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4534 svoboda 1
/*
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 * Copyright (c) 2009 Jiri Svoboda
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 * All rights reserved.
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 *
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 * Redistribution and use in source and binary forms, with or without
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 * modification, are permitted provided that the following conditions
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 * are met:
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 *
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 * - Redistributions of source code must retain the above copyright
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 *   notice, this list of conditions and the following disclaimer.
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 * - Redistributions in binary form must reproduce the above copyright
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 *   notice, this list of conditions and the following disclaimer in the
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 *   documentation and/or other materials provided with the distribution.
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 * - The name of the author may not be used to endorse or promote products
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 *   derived from this software without specific prior written permission.
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 *
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 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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 */
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/** @addtogroup bd
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 * @{
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 */
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/**
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 * @file
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 * @brief File-backed block device driver
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 *
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 * Allows accessing a file as a block device. Useful for, e.g., mounting
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 * a disk image.
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 */
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#include <stdio.h>
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#include <unistd.h>
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#include <ipc/ipc.h>
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#include <ipc/bd.h>
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#include <async.h>
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#include <as.h>
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#include <futex.h>
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#include <devmap.h>
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#include <sys/types.h>
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#include <errno.h>
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#include <bool.h>
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#define NAME "file_bd"
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static size_t comm_size;
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static FILE *img;
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static dev_handle_t dev_handle;
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static atomic_t dev_futex = FUTEX_INITIALIZER;
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static int file_bd_init(const char *fname);
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static void file_bd_connection(ipc_callid_t iid, ipc_call_t *icall);
4545 svoboda 63
static int file_bd_read(off_t blk_idx, size_t size, void *buf);
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static int file_bd_write(off_t blk_idx, size_t size, void *buf);
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int main(int argc, char **argv)
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{
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    int rc;
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    printf(NAME ": File-backed block device driver\n");
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    if (argc != 3) {
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        printf("Expected two arguments (image name, device name).\n");
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        return -1;
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    }
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    if (file_bd_init(argv[1]) != EOK)
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        return -1;
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    rc = devmap_device_register(argv[2], &dev_handle);
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    if (rc != EOK) {
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        devmap_hangup_phone(DEVMAP_DRIVER);
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        printf(NAME ": Unable to register device %s.\n",
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            argv[2]);
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        return rc;
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    }
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    printf(NAME ": Accepting connections\n");
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    async_manager();
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    /* Not reached */
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    return 0;
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}
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static int file_bd_init(const char *fname)
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{
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    int rc;
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    rc = devmap_driver_register(NAME, file_bd_connection);
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    if (rc < 0) {
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        printf(NAME ": Unable to register driver.\n");
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        return rc;
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    }
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    img = fopen(fname, "rb+");
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    if (img == NULL)
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        return EINVAL;
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    return EOK;
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}
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static void file_bd_connection(ipc_callid_t iid, ipc_call_t *icall)
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{
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    void *fs_va = NULL;
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    ipc_callid_t callid;
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    ipc_call_t call;
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    ipcarg_t method;
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    int flags;
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    int retval;
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    off_t idx;
4545 svoboda 121
    size_t size;
4534 svoboda 122
 
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    /* Answer the IPC_M_CONNECT_ME_TO call. */
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    ipc_answer_0(iid, EOK);
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    if (!ipc_share_out_receive(&callid, &comm_size, &flags)) {
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        ipc_answer_0(callid, EHANGUP);
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        return;
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    }
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    fs_va = as_get_mappable_page(comm_size);
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    if (fs_va == NULL) {
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        ipc_answer_0(callid, EHANGUP);
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        return;
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    }
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    (void) ipc_share_out_finalize(callid, fs_va);
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    while (1) {
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        callid = async_get_call(&call);
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        method = IPC_GET_METHOD(call);
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        switch (method) {
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        case IPC_M_PHONE_HUNGUP:
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            /* The other side has hung up. */
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            ipc_answer_0(callid, EOK);
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            return;
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        case BD_READ_BLOCK:
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        case BD_WRITE_BLOCK:
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            idx = IPC_GET_ARG1(call);
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            size = IPC_GET_ARG2(call);
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            if (size > comm_size) {
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                retval = EINVAL;
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                break;
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            }
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            if (method == BD_READ_BLOCK)
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                retval = file_bd_read(idx, size, fs_va);
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            else
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                retval = file_bd_write(idx, size, fs_va);
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            break;
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        default:
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            retval = EINVAL;
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            break;
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        }
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        ipc_answer_0(callid, retval);
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    }
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}
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4545 svoboda 168
static int file_bd_read(off_t blk_idx, size_t size, void *buf)
4534 svoboda 169
{
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    size_t n_rd;
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    printf("file_bd_read\n");
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    futex_down(&dev_futex);
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    printf("seek\n");
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    fseek(img, blk_idx * size, SEEK_SET);
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    printf("read\n");
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    n_rd = fread(buf, 1, size, img);
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    printf("done\n");
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    printf("done\n");
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    if (ferror(img)) {
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        futex_up(&dev_futex);
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        return EIO; /* Read error */
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    }
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    futex_up(&dev_futex);
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    if (n_rd < size)
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        return EINVAL;  /* Read beyond end of disk */
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    return EOK;
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}
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4545 svoboda 196
static int file_bd_write(off_t blk_idx, size_t size, void *buf)
4534 svoboda 197
{
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    size_t n_wr;
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    futex_down(&dev_futex);
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    fseek(img, blk_idx * size, SEEK_SET);
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    n_wr = fread(buf, 1, size, img);
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    if (ferror(img) || n_wr < size) {
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        futex_up(&dev_futex);
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        return EIO; /* Write error */
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    }
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    futex_up(&dev_futex);
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    return EOK;
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}
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/**
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 * @}
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 */