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;

}

/**

 * @}

 */