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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_ops.c
  35.  * @brief Operations that VFS offers to its clients.
  36.  */
  37.  
  38. #include "vfs.h"
  39. #include <ipc/ipc.h>
  40. #include <async.h>
  41. #include <errno.h>
  42. #include <stdio.h>
  43. #include <stdlib.h>
  44. #include <string.h>
  45. #include <bool.h>
  46. #include <futex.h>
  47. #include <rwlock.h>
  48. #include <libadt/list.h>
  49. #include <unistd.h>
  50. #include <ctype.h>
  51. #include <fcntl.h>
  52. #include <assert.h>
  53. #include <vfs/canonify.h>
  54.  
  55. /* Forward declarations of static functions. */
  56. static int vfs_truncate_internal(fs_handle_t, dev_handle_t, fs_index_t, size_t);
  57.  
  58. /** Pending mount structure. */
  59. typedef struct {
  60.     link_t link;
  61.     char *fs_name;            /**< File system name */
  62.     char *mp;                 /**< Mount point */
  63.     ipc_callid_t callid;      /**< Call ID waiting for the mount */
  64.     ipc_callid_t rid;         /**< Request ID */
  65.     dev_handle_t dev_handle;  /**< Device handle */
  66. } pending_req_t;
  67.  
  68. LIST_INITIALIZE(pending_req);
  69.  
  70. /**
  71.  * This rwlock prevents the race between a triplet-to-VFS-node resolution and a
  72.  * concurrent VFS operation which modifies the file system namespace.
  73.  */
  74. RWLOCK_INITIALIZE(namespace_rwlock);
  75.  
  76. futex_t rootfs_futex = FUTEX_INITIALIZER;
  77. vfs_pair_t rootfs = {
  78.     .fs_handle = 0,
  79.     .dev_handle = 0
  80. };
  81.  
  82. static void vfs_mount_internal(ipc_callid_t rid, dev_handle_t dev_handle,
  83.     fs_handle_t fs_handle, char *mp)
  84. {
  85.     /* Resolve the path to the mountpoint. */
  86.     vfs_lookup_res_t mp_res;
  87.     vfs_node_t *mp_node = NULL;
  88.     int rc;
  89.     int phone;
  90.     futex_down(&rootfs_futex);
  91.     if (rootfs.fs_handle) {
  92.         /* We already have the root FS. */
  93.         rwlock_write_lock(&namespace_rwlock);
  94.         if ((strlen(mp) == 1) && (mp[0] == '/')) {
  95.             /* Trying to mount root FS over root FS */
  96.             rwlock_write_unlock(&namespace_rwlock);
  97.             futex_up(&rootfs_futex);
  98.             ipc_answer_0(rid, EBUSY);
  99.             return;
  100.         }
  101.        
  102.         rc = vfs_lookup_internal(mp, L_DIRECTORY, &mp_res, NULL);
  103.         if (rc != EOK) {
  104.             /* The lookup failed for some reason. */
  105.             rwlock_write_unlock(&namespace_rwlock);
  106.             futex_up(&rootfs_futex);
  107.             ipc_answer_0(rid, rc);
  108.             return;
  109.         }
  110.        
  111.         mp_node = vfs_node_get(&mp_res);
  112.         if (!mp_node) {
  113.             rwlock_write_unlock(&namespace_rwlock);
  114.             futex_up(&rootfs_futex);
  115.             ipc_answer_0(rid, ENOMEM);
  116.             return;
  117.         }
  118.        
  119.         /*
  120.          * Now we hold a reference to mp_node.
  121.          * It will be dropped upon the corresponding VFS_UNMOUNT.
  122.          * This prevents the mount point from being deleted.
  123.          */
  124.         rwlock_write_unlock(&namespace_rwlock);
  125.     } else {
  126.         /* We still don't have the root file system mounted. */
  127.         if ((strlen(mp) == 1) && (mp[0] == '/')) {
  128.             vfs_lookup_res_t mr_res;
  129.             vfs_node_t *mr_node;
  130.             ipcarg_t rindex;
  131.             ipcarg_t rsize;
  132.             ipcarg_t rlnkcnt;
  133.            
  134.             /*
  135.              * For this simple, but important case,
  136.              * we are almost done.
  137.              */
  138.            
  139.             /* Tell the mountee that it is being mounted. */
  140.             phone = vfs_grab_phone(fs_handle);
  141.             rc = async_req_1_3(phone, VFS_MOUNTED,
  142.                 (ipcarg_t) dev_handle, &rindex, &rsize, &rlnkcnt);
  143.             vfs_release_phone(phone);
  144.            
