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/*

 * Copyright (c) 2007 Josef Cejka

 * 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.

 */

/**

 * @defgroup devmap Device mapper.

 * @brief   HelenOS device mapper.

 * @{

 */

/** @file

 */

#include <ipc/services.h>

#include <ipc/ns.h>

#include <async.h>

#include <stdio.h>

#include <errno.h>

#include <bool.h>

#include <futex.h>

#include <stdlib.h>

#include <string.h>

#include "devmap.h"

LIST_INITIALIZE(devices_list);

LIST_INITIALIZE(drivers_list);

/* order of locking:

 * drivers_list_futex

 * devices_list_futex

 * (devmap_driver_t *)->devices_futex

 * create_handle_futex

 **/

static atomic_t devices_list_futex = FUTEX_INITIALIZER;

static atomic_t drivers_list_futex = FUTEX_INITIALIZER;

static atomic_t create_handle_futex = FUTEX_INITIALIZER;

static int devmap_create_handle(void)

{

    static int last_handle = 0;

    int handle;

    /* TODO: allow reusing old handles after their unregistration

        and implement some version of LRU algorithm */

    /* FIXME: overflow */

    futex_down(&create_handle_futex);  

    last_handle += 1;

    handle = last_handle;

    futex_up(&create_handle_futex);

    return handle;

}

/** Initialize device mapper.

 *

 *

 */

static int devmap_init()

{

    /* TODO: */

    return EOK;

}

/** Find device with given name.

 *

 */

static devmap_device_t *devmap_device_find_name(const char *name)

{

    link_t *item;

    devmap_device_t *device = NULL;

    item = devices_list.next;

    while (item != &devices_list) {

        device = list_get_instance(item, devmap_device_t, devices);

        if (0 == strcmp(device->name, name)) {

            break;

        }

        item = item->next;

    }

    if (item == &devices_list) {

        printf("DevMap: no device named %s.\n", name);

        return NULL;

    }

    device = list_get_instance(item, devmap_device_t, devices);

    return device;

}

/** Find device with given handle.

 * @todo: use hash table

 */

static devmap_device_t *devmap_device_find_handle(int handle)

{

    link_t *item;

    devmap_device_t *device = NULL;

    futex_down(&devices_list_futex);

    item = (&devices_list)->next;

    while (item != &devices_list) {

        device = list_get_instance(item, devmap_device_t, devices);

        if (device->handle == handle) {

            break;

        }

        item = item->next;

    }

    if (item == &devices_list) {

        futex_up(&devices_list_futex);

        return NULL;

    }

    device = list_get_instance(item, devmap_device_t, devices);

    futex_up(&devices_list_futex);

    return device;

}

/** Unregister device and free it. Its assumed that driver's device list

 * is already locked.

 *

 */

static int devmap_device_unregister_core(devmap_device_t *device)

{

    list_remove(&(device->devices));

    list_remove(&(device->driver_devices));

    free(device->name);

    free(device);

    return EOK;

}

/** Read info about new driver and add it into linked list of registered drivers.

 */

static void devmap_driver_register(devmap_driver_t **odriver)

{

    size_t name_size;

    ipc_callid_t callid;

    ipc_call_t call;

    devmap_driver_t *driver;

    ipc_callid_t iid;

    ipc_call_t icall;

    *odriver = NULL;

    iid = async_get_call(&icall);

    if (IPC_GET_METHOD(icall) != DEVMAP_DRIVER_REGISTER) {

        ipc_answer_fast(iid, EREFUSED, 0, 0);

        return;

    }

    if (NULL == (driver = (devmap_driver_t *)malloc(sizeof(devmap_driver_t)))) {

        ipc_answer_fast(iid, ENOMEM, 0, 0);

        return;

    }

    /*

     * Get driver name

     */

    if (!ipc_data_receive(&callid, &call, NULL, &name_size)) {

        printf("Unexpected request: %u.\n", IPC_GET_METHOD(call));

        free(driver);

        ipc_answer_fast(callid, EREFUSED, 0, 0);

        ipc_answer_fast(iid, EREFUSED, 0, 0);

        return;

    }

    if (name_size > DEVMAP_NAME_MAXLEN) {

        printf("Too logn name: %u: maximum is %u.\n", name_size, DEVMAP_NAME_MAXLEN);

        free(driver);

        ipc_answer_fast(callid, EINVAL, 0, 0);

        ipc_answer_fast(iid, EREFUSED, 0, 0);

        return;

    }

    /*

     * Allocate buffer for device name.

