Subversion Repositories HelenOS

Rev

Rev 3009 | Rev 3153 | Go to most recent revision | Blame | Compare with Previous | Last modification | View Log | Download | RSS feed

  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. #include <ipc/services.h>
  54. #include <ipc/devmap.h>
  55. #include <sys/mman.h>
  56. #include <byteorder.h>
  57.  
  58. #define min(a, b)       ((a) < (b) ? (a) : (b))
  59. #define max(a, b)       ((a) > (b) ? (a) : (b))
  60.  
  61. #define DENTRIES_BUCKETS    256
  62.  
  63. #define NAMES_BUCKETS       4
  64.  
  65. #define BLOCK_SIZE          1024    // FIXME
  66. #define RD_BASE             1024    // FIXME
  67. #define RD_READ_BLOCK   (RD_BASE + 1)
  68.  
  69. /*
  70.  * For now, we don't distinguish between different dev_handles/instances. All
  71.  * requests resolve to the only instance, rooted in the following variable.
  72.  */
  73. static tmpfs_dentry_t *root;
  74.  
  75. /*
  76.  * Implementation of the libfs interface.
  77.  */
  78.  
  79. /* Forward declarations of static functions. */
  80. static void *tmpfs_match(void *, const char *);
  81. static void *tmpfs_node_get(dev_handle_t, fs_index_t);
  82. static void tmpfs_node_put(void *);
  83. static void *tmpfs_create_node(int);
  84. static bool tmpfs_link_node(void *, void *, const char *);
  85. static int tmpfs_unlink_node(void *, void *);
  86. static int tmpfs_destroy_node(void *);
  87.  
  88. /* Implementation of helper functions. */
  89. static fs_index_t tmpfs_index_get(void *nodep)
  90. {
  91.     return ((tmpfs_dentry_t *) nodep)->index;
  92. }
  93.  
  94. static size_t tmpfs_size_get(void *nodep)
  95. {
  96.     return ((tmpfs_dentry_t *) nodep)->size;
  97. }
  98.  
  99. static unsigned tmpfs_lnkcnt_get(void *nodep)
  100. {
  101.     return ((tmpfs_dentry_t *) nodep)->lnkcnt;
  102. }
  103.  
  104. static bool tmpfs_has_children(void *nodep)
  105. {
  106.     return ((tmpfs_dentry_t *) nodep)->child != NULL;
  107. }
  108.  
  109. static void *tmpfs_root_get(dev_handle_t dev_handle)
  110. {
  111.     return root;
  112. }
  113.  
  114. static char tmpfs_plb_get_char(unsigned pos)
  115. {
  116.     return tmpfs_reg.plb_ro[pos % PLB_SIZE];
  117. }
  118.  
  119. static bool tmpfs_is_directory(void *nodep)
  120. {
  121.     return ((tmpfs_dentry_t *) nodep)->type == TMPFS_DIRECTORY;
  122. }
  123.  
  124. static bool tmpfs_is_file(void *nodep)
  125. {
  126.     return ((tmpfs_dentry_t *) nodep)->type == TMPFS_FILE;
  127. }
  128.  
  129. /** libfs operations */
  130. libfs_ops_t tmpfs_libfs_ops = {
  131.     .match = tmpfs_match,
  132.     .node_get = tmpfs_node_get,
  133.     .node_put = tmpfs_node_put,
  134.     .create = tmpfs_create_node,
  135.     .destroy = tmpfs_destroy_node,
  136.     .link = tmpfs_link_node,
  137.     .unlink = tmpfs_unlink_node,
  138.     .index_get = tmpfs_index_get,
  139.     .size_get = tmpfs_size_get,
  140.     .lnkcnt_get = tmpfs_lnkcnt_get,
  141.     .has_children = tmpfs_has_children,
  142.     .root_get = tmpfs_root_get,
  143.     .plb_get_char = tmpfs_plb_get_char,
  144.     .is_directory = tmpfs_is_directory,
  145.     .is_file = tmpfs_is_file
  146. };
  147.  
