waste memory.

Possible actions:

1) leave it this way, a client does normaly does not have more than a few
ports

2) replace the linked list of ports by a array of pointers which is
dynamicly kmalloced. When a port is added or deleted we can simply allocate
a new array, copy the corresponding pointers, and delete the old one. We
then only need a pointer to this array, and an integer that tells us how
much elements are in array.

*/

/* return pointer to port structure - port is locked if found */
struct snd_seq_client_port *snd_seq_port_use_ptr(struct snd_seq_client *client,
                                                 int num)
{
        struct snd_seq_client_port *port;

        if (client == NULL)
                return NULL;
        guard(read_lock)(&client->ports_lock);
        list_for_each_entry(port, &client->ports_list_head, list) {
                if (port->addr.port == num) {
                        if (port->closing)
                                break; /* deleting now */
                        snd_use_lock_use(&port->use_lock);
                        return port;
                }
        }
        return NULL;            /* not found */
}


/* search for the next port - port is locked if found */
struct snd_seq_client_port *snd_seq_port_query_nearest(struct snd_seq_client *client,
                                                       struct snd_seq_port_info *pinfo)
{
        int num;
        struct snd_seq_client_port *port, *found;
        bool check_inactive = (pinfo->capability & SNDRV_SEQ_PORT_CAP_INACTIVE);

        num = pinfo->addr.port;
        found = NULL;
        guard(read_lock)(&client->ports_lock);
        list_for_each_entry(port, &client->ports_list_head, list) {
                if ((port->capability & SNDRV_SEQ_PORT_CAP_INACTIVE) &&
                    !check_inactive)
                        continue; /* skip inactive ports */
                if (port->addr.port < num)
                        continue;
                if (port->addr.port == num) {
                        found = port;
                        break;
                }
                if (found == NULL || port->addr.port < found->addr.port)
                        found = port;
        }
        if (found) {
                if (found->closing)
                        found = NULL;
                else
                        snd_use_lock_use(&found->use_lock);
        }
        return found;
}


/* initialize snd_seq_port_subs_info */
static void port_subs_info_init(struct snd_seq_port_subs_info *grp)
{
        INIT_LIST_HEAD(&grp->list_head);
        grp->count = 0;
        grp->exclusive = 0;
        rwlock_init(&grp->list_lock);
        init_rwsem(&grp->list_mutex);
        grp->open = NULL;
        grp->close = NULL;
}


/* create a port, 0 on success or a negative error code is returned
 * the caller needs to unref the port via snd_seq_port_unlock() appropriately
 */
int snd_seq_create_port(struct snd_seq_client *client,
                        struct snd_seq_client_port **port_ret)
{
        struct snd_seq_client_port *new_port;
        
        *port_ret = NULL;

        /* sanity check */
        if (snd_BUG_ON(!client))
                return -EINVAL;

        if (client->num_ports >= SNDRV_SEQ_MAX_PORTS) {
                pr_warn("ALSA: seq: too many ports for client %d\n", client->number);
                return -EINVAL;
        }

        /* create a new port */
        new_port = kzalloc_obj(*new_port);
        if (!new_port)
                return -ENOMEM; /* failure, out of memory */
        /* init port data */
        new_port->addr.client = client->number;
        new_port->addr.port = -1;
        new_port->owner = THIS_MODULE;
        snd_use_lock_init(&new_port->use_lock);
        port_subs_info_init(&new_port->c_src);
        port_subs_info_init(&new_port->c_dest);
        snd_use_lock_use(&new_port->use_lock);

        *port_ret = new_port;

        return 0;
}

/* insert the port; return the port address or a negative error code */
int snd_seq_insert_port(struct snd_seq_client *client, int port,
                        struct snd_seq_client_port *new_port)
{
        struct snd_seq_client_port *p;
        int num;

        num = max(port, 0);
        guard(mutex)(&client->ports_mutex);
        guard(write_lock_irq)(&client->ports_lock);
        struct list_head *insert_before = &client->ports_list_head;
        list_for_each_entry(p, &client->ports_list_head, list) {
                if (p->addr.port == port)
                        return -EBUSY;
                if (p->addr.port > num) {
                        insert_before = &p->list;
                        break;
                }
                if (port < 0) /* auto-probe mode */
                        num = p->addr.port + 1;
        }
        /* insert the new port */
        list_add_tail(&new_port->list, insert_before);
        client->num_ports++;
        new_port->addr.port = num;      /* store the port number in the port */
        if (!new_port->name[0])
                sprintf(new_port->name, "port-%d", num);