  145.             if (rc != EOK) {
  146.                 futex_up(&rootfs_futex);
  147.                 ipc_answer_0(rid, rc);
  148.                 return;
  149.             }
  150.            
  151.             mr_res.triplet.fs_handle = fs_handle;
  152.             mr_res.triplet.dev_handle = dev_handle;
  153.             mr_res.triplet.index = (fs_index_t) rindex;
  154.             mr_res.size = (size_t) rsize;
  155.             mr_res.lnkcnt = (unsigned) rlnkcnt;
  156.             mr_res.type = VFS_NODE_DIRECTORY;
  157.            
  158.             rootfs.fs_handle = fs_handle;
  159.             rootfs.dev_handle = dev_handle;
  160.             futex_up(&rootfs_futex);
  161.            
  162.             /* Add reference to the mounted root. */
  163.             mr_node = vfs_node_get(&mr_res);
  164.             assert(mr_node);
  165.            
  166.             ipc_answer_0(rid, rc);
  167.             return;
  168.         } else {
  169.             /*
  170.              * We can't resolve this without the root filesystem
  171.              * being mounted first.
  172.              */
  173.             futex_up(&rootfs_futex);
  174.             ipc_answer_0(rid, ENOENT);
  175.             return;
  176.         }
  177.     }
  178.     futex_up(&rootfs_futex);
  179.    
  180.     /*
  181.      * At this point, we have all necessary pieces: file system and device
  182.      * handles, and we know the mount point VFS node.
  183.      */
  184.    
  185.     phone = vfs_grab_phone(mp_res.triplet.fs_handle);
  186.     rc = async_req_4_0(phone, VFS_MOUNT,
  187.         (ipcarg_t) mp_res.triplet.dev_handle,
  188.         (ipcarg_t) mp_res.triplet.index,
  189.         (ipcarg_t) fs_handle,
  190.         (ipcarg_t) dev_handle);
  191.     vfs_release_phone(phone);
  192.    
  193.     if (rc != EOK) {
  194.         /* Mount failed, drop reference to mp_node. */
  195.         if (mp_node)
  196.             vfs_node_put(mp_node);
  197.     }
  198.    
  199.     ipc_answer_0(rid, rc);
  200. }
  201.  
  202. /** Process pending mount requests */
  203. void vfs_process_pending_mount()
  204. {
  205.     link_t *cur;
  206.    
  207. loop:
  208.     for (cur = pending_req.next; cur != &pending_req; cur = cur->next) {
  209.         pending_req_t *pr = list_get_instance(cur, pending_req_t, link);
  210.        
  211.         fs_handle_t fs_handle = fs_name_to_handle(pr->fs_name, true);
  212.         if (!fs_handle)
  213.             continue;
  214.        
  215.         /* Acknowledge that we know fs_name. */
  216.         ipc_answer_0(pr->callid, EOK);
  217.        
  218.         /* Do the mount */
  219.         vfs_mount_internal(pr->rid, pr->dev_handle, fs_handle, pr->mp);
  220.        
  221.         free(pr->fs_name);
  222.         free(pr->mp);
  223.         list_remove(cur);
  224.         free(pr);
  225.         goto loop;
  226.     }
  227. }
  228.  
  229. void vfs_mount(ipc_callid_t rid, ipc_call_t *request)
  230. {
  231.     /*
  232.      * We expect the library to do the device-name to device-handle
  233.      * translation for us, thus the device handle will arrive as ARG1
  234.      * in the request.
  235.      */
  236.     dev_handle_t dev_handle = (dev_handle_t) IPC_GET_ARG1(*request);
  237.    
  238.     /*
  239.      * Mount flags are passed as ARG2.
  240.      */
  241.     unsigned int flags = (unsigned int) IPC_GET_ARG2(*request);
  242.    
  243.     /*
  244.      * For now, don't make use of ARG3, but it can be used to
  245.      * carry mount options in the future.
  246.      */
  247.    
  248.     /* We want the client to send us the mount point. */
  249.     ipc_callid_t callid;
  250.     size_t size;
  251.     if (!ipc_data_write_receive(&callid, &size)) {
  252.         ipc_answer_0(callid, EINVAL);
  253.         ipc_answer_0(rid, EINVAL);
  254.         return;
  255.     }
  256.    
  257.     /* Check whether size is reasonable wrt. the mount point. */
  258.     if ((size < 1) || (size > MAX_PATH_LEN)) {
  259.         ipc_answer_0(callid, EINVAL);
  260.         ipc_answer_0(rid, EINVAL);
  261.         return;
  262.     }
  263.    
