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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.c
  35.  * @brief   VFS_MOUNT 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 "vfs.h"
  47.  
  48. vfs_node_t rootfs = { 0 };
  49.  
  50. static int lookup_root(int fs_handle, int dev_handle, vfs_node_t *root)
  51. {
  52.     vfs_node_t altroot = {
  53.         .fs_handle = fs_handle,
  54.         .dev_handle = dev_handle,
  55.         /*
  56.          * At this point, we don't know what is the index of the root
  57.          * node. Finally, that's what this function is about.
  58.          */
  59.     };
  60.  
  61.     return vfs_lookup_internal("/", 1, root, &altroot);
  62. }
  63.  
  64. void vfs_mount(ipc_callid_t rid, ipc_call_t *request)
  65. {
  66.     int dev_handle;
  67.  
  68.     /*
  69.      * We expect the library to do the device-name to device-handle
  70.      * translation for us, thus the device handle will arrive as ARG1
  71.      * in the request.
  72.      */
  73.     dev_handle = IPC_GET_ARG1(*request);
  74.  
  75.     /*
  76.      * For now, don't make use of ARG2 and ARG3, but they can be used to
  77.      * carry mount options in the future.
  78.      */
  79.  
  80.     /*
  81.      * Now, we expect the client to send us data with the name of the file
  82.      * system and the path of the mountpoint.
  83.      */
  84.     ipc_callid_t callid;
  85.     ipc_call_t call;
  86.     size_t size;
  87.     if (!ipc_data_receive(&callid, &call, NULL, &size)) {
  88.         ipc_answer_fast(callid, EINVAL, 0, 0);
  89.         ipc_answer_fast(rid, EINVAL, 0, 0);
  90.         return;
  91.     }
  92.  
  93.     /*
  94.      * There is no sense in receiving data that can't hold a single
  95.      * character of path. We won't accept data that exceed certain limits
  96.      * either.
  97.      */
  98.     if ((size < FS_NAME_MAXLEN + 1) ||
  99.         (size > FS_NAME_MAXLEN + MAX_PATH_LEN)) {
  100.         ipc_answer_fast(callid, EINVAL, 0, 0);
  101.         ipc_answer_fast(rid, EINVAL, 0, 0);
  102.         return;
  103.     }
  104.  
  105.     /*
  106.      * Allocate buffer for the data being received.
  107.      */
  108.     uint8_t *buf;
  109.     buf = malloc(size);
  110.     if (!buf) {
  111.         ipc_answer_fast(callid, ENOMEM, 0, 0);
  112.         ipc_answer_fast(rid, ENOMEM, 0, 0);
  113.         return;
  114.     }
  115.  
  116.     /*
  117.      * Deliver the data.
  118.      */
  119.     (void) ipc_data_deliver(callid, &call, buf, size);
  120.  
  121.     char fs_name[FS_NAME_MAXLEN + 1];
  122.     memcpy(fs_name, buf, FS_NAME_MAXLEN);
  123.     fs_name[FS_NAME_MAXLEN] = '\0';
  124.  
  125.     /*
  126.      * Check if we know a file system with the same name as is in fs_name.
  127.      * This will also give us its file system handle.
  128.      */
  129.     int fs_handle = fs_name_to_handle(fs_name, true);
  130.     if (!fs_handle) {
  131.         free(buf);
  132.         ipc_answer_fast(rid, ENOENT, 0, 0);
  133.         return;
  134.     }
  135.  
  136.     /*
  137.      * Lookup the root node of the filesystem being mounted.
  138.      */
  139.     int rc;
  140.     vfs_node_t mounted_root;
  141.     rc = lookup_root(fs_handle, dev_handle, &mounted_root);
  142.     if (rc != EOK) {
  143.         free(buf);
  144.         ipc_answer_fast(rid, rc, 0, 0);
  145.         return;
  146.     }
  147.  
  148.     /*
  149.      * Finally, we need to resolve the path to the mountpoint.
  150.      */
  151.     vfs_node_t mp;
  152.     if (rootfs.fs_handle) {
  153.         /*
  154.          * We already have the root FS.
  155.          */
  156.         rc = vfs_lookup_internal((char *) (buf + FS_NAME_MAXLEN),
  157.             size - FS_NAME_MAXLEN, &mp, NULL);
  158.         if (rc != EOK) {
  159.             /*
  160.              * The lookup failed for some reason.
  161.              */
  162.             free(buf);
  163.             ipc_answer_fast(rid, rc, 0, 0);
  164.             return;
  165.         }
  166.     } else {
  167.         /*
  168.          * We still don't have the root file system mounted.
  169.          */
  170.         if ((size - FS_NAME_MAXLEN == 1) &&
  171.             (buf[FS_NAME_MAXLEN] == '/')) {
  172.             /*
  173.              * For this simple, but important case, we are done.
  174.              */
  175.             rootfs = mounted_root;
  176.             free(buf);
  177.             ipc_answer_fast(rid, EOK, 0, 0);
  178.             return;
  179.         } else {
  180.             /*
  181.              * We can't resolve this without the root filesystem
  182.              * being mounted first.
  183.              */
  184.             free(buf);
  185.             ipc_answer_fast(rid, ENOENT, 0, 0);
  186.             return;
  187.         }
  188.     }
  189.        
  190.     /*
  191.      * At this point, we have all necessary pieces: file system and device
  192.      * handles, and we know the mount point VFS node and also the root node
  193.      * of the file system being mounted.
  194.      */
  195.    
  196. }
  197.  
  198. /**
  199.  * @}
  200.  */
  201.