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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    tmpfs_ops.c
  35.  * @brief   Implementation of VFS operations for the TMPFS file system
  36.  *      server.
  37.  */
  38.  
  39. #include "tmpfs.h"
  40. #include "../../vfs/vfs.h"
  41. #include <ipc/ipc.h>
  42. #include <async.h>
  43. #include <errno.h>
  44. #include <atomic.h>
  45. #include <stdlib.h>
  46. #include <string.h>
  47. #include <stdio.h>
  48. #include <assert.h>
  49. #include <sys/types.h>
  50. #include <libadt/hash_table.h>
  51. #include <as.h>
  52. #include <libfs.h>
  53.  
  54. #define min(a, b)       ((a) < (b) ? (a) : (b))
  55. #define max(a, b)       ((a) > (b) ? (a) : (b))
  56.  
  57. #define DENTRIES_BUCKETS    256
  58.  
  59. #define NAMES_BUCKETS       4
  60.  
  61. /** All root nodes have index 0. */
  62. #define TMPFS_SOME_ROOT     0
  63. /** Global counter for assigning node indices. Shared by all instances. */
  64. fs_index_t tmpfs_next_index = 1;
  65.  
  66. /*
  67.  * Implementation of the libfs interface.
  68.  */
  69.  
  70. /* Forward declarations of static functions. */
  71. static void *tmpfs_match(void *, const char *);
  72. static void *tmpfs_node_get(dev_handle_t, fs_index_t);
  73. static void tmpfs_node_put(void *);
  74. static void *tmpfs_create_node(dev_handle_t, int);
  75. static int tmpfs_link_node(void *, void *, const char *);
  76. static int tmpfs_unlink_node(void *, void *);
  77. static int tmpfs_destroy_node(void *);
  78.  
  79. /* Implementation of helper functions. */
  80. static fs_index_t tmpfs_index_get(void *nodep)
  81. {
  82.     return ((tmpfs_dentry_t *) nodep)->index;
  83. }
  84.  
  85. static size_t tmpfs_size_get(void *nodep)
  86. {
  87.     return ((tmpfs_dentry_t *) nodep)->size;
  88. }
  89.  
  90. static unsigned tmpfs_lnkcnt_get(void *nodep)
  91. {
  92.     return ((tmpfs_dentry_t *) nodep)->lnkcnt;
  93. }
  94.  
  95. static bool tmpfs_has_children(void *nodep)
  96. {
  97.     return ((tmpfs_dentry_t *) nodep)->child != NULL;
  98. }
  99.  
  100. static void *tmpfs_root_get(dev_handle_t dev_handle)
  101. {
  102.     return tmpfs_node_get(dev_handle, TMPFS_SOME_ROOT);
  103. }
  104.  
  105. static char tmpfs_plb_get_char(unsigned pos)
  106. {
  107.     return tmpfs_reg.plb_ro[pos % PLB_SIZE];
  108. }
  109.  
  110. static bool tmpfs_is_directory(void *nodep)
  111. {
  112.     return ((tmpfs_dentry_t *) nodep)->type == TMPFS_DIRECTORY;
  113. }
  114.  
  115. static bool tmpfs_is_file(void *nodep)
  116. {
  117.     return ((tmpfs_dentry_t *) nodep)->type == TMPFS_FILE;
  118. }
  119.  
  120. /** libfs operations */
  121. libfs_ops_t tmpfs_libfs_ops = {
  122.     .match = tmpfs_match,
  123.     .node_get = tmpfs_node_get,
  124.     .node_put = tmpfs_node_put,
  125.     .create = tmpfs_create_node,
  126.     .destroy = tmpfs_destroy_node,
  127.     .link = tmpfs_link_node,
  128.     .unlink = tmpfs_unlink_node,
  129.     .index_get = tmpfs_index_get,
  130.     .size_get = tmpfs_size_get,
  131.     .lnkcnt_get = tmpfs_lnkcnt_get,
  132.     .has_children = tmpfs_has_children,
  133.     .root_get = tmpfs_root_get,
  134.     .plb_get_char = tmpfs_plb_get_char,
  135.     .is_directory = tmpfs_is_directory,
  136.     .is_file = tmpfs_is_file
  137. };
  138.  
  139. /** Hash table of all directory entries. */
  140. hash_table_t dentries;
  141.  
  142. #define DENTRIES_KEY_INDEX  0
  143. #define DENTRIES_KEY_DEV    1
  144.  
