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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    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_LOOKUP)] = VFS_OP_DEFINED,
  58.         [IPC_METHOD_TO_VFS_OP(VFS_READ)] = VFS_OP_DEFINED,
  59.         [IPC_METHOD_TO_VFS_OP(VFS_WRITE)] = VFS_OP_DEFINED,
  60.         [IPC_METHOD_TO_VFS_OP(VFS_TRUNCATE)] = VFS_OP_DEFINED,
  61.         [IPC_METHOD_TO_VFS_OP(VFS_MOUNT)] = VFS_OP_NULL,
  62.         [IPC_METHOD_TO_VFS_OP(VFS_UNMOUNT)] = VFS_OP_NULL,
  63.         [IPC_METHOD_TO_VFS_OP(VFS_DESTROY)] = VFS_OP_DEFINED,
  64.     }
  65. };
  66.  
  67. fs_reg_t tmpfs_reg;
  68.  
  69. /**
  70.  * This connection fibril processes VFS requests from VFS.
  71.  *
  72.  * In order to support simultaneous VFS requests, our design is as follows.
  73.  * The connection fibril accepts VFS requests from VFS. If there is only one
  74.  * instance of the fibril, VFS will need to serialize all VFS requests it sends
  75.  * to FAT. To overcome this bottleneck, VFS can send TMPFS the
  76.  * IPC_M_CONNECT_ME_TO call. In that case, a new connection fibril will be
  77.  * created, which in turn will accept the call. Thus, a new phone will be
  78.  * 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, TMPFS 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, TMPFS might want to keep the connections open after the
  86.  * request has been completed.
  87.  */
  88. static void tmpfs_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-TMPFS 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_LOOKUP:
  107.             tmpfs_lookup(callid, &call);
  108.             break;
  109.         case VFS_READ:
  110.             tmpfs_read(callid, &call);
  111.             break;
  112.         case VFS_WRITE:
  113.             tmpfs_write(callid, &call);
  114.             break;
  115.         case VFS_TRUNCATE:
  116.             tmpfs_truncate(callid, &call);
  117.             break;
  118.         case VFS_DESTROY:
  119.             tmpfs_destroy(callid, &call);
  120.             break;
  121.         default:
  122.             ipc_answer_0(callid, ENOTSUP);
  123.             break;
  124.         }
  125.     }
  126. }
  127.  
  128. int main(int argc, char **argv)
  129. {
  130.     int vfs_phone;
  131.  
  132.     printf("TMPFS: HelenOS TMPFS file system server.\n");
  133.  
  134.     vfs_phone = ipc_connect_me_to(PHONE_NS, SERVICE_VFS, 0, 0);
  135.     while (vfs_phone < EOK) {
  136.         usleep(10000);
  137.         vfs_phone = ipc_connect_me_to(PHONE_NS, SERVICE_VFS, 0, 0);
  138.     }
  139.    
  140.     int rc;
  141.     rc = fs_register(vfs_phone, &tmpfs_reg, &tmpfs_vfs_info,
  142.         tmpfs_connection);
  143.     if (rc != EOK) {
  144.         printf("Failed to register the TMPFS file system (%d)\n", rc);
  145.         return rc;
  146.     }
  147.    
  148.     dprintf("TMPFS filesystem registered, fs_handle=%d.\n",
  149.         tmpfs_reg.fs_handle);
  150.  
  151.     async_manager();
  152.     /* not reached */
  153.     return 0;
  154. }
  155.  
  156. /**
  157.  * @}
  158.  */
  159.