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  1. /*
  2.  * Copyright (c) 2008 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_register.c
  35.  * @brief
  36.  */
  37.  
  38. #include <ipc/ipc.h>
  39. #include <ipc/services.h>
  40. #include <async.h>
  41. #include <fibril.h>
  42. #include <errno.h>
  43. #include <stdio.h>
  44. #include <stdlib.h>
  45. #include <string.h>
  46. #include <ctype.h>
  47. #include <bool.h>
  48. #include <futex.h>
  49. #include <libadt/list.h>
  50. #include <as.h>
  51. #include <assert.h>
  52. #include <atomic.h>
  53. #include "vfs.h"
  54.  
  55. atomic_t fs_head_futex = FUTEX_INITIALIZER;
  56. link_t fs_head;
  57.  
  58. atomic_t fs_handle_next = {
  59.     .count = 1
  60. };
  61.  
  62. /** Verify the VFS info structure.
  63.  *
  64.  * @param info      Info structure to be verified.
  65.  *
  66.  * @return      Non-zero if the info structure is sane, zero otherwise.
  67.  */
  68. static bool vfs_info_sane(vfs_info_t *info)
  69. {
  70.     int i;
  71.  
  72.     /*
  73.      * Check if the name is non-empty and is composed solely of ASCII
  74.      * characters [a-z]+[a-z0-9_-]*.
  75.      */
  76.     if (!islower(info->name[0])) {
  77.         dprintf("The name doesn't start with a lowercase character.\n");
  78.         return false;
  79.     }
  80.     for (i = 1; i < FS_NAME_MAXLEN; i++) {
  81.         if (!(islower(info->name[i]) || isdigit(info->name[i])) &&
  82.             (info->name[i] != '-') && (info->name[i] != '_')) {
  83.             if (info->name[i] == '\0') {
  84.                 break;
  85.             } else {
  86.                 dprintf("The name contains illegal "
  87.                     "characters.\n");
  88.                 return false;
  89.             }
  90.         }
  91.     }
  92.     /*
  93.      * This check is not redundant. It ensures that the name is
  94.      * NULL-terminated, even if FS_NAME_MAXLEN characters are used.
  95.      */
  96.     if (info->name[i] != '\0') {
  97.         dprintf("The name is not properly NULL-terminated.\n");
  98.         return false;
  99.     }
  100.    
  101.  
  102.     /*
  103.      * Check if the FS implements mandatory VFS operations.
  104.      */
  105.     if (info->ops[IPC_METHOD_TO_VFS_OP(VFS_LOOKUP)] != VFS_OP_DEFINED) {
  106.         dprintf("Operation VFS_LOOKUP not defined by the client.\n");
  107.         return false;
  108.     }
  109.     if (info->ops[IPC_METHOD_TO_VFS_OP(VFS_OPEN)] != VFS_OP_DEFINED) {
  110.         dprintf("Operation VFS_OPEN not defined by the client.\n");
  111.         return false;
  112.     }
  113.     if (info->ops[IPC_METHOD_TO_VFS_OP(VFS_CLOSE)] != VFS_OP_DEFINED) {
  114.         dprintf("Operation VFS_CLOSE not defined by the client.\n");
  115.         return false;
  116.     }
  117.     if (info->ops[IPC_METHOD_TO_VFS_OP(VFS_READ)] != VFS_OP_DEFINED) {
  118.         dprintf("Operation VFS_READ not defined by the client.\n");
  119.         return false;
  120.     }
  121.    
  122.     /*
  123.      * Check if each operation is either not defined, defined or default.
  124.      */
  125.     for (i = VFS_FIRST; i < VFS_LAST_CLNT; i++) {
  126.         if ((info->ops[IPC_METHOD_TO_VFS_OP(i)] != VFS_OP_NULL) &&
  127.             (info->ops[IPC_METHOD_TO_VFS_OP(i)] != VFS_OP_DEFAULT) &&
  128.             (info->ops[IPC_METHOD_TO_VFS_OP(i)] != VFS_OP_DEFINED)) {
  129.             dprintf("Operation info not understood.\n");
  130.             return false;
  131.         }
  132.     }
  133.     return true;
  134. }
  135.  
  136. /** VFS_REGISTER protocol function.
  137.  *
  138.  * @param rid       Hash of the call with the request.
  139.  * @param request   Call structure with the request.
  140.  */
  141. void vfs_register(ipc_callid_t rid, ipc_call_t *request)
  142. {
  143.     ipc_callid_t callid;
  144.     ipc_call_t call;
  145.     int rc;
  146.     size_t size;
  147.  
  148.     dprintf("Processing VFS_REGISTER request received from %p.\n",
  149.         request->in_phone_hash);
  150.  
  151.     /*
  152.      * The first call has to be IPC_M_DATA_SEND in which we receive the
  153.      * VFS info structure from the client FS.
  154.      */
  155.     if (!ipc_data_write_receive(&callid, &size)) {
  156.         /*
  157.          * The client doesn't obey the same protocol as we do.
