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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 <ipc/devmap.h>

#define NAME  "devmap"

/** Representation of device driver.

 *

 * Each driver is responsible for a set of devices.

 *

 */

typedef struct {

    /** Pointers to previous and next drivers in linked list */

    link_t drivers;

    /** Pointer to the linked list of devices controlled by this driver */

    link_t devices;

    /** Phone asociated with this driver */

    ipcarg_t phone;

    /** Device driver name */

    char *name;

    /** Futex for list of devices owned by this driver */

    atomic_t devices_futex;

} devmap_driver_t;

/** Info about registered device

 *

 */

typedef struct {

    /** Pointer to the previous and next device in the list of all devices */

    link_t devices;

    /** Pointer to the previous and next device in the list of devices

        owned by one driver */

    link_t driver_devices;

    /** Unique device identifier  */

    dev_handle_t handle;

    /** Device name */

    char *name;

    /** Device driver handling this device */

    devmap_driver_t *driver;

} devmap_device_t;

/** Pending lookup structure. */

typedef struct {

    link_t link;

    char *name;              /**< Device name */

    ipc_callid_t callid;     /**< Call ID waiting for the lookup */

} pending_req_t;

LIST_INITIALIZE(devices_list);

LIST_INITIALIZE(drivers_list);

LIST_INITIALIZE(pending_req);

/* Locking order:

 *  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 dev_handle_t last_handle = 0;

static dev_handle_t devmap_create_handle(void)

{

    /* TODO: allow reusing old handles after their unregistration

     * and implement some version of LRU algorithm

     */

    /* FIXME: overflow */

    futex_down(&create_handle_futex);

    last_handle++;

    futex_up(&create_handle_futex);

    return last_handle;

}

/** Find device with given name.

 *

 */

static devmap_device_t *devmap_device_find_name(const char *name)

{

    link_t *item = devices_list.next;

    devmap_device_t *device = NULL;

    while (item != &devices_list) {

        device = list_get_instance(item, devmap_device_t, devices);

        if (0 == str_cmp(device->name, name))

            break;

        item = item->next;

    }

    if (item == &devices_list)

        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(dev_handle_t handle)

{

    futex_down(&devices_list_futex);

    link_t *item = (&devices_list)->next;

    devmap_device_t *device = NULL;

    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. It's 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)

{

    *odriver = NULL;

    ipc_call_t icall;

    ipc_callid_t iid = async_get_call(&icall);

    if (IPC_GET_METHOD(icall) != DEVMAP_DRIVER_REGISTER) {

        ipc_answer_0(iid, EREFUSED);

        return;

    }

    devmap_driver_t *driver = (devmap_driver_t *) malloc(sizeof(devmap_driver_t));

    if (driver == NULL) {

        ipc_answer_0(iid, ENOMEM);

        return;

    }

    /*

     * Get driver name

     */

    ipc_callid_t callid;

    size_t name_size;

    if (!ipc_data_write_receive(&callid, &name_size)) {

        free(driver);

        ipc_answer_0(callid, EREFUSED);

        ipc_answer_0(iid, EREFUSED);

        return;

    }

    if (name_size > DEVMAP_NAME_MAXLEN) {

        free(driver);

        ipc_answer_0(callid, EINVAL);

        ipc_answer_0(iid, EREFUSED);

        return;

    }

    /*

     * Allocate buffer for device name.

     */

    driver->name = (char *) malloc(name_size + 1);

    if (driver->name == NULL) {

        free(driver);

        ipc_answer_0(callid, ENOMEM);

        ipc_answer_0(iid, EREFUSED);

        return;

    }

    /*

     * Send confirmation to sender and get data into buffer.

     */

    if (EOK != ipc_data_write_finalize(callid, driver->name, name_size)) {

        free(driver->name);

        free(driver);

        ipc_answer_0(iid, EREFUSED);

        return;

    }

    driver->name[name_size] = 0;

    /* 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

     */

    ipc_call_t call;

    callid = async_get_call(&call);

    if (IPC_M_CONNECT_TO_ME != IPC_GET_METHOD(call)) {

        ipc_answer_0(callid, ENOTSUP);

        free(driver->name);

        free(driver);

        ipc_answer_0(iid, ENOTSUP);

        return;

    }

    driver->phone = IPC_GET_ARG5(call);

    ipc_answer_0(callid, EOK);

    list_initialize(&(driver->drivers));

    futex_down(&drivers_list_futex);

    /* TODO:

     * check that no driver with name equal 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_0(iid, EOK);

    *odriver = driver;

}

/**

 * Unregister device driver, unregister all its devices and free driver

 * structure.

