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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.     return true;
  102. }
  103.  
  104. /** VFS_REGISTER protocol function.
  105.  *
  106.  * @param rid       Hash of the call with the request.
  107.  * @param request   Call structure with the request.
  108.  */
  109. void vfs_register(ipc_callid_t rid, ipc_call_t *request)
  110. {
  111.     ipc_callid_t callid;
  112.     ipc_call_t call;
  113.     int rc;
  114.     size_t size;
  115.  
  116.     dprintf("Processing VFS_REGISTER request received from %p.\n",
  117.         request->in_phone_hash);
  118.  
  119.     /*
  120.      * The first call has to be IPC_M_DATA_SEND in which we receive the
  121.      * VFS info structure from the client FS.
  122.      */
  123.     if (!ipc_data_write_receive(&callid, &size)) {
  124.         /*
  125.          * The client doesn't obey the same protocol as we do.
  126.          */
  127.         dprintf("Receiving of VFS info failed.\n");
  128.         ipc_answer_0(callid, EINVAL);
  129.         ipc_answer_0(rid, EINVAL);
  130.         return;
  131.     }
  132.    
  133.     dprintf("VFS info received, size = %d\n", size);
  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.         dprintf("Received VFS info has bad size.\n");
  145.         ipc_answer_0(callid, EINVAL);
  146.         ipc_answer_0(rid, EINVAL);
  147.         return;
  148.     }
  149.  
  150.     /*
  151.      * Allocate and initialize a buffer for the fs_info structure.
  152.      */
  153.     fs_info_t *fs_info;
  154.     fs_info = (fs_info_t *) malloc(sizeof(fs_info_t));
  155.     if (!fs_info) {
  156.         dprintf("Could not allocate memory for FS info.\n");
  157.         ipc_answer_0(callid, ENOMEM);
  158.         ipc_answer_0(rid, ENOMEM);
  159.         return;
  160.     }
  161.     link_initialize(&fs_info->fs_link);
  162.     futex_initialize(&fs_info->phone_futex, 1);
  163.        
  164.     rc = ipc_data_write_finalize(callid, &fs_info->vfs_info, size);
  165.     if (rc != EOK) {
  166.         dprintf("Failed to deliver the VFS info into our AS, rc=%d.\n",
  167.             rc);
  168.         free(fs_info);
  169.         ipc_answer_0(callid, rc);
  170.         ipc_answer_0(rid, rc);
  171.         return;
  172.     }
  173.  
  174.     dprintf("VFS info delivered.\n");
  175.        
  176.     if (!vfs_info_sane(&fs_info->vfs_info)) {
  177.         free(fs_info);
  178.         ipc_answer_0(callid, EINVAL);
  179.         ipc_answer_0(rid, EINVAL);
  180.         return;
  181.     }
  182.        
  183.     futex_down(&fs_head_futex);
  184.     fibril_inc_sercount();
  185.  
  186.     /*
  187.      * Check for duplicit registrations.
  188.      */
  189.     if (fs_name_to_handle(fs_info->vfs_info.name, false)) {
  190.         /*
  191.          * We already register a fs like this.
  192.          */
  193.         dprintf("FS is already registered.\n");
  194.         fibril_dec_sercount();
  195.         futex_up(&fs_head_futex);
  196.         free(fs_info);
  197.         ipc_answer_0(callid, EEXISTS);
  198.         ipc_answer_0(rid, EEXISTS);
  199.         return;
  200.     }
  201.  
  202.     /*
  203.      * Add fs_info to the list of registered FS's.
  204.      */
  205.     dprintf("Inserting FS into the list of registered file systems.\n");
  206.     list_append(&fs_info->fs_link, &fs_head);
  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.         dprintf("Unexpected call, method = %d\n", IPC_GET_METHOD(call));
  216.         list_remove(&fs_info->fs_link);
  217.         fibril_dec_sercount();
  218.         futex_up(&fs_head_futex);
  219.         free(fs_info);
  220.         ipc_answer_0(callid, EINVAL);
  221.         ipc_answer_0(rid, EINVAL);
  222.         return;
  223.     }
  224.     fs_info->phone = IPC_GET_ARG5(call);
  225.     ipc_answer_0(callid, EOK);
  226.  
  227.     dprintf("Callback connection to FS created.\n");
  228.  
  229.     /*
  230.      * The client will want us to send him the address space area with PLB.
  231.      */
  232.  
  233.     if (!ipc_share_in_receive(&callid, &size)) {
  234.         dprintf("Unexpected call, method = %d\n", IPC_GET_METHOD(call));
  235.         list_remove(&fs_info->fs_link);
  236.         fibril_dec_sercount();
  237.         futex_up(&fs_head_futex);
  238.         ipc_hangup(fs_info->phone);
  239.         free(fs_info);
  240.         ipc_answer_0(callid, EINVAL);
  241.         ipc_answer_0(rid, EINVAL);
  242.         return;
  243.     }
  244.    
  245.     /*
  246.      * We can only send the client address space area PLB_SIZE bytes long.
  247.      */
  248.     if (size != PLB_SIZE) {
  249.         dprintf("Client suggests wrong size of PFB, size = %d\n", size);
  250.         list_remove(&fs_info->fs_link);
  251.         fibril_dec_sercount();
  252.         futex_up(&fs_head_futex);
  253.         ipc_hangup(fs_info->phone);
  254.         free(fs_info);
  255.         ipc_answer_0(callid, EINVAL);
  256.         ipc_answer_0(rid, EINVAL);
  257.         return;
  258.     }
  259.  
