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  1. /*
  2.  * Copyright (c) 2006 Martin Decky
  3.  * Copyright (c) 2007 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 <as.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_REGISTER)] = VFS_OP_DEFINED,
  54.         [IPC_METHOD_TO_VFS_OP(VFS_MOUNT)] = VFS_OP_DEFINED,
  55.         [IPC_METHOD_TO_VFS_OP(VFS_UNMOUNT)] = VFS_OP_DEFINED,
  56.         [IPC_METHOD_TO_VFS_OP(VFS_LOOKUP)] = VFS_OP_DEFINED,
  57.         [IPC_METHOD_TO_VFS_OP(VFS_OPEN)] = VFS_OP_DEFINED,
  58.         [IPC_METHOD_TO_VFS_OP(VFS_CREATE)] = VFS_OP_DEFINED,
  59.         [IPC_METHOD_TO_VFS_OP(VFS_CLOSE)] = VFS_OP_DEFINED,
  60.         [IPC_METHOD_TO_VFS_OP(VFS_READ)] = VFS_OP_DEFINED,
  61.         [IPC_METHOD_TO_VFS_OP(VFS_WRITE)] = VFS_OP_NULL,
  62.         [IPC_METHOD_TO_VFS_OP(VFS_SEEK)] = VFS_OP_DEFAULT
  63.     }
  64. };
  65.  
  66. uint8_t *plb_ro = NULL;
  67.  
  68. int fs_handle = 0;
  69.  
  70. /**
  71.  * This connection fibril processes VFS requests from VFS.
  72.  *
  73.  * In order to support simultaneous VFS requests, our design is as follows.
  74.  * The connection fibril accepts VFS requests from VFS. If there is only one
  75.  * instance of the fibril, VFS will need to serialize all VFS requests it sends
  76.  * to FAT. To overcome this bottleneck, VFS can send FAT the IPC_M_CONNECT_ME_TO
  77.  * call. In that case, a new connection fibril will be created, which in turn
  78.  * will accept the call. Thus, a new phone will be opened for VFS.
  79.  *
  80.  * There are few issues with this arrangement. First, VFS can run out of
  81.  * available phones. In that case, VFS can close some other phones or use one
  82.  * phone for more serialized requests. Similarily, FAT can refuse to duplicate
  83.  * the connection. VFS should then just make use of already existing phones and
  84.  * route its requests through them. To avoid paying the fibril creation price
  85.  * upon each request, FAT might want to keep the connections open after the
  86.  * request has been completed.
  87.  */
  88. static void fat_connection(ipc_callid_t iid, ipc_call_t *icall)
  89. {
  90.     if (iid) {
  91.         /*
  92.          * This only happens for connections opened by
  93.          * IPC_M_CONNECT_ME_TO calls as opposed to callback connections
  94.          * created by IPC_M_CONNECT_TO_ME.
  95.          */
  96.         ipc_answer_0(iid, EOK);
  97.     }
  98.    
  99.     dprintf("VFS-FAT connection established.\n");
  100.     while (1) {
  101.         ipc_callid_t callid;
  102.         ipc_call_t call;
  103.    
  104.         callid = async_get_call(&call);
  105.         switch  (IPC_GET_METHOD(call)) {
  106.         case VFS_REGISTER:
  107.             ipc_answer_0(callid, EOK);
  108.             break;
  109.         case VFS_LOOKUP:
  110.             fat_lookup(callid, &call);
  111.             break;
  112.         default:
  113.             ipc_answer_0(callid, ENOTSUP);
  114.             break;
  115.         }
  116.     }
  117. }
  118.  
  119. int block_read(int dev_handle, unsigned long blkno, void *buf)
  120. {
  121. }
  122.  
  123. int main(int argc, char **argv)
  124. {
  125.     int vfs_phone;
  126.  
  127.     printf("FAT: HelenOS FAT file system server.\n");
  128.  
  129.     vfs_phone = ipc_connect_me_to(PHONE_NS, SERVICE_VFS, 0, 0);
  130.     while (vfs_phone < EOK) {
  131.         usleep(10000);
  132.         vfs_phone = ipc_connect_me_to(PHONE_NS, SERVICE_VFS, 0, 0);
  133.     }
  134.    
  135.     /*
  136.      * Tell VFS that we are here and want to get registered.
  137.      * We use the async framework because VFS will answer the request
  138.      * out-of-order, when it knows that the operation succeeded or failed.
  139.      */
  140.     ipc_call_t answer;
  141.     aid_t req = async_send_2(vfs_phone, VFS_REGISTER, 0, 0, &answer);
  142.  
  143.     /*
  144.      * Send our VFS info structure to VFS.
  145.      */
  146.     int rc = ipc_data_send(vfs_phone, &fat_vfs_info, sizeof(fat_vfs_info));
  147.     if (rc != EOK) {
  148.         async_wait_for(req, NULL);
  149.         return rc;
  150.     }
  151.  
  152.     /*
  153.      * Ask VFS for callback connection.
  154.      */
  155.     ipcarg_t phonehash;
  156.     ipc_connect_to_me(vfs_phone, 0, 0, &phonehash);
  157.  
  158.     /*
  159.      * Allocate piece of address space for PLB.
  160.      */
  161.     plb_ro = as_get_mappable_page(PLB_SIZE);
  162.     if (!plb_ro) {
  163.         async_wait_for(req, NULL);
  164.         return ENOMEM;
  165.     }
  166.  
  167.     /*
  168.      * Request sharing the Path Lookup Buffer with VFS.
  169.      */
  170.     rc = ipc_call_sync_2_0(vfs_phone, IPC_M_AS_AREA_RECV, (ipcarg_t) plb_ro,
  171.         PLB_SIZE);
  172.     if (rc) {
  173.         async_wait_for(req, NULL);
  174.         return rc;
  175.     }
  176.      
  177.     /*
  178.      * Pick up the answer for the request to the VFS_REQUEST call.
  179.      */
  180.     async_wait_for(req, NULL);
  181.     fs_handle = (int) IPC_GET_ARG1(answer);
  182.     dprintf("FAT filesystem registered, fs_handle=%d.\n", fs_handle);
  183.  
  184.     /*
  185.      * Create a connection fibril to handle the callback connection.
  186.      */
  187.     async_new_connection(phonehash, 0, NULL, fat_connection);
  188.    
  189.     /*
  190.      * Tell the async framework that other connections are to be handled by
  191.      * the same connection fibril as well.
  192.      */
  193.     async_set_client_connection(fat_connection);
  194.  
  195.     async_manager();
  196.     /* not reached */
  197.     return 0;
  198. }
  199.  
  200. /**
  201.  * @}
  202.  */
  203.