  148. /** Hash table of all directory entries. */
  149. hash_table_t dentries;
  150.  
  151. struct rdentry {
  152.     uint8_t type;
  153.     uint32_t len;
  154. } __attribute__((packed));
  155.  
  156. /* Implementation of hash table interface for the dentries hash table. */
  157. static hash_index_t dentries_hash(unsigned long *key)
  158. {
  159.     return *key % DENTRIES_BUCKETS;
  160. }
  161.  
  162. static int dentries_compare(unsigned long *key, hash_count_t keys,
  163.     link_t *item)
  164. {
  165.     tmpfs_dentry_t *dentry = hash_table_get_instance(item, tmpfs_dentry_t,
  166.         dh_link);
  167.     return dentry->index == *key;
  168. }
  169.  
  170. static void dentries_remove_callback(link_t *item)
  171. {
  172. }
  173.  
  174. /** TMPFS dentries hash table operations. */
  175. hash_table_operations_t dentries_ops = {
  176.     .hash = dentries_hash,
  177.     .compare = dentries_compare,
  178.     .remove_callback = dentries_remove_callback
  179. };
  180.  
  181. fs_index_t tmpfs_next_index = 1;
  182.  
  183. typedef struct {
  184.     char *name;
  185.     tmpfs_dentry_t *parent;
  186.     link_t link;
  187. } tmpfs_name_t;
  188.  
  189. /* Implementation of hash table interface for the names hash table. */
  190. static hash_index_t names_hash(unsigned long *key)
  191. {
  192.     tmpfs_dentry_t *dentry = (tmpfs_dentry_t *) *key;
  193.     return dentry->index % NAMES_BUCKETS;
  194. }
  195.  
  196. static int names_compare(unsigned long *key, hash_count_t keys, link_t *item)
  197. {
  198.     tmpfs_dentry_t *dentry = (tmpfs_dentry_t *) *key;
  199.     tmpfs_name_t *namep = hash_table_get_instance(item, tmpfs_name_t,
  200.         link);
  201.     return dentry == namep->parent;
  202. }
  203.  
  204. static void names_remove_callback(link_t *item)
  205. {
  206.     tmpfs_name_t *namep = hash_table_get_instance(item, tmpfs_name_t,
  207.         link);
  208.     free(namep->name);
  209.     free(namep);
  210. }
  211.  
  212. /** TMPFS node names hash table operations. */
  213. static hash_table_operations_t names_ops = {
  214.     .hash = names_hash,
  215.     .compare = names_compare,
  216.     .remove_callback = names_remove_callback
  217. };
  218.  
  219. static void tmpfs_name_initialize(tmpfs_name_t *namep)
  220. {
  221.     namep->name = NULL;
  222.     namep->parent = NULL;
  223.     link_initialize(&namep->link);
  224. }
  225.  
  226. static bool tmpfs_dentry_initialize(tmpfs_dentry_t *dentry)
  227. {
  228.     dentry->index = 0;
  229.     dentry->sibling = NULL;
  230.     dentry->child = NULL;
  231.     dentry->type = TMPFS_NONE;
  232.     dentry->lnkcnt = 0;
  233.     dentry->size = 0;
  234.     dentry->data = NULL;
  235.     link_initialize(&dentry->dh_link);
  236.     return (bool)hash_table_create(&dentry->names, NAMES_BUCKETS, 1,
  237.         &names_ops);
  238. }
  239.  
  240. static bool tmpfs_init(void)
  241. {
  242.     if (!hash_table_create(&dentries, DENTRIES_BUCKETS, 1, &dentries_ops))
  243.         return false;
  244.     root = (tmpfs_dentry_t *) tmpfs_create_node(L_DIRECTORY);
  245.     if (!root) {
  246.         hash_table_destroy(&dentries);
  247.         return false;
  248.     }
  249.     root->lnkcnt = 1;
  250.     return true;
  251. }
  252.  
  253. static bool tmpfs_blockread(int phone, void *buffer, size_t *bufpos, size_t *buflen, size_t *pos, void *dst, size_t size)
  254. {
  255.     size_t offset = 0;
  256.     size_t left = size;
  257.    
