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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. 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)

{

	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_0(iid, EREFUSED);

		return;

	} 

	if (NULL ==

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

		ipc_answer_0(iid, ENOMEM);

		return;

	}

	/* 

	 * Get driver name

	 */

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

		printf("Unexpected request.\n");

		free(driver);

		ipc_answer_0(callid, EREFUSED);

		ipc_answer_0(iid, EREFUSED);

		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_0(callid, EINVAL);

		ipc_answer_0(iid, EREFUSED);

		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_0(callid, ENOMEM);

		ipc_answer_0(iid, EREFUSED);

		return;

	}	

	/*

	 * Send confirmation to sender and get data into buffer.

	 */

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

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

		free(driver->name);

		free(driver);

		ipc_answer_0(iid, EREFUSED);

		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_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);

	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;

	size_t size;

	devmap_device_t *device;

	if (NULL == driver) {

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

		ipc_answer_0(iid, EREFUSED);

		return;

	}

	/* Create new device entry */

	if (NULL ==

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

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

		ipc_answer_0(iid, ENOMEM);

		return;

	}

	/* Get device name */

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

		free(device);

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

		ipc_answer_0(iid, EREFUSED);

		return;

	}

	if (size > DEVMAP_NAME_MAXLEN) {

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

		free(device);

		ipc_answer_0(callid, EINVAL);

		ipc_answer_0(iid, EREFUSED);

		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_0(callid, ENOMEM);

		ipc_answer_0(iid, EREFUSED);

		return;

	}

	ipc_data_write_deliver(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("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);	

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

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

	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_ARG2(*call);

	dev = devmap_device_find_handle(handle);

	if (NULL == dev) {

		printf("DEVMAP: No registered device with handle %d.\n",

		    handle);

		ipc_answer_0(callid, ENOENT);

		return;

	} 

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

	    IPC_GET_ARG3(*call), 0, IPC_FF_NONE);

	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;

	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_write_receive(&callid, NULL, &name_size)) {

		ipc_answer_0(callid, EREFUSED);

		ipc_answer_0(iid, EREFUSED);

		return;

	}

	if (name_size > DEVMAP_NAME_MAXLEN) {

		ipc_answer_0(callid, EINVAL);

		ipc_answer_0(iid, EREFUSED);

		return;

	}

	/*

	 * Allocate buffer for device name.

	 */

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

		ipc_answer_0(callid, ENOMEM);

		ipc_answer_0(iid, EREFUSED);

		return;

	}	

	/*

	 * Send confirmation to sender and get data into buffer.

	 */

	if (EOK != (retval = ipc_data_write_deliver(callid, name, name_size))) {

		ipc_answer_0(iid, EREFUSED);

		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_0(iid, ENOENT);

		return;

	}

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

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

	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_0(iid, ENOENT);

		return;

	}	

	ipc_answer_0(iid, EOK);

	name_size = strlen(device->name);

/*	FIXME:

	we have no channel from DEVMAP to client -> 

	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 */

	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_0(iid, EOK); 

	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_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_handle(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)

{

	ipc_callid_t callid;

	ipc_call_t call;

	bool cont = true;

	ipc_answer_0(iid, EOK); /* 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_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_0(callid, ENOENT);

			}

		}

	}

}

/** 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;

	case DEVMAP_CONNECT_TO_DEVICE:

			/* Connect client to selected device */

		printf("DEVMAP: connect to device %d.\n",

		    IPC_GET_ARG2(*icall));

		devmap_forward(iid, icall);

		break;

	default:

		ipc_answer_0(iid, ENOENT); /* 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, 0, &phonead) != 0) 

		return -1;

	async_manager();

	/* Never reached */

	return 0;

}

/** 

 * @}

 */