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  1. /*
  2.  * Copyright (c) 2009 Jiri Svoboda
  3.  * All rights reserved.
  4.  *
  5.  * Redistribution and use in source and binary forms, with or without
  6.  * modification, are permitted provided that the following conditions
  7.  * are met:
  8.  *
  9.  * - Redistributions of source code must retain the above copyright
  10.  *   notice, this list of conditions and the following disclaimer.
  11.  * - Redistributions in binary form must reproduce the above copyright
  12.  *   notice, this list of conditions and the following disclaimer in the
  13.  *   documentation and/or other materials provided with the distribution.
  14.  * - The name of the author may not be used to endorse or promote products
  15.  *   derived from this software without specific prior written permission.
  16.  *
  17.  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  18.  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  19.  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  20.  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  21.  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  22.  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  23.  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  24.  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  25.  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  26.  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  27.  */
  28.  
  29. /** @addtogroup bd
  30.  * @{
  31.  */
  32.  
  33. /**
  34.  * @file
  35.  * @brief File-backed block device driver
  36.  *
  37.  * Allows accessing a file as a block device. Useful for, e.g., mounting
  38.  * a disk image.
  39.  */
  40.  
  41. #include <stdio.h>
  42. #include <unistd.h>
  43. #include <ipc/ipc.h>
  44. #include <ipc/bd.h>
  45. #include <async.h>
  46. #include <as.h>
  47. #include <fibril_sync.h>
  48. #include <devmap.h>
  49. #include <sys/types.h>
  50. #include <errno.h>
  51. #include <bool.h>
  52. #include <task.h>
  53.  
  54. #define NAME "file_bd"
  55.  
  56. static size_t comm_size;
  57. static FILE *img;
  58.  
  59. static dev_handle_t dev_handle;
  60. static fibril_mutex_t dev_lock;
  61.  
  62. static int file_bd_init(const char *fname);
  63. static void file_bd_connection(ipc_callid_t iid, ipc_call_t *icall);
  64. static int file_bd_read(off_t blk_idx, size_t size, void *buf);
  65. static int file_bd_write(off_t blk_idx, size_t size, void *buf);
  66.  
  67. int main(int argc, char **argv)
  68. {
  69.     int rc;
  70.  
  71.     printf(NAME ": File-backed block device driver\n");
  72.  
  73.     if (argc != 3) {
  74.         printf("Expected two arguments (image name, device name).\n");
  75.         return -1;
  76.     }
  77.  
  78.     if (file_bd_init(argv[1]) != EOK)
  79.         return -1;
  80.  
  81.     rc = devmap_device_register(argv[2], &dev_handle);
  82.     if (rc != EOK) {
  83.         devmap_hangup_phone(DEVMAP_DRIVER);
  84.         printf(NAME ": Unable to register device %s.\n",
  85.             argv[2]);
  86.         return rc;
  87.     }
  88.  
  89.     printf(NAME ": Accepting connections\n");
  90.     task_retval(0);
  91.     async_manager();
  92.  
  93.     /* Not reached */
  94.     return 0;
  95. }
  96.  
  97. static int file_bd_init(const char *fname)
  98. {
  99.     int rc;
  100.  
  101.     rc = devmap_driver_register(NAME, file_bd_connection);
  102.     if (rc < 0) {
  103.         printf(NAME ": Unable to register driver.\n");
  104.         return rc;
  105.     }
  106.  
  107.     img = fopen(fname, "rb+");
  108.     if (img == NULL)
  109.         return EINVAL;
  110.  
  111.     fibril_mutex_initialize(&dev_lock);
  112.  
  113.     return EOK;
  114. }
  115.  
  116. static void file_bd_connection(ipc_callid_t iid, ipc_call_t *icall)
  117. {
  118.     void *fs_va = NULL;
  119.     ipc_callid_t callid;
  120.     ipc_call_t call;
  121.     ipcarg_t method;
  122.     int flags;
  123.     int retval;
  124.     off_t idx;
  125.     size_t size;
  126.  
  127.     /* Answer the IPC_M_CONNECT_ME_TO call. */
  128.     ipc_answer_0(iid, EOK);
  129.  
  130.     if (!ipc_share_out_receive(&callid, &comm_size, &flags)) {
  131.         ipc_answer_0(callid, EHANGUP);
  132.         return;
  133.     }
  134.  
  135.     fs_va = as_get_mappable_page(comm_size);
  136.     if (fs_va == NULL) {
  137.         ipc_answer_0(callid, EHANGUP);
  138.         return;
  139.     }
  140.  
  141.     (void) ipc_share_out_finalize(callid, fs_va);
  142.  
  143.     while (1) {
  144.         callid = async_get_call(&call);
  145.         method = IPC_GET_METHOD(call);
  146.         switch (method) {
  147.         case IPC_M_PHONE_HUNGUP:
  148.             /* The other side has hung up. */
  149.             ipc_answer_0(callid, EOK);
  150.             return;
  151.         case BD_READ_BLOCK:
  152.         case BD_WRITE_BLOCK:
  153.             idx = IPC_GET_ARG1(call);
  154.             size = IPC_GET_ARG2(call);
  155.             if (size > comm_size) {
  156.                 retval = EINVAL;
  157.                 break;
  158.             }
  159.             if (method == BD_READ_BLOCK)
  160.                 retval = file_bd_read(idx, size, fs_va);
  161.             else
  162.                 retval = file_bd_write(idx, size, fs_va);
  163.             break;
  164.         default:
  165.             retval = EINVAL;
  166.             break;
  167.         }
  168.         ipc_answer_0(callid, retval);
  169.     }
  170. }
  171.  
  172. static int file_bd_read(off_t blk_idx, size_t size, void *buf)
  173. {
  174.     size_t n_rd;
  175.  
  176.     fibril_mutex_lock(&dev_lock);
  177.  
  178.     fseek(img, blk_idx * size, SEEK_SET);
  179.     n_rd = fread(buf, 1, size, img);
  180.  
  181.     if (ferror(img)) {
  182.         fibril_mutex_unlock(&dev_lock);
  183.         return EIO; /* Read error */
  184.     }
  185.  
  186.     fibril_mutex_unlock(&dev_lock);
  187.  
  188.     if (n_rd < size)
  189.         return EINVAL;  /* Read beyond end of disk */
  190.  
  191.     return EOK;
  192. }
  193.  
  194. static int file_bd_write(off_t blk_idx, size_t size, void *buf)
  195. {
  196.     size_t n_wr;
  197.  
  198.     fibril_mutex_lock(&dev_lock);
  199.  
  200.     fseek(img, blk_idx * size, SEEK_SET);
  201.     n_wr = fread(buf, 1, size, img);
  202.  
  203.     if (ferror(img) || n_wr < size) {
  204.         fibril_mutex_unlock(&dev_lock);
  205.         return EIO; /* Write error */
  206.     }
  207.  
  208.     fibril_mutex_unlock(&dev_lock);
  209.  
  210.     return EOK;
  211. }
  212.  
  213. /**
  214.  * @}
  215.  */
  216.