  258.     while (left > 0) {
  259.         size_t rd;
  260.        
  261.         if (*bufpos + left < *buflen)
  262.             rd = left;
  263.         else
  264.             rd = *buflen - *bufpos;
  265.        
  266.         if (rd > 0) {
  267.             memcpy(dst + offset, buffer + *bufpos, rd);
  268.             offset += rd;
  269.             *bufpos += rd;
  270.             *pos += rd;
  271.             left -= rd;
  272.         }
  273.        
  274.         if (*bufpos == *buflen) {
  275.             int retval;
  276.             int rc = ipc_call_sync_2_1(phone, RD_READ_BLOCK, *pos / BLOCK_SIZE, BLOCK_SIZE, (sysarg_t *) &retval);
  277.             if ((rc != EOK) || (retval != EOK))
  278.                 return false;
  279.            
  280.             *bufpos = 0;
  281.             *buflen = BLOCK_SIZE;
  282.         }
  283.     }
  284.    
  285.     return true;
  286. }
  287.  
  288. static bool tmpfs_restore_recursion(int phone, void *block, size_t *bufpos, size_t *buflen, size_t *pos, tmpfs_dentry_t *parent)
  289. {
  290.     struct rdentry entry;
  291.    
  292.     do {
  293.         char *fname;
  294.         tmpfs_dentry_t *node;
  295.         uint32_t size;
  296.        
  297.         if (!tmpfs_blockread(phone, block, bufpos, buflen, pos, &entry, sizeof(entry)))
  298.             return false;
  299.        
  300.         entry.len = uint32_t_le2host(entry.len);
  301.        
  302.         switch (entry.type) {
  303.         case 0:
  304.             break;
  305.         case 1:
  306.             fname = malloc(entry.len + 1);
  307.             if (fname == NULL)
  308.                 return false;
  309.            
  310.             node = (tmpfs_dentry_t *) tmpfs_create_node(L_FILE);
  311.             if (node == NULL) {
  312.                 free(fname);
  313.                 return false;
  314.             }
  315.            
  316.             if (!tmpfs_blockread(phone, block, bufpos, buflen, pos, fname, entry.len)) {
  317.                 tmpfs_destroy_node((void *) node);
  318.                 free(fname);
  319.                 return false;
  320.             }
  321.             fname[entry.len] = 0;
  322.            
  323.             if (!tmpfs_link_node((void *) parent, (void *) node, fname)) {
  324.                 tmpfs_destroy_node((void *) node);
  325.                 free(fname);
  326.                 return false;
  327.             }
  328.             free(fname);
  329.            
  330.             if (!tmpfs_blockread(phone, block, bufpos, buflen, pos, &size, sizeof(size)))
  331.                 return false;
  332.            
  333.             size = uint32_t_le2host(size);
  334.            
  335.             node->data = malloc(size);
  336.             if (node->data == NULL)
  337.                 return false;
  338.            
  339.             node->size = size;
  340.             if (!tmpfs_blockread(phone, block, bufpos, buflen, pos, node->data, size))
  341.                 return false;
  342.            
  343.             break;
  344.         case 2:
  345.             fname = malloc(entry.len + 1);
  346.             if (fname == NULL)
  347.                 return false;
  348.            
  349.             node = (tmpfs_dentry_t *) tmpfs_create_node(L_DIRECTORY);
  350.             if (node == NULL) {
  351.                 free(fname);
  352.                 return false;
  353.             }
  354.            
  355.             if (!tmpfs_blockread(phone, block, bufpos, buflen, pos, fname, entry.len)) {
  356.                 tmpfs_destroy_node((void *) node);
  357.                 free(fname);
  358.                 return false;
  359.             }
  360.             fname[entry.len] = 0;
  361.            
  362.             if (!tmpfs_link_node((void *) parent, (void *) node, fname)) {
  363.                 tmpfs_destroy_node((void *) node);
  364.                 free(fname);
  365.                 return false;
  366.             }
  367.             free(fname);
  368.            
