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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 <futex.h>
  48. #include <devmap.h>
  49. #include <sys/types.h>
  50. #include <errno.h>
  51. #include <bool.h>
  52.  
  53. #define NAME "file_bd"
  54.  
  55. static size_t comm_size;
  56. static FILE *img;
  57.  
  58. static dev_handle_t dev_handle;
  59. static atomic_t dev_futex = FUTEX_INITIALIZER;
  60.  
  61. static int file_bd_init(const char *fname);
  62. static void file_bd_connection(ipc_callid_t iid, ipc_call_t *icall);
  63. static int file_bd_read(off_t blk_idx, off_t size, void *buf);
  64. static int file_bd_write(off_t blk_idx, off_t size, void *buf);
  65.  
  66. int main(int argc, char **argv)
  67. {
  68.     int rc;
  69.  
  70.     printf(NAME ": File-backed block device driver\n");
  71.  
  72.     if (argc != 3) {
  73.         printf("Expected two arguments (image name, device name).\n");
  74.         return -1;
  75.     }
  76.  
  77.     if (file_bd_init(argv[1]) != EOK)
  78.         return -1;
  79.  
  80.     rc = devmap_device_register(argv[2], &dev_handle);
  81.     if (rc != EOK) {
  82.         devmap_hangup_phone(DEVMAP_DRIVER);
  83.         printf(NAME ": Unable to register device %s.\n",
  84.             argv[2]);
  85.         return rc;
  86.     }
  87.  
  88.     printf(NAME ": Accepting connections\n");
  89.     async_manager();
  90.  
  91.     /* Not reached */
  92.     return 0;
  93. }
  94.  
  95. static int file_bd_init(const char *fname)
  96. {
  97.     int rc;
  98.  
  99.     rc = devmap_driver_register(NAME, file_bd_connection);
  100.     if (rc < 0) {
  101.         printf(NAME ": Unable to register driver.\n");
  102.         return rc;
  103.     }
  104.  
  105.     img = fopen(fname, "rb+");
  106.     if (img == NULL)
  107.         return EINVAL;
  108.  
  109.     return EOK;
  110. }
  111.  
  112. static void file_bd_connection(ipc_callid_t iid, ipc_call_t *icall)
  113. {
  114.     void *fs_va = NULL;
  115.     ipc_callid_t callid;
  116.     ipc_call_t call;
  117.     ipcarg_t method;
  118.     int flags;
  119.     int retval;
  120.     off_t idx;
  121.     off_t size;
  122.  
  123.     /* Answer the IPC_M_CONNECT_ME_TO call. */
  124.     ipc_answer_0(iid, EOK);
  125.  
  126.     if (!ipc_share_out_receive(&callid, &comm_size, &flags)) {
  127.         ipc_answer_0(callid, EHANGUP);
  128.         return;
  129.     }
  130.  
  131.     fs_va = as_get_mappable_page(comm_size);
  132.     if (fs_va == NULL) {
  133.         ipc_answer_0(callid, EHANGUP);
  134.         return;
  135.     }
  136.  
  137.     (void) ipc_share_out_finalize(callid, fs_va);
  138.  
  139.     while (1) {
  140.         callid = async_get_call(&call);
  141.         method = IPC_GET_METHOD(call);
  142.         switch (method) {
  143.         case IPC_M_PHONE_HUNGUP:
  144.             /* The other side has hung up. */
  145.             ipc_answer_0(callid, EOK);
  146.             return;
  147.         case BD_READ_BLOCK:
  148.         case BD_WRITE_BLOCK:
  149.             idx = IPC_GET_ARG1(call);
  150.             size = IPC_GET_ARG2(call);
  151.             if (size > comm_size) {
  152.                 retval = EINVAL;
  153.                 break;
  154.             }
  155.             if (method == BD_READ_BLOCK)
  156.                 retval = file_bd_read(idx, size, fs_va);
  157.             else
  158.                 retval = file_bd_write(idx, size, fs_va);
  159.             break;
  160.         default:
  161.             retval = EINVAL;
  162.             break;
  163.         }
  164.         ipc_answer_0(callid, retval);
  165.     }
  166. }
  167.  
  168. static int file_bd_read(off_t blk_idx, off_t size, void *buf)
  169. {
  170.     size_t n_rd;
  171.  
  172.     printf("file_bd_read\n");
  173.     futex_down(&dev_futex);
  174.  
  175.     printf("seek\n");
  176.     fseek(img, blk_idx * size, SEEK_SET);
  177.     printf("read\n");
  178.     n_rd = fread(buf, 1, size, img);
  179.     printf("done\n");
  180.  
  181.     printf("done\n");
  182.  
  183.     if (ferror(img)) {
  184.         futex_up(&dev_futex);
  185.         return EIO; /* Read error */
  186.     }
  187.  
  188.     futex_up(&dev_futex);
  189.  
  190.     if (n_rd < size)
  191.         return EINVAL;  /* Read beyond end of disk */
  192.  
  193.     return EOK;
  194. }
  195.  
  196. static int file_bd_write(off_t blk_idx, off_t size, void *buf)
  197. {
  198.     size_t n_wr;
  199.  
  200.     futex_down(&dev_futex);
  201.  
  202.     fseek(img, blk_idx * size, SEEK_SET);
  203.     n_wr = fread(buf, 1, size, img);
  204.  
  205.     if (ferror(img) || n_wr < size) {
  206.         futex_up(&dev_futex);
  207.         return EIO; /* Write error */
  208.     }
  209.  
  210.     futex_up(&dev_futex);
  211.  
  212.     return EOK;
  213. }
  214.  
  215. /**
  216.  * @}
  217.  */
  218.