  145. /* Implementation of hash table interface for the dentries hash table. */
  146. static hash_index_t dentries_hash(unsigned long key[])
  147. {
  148.     return key[DENTRIES_KEY_INDEX] % DENTRIES_BUCKETS;
  149. }
  150.  
  151. static int dentries_compare(unsigned long key[], hash_count_t keys,
  152.     link_t *item)
  153. {
  154.     tmpfs_dentry_t *dentry = hash_table_get_instance(item, tmpfs_dentry_t,
  155.         dh_link);
  156.     return (dentry->index == key[DENTRIES_KEY_INDEX] &&
  157.         dentry->dev_handle == key[DENTRIES_KEY_DEV]);
  158. }
  159.  
  160. static void dentries_remove_callback(link_t *item)
  161. {
  162. }
  163.  
  164. /** TMPFS dentries hash table operations. */
  165. hash_table_operations_t dentries_ops = {
  166.     .hash = dentries_hash,
  167.     .compare = dentries_compare,
  168.     .remove_callback = dentries_remove_callback
  169. };
  170.  
  171. typedef struct {
  172.     char *name;
  173.     tmpfs_dentry_t *parent;
  174.     link_t link;
  175. } tmpfs_name_t;
  176.  
  177. /* Implementation of hash table interface for the names hash table. */
  178. static hash_index_t names_hash(unsigned long *key)
  179. {
  180.     tmpfs_dentry_t *dentry = (tmpfs_dentry_t *) *key;
  181.     return dentry->index % NAMES_BUCKETS;
  182. }
  183.  
  184. static int names_compare(unsigned long *key, hash_count_t keys, link_t *item)
  185. {
  186.     tmpfs_dentry_t *dentry = (tmpfs_dentry_t *) *key;
  187.     tmpfs_name_t *namep = hash_table_get_instance(item, tmpfs_name_t,
  188.         link);
  189.     return dentry == namep->parent;
  190. }
  191.  
  192. static void names_remove_callback(link_t *item)
  193. {
  194.     tmpfs_name_t *namep = hash_table_get_instance(item, tmpfs_name_t,
  195.         link);
  196.     free(namep->name);
  197.     free(namep);
  198. }
  199.  
  200. /** TMPFS node names hash table operations. */
  201. static hash_table_operations_t names_ops = {
  202.     .hash = names_hash,
  203.     .compare = names_compare,
  204.     .remove_callback = names_remove_callback
  205. };
  206.  
  207. static void tmpfs_name_initialize(tmpfs_name_t *namep)
  208. {
  209.     namep->name = NULL;
  210.     namep->parent = NULL;
  211.     link_initialize(&namep->link);
  212. }
  213.  
  214. static bool tmpfs_dentry_initialize(tmpfs_dentry_t *dentry)
  215. {
  216.     dentry->index = 0;
  217.     dentry->dev_handle = 0;
  218.     dentry->sibling = NULL;
  219.     dentry->child = NULL;
  220.     dentry->type = TMPFS_NONE;
  221.     dentry->lnkcnt = 0;
  222.     dentry->size = 0;
  223.     dentry->data = NULL;
  224.     link_initialize(&dentry->dh_link);
  225.     return (bool)hash_table_create(&dentry->names, NAMES_BUCKETS, 1,
  226.         &names_ops);
  227. }
  228.  
  229. bool tmpfs_init(void)
  230. {
  231.     if (!hash_table_create(&dentries, DENTRIES_BUCKETS, 2, &dentries_ops))
  232.         return false;
  233.    
  234.     return true;
  235. }
  236.  
  237. static bool tmpfs_instance_init(dev_handle_t dev_handle)
  238. {
  239.     tmpfs_dentry_t *root;
  240.    
  241.     root = (tmpfs_dentry_t *) tmpfs_create_node(dev_handle, L_DIRECTORY);
  242.     if (!root)
  243.         return false;
  244.     root->lnkcnt = 0;   /* FS root is not linked */
  245.     return true;
  246. }
  247.  
  248. /** Compare one component of path to a directory entry.
  249.  *
  250.  * @param parentp   Pointer to node from which we descended.
  251.  * @param childp    Pointer to node to compare the path component with.
  252.  * @param component Array of characters holding component name.
  253.  *
  254.  * @return      True on match, false otherwise.
