Subversion Repositories HelenOS

Rev

Rev 2679 | Go to most recent revision | Blame | Last modification | View Log | Download | RSS feed

  1. /*
  2.  * Copyright (c) 2007 Jakub Jermar
  3.  * All rights reserved.
  4.  *
  5.  * Redistribution and use in source and binary forms, with or without
  6.  * modification, are permitted provided that the following conditions
  7.  * are met:
  8.  *
  9.  * - Redistributions of source code must retain the above copyright
  10.  *   notice, this list of conditions and the following disclaimer.
  11.  * - Redistributions in binary form must reproduce the above copyright
  12.  *   notice, this list of conditions and the following disclaimer in the
  13.  *   documentation and/or other materials provided with the distribution.
  14.  * - The name of the author may not be used to endorse or promote products
  15.  *   derived from this software without specific prior written permission.
  16.  *
  17.  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  18.  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  19.  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  20.  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  21.  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  22.  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  23.  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  24.  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  25.  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  26.  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  27.  */
  28.  
  29. /** @addtogroup fs
  30.  * @{
  31.  */
  32.  
  33. /**
  34.  * @file    vfs_rdwr.c
  35.  * @brief
  36.  */
  37.  
  38. #include "vfs.h"
  39. #include <ipc/ipc.h>
  40. #include <async.h>
  41. #include <errno.h>
  42. #include <rwlock.h>
  43.  
  44. static void vfs_rdwr(ipc_callid_t rid, ipc_call_t *request, bool read)
  45. {
  46.  
  47.     /*
  48.      * The following code strongly depends on the fact that the files data
  49.      * structure can be only accessed by a single fibril and all file
  50.      * operations are serialized (i.e. the reads and writes cannot
  51.      * interleave and a file cannot be closed while it is being read).
  52.      *
  53.      * Additional synchronization needs to be added once the table of
  54.      * open files supports parallel access!
  55.      */
  56.  
  57.     int fd = IPC_GET_ARG1(*request);
  58.  
  59.     /*
  60.      * Lookup the file structure corresponding to the file descriptor.
  61.      */
  62.     vfs_file_t *file = vfs_file_get(fd);
  63.     if (!file) {
  64.         ipc_answer_0(rid, ENOENT);
  65.         return;
  66.     }
  67.  
  68.     /*
  69.      * Now we need to receive a call with client's
  70.      * IPC_M_DATA_READ/IPC_M_DATA_WRITE request.
  71.      */
  72.     ipc_callid_t callid;
  73.     int res;
  74.     if (read)
  75.         res = ipc_data_read_receive(&callid, NULL);
  76.     else
  77.         res = ipc_data_write_receive(&callid, NULL);
  78.     if (!res) {
  79.         ipc_answer_0(callid, EINVAL);
  80.         ipc_answer_0(rid, EINVAL);
  81.         return;
  82.     }
  83.  
  84.     /*
  85.      * Lock the file's node so that no other client can read/write to it at
  86.      * the same time.
  87.      */
  88.     if (read)
  89.         rwlock_reader_lock(&file->node->contents_rwlock);
  90.     else
  91.         rwlock_writer_lock(&file->node->contents_rwlock);
  92.  
  93.     int fs_phone = vfs_grab_phone(file->node->fs_handle);  
  94.    
  95.     /*
  96.      * Make a VFS_READ/VFS_WRITE request at the destination FS server.
  97.      */
  98.     aid_t msg;
  99.     ipc_call_t answer;
  100.     msg = async_send_3(fs_phone, IPC_GET_METHOD(*request),
  101.         file->node->dev_handle, file->node->index, file->pos, &answer);
  102.    
  103.     /*
  104.      * Forward the IPC_M_DATA_READ/IPC_M_DATA_WRITE request to the
  105.      * destination FS server. The call will be routed as if sent by
  106.      * ourselves. Note that call arguments are immutable in this case so we
  107.      * don't have to bother.
  108.      */
  109.     ipc_forward_fast(callid, fs_phone, 0, 0, 0, IPC_FF_ROUTE_FROM_ME);
  110.  
  111.     vfs_release_phone(fs_phone);
  112.  
  113.     /*
  114.      * Wait for reply from the FS server.
  115.      */
  116.     ipcarg_t rc;
  117.     async_wait_for(msg, &rc);
  118.     size_t bytes = IPC_GET_ARG1(answer);
  119.  
  120.     /*
  121.      * Unlock the VFS node.
  122.      */
  123.     if (read)
  124.         rwlock_reader_unlock(&file->node->contents_rwlock);
  125.     else
  126.         rwlock_writer_unlock(&file->node->contents_rwlock);
  127.  
  128.     /*
  129.      * Update the position pointer.
  130.      */
  131.     file->pos += bytes;
  132.  
  133.     /*
  134.      * FS server's reply is the final result of the whole operation we
  135.      * return to the client.
  136.      */
  137.     ipc_answer_1(rid, rc, bytes);
  138. }
  139.  
  140.  
  141. void vfs_read(ipc_callid_t rid, ipc_call_t *request)
  142. {
  143.     vfs_rdwr(rid, request, true);
  144. }
  145.  
  146. void vfs_write(ipc_callid_t rid, ipc_call_t *request)
  147. {
  148.     vfs_rdwr(rid, request, false);
  149. }
  150.  
  151. /**
  152.  * @}
  153.  */
  154.