     */

    if (NULL == (driver->name = (char *)malloc(name_size + 1))) {

        printf("Cannot allocate space for driver name.\n");

        free(driver);

        ipc_answer_fast(callid, ENOMEM, 0, 0);

        ipc_answer_fast(iid, EREFUSED, 0, 0);

        return;

    }  

    /*

     * Send confirmation to sender and get data into buffer.

     */

    if (EOK != ipc_data_deliver(callid, &call, driver->name, name_size)) {

        printf("Cannot read driver name.\n");

        free(driver->name);

        free(driver);

        ipc_answer_fast(iid, EREFUSED, 0, 0);

        return;

    }

    driver->name[name_size] = 0;

    printf("Read driver name: '%s'.\n", driver->name);

    /* Initialize futex for list of devices owned by this driver */

    futex_initialize(&(driver->devices_futex) ,1);

    /*

     * Initialize list of asociated devices

     */

    list_initialize(&(driver->devices));

    /*

     * Create connection to the driver

     */

    callid = async_get_call(&call);

    if (IPC_M_CONNECT_TO_ME != IPC_GET_METHOD(call)) {

        printf("DevMap: Unexpected method: %u.\n", \

            IPC_GET_METHOD(call));

        ipc_answer_fast(callid, ENOTSUP, 0, 0);

        free(driver->name);

        free(driver);

        ipc_answer_fast(iid, ENOTSUP, 0, 0);

        return;

    }

    driver->phone = IPC_GET_ARG3(call);

    ipc_answer_fast(callid, EOK, 0, 0);

    list_initialize(&(driver->drivers));

    futex_down(&drivers_list_futex);   

    /* TODO: check that no driver with name equals to driver->name is registered */

    /*

     * Insert new driver into list of registered drivers

     */

    list_append(&(driver->drivers), &drivers_list);

    futex_up(&drivers_list_futex); 

    ipc_answer_fast(iid, EOK, 0, 0);

    printf("Driver registered.\n");

    *odriver = driver;

    return;

}

/** Unregister device driver, unregister all its devices and free driver structure.

 *

 */

static int devmap_driver_unregister(devmap_driver_t *driver)

{

    devmap_device_t *device;

    if (NULL == driver) {

        printf("Error: driver == NULL.\n");

        return EEXISTS;

    }

    printf("Unregister driver '%s'.\n", driver->name);

    futex_down(&drivers_list_futex);   

    ipc_hangup(driver->phone);

    /* remove it from list of drivers */

    list_remove(&(driver->drivers));

    /* unregister all its devices */

    futex_down(&devices_list_futex);   

    futex_down(&(driver->devices_futex));

    while (!list_empty(&(driver->devices))) {

        device = list_get_instance(driver->devices.next, devmap_device_t, driver_devices);

        printf("Unregister device '%s'.\n", device->name);

        devmap_device_unregister_core(device);

    }

    futex_up(&(driver->devices_futex));

    futex_up(&devices_list_futex); 

    futex_up(&drivers_list_futex); 

    /* free name and driver */

    if (NULL != driver->name) {

        free(driver->name);

    }

    free(driver);

    printf("Driver unregistered.\n");

    return EOK;

}

/** Register instance of device

 *

 */

static void devmap_device_register(ipc_callid_t iid, ipc_call_t *icall,

        devmap_driver_t *driver)

{

    ipc_callid_t callid;

    ipc_call_t call;

    size_t size;

    devmap_device_t *device;

    if (NULL == driver) {

        printf("Invalid driver registration.\n");

        ipc_answer_fast(iid, EREFUSED, 0, 0);

        return;

    }

    /* Create new device entry */

    if (NULL == (device = (devmap_device_t *)malloc(sizeof(devmap_device_t)))) {

        printf("Cannot allocate new device.\n");

        ipc_answer_fast(iid, ENOMEM, 0, 0);

        return;

    }

    /* Get device name */

    if (!ipc_data_receive(&callid, &call, NULL, &size)) {

        free(device);

        printf("Cannot read device name.\n");

        ipc_answer_fast(iid, EREFUSED, 0, 0);

        return;

    }

    if (size > DEVMAP_NAME_MAXLEN) {

        printf("Too long device name: %u.\n", size);

        free(device);

        ipc_answer_fast(callid, EINVAL, 0, 0);

        ipc_answer_fast(iid, EREFUSED, 0, 0);

        return;

    }

        /* +1 for terminating \0 */

    device->name = (char *)malloc(size + 1);

    if (NULL == device->name) {

        printf("Cannot read device name.\n");

        free(device);

        ipc_answer_fast(callid, ENOMEM, 0, 0);

        ipc_answer_fast(iid, EREFUSED, 0, 0);

        return;

    }

    ipc_data_deliver(callid, &call, device->name, size);

    device->name[size] = 0;

    list_initialize(&(device->devices));

    list_initialize(&(device->driver_devices));

    futex_down(&devices_list_futex);   