 *

 */

static int devmap_driver_unregister(devmap_driver_t *driver)

{

    if (driver == NULL)

        return EEXISTS;

    futex_down(&drivers_list_futex);

    if (driver->phone != 0)

        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))) {

        devmap_device_t *device = list_get_instance(driver->devices.next,

            devmap_device_t, driver_devices);

        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 (driver->name != NULL)

        free(driver->name);

    free(driver);

    return EOK;

}

/** Process pending lookup requests */

static void process_pending_lookup()

{

    link_t *cur;

loop:

    for (cur = pending_req.next; cur != &pending_req; cur = cur->next) {

        pending_req_t *pr = list_get_instance(cur, pending_req_t, link);

        const devmap_device_t *dev = devmap_device_find_name(pr->name);

        if (!dev)

            continue;

        ipc_answer_1(pr->callid, EOK, dev->handle);

        free(pr->name);

        list_remove(cur);

        free(pr);

        goto loop;

    }

}

/** Register instance of device

 *

 */

static void devmap_device_register(ipc_callid_t iid, ipc_call_t *icall,

    devmap_driver_t *driver)

{

    if (driver == NULL) {

        ipc_answer_0(iid, EREFUSED);

        return;

    }

    /* Create new device entry */

    devmap_device_t *device = (devmap_device_t *) malloc(sizeof(devmap_device_t));

    if (device == NULL) {

        ipc_answer_0(iid, ENOMEM);

        return;

    }

    /* Get device name */

    ipc_callid_t callid;

    size_t size;

    if (!ipc_data_write_receive(&callid, &size)) {

        free(device);

        ipc_answer_0(iid, EREFUSED);

        return;

    }

    if (size > DEVMAP_NAME_MAXLEN) {

        free(device);

        ipc_answer_0(callid, EINVAL);

        ipc_answer_0(iid, EREFUSED);

        return;

    }

    /* +1 for terminating \0 */

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

    if (device->name == NULL) {

        free(device);

        ipc_answer_0(callid, ENOMEM);

        ipc_answer_0(iid, EREFUSED);

        return;

    }

    ipc_data_write_finalize(callid, 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(NAME ": Device '%s' already registered\n", device->name);

        futex_up(&devices_list_futex); 

        free(device->name);

        free(device);

        ipc_answer_0(iid, EEXISTS);

        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);

    ipc_answer_1(iid, EOK, device->handle);

    process_pending_lookup();

}

/**

 *

 */

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)

{

    /*

     * Get handle from request

     */

    dev_handle_t handle = IPC_GET_ARG2(*call);

    devmap_device_t *dev = devmap_device_find_handle(handle);

    if ((dev == NULL) || (dev->driver == NULL) || (dev->driver->phone == 0)) {

        ipc_answer_0(callid, ENOENT);

        return;

    }

    ipc_forward_fast(callid, dev->driver->phone, dev->handle,

        IPC_GET_ARG3(*call), 0, IPC_FF_NONE);

}

/** 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)

{

    /*

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

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

     */

    ipc_callid_t callid;

    size_t size;

    if (!ipc_data_write_receive(&callid, &size)) {

        ipc_answer_0(callid, EREFUSED);

        ipc_answer_0(iid, EREFUSED);

        return;

    }

    if ((size < 1) || (size > DEVMAP_NAME_MAXLEN)) {

        ipc_answer_0(callid, EINVAL);

        ipc_answer_0(iid, EREFUSED);

        return;

    }

    /*

     * Allocate buffer for device name.

     */

    char *name = (char *) malloc(size + 1);

    if (name == NULL) {

        ipc_answer_0(callid, ENOMEM);

        ipc_answer_0(iid, EREFUSED);

        return;

    }

    /*

     * Send confirmation to sender and get data into buffer.

     */

    ipcarg_t retval = ipc_data_write_finalize(callid, name, size);

    if (retval != EOK) {

        ipc_answer_0(iid, EREFUSED);

        free(name);

        return;

    }

    name[size] = '\0';

    /*

     * Find device name in linked list of known devices.

     */

    const devmap_device_t *dev = devmap_device_find_name(name);

    /*

     * Device was not found.

     */

    if (dev == NULL) {

        if (IPC_GET_ARG1(*icall) & IPC_FLAG_BLOCKING) {

            /* Blocking lookup, add to pending list */

            pending_req_t *pr = (pending_req_t *) malloc(sizeof(pending_req_t));

            if (!pr) {

                ipc_answer_0(iid, ENOMEM);

                free(name);

                return;

            }

            pr->name = name;

            pr->callid = iid;

            list_append(&pr->link, &pending_req);

            return;

        }

        ipc_answer_0(iid, ENOENT);

        free(name);

        return;

    }

    ipc_answer_1(iid, EOK, dev->handle);

    free(name);

}

/** 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 = devmap_device_find_handle(IPC_GET_ARG1(*icall));

    /*

     * Device not found.

     */

    if (device == NULL) {

        ipc_answer_0(iid, ENOENT);

        return;

    }

    ipc_answer_0(iid, EOK);

    size_t name_size = str_size(device->name);

    /* FIXME:

     * We have no channel from DEVMAP to client, therefore

     * sending must be initiated by client.