  369.             if (!tmpfs_restore_recursion(phone, block, bufpos, buflen, pos, node))
  370.                 return false;
  371.            
  372.             break;
  373.         default:
  374.             return false;
  375.         }
  376.     } while (entry.type != 0);
  377.    
  378.     return true;
  379. }
  380.  
  381. static bool tmpfs_restore(dev_handle_t dev)
  382. {
  383.     void *block = mmap(NULL, BLOCK_SIZE,
  384.         PROTO_READ | PROTO_WRITE, MAP_ANONYMOUS | MAP_PRIVATE, 0, 0);
  385.    
  386.     if (block == NULL)
  387.         return false;
  388.    
  389.     int phone = ipc_connect_me_to(PHONE_NS, SERVICE_DEVMAP, DEVMAP_CONNECT_TO_DEVICE, dev);
  390.  
  391.     if (phone < 0) {
  392.         munmap(block, BLOCK_SIZE);
  393.         return false;
  394.     }
  395.    
  396.     if (ipc_share_out_start(phone, block, AS_AREA_READ | AS_AREA_WRITE) != EOK)
  397.         goto error;
  398.    
  399.     size_t bufpos = 0;
  400.     size_t buflen = 0;
  401.     size_t pos = 0;
  402.    
  403.     char tag[6];
  404.     if (!tmpfs_blockread(phone, block, &bufpos, &buflen, &pos, tag, 5))
  405.         goto error;
  406.    
  407.     tag[5] = 0;
  408.     if (strcmp(tag, "TMPFS") != 0)
  409.         goto error;
  410.    
  411.     if (!tmpfs_restore_recursion(phone, block, &bufpos, &buflen, &pos, root))
  412.         goto error;
  413.        
  414.     ipc_hangup(phone);
  415.     munmap(block, BLOCK_SIZE);
  416.     return true;
  417.    
  418. error:
  419.     ipc_hangup(phone);
  420.     munmap(block, BLOCK_SIZE);
  421.     return false;
  422. }
  423.  
  424. /** Compare one component of path to a directory entry.
  425.  *
  426.  * @param parentp   Pointer to node from which we descended.
  427.  * @param childp    Pointer to node to compare the path component with.
  428.  * @param component Array of characters holding component name.
  429.  *
  430.  * @return      True on match, false otherwise.
  431.  */
  432. static bool
  433. tmpfs_match_one(tmpfs_dentry_t *parentp, tmpfs_dentry_t *childp,
  434.     const char *component)
  435. {
  436.     unsigned long key = (unsigned long) parentp;
  437.     link_t *hlp = hash_table_find(&childp->names, &key);
  438.     assert(hlp);
  439.     tmpfs_name_t *namep = hash_table_get_instance(hlp, tmpfs_name_t, link);
  440.     return !strcmp(namep->name, component);
  441. }
  442.  
  443. void *tmpfs_match(void *prnt, const char *component)
  444. {
  445.     tmpfs_dentry_t *parentp = (tmpfs_dentry_t *) prnt;
  446.     tmpfs_dentry_t *childp = parentp->child;
  447.  
  448.     while (childp && !tmpfs_match_one(parentp, childp, component))
  449.         childp = childp->sibling;
  450.  
  451.     return (void *) childp;
  452. }
  453.  
  454. void *
  455. tmpfs_node_get(dev_handle_t dev_handle, fs_index_t index)
  456. {
  457.     unsigned long key = index;
  458.     link_t *lnk = hash_table_find(&dentries, &key);
  459.     if (!lnk)
  460.         return NULL;
  461.     return hash_table_get_instance(lnk, tmpfs_dentry_t, dh_link);
  462. }
  463.  
  464. void tmpfs_node_put(void *node)
  465. {
  466.     /* nothing to do */
  467. }
  468.  
  469. void *tmpfs_create_node(int lflag)
  470. {
  471.     assert((lflag & L_FILE) ^ (lflag & L_DIRECTORY));
  472.  
  473.     tmpfs_dentry_t *node = malloc(sizeof(tmpfs_dentry_t));
  474.     if (!node)
  475.         return NULL;
  476.  
