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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. /**
  59.  * This rwlock prevents the race between a triplet-to-VFS-node resolution and a
  60.  * concurrent VFS operation which modifies the file system namespace.
  61.  */
  62. RWLOCK_INITIALIZE(namespace_rwlock);
  63.  
  64. futex_t rootfs_futex = FUTEX_INITIALIZER;
  65. vfs_pair_t rootfs = {
  66.     .fs_handle = 0,
  67.     .dev_handle = 0
  68. };
  69.  
  70. void vfs_mount(ipc_callid_t rid, ipc_call_t *request)
  71. {
  72.     dev_handle_t dev_handle;
  73.     vfs_node_t *mp_node = NULL;
  74.     ipc_callid_t callid;
  75.     ipc_call_t data;
  76.     int rc;
  77.     int phone;
  78.     size_t size;
  79.  
  80.     /*
  81.      * We expect the library to do the device-name to device-handle
  82.      * translation for us, thus the device handle will arrive as ARG1
  83.      * in the request.
  84.      */
  85.     dev_handle = (dev_handle_t)IPC_GET_ARG1(*request);
  86.  
  87.     /*
  88.      * For now, don't make use of ARG2 and ARG3, but they can be used to
  89.      * carry mount options in the future.
  90.      */
  91.  
  92.     /*
  93.      * Now, we expect the client to send us data with the name of the file
  94.      * system.
  95.      */
  96.     if (!ipc_data_write_receive(&callid, &size)) {
  97.         ipc_answer_0(callid, EINVAL);
  98.         ipc_answer_0(rid, EINVAL);
  99.         return;
  100.     }
  101.  
  102.     /*
  103.      * Don't receive more than is necessary for storing a full file system
  104.      * name.
  105.      */
  106.     if (size < 1 || size > FS_NAME_MAXLEN) {
  107.         ipc_answer_0(callid, EINVAL);
  108.         ipc_answer_0(rid, EINVAL);
  109.         return;
  110.     }
  111.  
  112.     /* Deliver the file system name. */
  113.     char fs_name[FS_NAME_MAXLEN + 1];
  114.     (void) ipc_data_write_finalize(callid, fs_name, size);
  115.     fs_name[size] = '\0';
  116.    
  117.     /*
  118.      * Wait for IPC_M_PING so that we can return an error if we don't know
  119.      * fs_name.
  120.      */
  121.     callid = async_get_call(&data);
  122.     if (IPC_GET_METHOD(data) != IPC_M_PING) {
  123.         ipc_answer_0(callid, ENOTSUP);
  124.         ipc_answer_0(rid, ENOTSUP);
  125.         return;
  126.     }
  127.  
  128.     /*
  129.      * Check if we know a file system with the same name as is in fs_name.
  130.      * This will also give us its file system handle.
  131.      */
  132.     fs_handle_t fs_handle = fs_name_to_handle(fs_name, true);
  133.     if (!fs_handle) {
  134.         ipc_answer_0(callid, ENOENT);
  135.         ipc_answer_0(rid, ENOENT);
  136.         return;
  137.     }
  138.  
  139.     /* Acknowledge that we know fs_name. */
  140.     ipc_answer_0(callid, EOK);
  141.  
  142.     /* Now, we want the client to send us the mount point. */
  143.     if (!ipc_data_write_receive(&callid, &size)) {
  144.         ipc_answer_0(callid, EINVAL);
  145.         ipc_answer_0(rid, EINVAL);
  146.         return;
  147.     }
  148.  
  149.     /* Check whether size is reasonable wrt. the mount point. */
  150.     if (size < 1 || size > MAX_PATH_LEN) {
  151.         ipc_answer_0(callid, EINVAL);
  152.         ipc_answer_0(rid, EINVAL);
  153.         return;
  154.     }
  155.     /* Allocate buffer for the mount point data being received. */
  156.     uint8_t *buf;
  157.     buf = malloc(size + 1);
  158.     if (!buf) {
  159.         ipc_answer_0(callid, ENOMEM);
  160.         ipc_answer_0(rid, ENOMEM);
  161.         return;
  162.     }
  163.  