  264.     /* Allocate buffer for the mount point data being received. */
  265.     char *mp = malloc(size + 1);
  266.     if (!mp) {
  267.         ipc_answer_0(callid, ENOMEM);
  268.         ipc_answer_0(rid, ENOMEM);
  269.         return;
  270.     }
  271.    
  272.     /* Deliver the mount point. */
  273.     ipcarg_t retval = ipc_data_write_finalize(callid, mp, size);
  274.     if (retval != EOK) {
  275.         ipc_answer_0(rid, EREFUSED);
  276.         free(mp);
  277.         return;
  278.     }
  279.     mp[size] = '\0';
  280.    
  281.     /*
  282.      * Now, we expect the client to send us data with the name of the file
  283.      * system.
  284.      */
  285.     if (!ipc_data_write_receive(&callid, &size)) {
  286.         ipc_answer_0(callid, EINVAL);
  287.         ipc_answer_0(rid, EINVAL);
  288.         free(mp);
  289.         return;
  290.     }
  291.    
  292.     /*
  293.      * Don't receive more than is necessary for storing a full file system
  294.      * name.
  295.      */
  296.     if ((size < 1) || (size > FS_NAME_MAXLEN)) {
  297.         ipc_answer_0(callid, EINVAL);
  298.         ipc_answer_0(rid, EINVAL);
  299.         free(mp);
  300.         return;
  301.     }
  302.    
  303.     /*
  304.      * Allocate buffer for file system name.
  305.      */
  306.     char *fs_name = (char *) malloc(size + 1);
  307.     if (fs_name == NULL) {
  308.         ipc_answer_0(callid, ENOMEM);
  309.         ipc_answer_0(rid, EREFUSED);
  310.         free(mp);
  311.         return;
  312.     }
  313.    
  314.     /* Deliver the file system name. */
  315.     retval = ipc_data_write_finalize(callid, fs_name, size);
  316.     if (retval != EOK) {
  317.         ipc_answer_0(rid, EREFUSED);
  318.         free(mp);
  319.         free(fs_name);
  320.         return;
  321.     }
  322.     fs_name[size] = '\0';
  323.    
  324.     /*
  325.      * Check if we know a file system with the same name as is in fs_name.
  326.      * This will also give us its file system handle.
  327.      */
  328.     fs_handle_t fs_handle = fs_name_to_handle(fs_name, true);
  329.     if (!fs_handle) {
  330.         if (flags & IPC_FLAG_BLOCKING) {
  331.             /* Blocking mount, add to pending list */
  332.             pending_req_t *pr = (pending_req_t *) malloc(sizeof(pending_req_t));
  333.             if (!pr) {
  334.                 ipc_answer_0(callid, ENOMEM);
  335.                 ipc_answer_0(rid, ENOMEM);
  336.                 free(mp);
  337.                 free(fs_name);
  338.                 return;
  339.             }
  340.            
  341.             pr->fs_name = fs_name;
  342.             pr->mp = mp;
  343.             pr->callid = callid;
  344.             pr->rid = rid;
  345.             pr->dev_handle = dev_handle;
  346.             list_append(&pr->link, &pending_req);
  347.             return;
  348.         }
  349.        
  350.         ipc_answer_0(callid, ENOENT);
  351.         ipc_answer_0(rid, ENOENT);
  352.         free(mp);
  353.         free(fs_name);
  354.         return;
  355.     }
  356.    
  357.     /* Acknowledge that we know fs_name. */
  358.     ipc_answer_0(callid, EOK);
  359.    
  360.     /* Do the mount */
  361.     vfs_mount_internal(rid, dev_handle, fs_handle, mp);
  362.     free(mp);
  363.     free(fs_name);
  364. }
  365.  
  366. void vfs_open(ipc_callid_t rid, ipc_call_t *request)
  367. {
  368.     if (!vfs_files_init()) {
  369.         ipc_answer_0(rid, ENOMEM);
  370.         return;
  371.     }
  372.  
  373.     /*
  374.      * The POSIX interface is open(path, oflag, mode).
  375.      * We can receive oflags and mode along with the VFS_OPEN call; the path
  376.      * will need to arrive in another call.
  377.      *
  378.      * We also receive one private, non-POSIX set of flags called lflag
  379.      * used to pass information to vfs_lookup_internal().
  380.      */
  381.     int lflag = IPC_GET_ARG1(*request);
  382.     int oflag = IPC_GET_ARG2(*request);
  383.     int mode = IPC_GET_ARG3(*request);
  384.     size_t len;
  385.  
  386.     /*
  387.      * Make sure that we are called with exactly one of L_FILE and
  388.      * L_DIRECTORY.