  477.     if (!tmpfs_dentry_initialize(node)) {
  478.         free(node);
  479.         return NULL;
  480.     }
  481.     node->index = tmpfs_next_index++;
  482.     if (lflag & L_DIRECTORY)
  483.         node->type = TMPFS_DIRECTORY;
  484.     else
  485.         node->type = TMPFS_FILE;
  486.  
  487.     /* Insert the new node into the dentry hash table. */
  488.     unsigned long key = node->index;
  489.     hash_table_insert(&dentries, &key, &node->dh_link);
  490.     return (void *) node;
  491. }
  492.  
  493. bool tmpfs_link_node(void *prnt, void *chld, const char *nm)
  494. {
  495.     tmpfs_dentry_t *parentp = (tmpfs_dentry_t *) prnt;
  496.     tmpfs_dentry_t *childp = (tmpfs_dentry_t *) chld;
  497.  
  498.     assert(parentp->type == TMPFS_DIRECTORY);
  499.  
  500.     tmpfs_name_t *namep = malloc(sizeof(tmpfs_name_t));
  501.     if (!namep)
  502.         return false;
  503.     tmpfs_name_initialize(namep);
  504.     size_t len = strlen(nm);
  505.     namep->name = malloc(len + 1);
  506.     if (!namep->name) {
  507.         free(namep);
  508.         return false;
  509.     }
  510.     strcpy(namep->name, nm);
  511.     namep->parent = parentp;
  512.    
  513.     childp->lnkcnt++;
  514.  
  515.     unsigned long key = (unsigned long) parentp;
  516.     hash_table_insert(&childp->names, &key, &namep->link);
  517.  
  518.     /* Insert the new node into the namespace. */
  519.     if (parentp->child) {
  520.         tmpfs_dentry_t *tmp = parentp->child;
  521.         while (tmp->sibling)
  522.             tmp = tmp->sibling;
  523.         tmp->sibling = childp;
  524.     } else {
  525.         parentp->child = childp;
  526.     }
  527.  
  528.     return true;
  529. }
  530.  
  531. int tmpfs_unlink_node(void *prnt, void *chld)
  532. {
  533.     tmpfs_dentry_t *parentp = (tmpfs_dentry_t *)prnt;
  534.     tmpfs_dentry_t *childp = (tmpfs_dentry_t *)chld;
  535.  
  536.     if (!parentp)
  537.         return EBUSY;
  538.  
  539.     if (childp->child)
  540.         return ENOTEMPTY;
  541.  
  542.     if (parentp->child == childp) {
  543.         parentp->child = childp->sibling;
  544.     } else {
  545.         /* TODO: consider doubly linked list for organizing siblings. */
  546.         tmpfs_dentry_t *tmp = parentp->child;
  547.         while (tmp->sibling != childp)
  548.             tmp = tmp->sibling;
  549.         tmp->sibling = childp->sibling;
  550.     }
  551.     childp->sibling = NULL;
  552.  
  553.     unsigned long key = (unsigned long) parentp;
  554.     hash_table_remove(&childp->names, &key, 1);
  555.  
  556.     childp->lnkcnt--;
  557.  
  558.     return EOK;
  559. }
  560.  
  561. int tmpfs_destroy_node(void *nodep)
  562. {
  563.     tmpfs_dentry_t *dentry = (tmpfs_dentry_t *) nodep;
  564.    
  565.     assert(!dentry->lnkcnt);
  566.     assert(!dentry->child);
  567.     assert(!dentry->sibling);
  568.  
  569.     unsigned long key = dentry->index;
  570.     hash_table_remove(&dentries, &key, 1);
  571.  
  572.     hash_table_destroy(&dentry->names);
  573.  
  574.     if (dentry->type == TMPFS_FILE)
  575.         free(dentry->data);
  576.     free(dentry);
  577.     return EOK;
  578. }
  579.  