     *

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

     * if (rc != EOK) {

     *     async_wait_for(req, NULL);

     *     return rc;

     * }

     */

    /* TODO: send name in response */

}

static void devmap_get_count(ipc_callid_t iid, ipc_call_t *icall)

{

    futex_down(&devices_list_futex);

    ipc_answer_1(iid, EOK, list_count(&devices_list));

    futex_up(&devices_list_futex);

}

static void devmap_get_devices(ipc_callid_t iid, ipc_call_t *icall)

{

    futex_down(&devices_list_futex);

    ipc_callid_t callid;

    size_t size;

    if (!ipc_data_read_receive(&callid, &size)) {

        ipc_answer_0(callid, EREFUSED);

        ipc_answer_0(iid, EREFUSED);

        return;

    }

    if ((size % sizeof(dev_desc_t)) != 0) {

        ipc_answer_0(callid, EINVAL);

        ipc_answer_0(iid, EREFUSED);

        return;

    }

    count_t count = size / sizeof(dev_desc_t);

    dev_desc_t *desc = (dev_desc_t *) malloc(size);

    if (desc == NULL) {

        ipc_answer_0(callid, ENOMEM);

        ipc_answer_0(iid, EREFUSED);

        return;

    }

    count_t pos = 0;

    link_t *item = devices_list.next;

    while ((item != &devices_list) && (pos < count)) {

        devmap_device_t *device = list_get_instance(item, devmap_device_t, devices);

        desc[pos].handle = device->handle;

        str_cpy(desc[pos].name, DEVMAP_NAME_MAXLEN, device->name);

        pos++;

        item = item->next;

    }

    ipcarg_t retval = ipc_data_read_finalize(callid, desc, pos * sizeof(dev_desc_t));

    if (retval != EOK) {

        ipc_answer_0(iid, EREFUSED);

        free(desc);

        return;

    }

    free(desc);

    futex_up(&devices_list_futex);

    ipc_answer_1(iid, EOK, pos);

}

/** Initialize device mapper.

 *

 *

 */

static bool devmap_init()

{

    /* Create NULL device entry */

    devmap_device_t *device = (devmap_device_t *) malloc(sizeof(devmap_device_t));

    if (device == NULL)

        return false;

    device->name = str_dup("null");

    if (device->name == NULL) {

        free(device);

        return false;

    }

    list_initialize(&(device->devices));

    list_initialize(&(device->driver_devices));

    futex_down(&devices_list_futex);

    /* Get unique device handle */

    device->handle = devmap_create_handle();

    device->driver = NULL;

    /* Insert device into list of all devices  */

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

    futex_up(&devices_list_futex);

    return true;

}

/** Handle connection with device driver.

 *

 */

static void devmap_connection_driver(ipc_callid_t iid, ipc_call_t *icall)

{

    /* Accept connection */

    ipc_answer_0(iid, EOK);

    devmap_driver_t *driver = NULL;

    devmap_driver_register(&driver);

    if (NULL == driver)

        return;

    bool cont = true;

    while (cont) {

        ipc_call_t call;

        ipc_callid_t callid = async_get_call(&call);

        switch (IPC_GET_METHOD(call)) {

        case IPC_M_PHONE_HUNGUP:

            cont = false;

            /* Exit thread */

            continue;

        case DEVMAP_DRIVER_UNREGISTER:

            if (NULL == driver)

                ipc_answer_0(callid, ENOENT);

            else

                ipc_answer_0(callid, EOK);

            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_name(callid, &call);

            break;

        default:

            if (!(callid & IPC_CALLID_NOTIFICATION))

                ipc_answer_0(callid, ENOENT);

        }

    }

    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)

{

    /* Accept connection */

    ipc_answer_0(iid, EOK);

    bool cont = true;

    while (cont) {

        ipc_call_t call;

        ipc_callid_t callid = async_get_call(&call);

        switch (IPC_GET_METHOD(call)) {

        case IPC_M_PHONE_HUNGUP:

            cont = false;

            /* Exit thread */

            continue;

        case DEVMAP_DEVICE_GET_HANDLE:

            devmap_get_handle(callid, &call);

            break;

        case DEVMAP_DEVICE_GET_NAME:

            devmap_get_name(callid, &call);

            break;

        case DEVMAP_DEVICE_GET_COUNT:

            devmap_get_count(callid, &call);

            break;

        case DEVMAP_DEVICE_GET_DEVICES:

            devmap_get_devices(callid, &call);

            break;

        default:

            if (!(callid & IPC_CALLID_NOTIFICATION))

                ipc_answer_0(callid, ENOENT);

        }

    }

}

/** Function for handling connections to devmap

 *

 */

static void devmap_connection(ipc_callid_t iid, ipc_call_t *icall)

{

    /* Select interface */

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

    case DEVMAP_DRIVER:

        devmap_connection_driver(iid, icall);