        return num;
}

/* */
static int subscribe_port(struct snd_seq_client *client,
                          struct snd_seq_client_port *port,
                          struct snd_seq_port_subs_info *grp,
                          struct snd_seq_port_subscribe *info, int send_ack);
static int unsubscribe_port(struct snd_seq_client *client,
                            struct snd_seq_client_port *port,
                            struct snd_seq_port_subs_info *grp,
                            struct snd_seq_port_subscribe *info, int send_ack);


static struct snd_seq_client_port *get_client_port(struct snd_seq_addr *addr,
                                                   struct snd_seq_client **cp)
{
        *cp = snd_seq_client_use_ptr(addr->client);
        if (!*cp)
                return NULL;
        return snd_seq_port_use_ptr(*cp, addr->port);
}

static void delete_and_unsubscribe_port(struct snd_seq_client *client,
                                        struct snd_seq_client_port *port,
                                        struct snd_seq_subscribers *subs,
                                        bool is_src, bool ack);

static inline struct snd_seq_subscribers *
get_subscriber(struct list_head *p, bool is_src)
{
        if (is_src)
                return list_entry(p, struct snd_seq_subscribers, src_list);
        else
                return list_entry(p, struct snd_seq_subscribers, dest_list);
}

/*
 * remove all subscribers on the list
 * this is called from port_delete, for each src and dest list.
 */
static void clear_subscriber_list(struct snd_seq_client *client,
                                  struct snd_seq_client_port *port,
                                  struct snd_seq_port_subs_info *grp,
                                  int is_src)
{
        struct list_head *p, *n;

        list_for_each_safe(p, n, &grp->list_head) {
                struct snd_seq_subscribers *subs;

                subs = get_subscriber(p, is_src);
                struct snd_seq_client *c __free(snd_seq_client) = NULL;
                struct snd_seq_client_port *aport __free(snd_seq_port) =
                        is_src ?
                        get_client_port(&subs->info.dest, &c) :
                        get_client_port(&subs->info.sender, &c);
                delete_and_unsubscribe_port(client, port, subs, is_src, false);

                if (!aport) {
                        /* looks like the connected port is being deleted.
                         * we decrease the counter, and when both ports are deleted
                         * remove the subscriber info
                         */
                        if (atomic_dec_and_test(&subs->ref_count))
                                kfree(subs);
                        continue;
                }

                /* ok we got the connected port */
                delete_and_unsubscribe_port(c, aport, subs, !is_src, true);
                kfree(subs);
        }
}

/* delete port data */
static int port_delete(struct snd_seq_client *client,
                       struct snd_seq_client_port *port)
{
        /* set closing flag and wait for all port access are gone */
        port->closing = 1;
        snd_use_lock_sync(&port->use_lock); 

        /* clear subscribers info */
        clear_subscriber_list(client, port, &port->c_src, true);
        clear_subscriber_list(client, port, &port->c_dest, false);

        if (port->private_free)
                port->private_free(port->private_data);

        snd_BUG_ON(port->c_src.count != 0);
        snd_BUG_ON(port->c_dest.count != 0);

        kfree(port);
        return 0;
}


/* delete a port with the given port id */
int snd_seq_delete_port(struct snd_seq_client *client, int port)
{
        struct snd_seq_client_port *found = NULL, *p;

        scoped_guard(mutex, &client->ports_mutex) {
                guard(write_lock_irq)(&client->ports_lock);
                list_for_each_entry(p, &client->ports_list_head, list) {
                        if (p->addr.port == port) {
                                /* ok found.  delete from the list at first */
                                list_del(&p->list);
                                client->num_ports--;
                                found = p;
                                break;
                        }
                }
        }
        if (found)
                return port_delete(client, found);
        else
                return -ENOENT;
}

/* delete the all ports belonging to the given client */
int snd_seq_delete_all_ports(struct snd_seq_client *client)
{
        struct list_head deleted_list;
        struct snd_seq_client_port *port, *tmp;
        
        /* move the port list to deleted_list, and
         * clear the port list in the client data.
         */
        guard(mutex)(&client->ports_mutex);
        scoped_guard(write_lock_irq, &client->ports_lock) {
                if (!list_empty(&client->ports_list_head)) {
                        list_add(&deleted_list, &client->ports_list_head);
                        list_del_init(&client->ports_list_head);
                } else {
                        INIT_LIST_HEAD(&deleted_list);
                }
                client->num_ports = 0;
        }

