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  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_open.c
  35.  * @brief   VFS_OPEN method.
  36.  */
  37.  
  38. #include <ipc/ipc.h>
  39. #include <async.h>
  40. #include <errno.h>
  41. #include <stdlib.h>
  42. #include <string.h>
  43. #include <bool.h>
  44. #include <futex.h>
  45. #include <libadt/list.h>
  46. #include <sys/types.h>
  47. #include "vfs.h"
  48.  
  49. /** Per-connection futex protecting the files array. */
  50. __thread atomic_t files_futex = FUTEX_INITIALIZER;
  51.  
  52. /**
  53.  * This is a per-connection table of open files.
  54.  * Our assumption is that each client opens only one connection and therefore
  55.  * there is one table of open files per task. However, this may not be the case
  56.  * and the client can open more connections to VFS. In that case, there will be
  57.  * several tables and several file handle name spaces per task. Besides of this,
  58.  * the functionality will stay unchanged. So unless the client knows what it is
  59.  * doing, it should open one connection to VFS only.
  60.  *
  61.  * Allocation of the open files table is deferred until the client makes the
  62.  * first VFS_OPEN operation.
  63.  */
  64. __thread vfs_file_t *files = NULL;
  65.  
  66. /** Initialize the table of open files. */
  67. static bool vfs_conn_open_files_init(void)
  68. {
  69.     /*
  70.      * Optimized fast path that will never go to sleep unnecessarily.
  71.      * The assumption is that once files is non-zero, it will never be zero
  72.      * again.
  73.      */
  74.     if (files)
  75.         return true;
  76.        
  77.     futex_down(&files_futex);
  78.     if (!files) {
  79.         files = malloc(MAX_OPEN_FILES * sizeof(vfs_file_t));
  80.         if (!files) {
  81.             futex_up(&files_futex);
  82.             return false;
  83.         }
  84.         memset(files, 0, MAX_OPEN_FILES * sizeof(vfs_file_t));
  85.     }
  86.     futex_up(&files_futex);
  87.     return true;
  88. }
  89.  
  90. void vfs_open(ipc_callid_t rid, ipc_call_t *request)
  91. {
  92.     if (!vfs_conn_open_files_init()) {
  93.         ipc_answer_fast_0(rid, ENOMEM);
  94.         return;
  95.     }
  96.  
  97.     /*
  98.      * The POSIX interface is open(path, flags, mode).
  99.      * We can receive flags and mode along with the VFS_OPEN call; the path
  100.      * will need to arrive in another call.
  101.      */
  102.     int flags = IPC_GET_ARG1(*request);
  103.     int mode = IPC_GET_ARG2(*request);
  104.     size_t size;
  105.  
  106.     ipc_callid_t callid;
  107.     ipc_call_t call;
  108.  
  109.     if (!ipc_data_receive(&callid, &call, NULL, &size)) {
  110.         ipc_answer_fast_0(callid, EINVAL);
  111.         ipc_answer_fast_0(rid, EINVAL);
  112.         return;
  113.     }
  114.  
  115.     /*
  116.      * Now we are on the verge of accepting the path.
  117.      *
  118.      * There is one optimization we could do in the future: copy the path
  119.      * directly into the PLB using some kind of a callback.
  120.      */
  121.     char *path = malloc(size);
  122.    
  123.     if (!path) {
  124.         ipc_answer_fast_0(callid, ENOMEM);
  125.         ipc_answer_fast_0(rid, ENOMEM);
  126.         return;
  127.     }
  128.  
  129.     int rc;
  130.     if (rc = ipc_data_deliver(callid, &call, path, size)) {
  131.         ipc_answer_fast_0(rid, rc);
  132.         free(path);
  133.         return;
  134.     }
  135.    
  136.     /*
  137.      * The path is now populated and we can call vfs_lookup_internal().
  138.      */
  139.     vfs_triplet_t triplet;
  140.     rc = vfs_lookup_internal(path, size, &triplet, NULL);
  141.     if (rc) {
  142.         ipc_answer_fast_0(rid, rc);
  143.         free(path);
  144.         return;
  145.     }
  146.  
  147.     /*
  148.      * Path is no longer needed.
  149.      */
  150.     free(path);
  151.  
  152.     vfs_node_t *node = vfs_node_get(&triplet);
  153.     // TODO: not finished  
  154. }
  155.  
  156. /**
  157.  * @}
  158.  */
  159.