  164.     /* Deliver the mount point. */
  165.     (void) ipc_data_write_finalize(callid, buf, size);
  166.     buf[size] = '\0';
  167.  
  168.     /* Resolve the path to the mountpoint. */
  169.     vfs_lookup_res_t mp_res;
  170.     futex_down(&rootfs_futex);
  171.     if (rootfs.fs_handle) {
  172.         /* We already have the root FS. */
  173.         rwlock_write_lock(&namespace_rwlock);
  174.         if ((size == 1) && (buf[0] == '/')) {
  175.             /* Trying to mount root FS over root FS */
  176.             rwlock_write_unlock(&namespace_rwlock);
  177.             futex_up(&rootfs_futex);
  178.             free(buf);
  179.             ipc_answer_0(rid, EBUSY);
  180.             return;
  181.         }
  182.         rc = vfs_lookup_internal(buf, L_DIRECTORY, &mp_res, NULL);
  183.         if (rc != EOK) {
  184.             /* The lookup failed for some reason. */
  185.             rwlock_write_unlock(&namespace_rwlock);
  186.             futex_up(&rootfs_futex);
  187.             free(buf);
  188.             ipc_answer_0(rid, rc);
  189.             return;
  190.         }
  191.         mp_node = vfs_node_get(&mp_res);
  192.         if (!mp_node) {
  193.             rwlock_write_unlock(&namespace_rwlock);
  194.             futex_up(&rootfs_futex);
  195.             free(buf);
  196.             ipc_answer_0(rid, ENOMEM);
  197.             return;
  198.         }
  199.         /*
  200.          * Now we hold a reference to mp_node.
  201.          * It will be dropped upon the corresponding VFS_UNMOUNT.
  202.          * This prevents the mount point from being deleted.
  203.          */
  204.         rwlock_write_unlock(&namespace_rwlock);
  205.     } else {
  206.         /* We still don't have the root file system mounted. */
  207.         if ((size == 1) && (buf[0] == '/')) {
  208.             /*
  209.              * For this simple, but important case,
  210.              * we are almost done.
  211.              */
  212.             free(buf);
  213.            
  214.             /* Tell the mountee that it is being mounted. */
  215.             phone = vfs_grab_phone(fs_handle);
  216.             rc = async_req_1_0(phone, VFS_MOUNTED,
  217.                 (ipcarg_t) dev_handle);
  218.             vfs_release_phone(phone);
  219.  
  220.             if (rc == EOK) {
  221.                 rootfs.fs_handle = fs_handle;
  222.                 rootfs.dev_handle = dev_handle;
  223.             }
  224.  
  225.             futex_up(&rootfs_futex);
  226.             ipc_answer_0(rid, rc);
  227.             return;
  228.         } else {
  229.             /*
  230.              * We can't resolve this without the root filesystem
  231.              * being mounted first.
  232.              */
  233.             futex_up(&rootfs_futex);
  234.             free(buf);
  235.             ipc_answer_0(rid, ENOENT);
  236.             return;
  237.         }
  238.     }
  239.     futex_up(&rootfs_futex);
  240.    
  241.     free(buf);  /* The buffer is not needed anymore. */
  242.    
  243.     /*
  244.      * At this point, we have all necessary pieces: file system and device
  245.      * handles, and we know the mount point VFS node.
  246.      */
  247.  
  248.     phone = vfs_grab_phone(mp_res.triplet.fs_handle);
  249.     rc = async_req_4_0(phone, VFS_MOUNT,
  250.         (ipcarg_t) mp_res.triplet.dev_handle,
  251.         (ipcarg_t) mp_res.triplet.index,
  252.         (ipcarg_t) fs_handle,
  253.         (ipcarg_t) dev_handle);
  254.     vfs_release_phone(phone);
  255.  