        /* remove each port in deleted_list */
        list_for_each_entry_safe(port, tmp, &deleted_list, list) {
                list_del(&port->list);
                snd_seq_system_client_ev_port_exit(port->addr.client, port->addr.port);
                port_delete(client, port);
        }
        return 0;
}

/* set port info fields */
int snd_seq_set_port_info(struct snd_seq_client_port * port,
                          struct snd_seq_port_info * info)
{
        if (snd_BUG_ON(!port || !info))
                return -EINVAL;

        /* set port name */
        if (info->name[0])
                strscpy(port->name, info->name, sizeof(port->name));
        
        /* set capabilities */
        port->capability = info->capability;
        
        /* get port type */
        port->type = info->type;

        /* information about supported channels/voices */
        port->midi_channels = info->midi_channels;
        port->midi_voices = info->midi_voices;
        port->synth_voices = info->synth_voices;

        /* timestamping */
        port->timestamping = (info->flags & SNDRV_SEQ_PORT_FLG_TIMESTAMP) ? 1 : 0;
        port->time_real = (info->flags & SNDRV_SEQ_PORT_FLG_TIME_REAL) ? 1 : 0;
        port->time_queue = info->time_queue;

        /* UMP direction and group */
        port->direction = info->direction;
        port->ump_group = info->ump_group;
        if (port->ump_group > SNDRV_UMP_MAX_GROUPS)
                port->ump_group = 0;

        /* fill default port direction */
        if (!port->direction) {
                if (info->capability & SNDRV_SEQ_PORT_CAP_READ)
                        port->direction |= SNDRV_SEQ_PORT_DIR_INPUT;
                if (info->capability & SNDRV_SEQ_PORT_CAP_WRITE)
                        port->direction |= SNDRV_SEQ_PORT_DIR_OUTPUT;
        }

        port->is_midi1 = !!(info->flags & SNDRV_SEQ_PORT_FLG_IS_MIDI1);

        return 0;
}

/* get port info fields */
int snd_seq_get_port_info(struct snd_seq_client_port * port,
                          struct snd_seq_port_info * info)
{
        if (snd_BUG_ON(!port || !info))
                return -EINVAL;

        /* get port name */
        strscpy(info->name, port->name, sizeof(info->name));
        
        /* get capabilities */
        info->capability = port->capability;

        /* get port type */
        info->type = port->type;

        /* information about supported channels/voices */
        info->midi_channels = port->midi_channels;
        info->midi_voices = port->midi_voices;
        info->synth_voices = port->synth_voices;

        /* get subscriber counts */
        info->read_use = port->c_src.count;
        info->write_use = port->c_dest.count;
        
        /* timestamping */
        info->flags = 0;
        if (port->timestamping) {
                info->flags |= SNDRV_SEQ_PORT_FLG_TIMESTAMP;
                if (port->time_real)
                        info->flags |= SNDRV_SEQ_PORT_FLG_TIME_REAL;
                info->time_queue = port->time_queue;
        }

        if (port->is_midi1)
                info->flags |= SNDRV_SEQ_PORT_FLG_IS_MIDI1;

        /* UMP direction and group */
        info->direction = port->direction;
        info->ump_group = port->ump_group;

        return 0;
}



/*
 * call callback functions (if any):
 * the callbacks are invoked only when the first (for connection) or
 * the last subscription (for disconnection) is done.  Second or later
 * subscription results in increment of counter, but no callback is
 * invoked.
 * This feature is useful if these callbacks are associated with
 * initialization or termination of devices (see seq_midi.c).
 */

static int subscribe_port(struct snd_seq_client *client,
                          struct snd_seq_client_port *port,
                          struct snd_seq_port_subs_info *grp,
                          struct snd_seq_port_subscribe *info,
                          int send_ack)
{
        int err = 0;

        if (!try_module_get(port->owner))
                return -EFAULT;
        grp->count++;
        if (grp->open && grp->count == 1) {
                err = grp->open(port->private_data, info);
                if (err < 0) {
                        module_put(port->owner);
                        grp->count--;
                }
        }
        if (err >= 0 && send_ack && client->type == USER_CLIENT)
                snd_seq_client_notify_subscription(port->addr.client, port->addr.port,
                                                   info, SNDRV_SEQ_EVENT_PORT_SUBSCRIBED);

