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/*

 * Copyright (C) 2006 Ondrej Palkovsky

 * All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 *

 * - Redistributions of source code must retain the above copyright

 *   notice, this list of conditions and the following disclaimer.

 * - 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.

 * - The name of the author may not be used to endorse or promote products

 *   derived from this software without specific prior written permission.

 *

 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 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.

 */

#include <arch.h>

#include <proc/task.h>

#include <errno.h>

#include <mm/page.h>

#include <memstr.h>

#include <debug.h>

#include <ipc/ipc.h>

#include <ipc/sysipc.h>

#include <print.h>

#include <arch.h>

#include <proc/thread.h>

/* TODO: multi-threaded connect-to-me can cause race condition

 * on phone, add counter + thread_kill??

 *

 */

/** Return true if the method is a system method */

static inline int is_system_method(__native method)

{

    if (method <= IPC_M_LAST_SYSTEM)

        return 1;

    return 0;

}

/** Return true if the message with this method is forwardable

 *

 * - some system messages may be forwarded, for some of them

 *   it is useless

 */

static inline int is_forwardable(__native method)

{

    return 1;

}

/** Find call_t * in call table according to callid

 *

 * @return NULL on not found, otherwise pointer to call structure

 */

static inline call_t * get_call(__native callid)

{

    /* TODO: Traverse list of dispatched calls and find one */

    /* TODO: locking of call, ripping it from dispatched calls etc.  */

    return (call_t *) callid;

}

/** Return pointer to phone identified by phoneid or NULL if non-existent */

static phone_t * get_phone(__native phoneid)

{

    phone_t *phone;

    if (phoneid >= IPC_MAX_PHONES)

        return NULL;

    phone = &TASK->phones[phoneid];

    if (!phone->callee)

        return NULL;

    return phone;

}

/** Allocate new phone slot in current TASK structure */

static int phone_alloc(void)

{

    int i;

    spinlock_lock(&TASK->lock);

    for (i=0; i < IPC_MAX_PHONES; i++) {

        if (!TASK->phones[i].busy) {

            TASK->phones[i].busy = 1;

            break;

        }

    }

    spinlock_unlock(&TASK->lock);

    if (i >= IPC_MAX_PHONES)

        return -1;

    return i;

}

/** Disconnect phone */

static void phone_dealloc(int phoneid)

{

    spinlock_lock(&TASK->lock);

    ASSERT(TASK->phones[phoneid].busy);

    if (TASK->phones[phoneid].callee)

        ipc_phone_destroy(&TASK->phones[phoneid]);

    TASK->phones[phoneid].busy = 0;

    spinlock_unlock(&TASK->lock);

}

static void phone_connect(int phoneid, answerbox_t *box)

{

    phone_t *phone = &TASK->phones[phoneid];

    ipc_phone_connect(phone, box);

}

/****************************************************/

/* Functions that preprocess answer before sending

 * it to the recepient

 */

/** Return true if the caller (ipc_answer) should save

 * the old call contents and call answer_preprocess

 */

static inline int answer_will_preprocess(call_t *call)

{

    if (IPC_GET_METHOD(call->data) == IPC_M_CONNECTTOME)

        return 1;

    if (IPC_GET_METHOD(call->data) == IPC_M_CONNECTMETO)

        return 1;

    return 0;

}

/** Interpret process answer as control information */

static inline void answer_preprocess(call_t *answer, ipc_data_t *olddata)

{

    int phoneid;

    if (IPC_GET_METHOD(*olddata) == IPC_M_CONNECTTOME) {

        phoneid = IPC_GET_ARG3(*olddata);

        if (IPC_GET_RETVAL(answer->data)) {

            /* The connection was not accepted */

            phone_dealloc(phoneid);

        } else {

            /* The connection was accepted */

            phone_connect(phoneid,&answer->sender->answerbox);

        }

    } else if (IPC_GET_METHOD(*olddata) == IPC_M_CONNECTMETO) {

        /* If the users accepted call, connect */

        if (!IPC_GET_RETVAL(answer->data)) {

            ipc_phone_connect((phone_t *)IPC_GET_ARG3(*olddata),

                      &TASK->answerbox);

        }

    }

}

/****************************************************/

/* Functions called to process received call/answer

 * before passing to uspace

 */

/** Do basic kernel processing of received call answer */

static int process_answer(answerbox_t *box,call_t *call)

{

    return 0;

}

/** Do basic kernel processing of received call request

 *

 * @return 0 - the call should be passed to userspace, 1 - ignore call

 */

static int process_request(answerbox_t *box,call_t *call)