    /* Check that device with such name is not already registered */

    if (NULL != devmap_device_find_name(device->name)) {

        printf("Device '%s' already registered.\n", device->name);

        futex_up(&devices_list_futex); 

        free(device->name);

        free(device);

        ipc_answer_fast(iid, EEXISTS, 0, 0);

        return;

    }

    /* Get unique device handle */

    device->handle = devmap_create_handle();

    device->driver = driver;

    /* Insert device into list of all devices  */

    list_append(&(device->devices), &devices_list);

    /* Insert device into list of devices that belog to one driver */

    futex_down(&(device->driver->devices_futex));  

    list_append(&(device->driver_devices), &(device->driver->devices));

    futex_up(&(device->driver->devices_futex));

    futex_up(&devices_list_futex); 

    printf("Device '%s' registered.\n", device->name); 

    ipc_answer_fast(iid, EOK, device->handle, 0);

    return;

}

/**

 *

 */

static int devmap_device_unregister(ipc_callid_t iid, ipc_call_t *icall,

    devmap_driver_t *driver)

{

    /* TODO */

    return EOK;

}

/** Connect client to the device.

 * Find device driver owning requested device and forward

 * the message to it.

 *

 *

 */

static void devmap_forward(ipc_callid_t callid, ipc_call_t *call)

{

    devmap_device_t *dev;

    int handle;

    /*

     * Get handle from request

     */

    handle = IPC_GET_ARG1(*call);

    dev = devmap_device_find_handle(handle);

    if (NULL == dev) {

        printf("DevMap: No registered device with handle %d.\n", handle);

        ipc_answer_fast(callid, ENOENT, 0, 0);

        return;

    }

        /* FIXME: is this correct method how to pass argument on forwarding ?*/

    ipc_forward_fast(callid, dev->driver->phone, (ipcarg_t)(dev->handle), 0);

    return;

}

/** Find handle for device instance identified by name.

 * In answer will be send EOK and device handle in arg1 or a error

 * code from errno.h.

 */

static void devmap_get_handle(ipc_callid_t iid, ipc_call_t *icall)

{

    char *name = NULL;

    size_t name_size;

    const devmap_device_t *dev;

    ipc_callid_t callid;

    ipc_call_t call;

    ipcarg_t retval;

    /*

     * Wait for incoming message with device name (but do not

     * read the name itself until the buffer is allocated).

     */

    if (!ipc_data_receive(&callid, &call, NULL, &name_size)) {

        ipc_answer_fast(callid, EREFUSED, 0, 0);

        ipc_answer_fast(iid, EREFUSED, 0, 0);

        return;

    }

    if (name_size > DEVMAP_NAME_MAXLEN) {

        ipc_answer_fast(callid, EINVAL, 0, 0);

        ipc_answer_fast(iid, EREFUSED, 0, 0);

        return;

    }

    /*

     * Allocate buffer for device name.

     */

    if (NULL == (name = (char *)malloc(name_size))) {

        ipc_answer_fast(callid, ENOMEM, 0, 0);

        ipc_answer_fast(iid, EREFUSED, 0, 0);

        return;

    }  

    /*

     * Send confirmation to sender and get data into buffer.

     */

    if (EOK != (retval = ipc_data_deliver(callid, &call, name, name_size))) {

        ipc_answer_fast(iid, EREFUSED, 0, 0);

        return;

    }

    /*

     * Find device name in linked list of known devices.

     */

    dev = devmap_device_find_name(name);

    /*

     * Device was not found.

     */

    if (NULL == dev) {

        printf("DevMap: device %s has not been registered.\n", name);

        ipc_answer_fast(iid, ENOENT, 0, 0);

        return;

    }

    printf("DevMap: device %s has handler %d.\n", name, dev->handle);

    ipc_answer_fast(iid, EOK, dev->handle, 0);

    return;

}

/** Find name of device identified by id and send it to caller.

 *

 */

static void devmap_get_name(ipc_callid_t iid, ipc_call_t *icall)

{

    const devmap_device_t *device;

    size_t name_size;

    device = devmap_device_find_handle(IPC_GET_ARG1(*icall));

    /*

     * Device not found.

     */

    if (NULL == device) {

        ipc_answer_fast(iid, ENOENT, 0, 0);

        return;

    }  

    ipc_answer_fast(iid, EOK, 0, 0);

    name_size = strlen(device->name);

/*  FIXME:

    we have no channel from DevMap to client ->

    sending must be initiated by client

    int rc = ipc_data_send(phone, device->name, name_size);

    if (rc != EOK) {

        async_wait_for(req, NULL);

        return rc;

    }

*/ 

    /* TODO: send name in response */

    return;

}

/** Handle connection with device driver.