  255.  */
  256. static bool
  257. tmpfs_match_one(tmpfs_dentry_t *parentp, tmpfs_dentry_t *childp,
  258.     const char *component)
  259. {
  260.     unsigned long key = (unsigned long) parentp;
  261.     link_t *hlp = hash_table_find(&childp->names, &key);
  262.     assert(hlp);
  263.     tmpfs_name_t *namep = hash_table_get_instance(hlp, tmpfs_name_t, link);
  264.     return !str_cmp(namep->name, component);
  265. }
  266.  
  267. void *tmpfs_match(void *prnt, const char *component)
  268. {
  269.     tmpfs_dentry_t *parentp = (tmpfs_dentry_t *) prnt;
  270.     tmpfs_dentry_t *childp = parentp->child;
  271.  
  272.     while (childp && !tmpfs_match_one(parentp, childp, component))
  273.         childp = childp->sibling;
  274.  
  275.     return (void *) childp;
  276. }
  277.  
  278. void *
  279. tmpfs_node_get(dev_handle_t dev_handle, fs_index_t index)
  280. {
  281.     unsigned long key[] = {
  282.         [DENTRIES_KEY_INDEX] = index,
  283.         [DENTRIES_KEY_DEV] = dev_handle
  284.     };
  285.     link_t *lnk = hash_table_find(&dentries, key);
  286.     if (!lnk)
  287.         return NULL;
  288.     return hash_table_get_instance(lnk, tmpfs_dentry_t, dh_link);
  289. }
  290.  
  291. void tmpfs_node_put(void *node)
  292. {
  293.     /* nothing to do */
  294. }
  295.  
  296. void *tmpfs_create_node(dev_handle_t dev_handle, int lflag)
  297. {
  298.     assert((lflag & L_FILE) ^ (lflag & L_DIRECTORY));
  299.  
  300.     tmpfs_dentry_t *node = malloc(sizeof(tmpfs_dentry_t));
  301.     if (!node)
  302.         return NULL;
  303.  
  304.     if (!tmpfs_dentry_initialize(node)) {
  305.         free(node);
  306.         return NULL;
  307.     }
  308.     if (!tmpfs_root_get(dev_handle))
  309.         node->index = TMPFS_SOME_ROOT;
  310.     else
  311.         node->index = tmpfs_next_index++;
  312.     node->dev_handle = dev_handle;
  313.     if (lflag & L_DIRECTORY)
  314.         node->type = TMPFS_DIRECTORY;
  315.     else
  316.         node->type = TMPFS_FILE;
  317.  
  318.     /* Insert the new node into the dentry hash table. */
  319.     unsigned long key[] = {
  320.         [DENTRIES_KEY_INDEX] = node->index,
  321.         [DENTRIES_KEY_DEV] = node->dev_handle
  322.     };
  323.     hash_table_insert(&dentries, key, &node->dh_link);
  324.     return (void *) node;
  325. }
  326.  
  327. int tmpfs_link_node(void *prnt, void *chld, const char *nm)
  328. {
  329.     tmpfs_dentry_t *parentp = (tmpfs_dentry_t *) prnt;
  330.     tmpfs_dentry_t *childp = (tmpfs_dentry_t *) chld;
  331.  
  332.     assert(parentp->type == TMPFS_DIRECTORY);
  333.  
  334.     tmpfs_name_t *namep = malloc(sizeof(tmpfs_name_t));
  335.     if (!namep)
  336.         return ENOMEM;
  337.     tmpfs_name_initialize(namep);
  338.     size_t size = str_size(nm);
  339.     namep->name = malloc(size + 1);
  340.     if (!namep->name) {
  341.         free(namep);
  342.         return ENOMEM;
  343.     }
  344.     str_cpy(namep->name, size + 1, nm);
  345.     namep->parent = parentp;
  346.    
  347.     childp->lnkcnt++;
  348.  
  349.     unsigned long key = (unsigned long) parentp;
  350.     hash_table_insert(&childp->names, &key, &namep->link);
  351.  
  352.     /* Insert the new node into the namespace. */
  353.     if (parentp->child) {
  354.         tmpfs_dentry_t *tmp = parentp->child;
  355.         while (tmp->sibling)
  356.             tmp = tmp->sibling;
  357.         tmp->sibling = childp;
  358.     } else {
  359.         parentp->child = childp;
  360.     }
  361.  
  362.     return EOK;
  363. }
  364.  