  389.      */
  390.     if ((lflag & (L_FILE | L_DIRECTORY)) == 0 ||
  391.         (lflag & (L_FILE | L_DIRECTORY)) == (L_FILE | L_DIRECTORY)) {
  392.         ipc_answer_0(rid, EINVAL);
  393.         return;
  394.     }
  395.  
  396.     if (oflag & O_CREAT)
  397.         lflag |= L_CREATE;
  398.     if (oflag & O_EXCL)
  399.         lflag |= L_EXCLUSIVE;
  400.  
  401.     ipc_callid_t callid;
  402.  
  403.     if (!ipc_data_write_receive(&callid, &len)) {
  404.         ipc_answer_0(callid, EINVAL);
  405.         ipc_answer_0(rid, EINVAL);
  406.         return;
  407.     }
  408.     char *path = malloc(len + 1);
  409.     if (!path) {
  410.         ipc_answer_0(callid, ENOMEM);
  411.         ipc_answer_0(rid, ENOMEM);
  412.         return;
  413.     }
  414.     int rc;
  415.     if ((rc = ipc_data_write_finalize(callid, path, len))) {
  416.         ipc_answer_0(rid, rc);
  417.         free(path);
  418.         return;
  419.     }
  420.     path[len] = '\0';
  421.    
  422.     /*
  423.      * Avoid the race condition in which the file can be deleted before we
  424.      * find/create-and-lock the VFS node corresponding to the looked-up
  425.      * triplet.
  426.      */
  427.     if (lflag & L_CREATE)
  428.         rwlock_write_lock(&namespace_rwlock);
  429.     else
  430.         rwlock_read_lock(&namespace_rwlock);
  431.  
  432.     /* The path is now populated and we can call vfs_lookup_internal(). */
  433.     vfs_lookup_res_t lr;
  434.     rc = vfs_lookup_internal(path, lflag, &lr, NULL);
  435.     if (rc) {
  436.         if (lflag & L_CREATE)
  437.             rwlock_write_unlock(&namespace_rwlock);
  438.         else
  439.             rwlock_read_unlock(&namespace_rwlock);
  440.         ipc_answer_0(rid, rc);
  441.         free(path);
  442.         return;
  443.     }
  444.  
  445.     /* Path is no longer needed. */
  446.     free(path);
  447.  
  448.     vfs_node_t *node = vfs_node_get(&lr);
  449.     if (lflag & L_CREATE)
  450.         rwlock_write_unlock(&namespace_rwlock);
  451.     else
  452.         rwlock_read_unlock(&namespace_rwlock);
  453.  
  454.     /* Truncate the file if requested and if necessary. */
  455.     if (oflag & O_TRUNC) {
  456.         rwlock_write_lock(&node->contents_rwlock);
  457.         if (node->size) {
  458.             rc = vfs_truncate_internal(node->fs_handle,
  459.                 node->dev_handle, node->index, 0);
  460.             if (rc) {
  461.                 rwlock_write_unlock(&node->contents_rwlock);
  462.                 vfs_node_put(node);
  463.                 ipc_answer_0(rid, rc);
  464.                 return;
  465.             }
  466.             node->size = 0;
  467.         }
  468.         rwlock_write_unlock(&node->contents_rwlock);
  469.     }
  470.  
  471.     /*
  472.      * Get ourselves a file descriptor and the corresponding vfs_file_t
  473.      * structure.
  474.      */
  475.     int fd = vfs_fd_alloc();
  476.     if (fd < 0) {
  477.         vfs_node_put(node);
  478.         ipc_answer_0(rid, fd);
  479.         return;
  480.     }
  481.     vfs_file_t *file = vfs_file_get(fd);
  482.     file->node = node;
  483.     if (oflag & O_APPEND)
  484.         file->append = true;
  485.  
  486.     /*
  487.      * The following increase in reference count is for the fact that the
  488.      * file is being opened and that a file structure is pointing to it.
  489.      * It is necessary so that the file will not disappear when
  490.      * vfs_node_put() is called. The reference will be dropped by the
  491.      * respective VFS_CLOSE.
  492.      */
  493.     vfs_node_addref(node);
  494.     vfs_node_put(node);
  495.  
  496.     /* Success! Return the new file descriptor to the client. */
  497.     ipc_answer_1(rid, EOK, fd);
  498. }
  499.  
  500. void vfs_close(ipc_callid_t rid, ipc_call_t *request)
  501. {
  502.     int fd = IPC_GET_ARG1(*request);
  503.     int rc = vfs_fd_free(fd);
  504.     ipc_answer_0(rid, rc);
  505. }
  506.  
