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  1. /*
  2.  * Copyright (c) 2006 Martin Decky
  3.  * Copyright (c) 2008 Jakub Jermar
  4.  * All rights reserved.
  5.  *
  6.  * Redistribution and use in source and binary forms, with or without
  7.  * modification, are permitted provided that the following conditions
  8.  * are met:
  9.  *
  10.  * - Redistributions of source code must retain the above copyright
  11.  *   notice, this list of conditions and the following disclaimer.
  12.  * - Redistributions in binary form must reproduce the above copyright
  13.  *   notice, this list of conditions and the following disclaimer in the
  14.  *   documentation and/or other materials provided with the distribution.
  15.  * - The name of the author may not be used to endorse or promote products
  16.  *   derived from this software without specific prior written permission.
  17.  *
  18.  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  19.  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  20.  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  21.  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  22.  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  23.  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  24.  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  25.  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  26.  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  27.  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  28.  */
  29.  
  30. /** @addtogroup fs
  31.  * @{
  32.  */
  33.  
  34. /**
  35.  * @file    fat.c
  36.  * @brief   FAT file system driver for HelenOS.
  37.  */
  38.  
  39. #include "fat.h"
  40. #include <ipc/ipc.h>
  41. #include <ipc/services.h>
  42. #include <async.h>
  43. #include <errno.h>
  44. #include <unistd.h>
  45. #include <stdio.h>
  46. #include <libfs.h>
  47. #include "../../vfs/vfs.h"
  48.  
  49.  
  50. vfs_info_t fat_vfs_info = {
  51.     .name = "fat",
  52.     .ops = {
  53.         [IPC_METHOD_TO_VFS_OP(VFS_LOOKUP)] = VFS_OP_DEFINED,
  54.         [IPC_METHOD_TO_VFS_OP(VFS_READ)] = VFS_OP_DEFINED,
  55.         [IPC_METHOD_TO_VFS_OP(VFS_WRITE)] = VFS_OP_NULL,
  56.         [IPC_METHOD_TO_VFS_OP(VFS_TRUNCATE)] = VFS_OP_NULL,
  57.         [IPC_METHOD_TO_VFS_OP(VFS_MOUNT)] = VFS_OP_NULL,
  58.         [IPC_METHOD_TO_VFS_OP(VFS_UNMOUNT)] = VFS_OP_NULL,
  59.     }
  60. };
  61.  
  62. fs_reg_t fat_reg;
  63.  
  64. /**
  65.  * This connection fibril processes VFS requests from VFS.
  66.  *
  67.  * In order to support simultaneous VFS requests, our design is as follows.
  68.  * The connection fibril accepts VFS requests from VFS. If there is only one
  69.  * instance of the fibril, VFS will need to serialize all VFS requests it sends
  70.  * to FAT. To overcome this bottleneck, VFS can send FAT the IPC_M_CONNECT_ME_TO
  71.  * call. In that case, a new connection fibril will be created, which in turn
  72.  * will accept the call. Thus, a new phone will be opened for VFS.
  73.  *
  74.  * There are few issues with this arrangement. First, VFS can run out of
  75.  * available phones. In that case, VFS can close some other phones or use one
  76.  * phone for more serialized requests. Similarily, FAT can refuse to duplicate
  77.  * the connection. VFS should then just make use of already existing phones and
  78.  * route its requests through them. To avoid paying the fibril creation price
  79.  * upon each request, FAT might want to keep the connections open after the
  80.  * request has been completed.
  81.  */
  82. static void fat_connection(ipc_callid_t iid, ipc_call_t *icall)
  83. {
  84.     if (iid) {
  85.         /*
  86.          * This only happens for connections opened by
  87.          * IPC_M_CONNECT_ME_TO calls as opposed to callback connections
  88.          * created by IPC_M_CONNECT_TO_ME.
  89.          */
  90.         ipc_answer_0(iid, EOK);
  91.     }
  92.    
  93.     dprintf("VFS-FAT connection established.\n");
  94.     while (1) {
  95.         ipc_callid_t callid;
  96.         ipc_call_t call;
  97.    
  98.         callid = async_get_call(&call);
  99.         switch  (IPC_GET_METHOD(call)) {
  100.         case VFS_LOOKUP:
  101.             fat_lookup(callid, &call);
  102.             break;
  103.         default:
  104.             ipc_answer_0(callid, ENOTSUP);
  105.             break;
  106.         }
  107.     }
  108. }
  109.  
  110. int main(int argc, char **argv)
  111. {
  112.     int vfs_phone;
  113.  
  114.     printf("FAT: HelenOS FAT file system server.\n");
  115.  
  116.     vfs_phone = ipc_connect_me_to(PHONE_NS, SERVICE_VFS, 0, 0);
  117.     while (vfs_phone < EOK) {
  118.         usleep(10000);
  119.         vfs_phone = ipc_connect_me_to(PHONE_NS, SERVICE_VFS, 0, 0);
  120.     }
  121.    
  122.     int rc;
  123.     rc = fs_register(vfs_phone, &fat_reg, &fat_vfs_info, fat_connection);
  124.     if (rc != EOK) {
  125.         printf("Failed to register the FAT file system (%d)\n", rc);
  126.         return rc;
  127.     }
  128.    
  129.     dprintf("FAT filesystem registered, fs_handle=%d.\n",
  130.         fat_reg.fs_handle);
  131.  
  132.     async_manager();
  133.     /* not reached */
  134.     return 0;
  135. }
  136.  
  137. /**
  138.  * @}
  139.  */
  140.