  256.     if (rc != EOK) {
  257.         /* Mount failed, drop reference to mp_node. */
  258.         if (mp_node)
  259.             vfs_node_put(mp_node);
  260.     }
  261.    
  262.     ipc_answer_0(rid, rc);
  263. }
  264.  
  265. void vfs_open(ipc_callid_t rid, ipc_call_t *request)
  266. {
  267.     if (!vfs_files_init()) {
  268.         ipc_answer_0(rid, ENOMEM);
  269.         return;
  270.     }
  271.  
  272.     /*
  273.      * The POSIX interface is open(path, oflag, mode).
  274.      * We can receive oflags and mode along with the VFS_OPEN call; the path
  275.      * will need to arrive in another call.
  276.      *
  277.      * We also receive one private, non-POSIX set of flags called lflag
  278.      * used to pass information to vfs_lookup_internal().
  279.      */
  280.     int lflag = IPC_GET_ARG1(*request);
  281.     int oflag = IPC_GET_ARG2(*request);
  282.     int mode = IPC_GET_ARG3(*request);
  283.     size_t len;
  284.  
  285.     if (oflag & O_CREAT)
  286.         lflag |= L_CREATE;
  287.     if (oflag & O_EXCL)
  288.         lflag |= L_EXCLUSIVE;
  289.  
  290.     ipc_callid_t callid;
  291.  
  292.     if (!ipc_data_write_receive(&callid, &len)) {
  293.         ipc_answer_0(callid, EINVAL);
  294.         ipc_answer_0(rid, EINVAL);
  295.         return;
  296.     }
  297.     char *path = malloc(len + 1);
  298.     if (!path) {
  299.         ipc_answer_0(callid, ENOMEM);
  300.         ipc_answer_0(rid, ENOMEM);
  301.         return;
  302.     }
  303.     int rc;
  304.     if ((rc = ipc_data_write_finalize(callid, path, len))) {
  305.         ipc_answer_0(rid, rc);
  306.         free(path);
  307.         return;
  308.     }
  309.     path[len] = '\0';
  310.    
  311.     /*
  312.      * Avoid the race condition in which the file can be deleted before we
  313.      * find/create-and-lock the VFS node corresponding to the looked-up
  314.      * triplet.
  315.      */
  316.     if (lflag & L_CREATE)
  317.         rwlock_write_lock(&namespace_rwlock);
  318.     else
  319.         rwlock_read_lock(&namespace_rwlock);
  320.  
  321.     /* The path is now populated and we can call vfs_lookup_internal(). */
  322.     vfs_lookup_res_t lr;
  323.     rc = vfs_lookup_internal(path, lflag, &lr, NULL);
  324.     if (rc) {
  325.         if (lflag & L_CREATE)
  326.             rwlock_write_unlock(&namespace_rwlock);
  327.         else
  328.             rwlock_read_unlock(&namespace_rwlock);
  329.         ipc_answer_0(rid, rc);
  330.         free(path);
  331.         return;
  332.     }
  333.  
  334.     /* Path is no longer needed. */
  335.     free(path);
  336.  
  337.     vfs_node_t *node = vfs_node_get(&lr);
  338.     if (lflag & L_CREATE)
  339.         rwlock_write_unlock(&namespace_rwlock);
  340.     else
  341.         rwlock_read_unlock(&namespace_rwlock);
  342.  
  343.     /* Truncate the file if requested and if necessary. */
  344.     if (oflag & O_TRUNC) {
  345.         rwlock_write_lock(&node->contents_rwlock);
  346.         if (node->size) {
  347.             rc = vfs_truncate_internal(node->fs_handle,
  348.                 node->dev_handle, node->index, 0);
  349.             if (rc) {
  350.                 rwlock_write_unlock(&node->contents_rwlock);
  351.                 vfs_node_put(node);
  352.                 ipc_answer_0(rid, rc);
  353.                 return;
  354.             }
  355.             node->size = 0;
  356.         }
  357.         rwlock_write_unlock(&node->contents_rwlock);
  358.     }
  359.  