        return err;
}

static int unsubscribe_port(struct snd_seq_client *client,
                            struct snd_seq_client_port *port,
                            struct snd_seq_port_subs_info *grp,
                            struct snd_seq_port_subscribe *info,
                            int send_ack)
{
        int err = 0;

        if (! grp->count)
                return -EINVAL;
        grp->count--;
        if (grp->close && grp->count == 0)
                err = grp->close(port->private_data, info);
        if (send_ack && client->type == USER_CLIENT)
                snd_seq_client_notify_subscription(port->addr.client, port->addr.port,
                                                   info, SNDRV_SEQ_EVENT_PORT_UNSUBSCRIBED);
        module_put(port->owner);
        return err;
}



/* check if both addresses are identical */
static inline int addr_match(struct snd_seq_addr *r, struct snd_seq_addr *s)
{
        return (r->client == s->client) && (r->port == s->port);
}

/* check the two subscribe info match */
/* if flags is zero, checks only sender and destination addresses */
static int match_subs_info(struct snd_seq_port_subscribe *r,
                           struct snd_seq_port_subscribe *s)
{
        if (addr_match(&r->sender, &s->sender) &&
            addr_match(&r->dest, &s->dest)) {
                if (r->flags && r->flags == s->flags)
                        return r->queue == s->queue;
                else if (! r->flags)
                        return 1;
        }
        return 0;
}

static int check_and_subscribe_port(struct snd_seq_client *client,
                                    struct snd_seq_client_port *port,
                                    struct snd_seq_subscribers *subs,
                                    bool is_src, bool exclusive, bool ack)
{
        struct snd_seq_port_subs_info *grp;
        struct list_head *p;
        struct snd_seq_subscribers *s;
        int err;

        grp = is_src ? &port->c_src : &port->c_dest;
        guard(rwsem_write)(&grp->list_mutex);
        if (exclusive) {
                if (!list_empty(&grp->list_head))
                        return -EBUSY;
        } else {
                if (grp->exclusive)
                        return -EBUSY;
                /* check whether already exists */
                list_for_each(p, &grp->list_head) {
                        s = get_subscriber(p, is_src);
                        if (match_subs_info(&subs->info, &s->info))
                                return -EBUSY;
                }
        }

        err = subscribe_port(client, port, grp, &subs->info, ack);
        if (err < 0) {
                grp->exclusive = 0;
                return err;
        }

        /* add to list */
        guard(write_lock_irq)(&grp->list_lock);
        if (is_src)
                list_add_tail(&subs->src_list, &grp->list_head);
        else
                list_add_tail(&subs->dest_list, &grp->list_head);
        grp->exclusive = exclusive;
        atomic_inc(&subs->ref_count);

        return 0;
}

/* called with grp->list_mutex held */
static void __delete_and_unsubscribe_port(struct snd_seq_client *client,
                                          struct snd_seq_client_port *port,
                                          struct snd_seq_subscribers *subs,
                                          bool is_src, bool ack)
{
        struct snd_seq_port_subs_info *grp;
        struct list_head *list;
        bool empty;

        grp = is_src ? &port->c_src : &port->c_dest;
        list = is_src ? &subs->src_list : &subs->dest_list;
        scoped_guard(write_lock_irq, &grp->list_lock) {
                empty = list_empty(list);
                if (!empty)
                        list_del_init(list);
                grp->exclusive = 0;
        }

        if (!empty)
                unsubscribe_port(client, port, grp, &subs->info, ack);
}

static void delete_and_unsubscribe_port(struct snd_seq_client *client,
                                        struct snd_seq_client_port *port,
                                        struct snd_seq_subscribers *subs,
                                        bool is_src, bool ack)
{
        struct snd_seq_port_subs_info *grp;

        grp = is_src ? &port->c_src : &port->c_dest;
        guard(rwsem_write)(&grp->list_mutex);
        __delete_and_unsubscribe_port(client, port, subs, is_src, ack);
}