  260.     /*
  261.      * Commit to read-only sharing the PLB with the client.
  262.      */
  263.     (void) ipc_share_in_finalize(callid, plb,
  264.         AS_AREA_READ | AS_AREA_CACHEABLE);
  265.  
  266.     dprintf("Sharing PLB.\n");
  267.  
  268.     /*
  269.      * That was it. The FS has been registered.
  270.      * In reply to the VFS_REGISTER request, we assign the client file
  271.      * system a global file system handle.
  272.      */
  273.     fs_info->fs_handle = (fs_handle_t) atomic_postinc(&fs_handle_next);
  274.     ipc_answer_1(rid, EOK, (ipcarg_t) fs_info->fs_handle);
  275.    
  276.     fibril_dec_sercount();
  277.     futex_up(&fs_head_futex);
  278.    
  279.     dprintf("\"%.*s\" filesystem successfully registered, handle=%d.\n",
  280.         FS_NAME_MAXLEN, fs_info->vfs_info.name, fs_info->fs_handle);
  281.    
  282.     /* Process pending mount requests possibly waiting
  283.      * for this filesystem implementation.
  284.      */
  285.     vfs_process_pending_mount();
  286. }
  287.  
  288. /** For a given file system handle, implement policy for allocating a phone.
  289.  *
  290.  * @param handle    File system handle.
  291.  *
  292.  * @return      Phone over which a multi-call request can be safely
  293.  *          sent. Return 0 if no phone was found.
  294.  */
  295. int vfs_grab_phone(fs_handle_t handle)
  296. {
  297.     /*
  298.      * For now, we don't try to be very clever and very fast.
  299.      * We simply lookup the phone in the fs_head list. We currently don't
  300.      * open any additional phones (even though that itself would be pretty
  301.      * straightforward; housekeeping multiple open phones to a FS task would
  302.      * be more demanding). Instead, we simply take the respective
  303.      * phone_futex and keep it until vfs_release_phone().
  304.      */
  305.     futex_down(&fs_head_futex);
  306.     link_t *cur;
  307.     fs_info_t *fs;
  308.     for (cur = fs_head.next; cur != &fs_head; cur = cur->next) {
  309.         fs = list_get_instance(cur, fs_info_t, fs_link);
  310.         if (fs->fs_handle == handle) {
  311.             futex_up(&fs_head_futex);
  312.             /*
  313.              * For now, take the futex unconditionally.
  314.              * Oh yeah, serialization rocks.
  315.              * It will be up'ed in vfs_release_phone().
  316.              */
  317.             futex_down(&fs->phone_futex);
  318.             /*
  319.              * Avoid deadlock with other fibrils in the same thread
  320.              * by disabling fibril preemption.
  321.              */
  322.             fibril_inc_sercount();
  323.             return fs->phone;
  324.         }
  325.     }
  326.     futex_up(&fs_head_futex);
  327.     return 0;
  328. }
  329.  
  330. /** Tell VFS that the phone is in use for any request.
  331.  *
  332.  * @param phone     Phone to FS task.
  333.  */
  334. void vfs_release_phone(int phone)
  335. {
  336.     bool found = false;
  337.  
  338.     /*
  339.      * Undo the fibril_inc_sercount() done in vfs_grab_phone().
  340.      */
  341.     fibril_dec_sercount();
  342.    
  343.     futex_down(&fs_head_futex);
  344.     link_t *cur;
  345.     for (cur = fs_head.next; cur != &fs_head; cur = cur->next) {
  346.         fs_info_t *fs = list_get_instance(cur, fs_info_t, fs_link);
  347.         if (fs->phone == phone) {
  348.             found = true;
  349.             futex_up(&fs_head_futex);
  350.             futex_up(&fs->phone_futex);
  351.             return;
  352.         }
  353.     }
  354.     futex_up(&fs_head_futex);
  355.  
  356.     /*
  357.      * Not good to get here.
  358.      */
  359.     assert(found == true);
  360. }
  361.  
  362. /** Convert file system name to its handle.
  363.  *
  364.  * @param name      File system name.
  365.  * @param lock      If true, the function will down and up the
  366.  *          fs_head_futex.
  367.  *
  368.  * @return      File system handle or zero if file system not found.
  369.  */
  370. fs_handle_t fs_name_to_handle(char *name, bool lock)
  371. {
  372.     int handle = 0;
  373.    
  374.     if (lock)
  375.         futex_down(&fs_head_futex);
  376.     link_t *cur;
  377.     for (cur = fs_head.next; cur != &fs_head; cur = cur->next) {
  378.         fs_info_t *fs = list_get_instance(cur, fs_info_t, fs_link);
  379.         if (strncmp(fs->vfs_info.name, name,
  380.             sizeof(fs->vfs_info.name)) == 0) {
  381.             handle = fs->fs_handle;
  382.             break;
  383.         }
  384.     }
  385.     if (lock)
  386.         futex_up(&fs_head_futex);
  387.     return handle;
  388. }
  389.  
  390. /**
  391.  * @}
  392.  */
  393.