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4459 decky 1
/*
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 * Copyright (c) 2009 Martin Decky
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 * All rights reserved.
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 *
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 * Redistribution and use in source and binary forms, with or without
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 * modification, are permitted provided that the following conditions
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 * are met:
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 *
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 * - Redistributions of source code must retain the above copyright
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 *   notice, this list of conditions and the following disclaimer.
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 * - Redistributions in binary form must reproduce the above copyright
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 *   notice, this list of conditions and the following disclaimer in the
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 *   documentation and/or other materials provided with the distribution.
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 * - The name of the author may not be used to endorse or promote products
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 *   derived from this software without specific prior written permission.
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 *
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 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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 */
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/** @addtogroup ns
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 * @{
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 */
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#include <ipc/ipc.h>
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#include <libadt/hash_table.h>
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#include <assert.h>
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#include <errno.h>
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#include "service.h"
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#include "ns.h"
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#define SERVICE_HASH_TABLE_CHAINS  20
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/** Service hash table item. */
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typedef struct {
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    link_t link;
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    ipcarg_t service;        /**< Number of the service. */
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    ipcarg_t phone;          /**< Phone registered with the service. */
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    ipcarg_t in_phone_hash;  /**< Incoming phone hash. */
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} hashed_service_t;
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/** Compute hash index into service hash table.
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 *
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 * @param key Pointer keys. However, only the first key (i.e. service number)
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 *            is used to compute the hash index.
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 *
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 * @return Hash index corresponding to key[0].
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 *
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 */
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static hash_index_t service_hash(unsigned long *key)
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{
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    assert(key);
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    return (*key % SERVICE_HASH_TABLE_CHAINS);
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}
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/** Compare a key with hashed item.
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 *
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 * This compare function always ignores the third key.
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 * It exists only to make it possible to remove records
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 * originating from connection with key[1] in_phone_hash
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 * value. Note that this is close to being classified
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 * as a nasty hack.
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 *
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 * @param key  Array of keys.
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 * @param keys Must be lesser or equal to 3.
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 * @param item Pointer to a hash table item.
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 *
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 * @return Non-zero if the key matches the item, zero otherwise.
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 *
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 */
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static int service_compare(unsigned long key[], hash_count_t keys, link_t *item)
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{
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    assert(key);
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    assert(keys <= 3);
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    assert(item);
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    hashed_service_t *hs = hash_table_get_instance(item, hashed_service_t, link);
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    if (keys == 2)
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        return (key[1] == hs->in_phone_hash);
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    else
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        return (key[0] == hs->service);
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}
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/** Perform actions after removal of item from the hash table.
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 *
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 * @param item Item that was removed from the hash table.
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 *
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 */
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static void service_remove(link_t *item)
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{
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    assert(item);
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    free(hash_table_get_instance(item, hashed_service_t, link));
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}
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/** Operations for service hash table. */
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static hash_table_operations_t service_hash_table_ops = {
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    .hash = service_hash,
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    .compare = service_compare,
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    .remove_callback = service_remove
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};
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/** Service hash table structure. */
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static hash_table_t service_hash_table;
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/** Pending connection structure. */
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typedef struct {
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    link_t link;
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    ipcarg_t service;        /**< Number of the service. */
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    ipc_callid_t callid;     /**< Call ID waiting for the connection */
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    ipcarg_t arg2;           /**< Second argument */
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    ipcarg_t arg3;           /**< Third argument */
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} pending_conn_t;
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static link_t pending_conn;
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int service_init(void)
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{
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    if (!hash_table_create(&service_hash_table, SERVICE_HASH_TABLE_CHAINS,
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        3, &service_hash_table_ops)) {
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        printf(NAME ": No memory available for services\n");
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        return ENOMEM;
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    }
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    list_initialize(&pending_conn);
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    return EOK;
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}
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/** Process pending connection requests */
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void process_pending_conn(void)
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{
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    link_t *cur;
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loop:
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    for (cur = pending_conn.next; cur != &pending_conn; cur = cur->next) {
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        pending_conn_t *pr = list_get_instance(cur, pending_conn_t, link);
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        unsigned long keys[3] = {
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            pr->service,
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            0,
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        };
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        link_t *link = hash_table_find(&service_hash_table, keys);
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        if (!link)
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            continue;
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        hashed_service_t *hs = hash_table_get_instance(link, hashed_service_t, link);
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        ipcarg_t retval = ipc_forward_fast(pr->callid, hs->phone,
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            pr->arg2, pr->arg3, 0, IPC_FF_NONE);
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        if (!(pr->callid & IPC_CALLID_NOTIFICATION))
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            ipc_answer_0(pr->callid, retval);
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        list_remove(cur);
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        free(pr);
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        goto loop;
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    }
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}
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/** Register service.
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 *
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 * @param service Service to be registered.
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 * @param phone   Phone to be used for connections to the service.
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 * @param call    Pointer to call structure.
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 *
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 * @return Zero on success or a value from @ref errno.h.
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 *
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 */
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int register_service(ipcarg_t service, ipcarg_t phone, ipc_call_t *call)
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{
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    unsigned long keys[3] = {
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        service,
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        call->in_phone_hash,
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    };
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    if (hash_table_find(&service_hash_table, keys))
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        return EEXISTS;
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    hashed_service_t *hs = (hashed_service_t *) malloc(sizeof(hashed_service_t));
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    if (!hs)
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        return ENOMEM;
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    link_initialize(&hs->link);
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    hs->service = service;
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    hs->phone = phone;
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    hs->in_phone_hash = call->in_phone_hash;
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    hash_table_insert(&service_hash_table, keys, &hs->link);
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200
    return 0;
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}
202
 
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/** Connect client to service.
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 *
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 * @param service Service to be connected to.
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 * @param call    Pointer to call structure.
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 * @param callid  Call ID of the request.
208
 *
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 * @return Zero on success or a value from @ref errno.h.
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 *
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 */
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void connect_to_service(ipcarg_t service, ipc_call_t *call, ipc_callid_t callid)
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{
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    ipcarg_t retval;
215
    unsigned long keys[3] = {
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        service,
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        0,
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219
    };
220
 
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    link_t *link = hash_table_find(&service_hash_table, keys);
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    if (!link) {
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        if (IPC_GET_ARG4(*call) & IPC_FLAG_BLOCKING) {
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            /* Blocking connection, add to pending list */
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            pending_conn_t *pr =
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                (pending_conn_t *) malloc(sizeof(pending_conn_t));
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            if (!pr) {
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                retval = ENOMEM;
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                goto out;
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            }
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            pr->service = service;
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            pr->callid = callid;
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            pr->arg2 = IPC_GET_ARG2(*call);
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            pr->arg3 = IPC_GET_ARG3(*call);
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            list_append(&pr->link, &pending_conn);
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            return;
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        }
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        retval = ENOENT;
240
        goto out;
241
    }
242
 
243
    hashed_service_t *hs = hash_table_get_instance(link, hashed_service_t, link);
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    retval = ipc_forward_fast(callid, hs->phone, IPC_GET_ARG2(*call),
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        IPC_GET_ARG3(*call), 0, IPC_FF_NONE);
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247
out:
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    if (!(callid & IPC_CALLID_NOTIFICATION))
249
        ipc_answer_0(callid, retval);
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}
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/**
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 * @}
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 */