/* connect two ports */
int snd_seq_port_connect(struct snd_seq_client *connector,
                         struct snd_seq_client *src_client,
                         struct snd_seq_client_port *src_port,
                         struct snd_seq_client *dest_client,
                         struct snd_seq_client_port *dest_port,
                         struct snd_seq_port_subscribe *info)
{
        struct snd_seq_subscribers *subs;
        bool exclusive;
        int err;

        subs = kzalloc_obj(*subs);
        if (!subs)
                return -ENOMEM;

        subs->info = *info;
        atomic_set(&subs->ref_count, 0);
        INIT_LIST_HEAD(&subs->src_list);
        INIT_LIST_HEAD(&subs->dest_list);

        exclusive = !!(info->flags & SNDRV_SEQ_PORT_SUBS_EXCLUSIVE);

        err = check_and_subscribe_port(src_client, src_port, subs, true,
                                       exclusive,
                                       connector->number != src_client->number);
        if (err < 0)
                goto error;
        err = check_and_subscribe_port(dest_client, dest_port, subs, false,
                                       exclusive,
                                       connector->number != dest_client->number);
        if (err < 0)
                goto error_dest;

        return 0;

 error_dest:
        delete_and_unsubscribe_port(src_client, src_port, subs, true,
                                    connector->number != src_client->number);
 error:
        kfree(subs);
        return err;
}

/* remove the connection */
int snd_seq_port_disconnect(struct snd_seq_client *connector,
                            struct snd_seq_client *src_client,
                            struct snd_seq_client_port *src_port,
                            struct snd_seq_client *dest_client,
                            struct snd_seq_client_port *dest_port,
                            struct snd_seq_port_subscribe *info)
{
        struct snd_seq_port_subs_info *dest = &dest_port->c_dest;
        struct snd_seq_subscribers *subs;
        int err = -ENOENT;

        /* always start from deleting the dest port for avoiding concurrent
         * deletions
         */
        scoped_guard(rwsem_write, &dest->list_mutex) {
                /* look for the connection */
                list_for_each_entry(subs, &dest->list_head, dest_list) {
                        if (match_subs_info(info, &subs->info)) {
                                __delete_and_unsubscribe_port(dest_client, dest_port,
                                                              subs, false,
                                                              connector->number != dest_client->number);
                                err = 0;
                                break;
                        }
                }
        }
        if (err < 0)
                return err;

        delete_and_unsubscribe_port(src_client, src_port, subs, true,
                                    connector->number != src_client->number);
        kfree(subs);
        return 0;
}


/* get matched subscriber */
int snd_seq_port_get_subscription(struct snd_seq_port_subs_info *src_grp,
                                  struct snd_seq_addr *dest_addr,
                                  struct snd_seq_port_subscribe *subs)
{
        struct snd_seq_subscribers *s;
        int err = -ENOENT;

        guard(rwsem_read)(&src_grp->list_mutex);
        list_for_each_entry(s, &src_grp->list_head, src_list) {
                if (addr_match(dest_addr, &s->info.dest)) {
                        *subs = s->info;
                        err = 0;
                        break;
                }
        }
        return err;
}

/*
 * Attach a device driver that wants to receive events from the
 * sequencer.  Returns the new port number on success.
 * A driver that wants to receive the events converted to midi, will
 * use snd_seq_midisynth_register_port().
 */
/* exported */
int snd_seq_event_port_attach(int client,
                              struct snd_seq_port_callback *pcbp,
                              int cap, int type, int midi_channels,
                              int midi_voices, char *portname)
{
        struct snd_seq_port_info portinfo;
        int  ret;

        /* Set up the port */
        memset(&portinfo, 0, sizeof(portinfo));
        portinfo.addr.client = client;
        strscpy(portinfo.name, portname ? portname : "Unnamed port",
                sizeof(portinfo.name));

        portinfo.capability = cap;
        portinfo.type = type;
        portinfo.kernel = pcbp;
        portinfo.midi_channels = midi_channels;
        portinfo.midi_voices = midi_voices;

        /* Create it */
        ret = snd_seq_kernel_client_ctl(client,
                                        SNDRV_SEQ_IOCTL_CREATE_PORT,
                                        &portinfo);

        if (ret >= 0)
                ret = portinfo.addr.port;

        return ret;
}
EXPORT_SYMBOL(snd_seq_event_port_attach);

/*
 * Detach the driver from a port.
 */
/* exported */
int snd_seq_event_port_detach(int client, int port)
{
        struct snd_seq_port_info portinfo;
        int  err;

        memset(&portinfo, 0, sizeof(portinfo));
        portinfo.addr.client = client;
        portinfo.addr.port   = port;
        err = snd_seq_kernel_client_ctl(client,
                                        SNDRV_SEQ_IOCTL_DELETE_PORT,
                                        &portinfo);

        return err;
}
EXPORT_SYMBOL(snd_seq_event_port_detach);