  158.          */
  159.         dprintf("Receiving of VFS info failed.\n");
  160.         ipc_answer_0(callid, EINVAL);
  161.         ipc_answer_0(rid, EINVAL);
  162.         return;
  163.     }
  164.    
  165.     dprintf("VFS info received, size = %d\n", size);
  166.    
  167.     /*
  168.      * We know the size of the VFS info structure. See if the client
  169.      * understands this easy concept too.
  170.      */
  171.     if (size != sizeof(vfs_info_t)) {
  172.         /*
  173.          * The client is sending us something, which cannot be
  174.          * the info structure.
  175.          */
  176.         dprintf("Received VFS info has bad size.\n");
  177.         ipc_answer_0(callid, EINVAL);
  178.         ipc_answer_0(rid, EINVAL);
  179.         return;
  180.     }
  181.  
  182.     /*
  183.      * Allocate and initialize a buffer for the fs_info structure.
  184.      */
  185.     fs_info_t *fs_info;
  186.     fs_info = (fs_info_t *) malloc(sizeof(fs_info_t));
  187.     if (!fs_info) {
  188.         dprintf("Could not allocate memory for FS info.\n");
  189.         ipc_answer_0(callid, ENOMEM);
  190.         ipc_answer_0(rid, ENOMEM);
  191.         return;
  192.     }
  193.     link_initialize(&fs_info->fs_link);
  194.     futex_initialize(&fs_info->phone_futex, 1);
  195.        
  196.     rc = ipc_data_write_finalize(callid, &fs_info->vfs_info, size);
  197.     if (rc != EOK) {
  198.         dprintf("Failed to deliver the VFS info into our AS, rc=%d.\n",
  199.             rc);
  200.         free(fs_info);
  201.         ipc_answer_0(callid, rc);
  202.         ipc_answer_0(rid, rc);
  203.         return;
  204.     }
  205.  
  206.     dprintf("VFS info delivered.\n");
  207.        
  208.     if (!vfs_info_sane(&fs_info->vfs_info)) {
  209.         free(fs_info);
  210.         ipc_answer_0(callid, EINVAL);
  211.         ipc_answer_0(rid, EINVAL);
  212.         return;
  213.     }
  214.        
  215.     futex_down(&fs_head_futex);
  216.  
  217.     /*
  218.      * Check for duplicit registrations.
  219.      */
  220.     if (fs_name_to_handle(fs_info->vfs_info.name, false)) {
  221.         /*
  222.          * We already register a fs like this.
  223.          */
  224.         dprintf("FS is already registered.\n");
  225.         futex_up(&fs_head_futex);
  226.         free(fs_info);
  227.         ipc_answer_0(callid, EEXISTS);
  228.         ipc_answer_0(rid, EEXISTS);
  229.         return;
  230.     }
  231.  
  232.     /*
  233.      * Add fs_info to the list of registered FS's.
  234.      */
  235.     dprintf("Inserting FS into the list of registered file systems.\n");
  236.     list_append(&fs_info->fs_link, &fs_head);
  237.  
  238.     /*
  239.      * Now we want the client to send us the IPC_M_CONNECT_TO_ME call so
  240.      * that a callback connection is created and we have a phone through
  241.      * which to forward VFS requests to it.
  242.      */
  243.     callid = async_get_call(&call);
  244.     if (IPC_GET_METHOD(call) != IPC_M_CONNECT_TO_ME) {
  245.         dprintf("Unexpected call, method = %d\n", IPC_GET_METHOD(call));
  246.         list_remove(&fs_info->fs_link);
  247.         futex_up(&fs_head_futex);
  248.         free(fs_info);
  249.         ipc_answer_0(callid, EINVAL);
  250.         ipc_answer_0(rid, EINVAL);
  251.         return;
  252.     }
  253.     fs_info->phone = IPC_GET_ARG5(call);
  254.     ipc_answer_0(callid, EOK);
  255.  
  256.     dprintf("Callback connection to FS created.\n");
  257.  
  258.     /*
  259.      * The client will want us to send him the address space area with PLB.
  260.      */
  261.  
  262.     if (!ipc_share_in_receive(&callid, &size)) {
  263.         dprintf("Unexpected call, method = %d\n", IPC_GET_METHOD(call));
  264.         list_remove(&fs_info->fs_link);
  265.         futex_up(&fs_head_futex);
  266.         ipc_hangup(fs_info->phone);
  267.         free(fs_info);
  268.         ipc_answer_0(callid, EINVAL);
  269.         ipc_answer_0(rid, EINVAL);
  270.         return;
  271.     }
  272.    
  273.     /*
  274.      * We can only send the client address space area PLB_SIZE bytes long.
  275.      */
  276.     if (size != PLB_SIZE) {
  277.         dprintf("Client suggests wrong size of PFB, size = %d\n", size);
  278.         list_remove(&fs_info->fs_link);
  279.         futex_up(&fs_head_futex);
  280.         ipc_hangup(fs_info->phone);
  281.         free(fs_info);
  282.         ipc_answer_0(callid, EINVAL);
  283.         ipc_answer_0(rid, EINVAL);
  284.         return;
  285.     }
  286.  
