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