Subversion Repositories HelenOS

/*

 * Copyright (c) 2007 Jakub Jermar

 * 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.

 */

/** @addtogroup fs

 * @{

 */ 

/**

 * @file	vfs.c

 * @brief	VFS multiplexer for HelenOS.

 */

#include <ipc/ipc.h>

#include <ipc/services.h>

#include <async.h>

#include <errno.h>

#include <stdlib.h>

#include <string.h>

#include <ctype.h>

#include <bool.h>

#include <futex.h>

#include <libadt/list.h>

#include "vfs.h"

atomic_t fs_head_futex = FUTEX_INITIALIZER;

link_t fs_head;

/** Verify the VFS info structure.

 *

 * @param info		Info structure to be verified.

 *

 * @return		Non-zero if the info structure is sane, zero otherwise.

 */

static bool vfs_info_sane(vfs_info_t *info)

{

	int i;

	/*

	 * Check if the name is non-empty and is composed solely of ASCII

	 * characters [a-z]+[a-z0-9_-]*.

	 */

	if (!islower(info->name[0]))

		return false;

	for (i = 1; i < FS_NAME_MAXLEN; i++) {

		if (!(islower(info->name[i]) || isdigit(info->name[i])) &&

		    (info->name[i] != '-') && (info->name[i] != '_')) {

			if (info->name[i] == '\0')

				break;

			else

				return false;

		}

	}

	/*

	 * Check if the FS implements mandatory VFS operations.

	 */

	if (info->ops[IPC_METHOD_TO_VFS_OP(VFS_REGISTER)] != VFS_OP_DEFINED)

		return false;

	if (info->ops[IPC_METHOD_TO_VFS_OP(VFS_MOUNT)] != VFS_OP_DEFINED)

		return false;

	if (info->ops[IPC_METHOD_TO_VFS_OP(VFS_UNMOUNT)] != VFS_OP_DEFINED)

		return false;

	if (info->ops[IPC_METHOD_TO_VFS_OP(VFS_LOOKUP)] != VFS_OP_DEFINED)

		return false;

	if (info->ops[IPC_METHOD_TO_VFS_OP(VFS_OPEN)] != VFS_OP_DEFINED)

		return false;

	if (info->ops[IPC_METHOD_TO_VFS_OP(VFS_CLOSE)] != VFS_OP_DEFINED)

		return false;

	if (info->ops[IPC_METHOD_TO_VFS_OP(VFS_READ)] != VFS_OP_DEFINED)

		return false;

	/*

	 * Check if each operation is either not defined, defined or default.

	 */

	for (i = VFS_FIRST; i < VFS_LAST; i++) {

		if ((IPC_METHOD_TO_VFS_OP(i) != VFS_OP_NULL) && 

		    (IPC_METHOD_TO_VFS_OP(i) != VFS_OP_DEFAULT) && 

		    (IPC_METHOD_TO_VFS_OP(i) != VFS_OP_DEFINED))

			return false;	

	}

	return true;

}

/** VFS_REGISTER protocol function.

 *

 * @param rid		Hash of the call with the request.

 * @param request	Call structure with the request.

 */

static void vfs_register(ipc_callid_t rid, ipc_call_t *request)

{

	ipc_callid_t callid;

	ipc_call_t call;

	int rc;

	size_t size;

	/*

	 * The first call has to be IPC_M_DATA_SEND in which we receive the

	 * VFS info structure from the client FS.

	 */

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

		/*

		 * The client doesn't obey the same protocol as we do.

		 */ 

		ipc_answer_fast(callid, EINVAL, 0, 0);

		ipc_answer_fast(rid, EINVAL, 0, 0);

		return;

	}

	/*

	 * We know the size of the VFS info structure. See if the client

	 * understands this easy concept too.

	 */

	if (size != sizeof(vfs_info_t)) {

		/*

		 * The client is sending us something, which cannot be

		 * the info structure.

		 */

		ipc_answer_fast(callid, EINVAL, 0, 0);

		ipc_answer_fast(rid, EINVAL, 0, 0);

		return;

	}

	fs_info_t *fs_info;

	/*

	 * Allocate and initialize a buffer for the fs_info structure.