  287.     /*
  288.      * Commit to read-only sharing the PLB with the client.
  289.      */
  290.     (void) ipc_share_in_finalize(callid, plb,
  291.         AS_AREA_READ | AS_AREA_CACHEABLE);
  292.  
  293.     dprintf("Sharing PLB.\n");
  294.  
  295.     /*
  296.      * That was it. The FS has been registered.
  297.      * In reply to the VFS_REGISTER request, we assign the client file
  298.      * system a global file system handle.
  299.      */
  300.     fs_info->fs_handle = (int) atomic_postinc(&fs_handle_next);
  301.     ipc_answer_1(rid, EOK, (ipcarg_t) fs_info->fs_handle);
  302.    
  303.     futex_up(&fs_head_futex);
  304.    
  305.     dprintf("\"%.*s\" filesystem successfully registered, handle=%d.\n",
  306.         FS_NAME_MAXLEN, fs_info->vfs_info.name, fs_info->fs_handle);
  307. }
  308.  
  309. /** For a given file system handle, implement policy for allocating a phone.
  310.  *
  311.  * @param handle    File system handle.
  312.  *
  313.  * @return      Phone over which a multi-call request can be safely
  314.  *          sent. Return 0 if no phone was found.
  315.  */
  316. int vfs_grab_phone(int handle)
  317. {
  318.     /*
  319.      * For now, we don't try to be very clever and very fast.
  320.      * We simply lookup the phone in the fs_head list. We currently don't
  321.      * open any additional phones (even though that itself would be pretty
  322.      * straightforward; housekeeping multiple open phones to a FS task would
  323.      * be more demanding). Instead, we simply take the respective
  324.      * phone_futex and keep it until vfs_release_phone().
  325.      */
  326.     futex_down(&fs_head_futex);
  327.     link_t *cur;
  328.     fs_info_t *fs;
  329.     for (cur = fs_head.next; cur != &fs_head; cur = cur->next) {
  330.         fs = list_get_instance(cur, fs_info_t, fs_link);
  331.         if (fs->fs_handle == handle) {
  332.             futex_up(&fs_head_futex);
  333.             /*
  334.              * For now, take the futex unconditionally.
  335.              * Oh yeah, serialization rocks.
  336.              * It will be up'ed in vfs_release_phone().
  337.              */
  338.             futex_down(&fs->phone_futex);
  339.             /*
  340.              * Avoid deadlock with other fibrils in the same thread
  341.              * by disabling fibril preemption.
  342.              */
  343.             fibril_inc_sercount();
  344.             return fs->phone;
  345.         }
  346.     }
  347.     futex_up(&fs_head_futex);
  348.     return 0;
  349. }
  350.  
  351. /** Tell VFS that the phone is in use for any request.
  352.  *
  353.  * @param phone     Phone to FS task.
  354.  */
  355. void vfs_release_phone(int phone)
  356. {
  357.     bool found = false;
  358.  
  359.     /*
  360.      * Undo the fibril_inc_sercount() done in vfs_grab_phone().
  361.      */
  362.     fibril_dec_sercount();
  363.    
  364.     futex_down(&fs_head_futex);
  365.     link_t *cur;
  366.     for (cur = fs_head.next; cur != &fs_head; cur = cur->next) {
  367.         fs_info_t *fs = list_get_instance(cur, fs_info_t, fs_link);
  368.         if (fs->phone == phone) {
  369.             found = true;
  370.             futex_up(&fs_head_futex);
  371.             futex_up(&fs->phone_futex);
  372.             return;
  373.         }
  374.     }
  375.     futex_up(&fs_head_futex);
  376.  
  377.     /*
  378.      * Not good to get here.
  379.      */
  380.     assert(found == true);
  381. }
  382.  
  383. /** Convert file system name to its handle.
  384.  *
  385.  * @param name      File system name.
  386.  * @param lock      If true, the function will down and up the
  387.  *          fs_head_futex.
  388.  *
  389.  * @return      File system handle or zero if file system not found.
  390.  */
  391. int fs_name_to_handle(char *name, bool lock)
  392. {
  393.     int handle = 0;
  394.    
  395.     if (lock)
  396.         futex_down(&fs_head_futex);
  397.     link_t *cur;
  398.     for (cur = fs_head.next; cur != &fs_head; cur = cur->next) {
  399.         fs_info_t *fs = list_get_instance(cur, fs_info_t, fs_link);
  400.         if (strncmp(fs->vfs_info.name, name,
  401.             sizeof(fs->vfs_info.name)) == 0) {
  402.             handle = fs->fs_handle;
  403.             break;
  404.         }
  405.     }
  406.     if (lock)
  407.         futex_up(&fs_head_futex);
  408.     return handle;
  409. }
  410.  
  411. /**
  412.  * @}
  413.  */
  414.