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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    tmpfs.c
  36.  * @brief   File system driver for in-memory file system.
  37.  *
  38.  * Every instance of tmpfs exists purely in memory and has neither a disk layout
  39.  * nor any permanent storage (e.g. disk blocks). With each system reboot, data
  40.  * stored in a tmpfs file system is lost.
  41.  */
  42.  
  43. #include "tmpfs.h"
  44. #include <ipc/ipc.h>
  45. #include <ipc/services.h>
  46. #include <async.h>
  47. #include <errno.h>
  48. #include <unistd.h>
  49. #include <stdio.h>
  50. #include <libfs.h>
  51. #include "../../vfs/vfs.h"
  52.  
  53.  
  54. vfs_info_t tmpfs_vfs_info = {
  55.     .name = "tmpfs",
  56.     .ops = {
  57.         [IPC_METHOD_TO_VFS_OP(VFS_REGISTER)] = VFS_OP_DEFINED,
  58.         [IPC_METHOD_TO_VFS_OP(VFS_MOUNT)] = VFS_OP_DEFINED,
  59.         [IPC_METHOD_TO_VFS_OP(VFS_UNMOUNT)] = VFS_OP_DEFINED,
  60.         [IPC_METHOD_TO_VFS_OP(VFS_LOOKUP)] = VFS_OP_DEFINED,
  61.         [IPC_METHOD_TO_VFS_OP(VFS_OPEN)] = VFS_OP_DEFINED,
  62.         [IPC_METHOD_TO_VFS_OP(VFS_CREATE)] = VFS_OP_DEFINED,
  63.         [IPC_METHOD_TO_VFS_OP(VFS_CLOSE)] = VFS_OP_DEFINED,
  64.         [IPC_METHOD_TO_VFS_OP(VFS_READ)] = VFS_OP_DEFINED,
  65.         [IPC_METHOD_TO_VFS_OP(VFS_WRITE)] = VFS_OP_DEFINED,
  66.         [IPC_METHOD_TO_VFS_OP(VFS_SEEK)] = VFS_OP_DEFAULT
  67.     }
  68. };
  69.  
  70. fs_reg_t tmpfs_reg;
  71.  
  72. /**
  73.  * This connection fibril processes VFS requests from VFS.
  74.  *
  75.  * In order to support simultaneous VFS requests, our design is as follows.
  76.  * The connection fibril accepts VFS requests from VFS. If there is only one
  77.  * instance of the fibril, VFS will need to serialize all VFS requests it sends
  78.  * to FAT. To overcome this bottleneck, VFS can send TMPFS the
  79.  * IPC_M_CONNECT_ME_TO call. In that case, a new connection fibril will be
  80.  * created, which in turn will accept the call. Thus, a new phone will be
  81.  * opened for VFS.
  82.  *
  83.  * There are few issues with this arrangement. First, VFS can run out of
  84.  * available phones. In that case, VFS can close some other phones or use one
  85.  * phone for more serialized requests. Similarily, TMPFS can refuse to duplicate
  86.  * the connection. VFS should then just make use of already existing phones and
  87.  * route its requests through them. To avoid paying the fibril creation price
  88.  * upon each request, TMPFS might want to keep the connections open after the
  89.  * request has been completed.
  90.  */
  91. static void tmpfs_connection(ipc_callid_t iid, ipc_call_t *icall)
  92. {
  93.     if (iid) {
  94.         /*
  95.          * This only happens for connections opened by
  96.          * IPC_M_CONNECT_ME_TO calls as opposed to callback connections
  97.          * created by IPC_M_CONNECT_TO_ME.
  98.          */
  99.         ipc_answer_0(iid, EOK);
  100.     }
  101.    
  102.     dprintf("VFS-TMPFS connection established.\n");
  103.     while (1) {
  104.         ipc_callid_t callid;
  105.         ipc_call_t call;
  106.    
  107.         callid = async_get_call(&call);
  108.         switch  (IPC_GET_METHOD(call)) {
  109.         case VFS_REGISTER:
  110.             ipc_answer_0(callid, EOK);
  111.             break;
  112.         case VFS_LOOKUP:
  113.             tmpfs_lookup(callid, &call);
  114.             break;
  115.         default:
  116.             ipc_answer_0(callid, ENOTSUP);
  117.             break;
  118.         }
  119.     }
  120. }
  121.  
  122. int main(int argc, char **argv)
  123. {
  124.     int vfs_phone;
  125.  
  126.     printf("TMPFS: HelenOS TMPFS file system server.\n");
  127.  
  128.     vfs_phone = ipc_connect_me_to(PHONE_NS, SERVICE_VFS, 0, 0);
  129.     while (vfs_phone < EOK) {
  130.         usleep(10000);
  131.         vfs_phone = ipc_connect_me_to(PHONE_NS, SERVICE_VFS, 0, 0);
  132.     }
  133.    
  134.     int rc;
  135.     rc = fs_register(vfs_phone, &tmpfs_reg, &tmpfs_vfs_info,
  136.         tmpfs_connection);
  137.     if (rc != EOK) {
  138.         printf("Failed to register the TMPFS file system (%d)\n", rc);
  139.         return rc;
  140.     }
  141.    
  142.     dprintf("TMPFS filesystem registered, fs_handle=%d.\n",
  143.         tmpfs_reg.fs_handle);
  144.  
  145.     async_manager();
  146.     /* not reached */
  147.     return 0;
  148. }
  149.  
  150. /**
  151.  * @}
  152.  */
  153.