	 */

	fs_info = (fs_info_t *) malloc(sizeof(fs_info_t));

	if (!fs_info) {

		ipc_answer_fast(callid, ENOMEM, 0, 0);

		ipc_answer_fast(rid, ENOMEM, 0, 0);

		return;

	}

	link_initialize(&fs_info->fs_link);

	rc = ipc_data_deliver(callid, &call, &fs_info->vfs_info, size);

	if (!rc) {

		free(fs_info);

		ipc_answer_fast(callid, rc, 0, 0);

		ipc_answer_fast(rid, rc, 0, 0);

		return;

	}

	if (!vfs_info_sane(&fs_info->vfs_info)) {

		free(fs_info);

		ipc_answer_fast(callid, EINVAL, 0, 0);

		ipc_answer_fast(rid, EINVAL, 0, 0);

		return;

	}

	futex_down(&fs_head_futex);

	/*

	 * Check for duplicit registrations.

	 */

	link_t *cur;

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

		fs_info_t *fi = list_get_instance(cur, fs_info_t,

		    fs_link);

		/* TODO: replace strcmp with strncmp once we have it */

		if (strcmp(fs_info->vfs_info.name, fi->vfs_info.name) == 0) {

			/*

			 * We already register a fs like this.

			 */

			futex_up(&fs_head_futex);

			free(fs_info);

			ipc_answer_fast(callid, EEXISTS, 0, 0);

			ipc_answer_fast(rid, EEXISTS, 0, 0);

			return;

		}

	}

	/*

	 * Add fs_info to the list of registered FS's.

	 */

	list_append(&fs_info->fs_link, &fs_head);

	/*

	 * ACK receiving a properly formatted, non-duplicit vfs_info.

	 */

	ipc_answer_fast(callid, EOK, 0, 0);

	/*

	 * Now we want the client to send us the IPC_M_CONNECT_TO_ME call so

	 * that a callback connection is created and we have a phone through

	 * which to forward VFS requests to it.

	 */

	callid = async_get_call(&call);

	if (IPC_GET_METHOD(call) != IPC_M_CONNECT_TO_ME) {

		list_remove(&fs_info->fs_link);

		futex_up(&fs_head_futex);

		free(fs_info);

		ipc_answer_fast(callid, EINVAL, 0, 0);

		ipc_answer_fast(rid, EINVAL, 0, 0);

		return;

	}

	fs_info->phone = IPC_GET_ARG3(call);

	ipc_answer_fast(callid, EOK, 0, 0);

	futex_up(&fs_head_futex);

	/*

	 * That was it. The FS has been registered.

	 */

	ipc_answer_fast(rid, EOK, 0, 0);

}

static void vfs_connection(ipc_callid_t iid, ipc_call_t *icall)

{

	bool keep_on_going = 1;

	/*

	 * The connection was opened via the IPC_CONNECT_ME_TO call.

	 * This call needs to be answered.

	 */

	ipc_answer_fast(iid, EOK, 0, 0);

	/*

	 * Here we enter the main connection fibril loop.

	 * The logic behind this loop and the protocol is that we'd like to keep

	 * each connection open for a while before we close it. The benefit of

	 * this is that the client doesn't have to establish a new connection

	 * upon each request.  On the other hand, the client must be ready to

	 * re-establish a connection if we hang it up due to reaching of maximum

	 * number of requests per connection or due to the client timing out.

	 */

	while (keep_on_going) {

		ipc_callid_t callid;

		ipc_call_t call;

		callid = async_get_call(&call);

		switch (IPC_GET_METHOD(call)) {

		case IPC_M_PHONE_HUNGUP:

			keep_on_going = false;

			break;

		case VFS_REGISTER:

			vfs_register(callid, &call);

			keep_on_going = false;

			break;

		case VFS_MOUNT:

		case VFS_UNMOUNT:

		case VFS_OPEN:

		case VFS_CREATE:

		case VFS_CLOSE:

		case VFS_READ:

		case VFS_WRITE:

		case VFS_SEEK:

		default:

			ipc_answer_fast(callid, ENOTSUP, 0, 0);

			break;

		}

	}

	/* TODO: cleanup after the client */

}

int main(int argc, char **argv)

{

	ipcarg_t phonead;

	list_initialize(&fs_head);

	async_set_client_connection(vfs_connection);

	ipc_connect_to_me(PHONE_NS, SERVICE_VFS, 0, &phonead);

	async_manager();

	return 0;

}

/**

 * @}

 */