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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 <ipc/ipc.h>
  40. #include <ipc/services.h>
  41. #include <async.h>
  42. #include <errno.h>
  43. #include <unistd.h>
  44. #include <stdio.h>
  45. #include <as.h>
  46. #include "../../vfs/vfs.h"
  47.  
  48. #define dprintf(...)    printf(__VA_ARGS__)
  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. Similarly, 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_fast(iid, EOK, 0, 0);
  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.         default:
  107.             ipc_answer_fast(callid, ENOTSUP, 0, 0);
  108.             break;
  109.         }
  110.     }
  111. }
  112.  
  113. int main(int argc, char **argv)
  114. {
  115.     int vfs_phone;
  116.  
  117.     printf("FAT: HelenOS FAT file system server.\n");
  118.  
  119.     vfs_phone = ipc_connect_me_to(PHONE_NS, SERVICE_VFS, 0);
  120.     while (vfs_phone < EOK) {
  121.         usleep(10000);
  122.         vfs_phone = ipc_connect_me_to(PHONE_NS, SERVICE_VFS, 0);
  123.     }
  124.    
  125.     /*
  126.      * Tell VFS that we are here and want to get registered.
  127.      * We use the async framework because VFS will answer the request
  128.      * out-of-order, when it knows that the operation succeeded or failed.
  129.      */
  130.     ipc_call_t answer;
  131.     aid_t req = async_send_2(vfs_phone, VFS_REGISTER, 0, 0, &answer);
  132.  
  133.     /*
  134.      * Send our VFS info structure to VFS.
  135.      */
  136.     int rc = ipc_data_send(vfs_phone, &fat_vfs_info, sizeof(fat_vfs_info));
  137.     if (rc != EOK) {
  138.         async_wait_for(req, NULL);
  139.         return rc;
  140.     }
  141.  
  142.     /*
  143.      * Ask VFS for callback connection.
  144.      */
  145.     ipcarg_t phonehash;
  146.     ipc_connect_to_me(vfs_phone, 0, 0, &phonehash);
  147.  
  148.     /*
  149.      * Allocate piece of address space for PLB.
  150.      */
  151.     plb_ro = as_get_mappable_page(PLB_SIZE);
  152.     if (!plb_ro) {
  153.         async_wait_for(req, NULL);
  154.         return ENOMEM;
  155.     }
  156.  
  157.     /*
  158.      * Request sharing the Path Lookup Buffer with VFS.
  159.      */
  160.     rc = ipc_call_sync_3(vfs_phone, IPC_M_AS_AREA_RECV, (ipcarg_t) plb_ro,
  161.         PLB_SIZE, 0, NULL, NULL, NULL);
  162.     if (rc) {
  163.         async_wait_for(req, NULL);
  164.         return rc;
  165.     }
  166.      
  167.     /*
  168.      * Pick up the answer for the request to the VFS_REQUEST call.
  169.      */
  170.     async_wait_for(req, NULL);
  171.     fs_handle = (int) IPC_GET_ARG1(answer);
  172.     dprintf("FAT filesystem registered, fs_handle=%d.\n", fs_handle);
  173.  
  174.     /*
  175.      * Create a connection fibril to handle the callback connection.
  176.      */
  177.     async_new_connection(phonehash, 0, NULL, fat_connection);
  178.    
  179.     /*
  180.      * Tell the async framework that other connections are to be handled by
  181.      * the same connection fibril as well.
  182.      */
  183.     async_set_client_connection(fat_connection);
  184.  
  185.     async_create_manager();
  186.  
  187.     /*
  188.      * TODO: Interestingly, if we merely return, the only thread dies.
  189.      *   If the only thread dies, the whole task is destroyed.
  190.      *   Prevent the thread from exiting when there are active fibrils.
  191.      */
  192.     fibril_schedule_next_adv(FIBRIL_FROM_DEAD);
  193.     /* not reached */
  194.  
  195.     return 0;
  196. }
  197.  
  198. /**
  199.  * @}
  200.  */
  201.