  507. static void vfs_rdwr(ipc_callid_t rid, ipc_call_t *request, bool read)
  508. {
  509.  
  510.     /*
  511.      * The following code strongly depends on the fact that the files data
  512.      * structure can be only accessed by a single fibril and all file
  513.      * operations are serialized (i.e. the reads and writes cannot
  514.      * interleave and a file cannot be closed while it is being read).
  515.      *
  516.      * Additional synchronization needs to be added once the table of
  517.      * open files supports parallel access!
  518.      */
  519.  
  520.     int fd = IPC_GET_ARG1(*request);
  521.    
  522.     /* Lookup the file structure corresponding to the file descriptor. */
  523.     vfs_file_t *file = vfs_file_get(fd);
  524.     if (!file) {
  525.         ipc_answer_0(rid, ENOENT);
  526.         return;
  527.     }
  528.    
  529.     /*
  530.      * Now we need to receive a call with client's
  531.      * IPC_M_DATA_READ/IPC_M_DATA_WRITE request.
  532.      */
  533.     ipc_callid_t callid;
  534.     int res;
  535.     if (read)
  536.         res = ipc_data_read_receive(&callid, NULL);
  537.     else
  538.         res = ipc_data_write_receive(&callid, NULL);
  539.     if (!res) {
  540.         ipc_answer_0(callid, EINVAL);
  541.         ipc_answer_0(rid, EINVAL);
  542.         return;
  543.     }
  544.    
  545.     /*
  546.      * Lock the open file structure so that no other thread can manipulate
  547.      * the same open file at a time.
  548.      */
  549.     futex_down(&file->lock);
  550.  
  551.     /*
  552.      * Lock the file's node so that no other client can read/write to it at
  553.      * the same time.
  554.      */
  555.     if (read)
  556.         rwlock_read_lock(&file->node->contents_rwlock);
  557.     else
  558.         rwlock_write_lock(&file->node->contents_rwlock);
  559.  
  560.     if (file->node->type == VFS_NODE_DIRECTORY) {
  561.         /*
  562.          * Make sure that no one is modifying the namespace
  563.          * while we are in readdir().
  564.          */
  565.         assert(read);
  566.         rwlock_read_lock(&namespace_rwlock);
  567.     }
  568.    
  569.     int fs_phone = vfs_grab_phone(file->node->fs_handle);  
  570.    
  571.     /* Make a VFS_READ/VFS_WRITE request at the destination FS server. */
  572.     aid_t msg;
  573.     ipc_call_t answer;
  574.     if (!read && file->append)
  575.         file->pos = file->node->size;
  576.     msg = async_send_3(fs_phone, IPC_GET_METHOD(*request),
  577.         file->node->dev_handle, file->node->index, file->pos, &answer);
  578.    
  579.     /*
  580.      * Forward the IPC_M_DATA_READ/IPC_M_DATA_WRITE request to the
  581.      * destination FS server. The call will be routed as if sent by
  582.      * ourselves. Note that call arguments are immutable in this case so we
  583.      * don't have to bother.
  584.      */
  585.     ipc_forward_fast(callid, fs_phone, 0, 0, 0, IPC_FF_ROUTE_FROM_ME);
  586.    
  587.     vfs_release_phone(fs_phone);
  588.    
  589.     /* Wait for reply from the FS server. */
  590.     ipcarg_t rc;
  591.     async_wait_for(msg, &rc);
  592.     size_t bytes = IPC_GET_ARG1(answer);
  593.  
  594.     if (file->node->type == VFS_NODE_DIRECTORY)
  595.         rwlock_read_unlock(&namespace_rwlock);
  596.    
  597.     /* Unlock the VFS node. */
  598.     if (read)
  599.         rwlock_read_unlock(&file->node->contents_rwlock);
  600.     else {
  601.         /* Update the cached version of node's size. */
  602.         if (rc == EOK)
  603.             file->node->size = IPC_GET_ARG2(answer);
  604.         rwlock_write_unlock(&file->node->contents_rwlock);
  605.     }
  606.    
  607.     /* Update the position pointer and unlock the open file. */
  608.     if (rc == EOK)
  609.         file->pos += bytes;
  610.     futex_up(&file->lock);
  611.    
  612.     /*
  613.      * FS server's reply is the final result of the whole operation we
  614.      * return to the client.
  615.      */
  616.     ipc_answer_1(rid, rc, bytes);
  617. }
  618.  
  619. void vfs_read(ipc_callid_t rid, ipc_call_t *request)
  620. {
  621.     vfs_rdwr(rid, request, true);
  622. }
  623.  
