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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 multiplexer for HelenOS.
  36.  */
  37.  
  38. #include <ipc/ipc.h>
  39. #include <ipc/services.h>
  40. #include <async.h>
  41. #include <errno.h>
  42. #include <stdlib.h>
  43. #include <string.h>
  44. #include <ctype.h>
  45. #include <bool.h>
  46. #include <futex.h>
  47. #include <libadt/list.h>
  48. #include "vfs.h"
  49.  
  50. atomic_t fs_head_futex = FUTEX_INITIALIZER;
  51. link_t fs_head;
  52.  
  53. /** Verify the VFS info structure.
  54.  *
  55.  * @param info      Info structure to be verified.
  56.  *
  57.  * @return      Non-zero if the info structure is sane, zero otherwise.
  58.  */
  59. static bool vfs_info_sane(vfs_info_t *info)
  60. {
  61.     int i;
  62.  
  63.     /*
  64.      * Check if the name is non-empty and is composed solely of ASCII
  65.      * characters [a-z]+[a-z0-9_-]*.
  66.      */
  67.     if (!islower(info->name[0]))
  68.         return false;
  69.     for (i = 1; i < FS_NAME_MAXLEN; i++) {
  70.         if (!(islower(info->name[i]) || isdigit(info->name[i])) &&
  71.             (info->name[i] != '-') && (info->name[i] != '_')) {
  72.             if (info->name[i] == '\0')
  73.                 break;
  74.             else
  75.                 return false;
  76.         }
  77.     }
  78.    
  79.  
  80.     /*
  81.      * Check if the FS implements mandatory VFS operations.
  82.      */
  83.     if (info->ops[IPC_METHOD_TO_VFS_OP(VFS_REGISTER)] != VFS_OP_DEFINED)
  84.         return false;
  85.     if (info->ops[IPC_METHOD_TO_VFS_OP(VFS_MOUNT)] != VFS_OP_DEFINED)
  86.         return false;
  87.     if (info->ops[IPC_METHOD_TO_VFS_OP(VFS_UNMOUNT)] != VFS_OP_DEFINED)
  88.         return false;
  89.     if (info->ops[IPC_METHOD_TO_VFS_OP(VFS_LOOKUP)] != VFS_OP_DEFINED)
  90.         return false;
  91.     if (info->ops[IPC_METHOD_TO_VFS_OP(VFS_OPEN)] != VFS_OP_DEFINED)
  92.         return false;
  93.     if (info->ops[IPC_METHOD_TO_VFS_OP(VFS_CLOSE)] != VFS_OP_DEFINED)
  94.         return false;
  95.     if (info->ops[IPC_METHOD_TO_VFS_OP(VFS_READ)] != VFS_OP_DEFINED)
  96.         return false;
  97.    
  98.     /*
  99.      * Check if each operation is either not defined, defined or default.
  100.      */
  101.     for (i = VFS_FIRST; i < VFS_LAST; i++) {
  102.         if ((IPC_METHOD_TO_VFS_OP(i) != VFS_OP_NULL) &&
  103.             (IPC_METHOD_TO_VFS_OP(i) != VFS_OP_DEFAULT) &&
  104.             (IPC_METHOD_TO_VFS_OP(i) != VFS_OP_DEFINED))
  105.             return false;  
  106.     }
  107.     return true;
  108. }
  109.  
  110. /** VFS_REGISTER protocol function.
  111.  *
  112.  * @param rid       Hash of the call with the request.
  113.  * @param request   Call structure with the request.
  114.  */
  115. static void vfs_register(ipc_callid_t rid, ipc_call_t *request)
  116. {
  117.     ipc_callid_t callid;
  118.     ipc_call_t call;
  119.     int rc;
  120.     size_t size;
  121.  
  122.     /*
  123.      * The first call has to be IPC_M_DATA_SEND in which we receive the
  124.      * VFS info structure from the client FS.
  125.      */
  126.     if (!ipc_data_send_accept(&callid, &call, NULL, &size)) {
  127.         /*
  128.          * The client doesn't obey the same protocol as we do.
  129.          */
  130.         ipc_answer_fast(callid, EINVAL, 0, 0);
  131.         ipc_answer_fast(rid, EINVAL, 0, 0);
  132.         return;
  133.     }
  134.    
  135.     /*
  136.      * We know the size of the VFS info structure. See if the client
  137.      * understands this easy concept too.
  138.      */
  139.     if (size != sizeof(vfs_info_t)) {
  140.         /*
  141.          * The client is sending us something, which cannot be
  142.          * the info structure.
  143.          */
  144.         ipc_answer_fast(callid, EINVAL, 0, 0);
  145.         ipc_answer_fast(rid, EINVAL, 0, 0);
  146.         return;
  147.     }
  148.     fs_info_t *fs_info;
  149.  
  150.     /*
  151.      * Allocate and initialize a buffer for the fs_info structure.
  152.      */
  153.     fs_info = (fs_info_t *) malloc(sizeof(fs_info_t));
  154.     if (!fs_info) {
  155.         ipc_answer_fast(callid, ENOMEM, 0, 0);
  156.         ipc_answer_fast(rid, ENOMEM, 0, 0);
  157.         return;
  158.     }
  159.     link_initialize(&fs_info->fs_link);
  160.        