  365. int tmpfs_unlink_node(void *prnt, void *chld)
  366. {
  367.     tmpfs_dentry_t *parentp = (tmpfs_dentry_t *)prnt;
  368.     tmpfs_dentry_t *childp = (tmpfs_dentry_t *)chld;
  369.  
  370.     if (!parentp)
  371.         return EBUSY;
  372.  
  373.     if (childp->child)
  374.         return ENOTEMPTY;
  375.  
  376.     if (parentp->child == childp) {
  377.         parentp->child = childp->sibling;
  378.     } else {
  379.         /* TODO: consider doubly linked list for organizing siblings. */
  380.         tmpfs_dentry_t *tmp = parentp->child;
  381.         while (tmp->sibling != childp)
  382.             tmp = tmp->sibling;
  383.         tmp->sibling = childp->sibling;
  384.     }
  385.     childp->sibling = NULL;
  386.  
  387.     unsigned long key = (unsigned long) parentp;
  388.     hash_table_remove(&childp->names, &key, 1);
  389.  
  390.     childp->lnkcnt--;
  391.  
  392.     return EOK;
  393. }
  394.  
  395. int tmpfs_destroy_node(void *nodep)
  396. {
  397.     tmpfs_dentry_t *dentry = (tmpfs_dentry_t *) nodep;
  398.    
  399.     assert(!dentry->lnkcnt);
  400.     assert(!dentry->child);
  401.     assert(!dentry->sibling);
  402.  
  403.     unsigned long key[] = {
  404.         [DENTRIES_KEY_INDEX] = dentry->index,
  405.         [DENTRIES_KEY_DEV] = dentry->dev_handle
  406.     };
  407.     hash_table_remove(&dentries, key, 2);
  408.  
  409.     hash_table_destroy(&dentry->names);
  410.  
  411.     if (dentry->type == TMPFS_FILE)
  412.         free(dentry->data);
  413.     free(dentry);
  414.     return EOK;
  415. }
  416.  
  417. void tmpfs_mounted(ipc_callid_t rid, ipc_call_t *request)
  418. {
  419.     dev_handle_t dev_handle = (dev_handle_t) IPC_GET_ARG1(*request);
  420.  
  421.     /* accept the mount options */
  422.     ipc_callid_t callid;
  423.     size_t size;
  424.     if (!ipc_data_write_receive(&callid, &size)) {
  425.         ipc_answer_0(callid, EINVAL);
  426.         ipc_answer_0(rid, EINVAL);
  427.         return;
  428.     }
  429.     char *opts = malloc(size + 1);
  430.     if (!opts) {
  431.         ipc_answer_0(callid, ENOMEM);
  432.         ipc_answer_0(rid, ENOMEM);
  433.         return;
  434.     }
  435.     ipcarg_t retval = ipc_data_write_finalize(callid, opts, size);
  436.     if (retval != EOK) {
  437.         ipc_answer_0(rid, retval);
  438.         free(opts);
  439.         return;
  440.     }
  441.     opts[size] = '\0';
  442.  
  443.     /* Initialize TMPFS instance. */
  444.     if (!tmpfs_instance_init(dev_handle)) {
  445.         ipc_answer_0(rid, ENOMEM);
  446.         return;
  447.     }
  448.  
  449.     tmpfs_dentry_t *root = tmpfs_root_get(dev_handle);
  450.     if (str_cmp(opts, "restore") == 0) {
  451.         if (tmpfs_restore(dev_handle))
  452.             ipc_answer_3(rid, EOK, root->index, root->size,
  453.                 root->lnkcnt);
  454.         else
  455.             ipc_answer_0(rid, ELIMIT);
  456.     } else {
  457.         ipc_answer_3(rid, EOK, root->index, root->size, root->lnkcnt);
  458.     }
  459. }
  460.  
  461. void tmpfs_mount(ipc_callid_t rid, ipc_call_t *request)
  462. {
  463.     dev_handle_t mp_dev_handle = (dev_handle_t) IPC_GET_ARG1(*request);
  464.     fs_index_t mp_index = (fs_index_t) IPC_GET_ARG2(*request);
  465.     fs_handle_t mr_fs_handle = (fs_handle_t) IPC_GET_ARG3(*request);
  466.     dev_handle_t mr_dev_handle = (dev_handle_t) IPC_GET_ARG4(*request);
  467.    
  468.     ipc_answer_0(rid, ENOTSUP);
  469. }
  470.  