  624. void vfs_write(ipc_callid_t rid, ipc_call_t *request)
  625. {
  626.     vfs_rdwr(rid, request, false);
  627. }
  628.  
  629. void vfs_seek(ipc_callid_t rid, ipc_call_t *request)
  630. {
  631.     int fd = (int) IPC_GET_ARG1(*request);
  632.     off_t off = (off_t) IPC_GET_ARG2(*request);
  633.     int whence = (int) IPC_GET_ARG3(*request);
  634.  
  635.  
  636.     /* Lookup the file structure corresponding to the file descriptor. */
  637.     vfs_file_t *file = vfs_file_get(fd);
  638.     if (!file) {
  639.         ipc_answer_0(rid, ENOENT);
  640.         return;
  641.     }
  642.  
  643.     off_t newpos;
  644.     futex_down(&file->lock);
  645.     if (whence == SEEK_SET) {
  646.         file->pos = off;
  647.         futex_up(&file->lock);
  648.         ipc_answer_1(rid, EOK, off);
  649.         return;
  650.     }
  651.     if (whence == SEEK_CUR) {
  652.         if (file->pos + off < file->pos) {
  653.             futex_up(&file->lock);
  654.             ipc_answer_0(rid, EOVERFLOW);
  655.             return;
  656.         }
  657.         file->pos += off;
  658.         newpos = file->pos;
  659.         futex_up(&file->lock);
  660.         ipc_answer_1(rid, EOK, newpos);
  661.         return;
  662.     }
  663.     if (whence == SEEK_END) {
  664.         rwlock_read_lock(&file->node->contents_rwlock);
  665.         size_t size = file->node->size;
  666.         rwlock_read_unlock(&file->node->contents_rwlock);
  667.         if (size + off < size) {
  668.             futex_up(&file->lock);
  669.             ipc_answer_0(rid, EOVERFLOW);
  670.             return;
  671.         }
  672.         newpos = size + off;
  673.         futex_up(&file->lock);
  674.         ipc_answer_1(rid, EOK, newpos);
  675.         return;
  676.     }
  677.     futex_up(&file->lock);
  678.     ipc_answer_0(rid, EINVAL);
  679. }
  680.  
  681. int
  682. vfs_truncate_internal(fs_handle_t fs_handle, dev_handle_t dev_handle,
  683.     fs_index_t index, size_t size)
  684. {
  685.     ipcarg_t rc;
  686.     int fs_phone;
  687.    
  688.     fs_phone = vfs_grab_phone(fs_handle);
  689.     rc = async_req_3_0(fs_phone, VFS_TRUNCATE, (ipcarg_t)dev_handle,
  690.         (ipcarg_t)index, (ipcarg_t)size);
  691.     vfs_release_phone(fs_phone);
  692.     return (int)rc;
  693. }
  694.  
  695. void vfs_truncate(ipc_callid_t rid, ipc_call_t *request)
  696. {
  697.     int fd = IPC_GET_ARG1(*request);
  698.     size_t size = IPC_GET_ARG2(*request);
  699.     int rc;
  700.  
  701.     vfs_file_t *file = vfs_file_get(fd);
  702.     if (!file) {
  703.         ipc_answer_0(rid, ENOENT);
  704.         return;
  705.     }
  706.     futex_down(&file->lock);
  707.  
  708.     rwlock_write_lock(&file->node->contents_rwlock);
  709.     rc = vfs_truncate_internal(file->node->fs_handle,
  710.         file->node->dev_handle, file->node->index, size);
  711.     if (rc == EOK)
  712.         file->node->size = size;
  713.     rwlock_write_unlock(&file->node->contents_rwlock);
  714.  
  715.     futex_up(&file->lock);
  716.     ipc_answer_0(rid, (ipcarg_t)rc);
  717. }
  718.  
  719. void vfs_mkdir(ipc_callid_t rid, ipc_call_t *request)
  720. {
  721.     int mode = IPC_GET_ARG1(*request);
  722.  
  723.     size_t len;
  724.     ipc_callid_t callid;
  725.  
  726.     if (!ipc_data_write_receive(&callid, &len)) {
  727.         ipc_answer_0(callid, EINVAL);
  728.         ipc_answer_0(rid, EINVAL);
  729.         return;
  730.     }
  731.     char *path = malloc(len + 1);
  732.     if (!path) {
  733.         ipc_answer_0(callid, ENOMEM);
  734.         ipc_answer_0(rid, ENOMEM);
  735.         return;
  736.     }
  737.     int rc;
  738.     if ((rc = ipc_data_write_finalize(callid, path, len))) {
  739.         ipc_answer_0(rid, rc);
  740.         free(path);
  741.         return;
  742.     }
  743.     path[len] = '\0';
  744.    