  360.     /*
  361.      * Get ourselves a file descriptor and the corresponding vfs_file_t
  362.      * structure.
  363.      */
  364.     int fd = vfs_fd_alloc();
  365.     if (fd < 0) {
  366.         vfs_node_put(node);
  367.         ipc_answer_0(rid, fd);
  368.         return;
  369.     }
  370.     vfs_file_t *file = vfs_file_get(fd);
  371.     file->node = node;
  372.     if (oflag & O_APPEND)
  373.         file->append = true;
  374.  
  375.     /*
  376.      * The following increase in reference count is for the fact that the
  377.      * file is being opened and that a file structure is pointing to it.
  378.      * It is necessary so that the file will not disappear when
  379.      * vfs_node_put() is called. The reference will be dropped by the
  380.      * respective VFS_CLOSE.
  381.      */
  382.     vfs_node_addref(node);
  383.     vfs_node_put(node);
  384.  
  385.     /* Success! Return the new file descriptor to the client. */
  386.     ipc_answer_1(rid, EOK, fd);
  387. }
  388.  
  389. void vfs_close(ipc_callid_t rid, ipc_call_t *request)
  390. {
  391.     int fd = IPC_GET_ARG1(*request);
  392.     int rc = vfs_fd_free(fd);
  393.     ipc_answer_0(rid, rc);
  394. }
  395.  
  396. static void vfs_rdwr(ipc_callid_t rid, ipc_call_t *request, bool read)
  397. {
  398.  
  399.     /*
  400.      * The following code strongly depends on the fact that the files data
  401.      * structure can be only accessed by a single fibril and all file
  402.      * operations are serialized (i.e. the reads and writes cannot
  403.      * interleave and a file cannot be closed while it is being read).
  404.      *
  405.      * Additional synchronization needs to be added once the table of
  406.      * open files supports parallel access!
  407.      */
  408.  
  409.     int fd = IPC_GET_ARG1(*request);
  410.    
  411.     /* Lookup the file structure corresponding to the file descriptor. */
  412.     vfs_file_t *file = vfs_file_get(fd);
  413.     if (!file) {
  414.         ipc_answer_0(rid, ENOENT);
  415.         return;
  416.     }
  417.    
  418.     /*
  419.      * Now we need to receive a call with client's
  420.      * IPC_M_DATA_READ/IPC_M_DATA_WRITE request.
  421.      */
  422.     ipc_callid_t callid;
  423.     int res;
  424.     if (read)
  425.         res = ipc_data_read_receive(&callid, NULL);
  426.     else
  427.         res = ipc_data_write_receive(&callid, NULL);
  428.     if (!res) {
  429.         ipc_answer_0(callid, EINVAL);
  430.         ipc_answer_0(rid, EINVAL);
  431.         return;
  432.     }
  433.    
  434.     /*
  435.      * Lock the open file structure so that no other thread can manipulate
  436.      * the same open file at a time.
  437.      */
  438.     futex_down(&file->lock);
  439.    
  440.     /*
  441.      * Lock the file's node so that no other client can read/write to it at
  442.      * the same time.
  443.      */
  444.     if (read)
  445.         rwlock_read_lock(&file->node->contents_rwlock);
  446.     else
  447.         rwlock_write_lock(&file->node->contents_rwlock);
  448.    
  449.     int fs_phone = vfs_grab_phone(file->node->fs_handle);  
  450.    
  451.     /* Make a VFS_READ/VFS_WRITE request at the destination FS server. */
  452.     aid_t msg;
  453.     ipc_call_t answer;
  454.     if (!read && file->append)
  455.         file->pos = file->node->size;
  456.     msg = async_send_3(fs_phone, IPC_GET_METHOD(*request),
  457.         file->node->dev_handle, file->node->index, file->pos, &answer);
  458.    