  471. void tmpfs_lookup(ipc_callid_t rid, ipc_call_t *request)
  472. {
  473.     libfs_lookup(&tmpfs_libfs_ops, tmpfs_reg.fs_handle, rid, request);
  474. }
  475.  
  476. void tmpfs_read(ipc_callid_t rid, ipc_call_t *request)
  477. {
  478.     dev_handle_t dev_handle = (dev_handle_t)IPC_GET_ARG1(*request);
  479.     fs_index_t index = (fs_index_t)IPC_GET_ARG2(*request);
  480.     off_t pos = (off_t)IPC_GET_ARG3(*request);
  481.  
  482.     /*
  483.      * Lookup the respective dentry.
  484.      */
  485.     link_t *hlp;
  486.     unsigned long key[] = {
  487.         [DENTRIES_KEY_INDEX] = index,
  488.         [DENTRIES_KEY_DEV] = dev_handle,
  489.     };
  490.     hlp = hash_table_find(&dentries, key);
  491.     if (!hlp) {
  492.         ipc_answer_0(rid, ENOENT);
  493.         return;
  494.     }
  495.     tmpfs_dentry_t *dentry = hash_table_get_instance(hlp, tmpfs_dentry_t,
  496.         dh_link);
  497.  
  498.     /*
  499.      * Receive the read request.
  500.      */
  501.     ipc_callid_t callid;
  502.     size_t size;
  503.     if (!ipc_data_read_receive(&callid, &size)) {
  504.         ipc_answer_0(callid, EINVAL);  
  505.         ipc_answer_0(rid, EINVAL);
  506.         return;
  507.     }
  508.  
  509.     size_t bytes;
  510.     if (dentry->type == TMPFS_FILE) {
  511.         bytes = max(0, min(dentry->size - pos, size));
  512.         (void) ipc_data_read_finalize(callid, dentry->data + pos,
  513.             bytes);
  514.     } else {
  515.         int i;
  516.         tmpfs_dentry_t *cur;
  517.        
  518.         assert(dentry->type == TMPFS_DIRECTORY);
  519.        
  520.         /*
  521.          * Yes, we really use O(n) algorithm here.
  522.          * If it bothers someone, it could be fixed by introducing a
  523.          * hash table.
  524.          */
  525.         for (i = 0, cur = dentry->child; i < pos && cur; i++,
  526.             cur = cur->sibling)
  527.             ;
  528.  
  529.         if (!cur) {
  530.             ipc_answer_0(callid, ENOENT);
  531.             ipc_answer_1(rid, ENOENT, 0);
  532.             return;
  533.         }
  534.  
  535.         unsigned long key = (unsigned long) dentry;
  536.         link_t *hlp = hash_table_find(&cur->names, &key);
  537.         assert(hlp);
  538.         tmpfs_name_t *namep = hash_table_get_instance(hlp, tmpfs_name_t,
  539.             link);
  540.  
  541.         (void) ipc_data_read_finalize(callid, namep->name,
  542.             str_size(namep->name) + 1);
  543.         bytes = 1;
  544.     }
  545.  
  546.     /*
  547.      * Answer the VFS_READ call.
  548.      */
  549.     ipc_answer_1(rid, EOK, bytes);
  550. }
  551.  
  552. void tmpfs_write(ipc_callid_t rid, ipc_call_t *request)
  553. {
  554.     dev_handle_t dev_handle = (dev_handle_t)IPC_GET_ARG1(*request);
  555.     fs_index_t index = (fs_index_t)IPC_GET_ARG2(*request);
  556.     off_t pos = (off_t)IPC_GET_ARG3(*request);
  557.  
  558.     /*
  559.      * Lookup the respective dentry.
  560.      */
  561.     link_t *hlp;
  562.     unsigned long key[] = {
  563.         [DENTRIES_KEY_INDEX] = index,
  564.         [DENTRIES_KEY_DEV] = dev_handle
  565.     };
  566.     hlp = hash_table_find(&dentries, key);
  567.     if (!hlp) {
  568.         ipc_answer_0(rid, ENOENT);
  569.         return;
  570.     }
  571.     tmpfs_dentry_t *dentry = hash_table_get_instance(hlp, tmpfs_dentry_t,
  572.         dh_link);
  573.  
  574.     /*
  575.      * Receive the write request.