  745.     rwlock_write_lock(&namespace_rwlock);
  746.     int lflag = L_DIRECTORY | L_CREATE | L_EXCLUSIVE;
  747.     rc = vfs_lookup_internal(path, lflag, NULL, NULL);
  748.     rwlock_write_unlock(&namespace_rwlock);
  749.     free(path);
  750.     ipc_answer_0(rid, rc);
  751. }
  752.  
  753. void vfs_unlink(ipc_callid_t rid, ipc_call_t *request)
  754. {
  755.     int lflag = IPC_GET_ARG1(*request);
  756.  
  757.     size_t len;
  758.     ipc_callid_t callid;
  759.  
  760.     if (!ipc_data_write_receive(&callid, &len)) {
  761.         ipc_answer_0(callid, EINVAL);
  762.         ipc_answer_0(rid, EINVAL);
  763.         return;
  764.     }
  765.     char *path = malloc(len + 1);
  766.     if (!path) {
  767.         ipc_answer_0(callid, ENOMEM);
  768.         ipc_answer_0(rid, ENOMEM);
  769.         return;
  770.     }
  771.     int rc;
  772.     if ((rc = ipc_data_write_finalize(callid, path, len))) {
  773.         ipc_answer_0(rid, rc);
  774.         free(path);
  775.         return;
  776.     }
  777.     path[len] = '\0';
  778.    
  779.     rwlock_write_lock(&namespace_rwlock);
  780.     lflag &= L_DIRECTORY;   /* sanitize lflag */
  781.     vfs_lookup_res_t lr;
  782.     rc = vfs_lookup_internal(path, lflag | L_UNLINK, &lr, NULL);
  783.     free(path);
  784.     if (rc != EOK) {
  785.         rwlock_write_unlock(&namespace_rwlock);
  786.         ipc_answer_0(rid, rc);
  787.         return;
  788.     }
  789.  
  790.     /*
  791.      * The name has already been unlinked by vfs_lookup_internal().
  792.      * We have to get and put the VFS node to ensure that it is
  793.      * VFS_DESTROY'ed after the last reference to it is dropped.
  794.      */
  795.     vfs_node_t *node = vfs_node_get(&lr);
  796.     futex_down(&nodes_futex);
  797.     node->lnkcnt--;
  798.     futex_up(&nodes_futex);
  799.     rwlock_write_unlock(&namespace_rwlock);
  800.     vfs_node_put(node);
  801.     ipc_answer_0(rid, EOK);
  802. }
  803.  
  804. void vfs_rename(ipc_callid_t rid, ipc_call_t *request)
  805. {
  806.     size_t len;
  807.     ipc_callid_t callid;
  808.     int rc;
  809.  
  810.     /* Retrieve the old path. */
  811.     if (!ipc_data_write_receive(&callid, &len)) {
  812.         ipc_answer_0(callid, EINVAL);
  813.         ipc_answer_0(rid, EINVAL);
  814.         return;
  815.     }
  816.     char *old = malloc(len + 1);
  817.     if (!old) {
  818.         ipc_answer_0(callid, ENOMEM);
  819.         ipc_answer_0(rid, ENOMEM);
  820.         return;
  821.     }
  822.     if ((rc = ipc_data_write_finalize(callid, old, len))) {
  823.         ipc_answer_0(rid, rc);
  824.         free(old);
  825.         return;
  826.     }
  827.     old[len] = '\0';
  828.    
  829.     /* Retrieve the new path. */
  830.     if (!ipc_data_write_receive(&callid, &len)) {
  831.         ipc_answer_0(callid, EINVAL);
  832.         ipc_answer_0(rid, EINVAL);
  833.         free(old);
  834.         return;
  835.     }
  836.     char *new = malloc(len + 1);
  837.     if (!new) {
  838.         ipc_answer_0(callid, ENOMEM);
  839.         ipc_answer_0(rid, ENOMEM);
  840.         free(old);
  841.         return;
  842.     }
  843.     if ((rc = ipc_data_write_finalize(callid, new, len))) {
  844.         ipc_answer_0(rid, rc);
  845.         free(old);
  846.         free(new);
  847.         return;
  848.     }
  849.     new[len] = '\0';
  850.  
  851.     char *oldc = canonify(old, &len);
  852.     char *newc = canonify(new, NULL);
  853.     if (!oldc || !newc) {
  854.         ipc_answer_0(rid, EINVAL);
  855.         free(old);
  856.         free(new);
  857.         return;
  858.     }
  859.     if (!strncmp(newc, oldc, len)) {
  860.         /* oldc is a prefix of newc */
  861.         ipc_answer_0(rid, EINVAL);
  862.         free(old);
  863.         free(new);
  864.         return;
  865.     }
  866.    
