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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. #define NAME "tmpfs"
  54.  
  55.  
  56. vfs_info_t tmpfs_vfs_info = {
  57.     .name = "tmpfs",
  58.     .ops = {
  59.         [IPC_METHOD_TO_VFS_OP(VFS_LOOKUP)] = VFS_OP_DEFINED,
  60.         [IPC_METHOD_TO_VFS_OP(VFS_READ)] = VFS_OP_DEFINED,
  61.         [IPC_METHOD_TO_VFS_OP(VFS_WRITE)] = VFS_OP_DEFINED,
  62.         [IPC_METHOD_TO_VFS_OP(VFS_TRUNCATE)] = VFS_OP_DEFINED,
  63.         [IPC_METHOD_TO_VFS_OP(VFS_MOUNT)] = VFS_OP_DEFINED,
  64.         [IPC_METHOD_TO_VFS_OP(VFS_UNMOUNT)] = VFS_OP_NULL,
  65.         [IPC_METHOD_TO_VFS_OP(VFS_DESTROY)] = VFS_OP_DEFINED,
  66.     }
  67. };
  68.  
  69. fs_reg_t tmpfs_reg;
  70.  
  71. /**
  72.  * This connection fibril processes VFS requests from VFS.
  73.  *
  74.  * In order to support simultaneous VFS requests, our design is as follows.
  75.  * The connection fibril accepts VFS requests from VFS. If there is only one
  76.  * instance of the fibril, VFS will need to serialize all VFS requests it sends
  77.  * to FAT. To overcome this bottleneck, VFS can send TMPFS the
  78.  * IPC_M_CONNECT_ME_TO call. In that case, a new connection fibril will be
  79.  * created, which in turn will accept the call. Thus, a new phone will be
  80.  * opened for VFS.
  81.  *
  82.  * There are few issues with this arrangement. First, VFS can run out of
  83.  * available phones. In that case, VFS can close some other phones or use one
  84.  * phone for more serialized requests. Similarily, TMPFS can refuse to duplicate
  85.  * the connection. VFS should then just make use of already existing phones and
  86.  * route its requests through them. To avoid paying the fibril creation price
  87.  * upon each request, TMPFS might want to keep the connections open after the
  88.  * request has been completed.
  89.  */
  90. static void tmpfs_connection(ipc_callid_t iid, ipc_call_t *icall)
  91. {
  92.     if (iid) {
  93.         /*
  94.          * This only happens for connections opened by
  95.          * IPC_M_CONNECT_ME_TO calls as opposed to callback connections
  96.          * created by IPC_M_CONNECT_TO_ME.
  97.          */
  98.         ipc_answer_0(iid, EOK);
  99.     }
  100.    
  101.     dprintf("VFS-TMPFS connection established.\n");
  102.     while (1) {
  103.         ipc_callid_t callid;
  104.         ipc_call_t call;
  105.    
  106.         callid = async_get_call(&call);
  107.         switch  (IPC_GET_METHOD(call)) {
  108.         case VFS_MOUNT:
  109.             tmpfs_mount(callid, &call);
  110.             break;
  111.         case VFS_LOOKUP:
  112.             tmpfs_lookup(callid, &call);
  113.             break;
  114.         case VFS_READ:
  115.             tmpfs_read(callid, &call);
  116.             break;
  117.         case VFS_WRITE:
  118.             tmpfs_write(callid, &call);
  119.             break;
  120.         case VFS_TRUNCATE:
  121.             tmpfs_truncate(callid, &call);
  122.             break;
  123.         case VFS_DESTROY:
  124.             tmpfs_destroy(callid, &call);
  125.             break;
  126.         default:
  127.             ipc_answer_0(callid, ENOTSUP);
  128.             break;
  129.         }
  130.     }
  131. }
  132.  
  133. int main(int argc, char **argv)
  134. {
  135.     int vfs_phone;
  136.  
  137.     printf(NAME ": HelenOS TMPFS file system server\n");
  138.  
  139.     vfs_phone = ipc_connect_me_to(PHONE_NS, SERVICE_VFS, 0, 0);
  140.     while (vfs_phone < EOK) {
  141.         usleep(10000);
  142.         vfs_phone = ipc_connect_me_to(PHONE_NS, SERVICE_VFS, 0, 0);
  143.     }
  144.    
  145.     int rc;
  146.     rc = fs_register(vfs_phone, &tmpfs_reg, &tmpfs_vfs_info,
  147.         tmpfs_connection);
  148.     if (rc != EOK) {
  149.         printf(NAME ": Failed to register file system (%d)\n", rc);
  150.         return rc;
  151.     }
  152.    
  153.     printf(NAME ": Accepting connections\n");
  154.     async_manager();
  155.     /* not reached */
  156.     return 0;
  157. }
  158.  
  159. /**
  160.  * @}
  161.  */
  162.