 *

 */

static void

devmap_connection_driver(ipc_callid_t iid, ipc_call_t *icall)

{

    ipc_callid_t callid;

    ipc_call_t call;

    bool cont = true;

    devmap_driver_t *driver = NULL;

    ipc_answer_fast(iid, EOK, 0, 0);

    devmap_driver_register(&driver);

    if (NULL == driver) {

        printf("DevMap: driver registration failed.\n");

        return;

    }

    while (cont) {

        callid = async_get_call(&call);

        switch (IPC_GET_METHOD(call)) {

        case IPC_M_PHONE_HUNGUP:

            printf("DevMap: connection hung up.\n");

            cont = false;

            continue; /* Exit thread */

        case DEVMAP_DRIVER_UNREGISTER:

            printf("DevMap: unregister driver.\n");

            if (NULL == driver) {

                printf("DevMap: driver was not registered!\n");

                ipc_answer_fast(callid, ENOENT, 0, 0);

            } else {

                ipc_answer_fast(callid, EOK, 0, 0);

            }

            break;

        case DEVMAP_DEVICE_REGISTER:

            /* Register one instance of device */

            devmap_device_register(callid, &call, driver);

            break;

        case DEVMAP_DEVICE_UNREGISTER:

            /* Remove instance of device identified by handler */

            devmap_device_unregister(callid, &call, driver);

            break;

        case DEVMAP_DEVICE_GET_HANDLE:

            devmap_get_handle(callid, &call);

            break;

        case DEVMAP_DEVICE_GET_NAME:

            devmap_get_handle(callid, &call);

            break;

        default:

            if (!(callid & IPC_CALLID_NOTIFICATION)) {

                ipc_answer_fast(callid, ENOENT, 0, 0);

            }

        }

    }

    if (NULL != driver) {

            /*

             * Unregister the device driver and all its devices.

             */

        devmap_driver_unregister(driver);

        driver = NULL;

    }

}

/** Handle connection with device client.

 *

 */

static void

devmap_connection_client(ipc_callid_t iid, ipc_call_t *icall)

{

    ipc_callid_t callid;

    ipc_call_t call;

    bool cont = true;

    ipc_answer_fast(iid, EOK, 0, 0); /* Accept connection */

    while (cont) {

        callid = async_get_call(&call);

        switch (IPC_GET_METHOD(call)) {

        case IPC_M_PHONE_HUNGUP:

            printf("DevMap: connection hung up.\n");

            cont = false;

            continue; /* Exit thread */

        case DEVMAP_DEVICE_CONNECT_ME_TO:

            /* Connect client to selected device */

            printf("DevMap: connect to device %d.\n", IPC_GET_ARG1(call));

            devmap_forward(callid, &call);

            break;

        case DEVMAP_DEVICE_GET_HANDLE:

            devmap_get_handle(callid, &call);

            break;

        case DEVMAP_DEVICE_GET_NAME:

            /* TODO */

            devmap_get_name(callid, &call);

            break;

        default:

            if (!(callid & IPC_CALLID_NOTIFICATION)) {

                ipc_answer_fast(callid, ENOENT, 0, 0);

            }

        }

    }

}

/** Function for handling connections to devmap

 *

 */

static void

devmap_connection(ipc_callid_t iid, ipc_call_t *icall)

{

    printf("DevMap: new connection.\n");

        /* Select interface */

    switch ((ipcarg_t)(IPC_GET_ARG1(*icall))) {

        case DEVMAP_DRIVER:

            devmap_connection_driver(iid, icall);

            break;

        case DEVMAP_CLIENT:

            devmap_connection_client(iid, icall);

            break;

        default:

            ipc_answer_fast(iid, ENOENT, 0, 0); /* No such interface */

            printf("DevMap: Unknown interface %u.\n", \

                (ipcarg_t)(IPC_GET_ARG1(*icall)));

    }

    /* Cleanup */

    printf("DevMap: connection closed.\n");

    return;

}

/**

 *

 */

int main(int argc, char *argv[])

{

    ipcarg_t phonead;

    printf("DevMap: HelenOS device mapper.\n");

    if (devmap_init() != 0) {

        printf("Error while initializing DevMap service.\n");

        return -1;

    }

        /* Set a handler of incomming connections */

    async_set_client_connection(devmap_connection);

        /* Register device mapper at naming service */

    if (ipc_connect_to_me(PHONE_NS, SERVICE_DEVMAP, 0, &phonead) != 0)

        return -1;

    async_manager();

    /* Never reached */

    return 0;

}

/**

 * @}

 */