  161.     rc = ipc_data_send_answer(callid, &call, &fs_info->vfs_info, size);
  162.     if (!rc) {
  163.         free(fs_info);
  164.         ipc_answer_fast(callid, rc, 0, 0);
  165.         ipc_answer_fast(rid, rc, 0, 0);
  166.         return;
  167.     }
  168.        
  169.     if (!vfs_info_sane(&fs_info->vfs_info)) {
  170.         free(fs_info);
  171.         ipc_answer_fast(callid, EINVAL, 0, 0);
  172.         ipc_answer_fast(rid, EINVAL, 0, 0);
  173.         return;
  174.     }
  175.        
  176.     futex_down(&fs_head_futex);
  177.  
  178.     /*
  179.      * Check for duplicit registrations.
  180.      */
  181.     link_t *cur;
  182.     for (cur = fs_head.next; cur != &fs_head; cur = cur->next) {
  183.         fs_info_t *fi = list_get_instance(cur, fs_info_t,
  184.             fs_link);
  185.         /* TODO: replace strcmp with strncmp once we have it */
  186.         if (strcmp(fs_info->vfs_info.name, fi->vfs_info.name) == 0) {
  187.             /*
  188.              * We already register a fs like this.
  189.              */
  190.             futex_up(&fs_head_futex);
  191.             free(fs_info);
  192.             ipc_answer_fast(callid, EEXISTS, 0, 0);
  193.             ipc_answer_fast(rid, EEXISTS, 0, 0);
  194.             return;
  195.         }
  196.     }
  197.  
  198.     /*
  199.      * Add fs_info to the list of registered FS's.
  200.      */
  201.     list_append(&fs_info->fs_link, &fs_head);
  202.  
  203.     /*
  204.      * ACK receiving a properly formatted, non-duplicit vfs_info.
  205.      */
  206.     ipc_answer_fast(callid, EOK, 0, 0);
  207.    
  208.     /*
  209.      * Now we want the client to send us the IPC_M_CONNECT_TO_ME call so
  210.      * that a callback connection is created and we have a phone through
  211.      * which to forward VFS requests to it.
  212.      */
  213.     callid = async_get_call(&call);
  214.     if (IPC_GET_METHOD(call) != IPC_M_CONNECT_TO_ME) {
  215.         list_remove(&fs_info->fs_link);
  216.         futex_up(&fs_head_futex);
  217.         free(fs_info);
  218.         ipc_answer_fast(callid, EINVAL, 0, 0);
  219.         ipc_answer_fast(rid, EINVAL, 0, 0);
  220.         return;
  221.     }
  222.     fs_info->phone = IPC_GET_ARG3(call);
  223.     ipc_answer_fast(callid, EOK, 0, 0);
  224.  
  225.     futex_up(&fs_head_futex);
  226.  
  227.     /*
  228.      * That was it. The FS has been registered.
  229.      */
  230.     ipc_answer_fast(rid, EOK, 0, 0);
  231. }
  232.  
  233. static void vfs_connection(ipc_callid_t iid, ipc_call_t *icall)
  234. {
  235.     bool keep_on_going = 1;
  236.  
  237.     /*
  238.      * The connection was opened via the IPC_CONNECT_ME_TO call.
  239.      * This call needs to be answered.
  240.      */
  241.     ipc_answer_fast(iid, EOK, 0, 0);
  242.  
  243.     /*
  244.      * Here we enter the main connection fibril loop.
  245.      * The logic behind this loop and the protocol is that we'd like to keep
  246.      * each connection open for a while before we close it. The benefit of
  247.      * this is that the client doesn't have to establish a new connection
  248.      * upon each request.  On the other hand, the client must be ready to
  249.      * re-establish a connection if we hang it up due to reaching of maximum
  250.      * number of requests per connection or due to the client timing out.
  251.      */
  252.      
  253.     while (keep_on_going) {
  254.         ipc_callid_t callid;
  255.         ipc_call_t call;
  256.  
  257.         callid = async_get_call(&call);
  258.        
  259.         switch (IPC_GET_METHOD(call)) {
  260.         case IPC_M_PHONE_HUNGUP:
  261.             keep_on_going = false;
  262.             break;
  263.         case VFS_REGISTER:
  264.             vfs_register(callid, &call);
  265.             keep_on_going = false;
  266.             break;
  267.         case VFS_MOUNT:
  268.         case VFS_UNMOUNT:
  269.         case VFS_OPEN:
  270.         case VFS_CREATE:
  271.         case VFS_CLOSE:
  272.         case VFS_READ:
  273.         case VFS_WRITE:
  274.         case VFS_SEEK:
  275.         default:
  276.             ipc_answer_fast(callid, ENOTSUP, 0, 0);
  277.             break;
  278.         }
  279.     }
  280.  
  281.     /* TODO: cleanup after the client */
  282.    
  283. }
  284.  
  285. int main(int argc, char **argv)
  286. {
  287.     ipcarg_t phonead;
  288.  
  289.     list_initialize(&fs_head);
  290.     async_set_client_connection(vfs_connection);
  291.     ipc_connect_to_me(PHONE_NS, SERVICE_VFS, 0, &phonead);
  292.     async_manager();
  293.     return 0;
  294. }
  295.  
  296. /**
  297.  * @}
  298.  */
  299.