{

    int phoneid;

    if (IPC_GET_METHOD(call->data) == IPC_M_CONNECTTOME) {

        phoneid = phone_alloc();

        if (phoneid < 0) { /* Failed to allocate phone */

            IPC_SET_RETVAL(call->data, ELIMIT);

            ipc_answer(box,call);

            return -1;

        }

        IPC_SET_ARG3(call->data, phoneid);

    }

    return 0;

}

/** Send a call over IPC, wait for reply, return to user

 *

 * @return Call identification, returns -1 on fatal error,

           -2 on 'Too many async request, handle answers first

 */

__native sys_ipc_call_sync_fast(__native phoneid, __native method,

                __native arg1, __native *data)

{

    call_t call;

    phone_t *phone;

    phone = get_phone(phoneid);

    if (!phone)

        return ENOENT;

    if (is_system_method(method))

        return EPERM;

    ipc_call_init(&call);

    IPC_SET_METHOD(call.data, method);

    IPC_SET_ARG1(call.data, arg1);

    ipc_call_sync(phone, &call);

    copy_to_uspace(data, &call.data, sizeof(call.data));

    return 0;

}

/** Synchronous IPC call allowing to send whole message */

__native sys_ipc_call_sync(__native phoneid, __native *question,

               __native *reply)

{

    call_t call;

    phone_t *phone;

    phone = get_phone(phoneid);

    if (!phone)

        return ENOENT;

    ipc_call_init(&call);

    copy_from_uspace(&call.data, question, sizeof(call.data));

    if (is_system_method(IPC_GET_METHOD(call.data)))

        return EPERM;

    ipc_call_sync(phone, &call);

    copy_to_uspace(reply, &call.data, sizeof(call.data));

    return 0;

}

/** Check that the task did not exceed allowed limit

 *

 * @return 0 - Limit OK,   -1 - limit exceeded

 */

static int check_call_limit(void)

{

    if (atomic_preinc(&TASK->active_calls) > IPC_MAX_ASYNC_CALLS) {

        atomic_dec(&TASK->active_calls);

        return -1;

    }

    return 0;

}

/** Send an asynchronous call over ipc

 *

 * @return Call identification, returns -1 on fatal error,

           -2 on 'Too many async request, handle answers first

 */

__native sys_ipc_call_async_fast(__native phoneid, __native method,

                 __native arg1, __native arg2)

{

    call_t *call;

    phone_t *phone;

    phone = get_phone(phoneid);

    if (!phone)

        return IPC_CALLRET_FATAL;

    if (is_system_method(method))

        return IPC_CALLRET_FATAL;

    if (check_call_limit())

        return IPC_CALLRET_TEMPORARY;

    call = ipc_call_alloc();

    IPC_SET_METHOD(call->data, method);

    IPC_SET_ARG1(call->data, arg1);

    IPC_SET_ARG2(call->data, arg2);

    ipc_call(phone, call);

    return (__native) call;

}

/** Synchronous IPC call allowing to send whole message

 *

 * @return The same as sys_ipc_call_async

 */

__native sys_ipc_call_async(__native phoneid, __native *data)

{

    call_t *call;

    phone_t *phone;

    phone = get_phone(phoneid);

    if (!phone)

        return IPC_CALLRET_FATAL;

    if (check_call_limit())

        return IPC_CALLRET_TEMPORARY;

    call = ipc_call_alloc();

    copy_from_uspace(&call->data, data, sizeof(call->data));

    if (is_system_method(IPC_GET_METHOD(call->data))) {

        ipc_call_free(call);

        return EPERM;

    }

    ipc_call(phone, call);

    return (__native) call;

}

/** Forward received call to another destination

 *

 * The arg1 and arg2 are changed in the forwarded message

 *

 * Warning: If implementing non-fast version, make sure that

 *          arg3 is not rewritten for certain system IPC

 */

__native sys_ipc_forward_fast(__native callid, __native phoneid,

                  __native method, __native arg1)

{

    call_t *call;

    phone_t *phone;

    call = get_call(callid);

    if (!call)

        return ENOENT;

    phone = get_phone(phoneid);

    if (!phone) {

        IPC_SET_RETVAL(call->data, EFORWARD);

        ipc_answer(&TASK->answerbox, call);

        return ENOENT;

    }

    if (!is_forwardable(IPC_GET_METHOD(call->data))) {

        IPC_SET_RETVAL(call->data, EFORWARD);

        ipc_answer(&TASK->answerbox, call);

        return EPERM;

    }

    /* Userspace is not allowed to change method of system methods

     * on forward, allow changing ARG1 and ARG2 by means of method and arg1

     */

    if (is_system_method(IPC_GET_METHOD(call->data))) {

        IPC_SET_ARG1(call->data, method);

        IPC_SET_ARG2(call->data, arg1);