  580. void tmpfs_mount(ipc_callid_t rid, ipc_call_t *request)
  581. {
  582.     dev_handle_t mr_dev_handle = (dev_handle_t) IPC_GET_ARG1(*request);
  583.     fs_index_t mr_index = (fs_index_t) IPC_GET_ARG2(*request);
  584.     fs_handle_t mp_fs_handle = (fs_handle_t) IPC_GET_ARG3(*request);
  585.     dev_handle_t mp_dev_handle = (dev_handle_t) IPC_GET_ARG4(*request);
  586.     fs_index_t mp_index = (fs_index_t) IPC_GET_ARG5(*request);
  587.    
  588.     if ((mr_index == root->index) &&
  589.         (mp_fs_handle == tmpfs_reg.fs_handle) &&
  590.         (mp_index == mr_index)) {
  591.        
  592.         if (mr_dev_handle >= 0) {
  593.             if (tmpfs_restore(mr_dev_handle))
  594.                 ipc_answer_0(rid, EOK);
  595.             else
  596.                 ipc_answer_0(rid, ELIMIT);
  597.         } else
  598.             ipc_answer_0(rid, EOK);
  599.     } else
  600.         ipc_answer_0(rid, ENOTSUP);
  601. }
  602.  
  603. void tmpfs_lookup(ipc_callid_t rid, ipc_call_t *request)
  604. {
  605.     /* Initialize TMPFS. */
  606.     if (!root && !tmpfs_init()) {
  607.         ipc_answer_0(rid, ENOMEM);
  608.         return;
  609.     }
  610.     libfs_lookup(&tmpfs_libfs_ops, tmpfs_reg.fs_handle, rid, request);
  611. }
  612.  
  613. void tmpfs_read(ipc_callid_t rid, ipc_call_t *request)
  614. {
  615.     dev_handle_t dev_handle = (dev_handle_t)IPC_GET_ARG1(*request);
  616.     fs_index_t index = (fs_index_t)IPC_GET_ARG2(*request);
  617.     off_t pos = (off_t)IPC_GET_ARG3(*request);
  618.  
  619.     /*
  620.      * Lookup the respective dentry.
  621.      */
  622.     link_t *hlp;
  623.     unsigned long key = index;
  624.     hlp = hash_table_find(&dentries, &key);
  625.     if (!hlp) {
  626.         ipc_answer_0(rid, ENOENT);
  627.         return;
  628.     }
  629.     tmpfs_dentry_t *dentry = hash_table_get_instance(hlp, tmpfs_dentry_t,
  630.         dh_link);
  631.  
  632.     /*
  633.      * Receive the read request.
  634.      */
  635.     ipc_callid_t callid;
  636.     size_t len;
  637.     if (!ipc_data_read_receive(&callid, &len)) {
  638.         ipc_answer_0(callid, EINVAL);  
  639.         ipc_answer_0(rid, EINVAL);
  640.         return;
  641.     }
  642.  
  643.     size_t bytes;
  644.     if (dentry->type == TMPFS_FILE) {
  645.         bytes = max(0, min(dentry->size - pos, len));
  646.         (void) ipc_data_read_finalize(callid, dentry->data + pos,
  647.             bytes);
  648.     } else {
  649.         int i;
  650.         tmpfs_dentry_t *cur;
  651.        
  652.         assert(dentry->type == TMPFS_DIRECTORY);
  653.        
  654.         /*
  655.          * Yes, we really use O(n) algorithm here.
  656.          * If it bothers someone, it could be fixed by introducing a
  657.          * hash table.
  658.          */
  659.         for (i = 0, cur = dentry->child; i < pos && cur; i++,
  660.             cur = cur->sibling)
  661.             ;
  662.  
  663.         if (!cur) {
  664.             ipc_answer_0(callid, ENOENT);
  665.             ipc_answer_1(rid, ENOENT, 0);
  666.             return;
  667.         }
  668.  
  669.         unsigned long key = (unsigned long) dentry;
  670.         link_t *hlp = hash_table_find(&cur->names, &key);
  671.         assert(hlp);
  672.         tmpfs_name_t *namep = hash_table_get_instance(hlp, tmpfs_name_t,
  673.             link);
  674.  