  459.     /*
  460.      * Forward the IPC_M_DATA_READ/IPC_M_DATA_WRITE request to the
  461.      * destination FS server. The call will be routed as if sent by
  462.      * ourselves. Note that call arguments are immutable in this case so we
  463.      * don't have to bother.
  464.      */
  465.     ipc_forward_fast(callid, fs_phone, 0, 0, 0, IPC_FF_ROUTE_FROM_ME);
  466.    
  467.     vfs_release_phone(fs_phone);
  468.    
  469.     /* Wait for reply from the FS server. */
  470.     ipcarg_t rc;
  471.     async_wait_for(msg, &rc);
  472.     size_t bytes = IPC_GET_ARG1(answer);
  473.    
  474.     /* Unlock the VFS node. */
  475.     if (read)
  476.         rwlock_read_unlock(&file->node->contents_rwlock);
  477.     else {
  478.         /* Update the cached version of node's size. */
  479.         if (rc == EOK)
  480.             file->node->size = IPC_GET_ARG2(answer);
  481.         rwlock_write_unlock(&file->node->contents_rwlock);
  482.     }
  483.    
  484.     /* Update the position pointer and unlock the open file. */
  485.     if (rc == EOK)
  486.         file->pos += bytes;
  487.     futex_up(&file->lock);
  488.    
  489.     /*
  490.      * FS server's reply is the final result of the whole operation we
  491.      * return to the client.
  492.      */
  493.     ipc_answer_1(rid, rc, bytes);
  494. }
  495.  
  496. void vfs_read(ipc_callid_t rid, ipc_call_t *request)
  497. {
  498.     vfs_rdwr(rid, request, true);
  499. }
  500.  
  501. void vfs_write(ipc_callid_t rid, ipc_call_t *request)
  502. {
  503.     vfs_rdwr(rid, request, false);
  504. }
  505.  
  506. void vfs_seek(ipc_callid_t rid, ipc_call_t *request)
  507. {
  508.     int fd = (int) IPC_GET_ARG1(*request);
  509.     off_t off = (off_t) IPC_GET_ARG2(*request);
  510.     int whence = (int) IPC_GET_ARG3(*request);
  511.  
  512.  
  513.     /* Lookup the file structure corresponding to the file descriptor. */
  514.     vfs_file_t *file = vfs_file_get(fd);
  515.     if (!file) {
  516.         ipc_answer_0(rid, ENOENT);
  517.         return;
  518.     }
  519.  
  520.     off_t newpos;
  521.     futex_down(&file->lock);
  522.     if (whence == SEEK_SET) {
  523.         file->pos = off;
  524.         futex_up(&file->lock);
  525.         ipc_answer_1(rid, EOK, off);
  526.         return;
  527.     }
  528.     if (whence == SEEK_CUR) {
  529.         if (file->pos + off < file->pos) {
  530.             futex_up(&file->lock);
  531.             ipc_answer_0(rid, EOVERFLOW);
  532.             return;
  533.         }
  534.         file->pos += off;
  535.         newpos = file->pos;
  536.         futex_up(&file->lock);
  537.         ipc_answer_1(rid, EOK, newpos);
  538.         return;
  539.     }
  540.     if (whence == SEEK_END) {
  541.         rwlock_read_lock(&file->node->contents_rwlock);
  542.         size_t size = file->node->size;
  543.         rwlock_read_unlock(&file->node->contents_rwlock);
  544.         if (size + off < size) {
  545.             futex_up(&file->lock);
  546.             ipc_answer_0(rid, EOVERFLOW);
  547.             return;
  548.         }
  549.         newpos = size + off;
  550.         futex_up(&file->lock);
  551.         ipc_answer_1(rid, EOK, newpos);
  552.         return;
  553.     }
  554.     futex_up(&file->lock);
  555.     ipc_answer_0(rid, EINVAL);
  556. }
  557.  
