source: mainline/uspace/srv/vfs/vfs.c@ 26f2af0

/*
 * 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;
}

/**
 * @}
 */