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/*

 * Copyright (c) 2009 Jiri Svoboda

 * 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 bd

 * @{

 */

/**

 * @file

 * @brief File-backed block device driver

 *

 * Allows accessing a file as a block device. Useful for, e.g., mounting

 * a disk image.

 */

#include <stdio.h>

#include <unistd.h>

#include <ipc/ipc.h>

#include <ipc/bd.h>

#include <async.h>

#include <as.h>

#include <futex.h>

#include <devmap.h>

#include <sys/types.h>

#include <errno.h>

#include <bool.h>

#define NAME "file_bd"

static size_t comm_size;

static FILE *img;

static dev_handle_t dev_handle;

static atomic_t dev_futex = FUTEX_INITIALIZER;

static int file_bd_init(const char *fname);

static void file_bd_connection(ipc_callid_t iid, ipc_call_t *icall);

static int file_bd_read(off_t blk_idx, off_t size, void *buf);

static int file_bd_write(off_t blk_idx, off_t size, void *buf);

int main(int argc, char **argv)

{

    int rc;

    printf(NAME ": File-backed block device driver\n");

    if (argc != 3) {

        printf("Expected two arguments (image name, device name).\n");

        return -1;

    }

    if (file_bd_init(argv[1]) != EOK)

        return -1;

    rc = devmap_device_register(argv[2], &dev_handle);

    if (rc != EOK) {

        devmap_hangup_phone(DEVMAP_DRIVER);

        printf(NAME ": Unable to register device %s.\n",

            argv[2]);

        return rc;

    }

    printf(NAME ": Accepting connections\n");

    async_manager();

    /* Not reached */

    return 0;

}

static int file_bd_init(const char *fname)

{

    int rc;

    rc = devmap_driver_register(NAME, file_bd_connection);

    if (rc < 0) {

        printf(NAME ": Unable to register driver.\n");

        return rc;

    }

    img = fopen(fname, "rb+");

    if (img == NULL)

        return EINVAL;

    return EOK;

}

static void file_bd_connection(ipc_callid_t iid, ipc_call_t *icall)

{

    void *fs_va = NULL;

    ipc_callid_t callid;

    ipc_call_t call;

    ipcarg_t method;

    int flags;

    int retval;

    off_t idx;

    off_t size;

    /* Answer the IPC_M_CONNECT_ME_TO call. */

    ipc_answer_0(iid, EOK);

    if (!ipc_share_out_receive(&callid, &comm_size, &flags)) {

        ipc_answer_0(callid, EHANGUP);

        return;

    }

    fs_va = as_get_mappable_page(comm_size);

    if (fs_va == NULL) {

        ipc_answer_0(callid, EHANGUP);

        return;

    }

    (void) ipc_share_out_finalize(callid, fs_va);

    while (1) {

        callid = async_get_call(&call);

        method = IPC_GET_METHOD(call);

        switch (method) {

        case IPC_M_PHONE_HUNGUP:

            /* The other side has hung up. */

            ipc_answer_0(callid, EOK);

            return;

        case BD_READ_BLOCK:

        case BD_WRITE_BLOCK:

            idx = IPC_GET_ARG1(call);

            size = IPC_GET_ARG2(call);

            if (size > comm_size) {

                retval = EINVAL;

                break;

            }

            if (method == BD_READ_BLOCK)

                retval = file_bd_read(idx, size, fs_va);

            else

                retval = file_bd_write(idx, size, fs_va);

            break;

        default:

            retval = EINVAL;

            break;

        }

        ipc_answer_0(callid, retval);

    }

}

static int file_bd_read(off_t blk_idx, off_t size, void *buf)

{

    size_t n_rd;

    printf("file_bd_read\n");

    futex_down(&dev_futex);

    printf("seek\n");

    fseek(img, blk_idx * size, SEEK_SET);

    printf("read\n");

    n_rd = fread(buf, 1, size, img);

    printf("done\n");

    printf("done\n");

    if (ferror(img)) {

        futex_up(&dev_futex);

        return EIO; /* Read error */

    }

    futex_up(&dev_futex);

    if (n_rd < size)

        return EINVAL;  /* Read beyond end of disk */

    return EOK;

}

static int file_bd_write(off_t blk_idx, off_t size, void *buf)

{

    size_t n_wr;

    futex_down(&dev_futex);

    fseek(img, blk_idx * size, SEEK_SET);

    n_wr = fread(buf, 1, size, img);

    if (ferror(img) || n_wr < size) {

        futex_up(&dev_futex);

        return EIO; /* Write error */

    }

    futex_up(&dev_futex);

    return EOK;

}

/**

 * @}

 */