  558. int
  559. vfs_truncate_internal(fs_handle_t fs_handle, dev_handle_t dev_handle,
  560.     fs_index_t index, size_t size)
  561. {
  562.     ipcarg_t rc;
  563.     int fs_phone;
  564.    
  565.     fs_phone = vfs_grab_phone(fs_handle);
  566.     rc = async_req_3_0(fs_phone, VFS_TRUNCATE, (ipcarg_t)dev_handle,
  567.         (ipcarg_t)index, (ipcarg_t)size);
  568.     vfs_release_phone(fs_phone);
  569.     return (int)rc;
  570. }
  571.  
  572. void vfs_truncate(ipc_callid_t rid, ipc_call_t *request)
  573. {
  574.     int fd = IPC_GET_ARG1(*request);
  575.     size_t size = IPC_GET_ARG2(*request);
  576.     int rc;
  577.  
  578.     vfs_file_t *file = vfs_file_get(fd);
  579.     if (!file) {
  580.         ipc_answer_0(rid, ENOENT);
  581.         return;
  582.     }
  583.     futex_down(&file->lock);
  584.  
  585.     rwlock_write_lock(&file->node->contents_rwlock);
  586.     rc = vfs_truncate_internal(file->node->fs_handle,
  587.         file->node->dev_handle, file->node->index, size);
  588.     if (rc == EOK)
  589.         file->node->size = size;
  590.     rwlock_write_unlock(&file->node->contents_rwlock);
  591.  
  592.     futex_up(&file->lock);
  593.     ipc_answer_0(rid, (ipcarg_t)rc);
  594. }
  595.  
  596. void vfs_mkdir(ipc_callid_t rid, ipc_call_t *request)
  597. {
  598.     int mode = IPC_GET_ARG1(*request);
  599.  
  600.     size_t len;
  601.     ipc_callid_t callid;
  602.  
  603.     if (!ipc_data_write_receive(&callid, &len)) {
  604.         ipc_answer_0(callid, EINVAL);
  605.         ipc_answer_0(rid, EINVAL);
  606.         return;
  607.     }
  608.     char *path = malloc(len + 1);
  609.     if (!path) {
  610.         ipc_answer_0(callid, ENOMEM);
  611.         ipc_answer_0(rid, ENOMEM);
  612.         return;
  613.     }
  614.     int rc;
  615.     if ((rc = ipc_data_write_finalize(callid, path, len))) {
  616.         ipc_answer_0(rid, rc);
  617.         free(path);
  618.         return;
  619.     }
  620.     path[len] = '\0';
  621.    
  622.     rwlock_write_lock(&namespace_rwlock);
  623.     int lflag = L_DIRECTORY | L_CREATE | L_EXCLUSIVE;
  624.     rc = vfs_lookup_internal(path, lflag, NULL, NULL);
  625.     rwlock_write_unlock(&namespace_rwlock);
  626.     free(path);
  627.     ipc_answer_0(rid, rc);
  628. }
  629.  
  630. void vfs_unlink(ipc_callid_t rid, ipc_call_t *request)
  631. {
  632.     int lflag = IPC_GET_ARG1(*request);
  633.  
  634.     size_t len;
  635.     ipc_callid_t callid;
  636.  
  637.     if (!ipc_data_write_receive(&callid, &len)) {
  638.         ipc_answer_0(callid, EINVAL);
  639.         ipc_answer_0(rid, EINVAL);
  640.         return;
  641.     }
  642.     char *path = malloc(len + 1);
  643.     if (!path) {
  644.         ipc_answer_0(callid, ENOMEM);
  645.         ipc_answer_0(rid, ENOMEM);
  646.         return;
  647.     }
  648.     int rc;
  649.     if ((rc = ipc_data_write_finalize(callid, path, len))) {
  650.         ipc_answer_0(rid, rc);
  651.         free(path);
  652.         return;
  653.     }
  654.     path[len] = '\0';
  655.    