    } else {

        IPC_SET_METHOD(call->data, method);

        IPC_SET_ARG1(call->data, arg1);

    }

    ipc_forward(call, phone->callee, &TASK->answerbox);

    return 0;

}

/** Send IPC answer */

__native sys_ipc_answer_fast(__native callid, __native retval,

                 __native arg1, __native arg2)

{

    call_t *call;

    ipc_data_t saved_data;

    int preprocess = 0;

    call = get_call(callid);

    if (!call)

        return ENOENT;

    if (answer_will_preprocess(call)) {

        memcpy(&saved_data, &call->data, sizeof(call->data));

        preprocess = 1;

    }

    IPC_SET_RETVAL(call->data, retval);

    IPC_SET_ARG1(call->data, arg1);

    IPC_SET_ARG2(call->data, arg2);

    if (preprocess)

        answer_preprocess(call, &saved_data);

    ipc_answer(&TASK->answerbox, call);

    return 0;

}

/** Send IPC answer */

inline __native sys_ipc_answer(__native callid, __native *data)

{

    call_t *call;

    ipc_data_t saved_data;

    int preprocess = 0;

    call = get_call(callid);

    if (!call)

        return ENOENT;

    if (answer_will_preprocess(call)) {

        memcpy(&saved_data, &call->data, sizeof(call->data));

        preprocess = 1;

    }

    copy_from_uspace(&call->data, data, sizeof(call->data));

    if (preprocess)

        answer_preprocess(call, &saved_data);

    ipc_answer(&TASK->answerbox, call);

    return 0;

}

/** Ask the other side of connection to do 'callback' connection

 *

 * @return 0 if no error, error otherwise

 */

__native sys_ipc_connect_to_me(__native phoneid, __native arg1,

                   __native arg2, task_id_t *taskid)

{

    call_t call;

    phone_t *phone;

    phone = get_phone(phoneid);

    if (!phone)

        return ENOENT;

    ipc_call_init(&call);

    IPC_SET_METHOD(call.data, IPC_M_CONNECTTOME);

    IPC_SET_ARG1(call.data, arg1);

    IPC_SET_ARG2(call.data, arg2);

    ipc_call_sync(phone, &call);

    if (!IPC_GET_RETVAL(call.data) && taskid)

        copy_to_uspace(taskid,

                   &phone->callee->task->taskid,

                   sizeof(TASK->taskid));

    return IPC_GET_RETVAL(call.data);

}

/** Ask target process to connect me somewhere

 *

 * @return phoneid - on success, error otherwise

 */

__native sys_ipc_connect_me_to(__native phoneid, __native arg1,

                   __native arg2)

{

    call_t call;

    phone_t *phone;

    int newphid;

    phone = get_phone(phoneid);

    if (!phone)

        return ENOENT;

    newphid = phone_alloc();

    if (newphid < 0)

        return ELIMIT;

    ipc_call_init(&call);

    IPC_SET_METHOD(call.data, IPC_M_CONNECTMETO);

    IPC_SET_ARG1(call.data, arg1);

    IPC_SET_ARG2(call.data, arg2);

    IPC_SET_ARG3(call.data, (__native)&TASK->phones[newphid]);

    ipc_call_sync(phone, &call);

    if (IPC_GET_RETVAL(call.data)) { /* Connection failed */

        phone_dealloc(newphid);

        return IPC_GET_RETVAL(call.data);

    }

    return newphid;

}

/** Wait for incoming ipc call or answer

 *

 * Generic function - can serve either as inkernel or userspace call

 * - inside kernel does probably unnecessary copying of data (TODO)

 *

 * @param result

 * @param taskid

 * @param flags

 * @return Callid, if callid & 1, then the call is answer

 */

inline __native sys_ipc_wait_for_call(ipc_data_t *calldata,

                      task_id_t *taskid,

                      __native flags)

{

    call_t *call;

restart:   

    call = ipc_wait_for_call(&TASK->answerbox, flags);

    if (call->flags & IPC_CALL_ANSWERED) {

        if (process_answer(&TASK->answerbox, call))

            goto restart;

        copy_to_uspace(calldata, &call->data, sizeof(call->data));

        atomic_dec(&TASK->active_calls);

        ASSERT(! (call->flags & IPC_CALL_STATIC_ALLOC));

        ipc_call_free(call);

        return ((__native)call) | IPC_CALLID_ANSWERED;

    }

    if (process_request(&TASK->answerbox, call))

        goto restart;

    copy_to_uspace(calldata, &call->data, sizeof(call->data));

    copy_to_uspace(taskid, (void *)&TASK->taskid, sizeof(TASK->taskid));

    return (__native)call;

}