  576.      */
  577.     ipc_callid_t callid;
  578.     size_t size;
  579.     if (!ipc_data_write_receive(&callid, &size)) {
  580.         ipc_answer_0(callid, EINVAL);  
  581.         ipc_answer_0(rid, EINVAL);
  582.         return;
  583.     }
  584.  
  585.     /*
  586.      * Check whether the file needs to grow.
  587.      */
  588.     if (pos + size <= dentry->size) {
  589.         /* The file size is not changing. */
  590.         (void) ipc_data_write_finalize(callid, dentry->data + pos, size);
  591.         ipc_answer_2(rid, EOK, size, dentry->size);
  592.         return;
  593.     }
  594.     size_t delta = (pos + size) - dentry->size;
  595.     /*
  596.      * At this point, we are deliberately extremely straightforward and
  597.      * simply realloc the contents of the file on every write that grows the
  598.      * file. In the end, the situation might not be as bad as it may look:
  599.      * our heap allocator can save us and just grow the block whenever
  600.      * possible.
  601.      */
  602.     void *newdata = realloc(dentry->data, dentry->size + delta);
  603.     if (!newdata) {
  604.         ipc_answer_0(callid, ENOMEM);
  605.         ipc_answer_2(rid, EOK, 0, dentry->size);
  606.         return;
  607.     }
  608.     /* Clear any newly allocated memory in order to emulate gaps. */
  609.     memset(newdata + dentry->size, 0, delta);
  610.     dentry->size += delta;
  611.     dentry->data = newdata;
  612.     (void) ipc_data_write_finalize(callid, dentry->data + pos, size);
  613.     ipc_answer_2(rid, EOK, size, dentry->size);
  614. }
  615.  
  616. void tmpfs_truncate(ipc_callid_t rid, ipc_call_t *request)
  617. {
  618.     dev_handle_t dev_handle = (dev_handle_t)IPC_GET_ARG1(*request);
  619.     fs_index_t index = (fs_index_t)IPC_GET_ARG2(*request);
  620.     size_t size = (off_t)IPC_GET_ARG3(*request);
  621.  
  622.     /*
  623.      * Lookup the respective dentry.
  624.      */
  625.     link_t *hlp;
  626.     unsigned long key[] = {
  627.         [DENTRIES_KEY_INDEX] = index,
  628.         [DENTRIES_KEY_DEV] = dev_handle
  629.     };
  630.     hlp = hash_table_find(&dentries, key);
  631.     if (!hlp) {
  632.         ipc_answer_0(rid, ENOENT);
  633.         return;
  634.     }
  635.     tmpfs_dentry_t *dentry = hash_table_get_instance(hlp, tmpfs_dentry_t,
  636.         dh_link);
  637.  
  638.     if (size == dentry->size) {
  639.         ipc_answer_0(rid, EOK);
  640.         return;
  641.     }
  642.  
  643.     void *newdata = realloc(dentry->data, size);
  644.     if (!newdata) {
  645.         ipc_answer_0(rid, ENOMEM);
  646.         return;
  647.     }
  648.     if (size > dentry->size) {
  649.         size_t delta = size - dentry->size;
  650.         memset(newdata + dentry->size, 0, delta);
  651.     }
  652.     dentry->size = size;
  653.     dentry->data = newdata;
  654.     ipc_answer_0(rid, EOK);
  655. }
  656.  
  657. void tmpfs_destroy(ipc_callid_t rid, ipc_call_t *request)
  658. {
  659.     dev_handle_t dev_handle = (dev_handle_t)IPC_GET_ARG1(*request);
  660.     fs_index_t index = (fs_index_t)IPC_GET_ARG2(*request);
  661.     int rc;
  662.  
  663.     link_t *hlp;
  664.     unsigned long key[] = {
  665.         [DENTRIES_KEY_INDEX] = index,
  666.         [DENTRIES_KEY_DEV] = dev_handle
  667.     };
  668.     hlp = hash_table_find(&dentries, key);
  669.     if (!hlp) {
  670.         ipc_answer_0(rid, ENOENT);
  671.         return;
  672.     }
  673.     tmpfs_dentry_t *dentry = hash_table_get_instance(hlp, tmpfs_dentry_t,
  674.         dh_link);
  675.     rc = tmpfs_destroy_node(dentry);
  676.     ipc_answer_0(rid, rc);
  677. }
  678.  
  679. /**
  680.  * @}
  681.  */
  682.