  656.     rwlock_write_lock(&namespace_rwlock);
  657.     lflag &= L_DIRECTORY;   /* sanitize lflag */
  658.     vfs_lookup_res_t lr;
  659.     rc = vfs_lookup_internal(path, lflag | L_UNLINK, &lr, NULL);
  660.     free(path);
  661.     if (rc != EOK) {
  662.         rwlock_write_unlock(&namespace_rwlock);
  663.         ipc_answer_0(rid, rc);
  664.         return;
  665.     }
  666.  
  667.     /*
  668.      * The name has already been unlinked by vfs_lookup_internal().
  669.      * We have to get and put the VFS node to ensure that it is
  670.      * VFS_DESTROY'ed after the last reference to it is dropped.
  671.      */
  672.     vfs_node_t *node = vfs_node_get(&lr);
  673.     futex_down(&nodes_futex);
  674.     node->lnkcnt--;
  675.     futex_up(&nodes_futex);
  676.     rwlock_write_unlock(&namespace_rwlock);
  677.     vfs_node_put(node);
  678.     ipc_answer_0(rid, EOK);
  679. }
  680.  
  681. void vfs_rename(ipc_callid_t rid, ipc_call_t *request)
  682. {
  683.     size_t len;
  684.     ipc_callid_t callid;
  685.     int rc;
  686.  
  687.     /* Retrieve the old path. */
  688.     if (!ipc_data_write_receive(&callid, &len)) {
  689.         ipc_answer_0(callid, EINVAL);
  690.         ipc_answer_0(rid, EINVAL);
  691.         return;
  692.     }
  693.     char *old = malloc(len + 1);
  694.     if (!old) {
  695.         ipc_answer_0(callid, ENOMEM);
  696.         ipc_answer_0(rid, ENOMEM);
  697.         return;
  698.     }
  699.     if ((rc = ipc_data_write_finalize(callid, old, len))) {
  700.         ipc_answer_0(rid, rc);
  701.         free(old);
  702.         return;
  703.     }
  704.     old[len] = '\0';
  705.    
  706.     /* Retrieve the new path. */
  707.     if (!ipc_data_write_receive(&callid, &len)) {
  708.         ipc_answer_0(callid, EINVAL);
  709.         ipc_answer_0(rid, EINVAL);
  710.         free(old);
  711.         return;
  712.     }
  713.     char *new = malloc(len + 1);
  714.     if (!new) {
  715.         ipc_answer_0(callid, ENOMEM);
  716.         ipc_answer_0(rid, ENOMEM);
  717.         free(old);
  718.         return;
  719.     }
  720.     if ((rc = ipc_data_write_finalize(callid, new, len))) {
  721.         ipc_answer_0(rid, rc);
  722.         free(old);
  723.         free(new);
  724.         return;
  725.     }
  726.     new[len] = '\0';
  727.  
  728.     char *oldc = canonify(old, &len);
  729.     char *newc = canonify(new, NULL);
  730.     if (!oldc || !newc) {
  731.         ipc_answer_0(rid, EINVAL);
  732.         free(old);
  733.         free(new);
  734.         return;
  735.     }
  736.     if (!strncmp(newc, oldc, len)) {
  737.         /* oldc is a prefix of newc */
  738.         ipc_answer_0(rid, EINVAL);
  739.         free(old);
  740.         free(new);
  741.         return;
  742.     }
  743.    