  867.     vfs_lookup_res_t old_lr;
  868.     vfs_lookup_res_t new_lr;
  869.     vfs_lookup_res_t new_par_lr;
  870.     rwlock_write_lock(&namespace_rwlock);
  871.     /* Lookup the node belonging to the old file name. */
  872.     rc = vfs_lookup_internal(oldc, L_NONE, &old_lr, NULL);
  873.     if (rc != EOK) {
  874.         rwlock_write_unlock(&namespace_rwlock);
  875.         ipc_answer_0(rid, rc);
  876.         free(old);
  877.         free(new);
  878.         return;
  879.     }
  880.     vfs_node_t *old_node = vfs_node_get(&old_lr);
  881.     if (!old_node) {
  882.         rwlock_write_unlock(&namespace_rwlock);
  883.         ipc_answer_0(rid, ENOMEM);
  884.         free(old);
  885.         free(new);
  886.         return;
  887.     }
  888.     /* Lookup parent of the new file name. */
  889.     rc = vfs_lookup_internal(newc, L_PARENT, &new_par_lr, NULL);
  890.     if (rc != EOK) {
  891.         rwlock_write_unlock(&namespace_rwlock);
  892.         ipc_answer_0(rid, rc);
  893.         free(old);
  894.         free(new);
  895.         return;
  896.     }
  897.     /* Check whether linking to the same file system instance. */
  898.     if ((old_node->fs_handle != new_par_lr.triplet.fs_handle) ||
  899.         (old_node->dev_handle != new_par_lr.triplet.dev_handle)) {
  900.         rwlock_write_unlock(&namespace_rwlock);
  901.         ipc_answer_0(rid, EXDEV);   /* different file systems */
  902.         free(old);
  903.         free(new);
  904.         return;
  905.     }
  906.     /* Destroy the old link for the new name. */
  907.     vfs_node_t *new_node = NULL;
  908.     rc = vfs_lookup_internal(newc, L_UNLINK, &new_lr, NULL);
  909.     switch (rc) {
  910.     case ENOENT:
  911.         /* simply not in our way */
  912.         break;
  913.     case EOK:
  914.         new_node = vfs_node_get(&new_lr);
  915.         if (!new_node) {
  916.             rwlock_write_unlock(&namespace_rwlock);
  917.             ipc_answer_0(rid, ENOMEM);
  918.             free(old);
  919.             free(new);
  920.             return;
  921.         }
  922.         futex_down(&nodes_futex);
  923.         new_node->lnkcnt--;
  924.         futex_up(&nodes_futex);
  925.         break;
  926.     default:
  927.         rwlock_write_unlock(&namespace_rwlock);
  928.         ipc_answer_0(rid, ENOTEMPTY);
  929.         free(old);
  930.         free(new);
  931.         return;
  932.     }
  933.     /* Create the new link for the new name. */
  934.     rc = vfs_lookup_internal(newc, L_LINK, NULL, NULL, old_node->index);
  935.     if (rc != EOK) {
  936.         rwlock_write_unlock(&namespace_rwlock);
  937.         if (new_node)
  938.             vfs_node_put(new_node);
  939.         ipc_answer_0(rid, rc);
  940.         free(old);
  941.         free(new);
  942.         return;
  943.     }
  944.     futex_down(&nodes_futex);
  945.     old_node->lnkcnt++;
  946.     futex_up(&nodes_futex);
  947.     /* Destroy the link for the old name. */
  948.     rc = vfs_lookup_internal(oldc, L_UNLINK, NULL, NULL);
  949.     if (rc != EOK) {
  950.         rwlock_write_unlock(&namespace_rwlock);
  951.         vfs_node_put(old_node);
  952.         if (new_node)
  953.             vfs_node_put(new_node);
  954.         ipc_answer_0(rid, rc);
  955.         free(old);
  956.         free(new);
  957.         return;
  958.     }
  959.     futex_down(&nodes_futex);
  960.     old_node->lnkcnt--;
  961.     futex_up(&nodes_futex);
  962.     rwlock_write_unlock(&namespace_rwlock);
  963.     vfs_node_put(old_node);
  964.     if (new_node)
  965.         vfs_node_put(new_node);
  966.     free(old);
  967.     free(new);
  968.     ipc_answer_0(rid, EOK);
  969. }
  970.  
  971. /**
  972.  * @}
  973.  */
  974.