  744.     vfs_lookup_res_t old_lr;
  745.     vfs_lookup_res_t new_lr;
  746.     vfs_lookup_res_t new_par_lr;
  747.     rwlock_write_lock(&namespace_rwlock);
  748.     /* Lookup the node belonging to the old file name. */
  749.     rc = vfs_lookup_internal(oldc, L_NONE, &old_lr, NULL);
  750.     if (rc != EOK) {
  751.         rwlock_write_unlock(&namespace_rwlock);
  752.         ipc_answer_0(rid, rc);
  753.         free(old);
  754.         free(new);
  755.         return;
  756.     }
  757.     vfs_node_t *old_node = vfs_node_get(&old_lr);
  758.     if (!old_node) {
  759.         rwlock_write_unlock(&namespace_rwlock);
  760.         ipc_answer_0(rid, ENOMEM);
  761.         free(old);
  762.         free(new);
  763.         return;
  764.     }
  765.     /* Lookup parent of the new file name. */
  766.     rc = vfs_lookup_internal(newc, L_PARENT, &new_par_lr, NULL);
  767.     if (rc != EOK) {
  768.         rwlock_write_unlock(&namespace_rwlock);
  769.         ipc_answer_0(rid, rc);
  770.         free(old);
  771.         free(new);
  772.         return;
  773.     }
  774.     /* Check whether linking to the same file system instance. */
  775.     if ((old_node->fs_handle != new_par_lr.triplet.fs_handle) ||
  776.         (old_node->dev_handle != new_par_lr.triplet.dev_handle)) {
  777.         rwlock_write_unlock(&namespace_rwlock);
  778.         ipc_answer_0(rid, EXDEV);   /* different file systems */
  779.         free(old);
  780.         free(new);
  781.         return;
  782.     }
  783.     /* Destroy the old link for the new name. */
  784.     vfs_node_t *new_node = NULL;
  785.     rc = vfs_lookup_internal(newc, L_UNLINK, &new_lr, NULL);
  786.     switch (rc) {
  787.     case ENOENT:
  788.         /* simply not in our way */
  789.         break;
  790.     case EOK:
  791.         new_node = vfs_node_get(&new_lr);
  792.         if (!new_node) {
  793.             rwlock_write_unlock(&namespace_rwlock);
  794.             ipc_answer_0(rid, ENOMEM);
  795.             free(old);
  796.             free(new);
  797.             return;
  798.         }
  799.         futex_down(&nodes_futex);
  800.         new_node->lnkcnt--;
  801.         futex_up(&nodes_futex);
  802.         break;
  803.     default:
  804.         rwlock_write_unlock(&namespace_rwlock);
  805.         ipc_answer_0(rid, ENOTEMPTY);
  806.         free(old);
  807.         free(new);
  808.         return;
  809.     }
  810.     /* Create the new link for the new name. */
  811.     rc = vfs_lookup_internal(newc, L_LINK, NULL, NULL, old_node->index);
  812.     if (rc != EOK) {
  813.         rwlock_write_unlock(&namespace_rwlock);
  814.         if (new_node)
  815.             vfs_node_put(new_node);
  816.         ipc_answer_0(rid, rc);
  817.         free(old);
  818.         free(new);
  819.         return;
  820.     }
  821.     futex_down(&nodes_futex);
  822.     old_node->lnkcnt++;
  823.     futex_up(&nodes_futex);
  824.     /* Destroy the link for the old name. */
  825.     rc = vfs_lookup_internal(oldc, L_UNLINK, NULL, NULL);
  826.     if (rc != EOK) {
  827.         rwlock_write_unlock(&namespace_rwlock);
  828.         vfs_node_put(old_node);
  829.         if (new_node)
  830.             vfs_node_put(new_node);
  831.         ipc_answer_0(rid, rc);
  832.         free(old);
  833.         free(new);
  834.         return;
  835.     }
  836.     futex_down(&nodes_futex);
  837.     old_node->lnkcnt--;
  838.     futex_up(&nodes_futex);
  839.     rwlock_write_unlock(&namespace_rwlock);
  840.     vfs_node_put(old_node);
  841.     if (new_node)
  842.         vfs_node_put(new_node);
  843.     free(old);
  844.     free(new);
  845.     ipc_answer_0(rid, EOK);
  846. }
  847.  
  848. /**
  849.  * @}
  850.  */
  851.