  675.         (void) ipc_data_read_finalize(callid, namep->name,
  676.             strlen(namep->name) + 1);
  677.         bytes = 1;
  678.     }
  679.  
  680.     /*
  681.      * Answer the VFS_READ call.
  682.      */
  683.     ipc_answer_1(rid, EOK, bytes);
  684. }
  685.  
  686. void tmpfs_write(ipc_callid_t rid, ipc_call_t *request)
  687. {
  688.     dev_handle_t dev_handle = (dev_handle_t)IPC_GET_ARG1(*request);
  689.     fs_index_t index = (fs_index_t)IPC_GET_ARG2(*request);
  690.     off_t pos = (off_t)IPC_GET_ARG3(*request);
  691.  
  692.     /*
  693.      * Lookup the respective dentry.
  694.      */
  695.     link_t *hlp;
  696.     unsigned long key = index;
  697.     hlp = hash_table_find(&dentries, &key);
  698.     if (!hlp) {
  699.         ipc_answer_0(rid, ENOENT);
  700.         return;
  701.     }
  702.     tmpfs_dentry_t *dentry = hash_table_get_instance(hlp, tmpfs_dentry_t,
  703.         dh_link);
  704.  
  705.     /*
  706.      * Receive the write request.
  707.      */
  708.     ipc_callid_t callid;
  709.     size_t len;
  710.     if (!ipc_data_write_receive(&callid, &len)) {
  711.         ipc_answer_0(callid, EINVAL);  
  712.         ipc_answer_0(rid, EINVAL);
  713.         return;
  714.     }
  715.  
  716.     /*
  717.      * Check whether the file needs to grow.
  718.      */
  719.     if (pos + len <= dentry->size) {
  720.         /* The file size is not changing. */
  721.         (void) ipc_data_write_finalize(callid, dentry->data + pos, len);
  722.         ipc_answer_2(rid, EOK, len, dentry->size);
  723.         return;
  724.     }
  725.     size_t delta = (pos + len) - dentry->size;
  726.     /*
  727.      * At this point, we are deliberately extremely straightforward and
  728.      * simply realloc the contents of the file on every write that grows the
  729.      * file. In the end, the situation might not be as bad as it may look:
  730.      * our heap allocator can save us and just grow the block whenever
  731.      * possible.
  732.      */
  733.     void *newdata = realloc(dentry->data, dentry->size + delta);
  734.     if (!newdata) {
  735.         ipc_answer_0(callid, ENOMEM);
  736.         ipc_answer_2(rid, EOK, 0, dentry->size);
  737.         return;
  738.     }
  739.     /* Clear any newly allocated memory in order to emulate gaps. */
  740.     memset(newdata + dentry->size, 0, delta);
  741.     dentry->size += delta;
  742.     dentry->data = newdata;
  743.     (void) ipc_data_write_finalize(callid, dentry->data + pos, len);
  744.     ipc_answer_2(rid, EOK, len, dentry->size);
  745. }
  746.  
  747. void tmpfs_truncate(ipc_callid_t rid, ipc_call_t *request)
  748. {
  749.     dev_handle_t dev_handle = (dev_handle_t)IPC_GET_ARG1(*request);
  750.     fs_index_t index = (fs_index_t)IPC_GET_ARG2(*request);
  751.     size_t size = (off_t)IPC_GET_ARG3(*request);
  752.  
  753.     /*
  754.      * Lookup the respective dentry.
  755.      */
  756.     link_t *hlp;
  757.     unsigned long key = index;
  758.     hlp = hash_table_find(&dentries, &key);
  759.     if (!hlp) {
  760.         ipc_answer_0(rid, ENOENT);
  761.         return;
  762.     }
  763.     tmpfs_dentry_t *dentry = hash_table_get_instance(hlp, tmpfs_dentry_t,
  764.         dh_link);
  765.  
  766.     if (size == dentry->size) {
  767.         ipc_answer_0(rid, EOK);
  768.         return;
  769.     }
  770.  
  771.     void *newdata = realloc(dentry->data, size);
  772.     if (!newdata) {
  773.         ipc_answer_0(rid, ENOMEM);
  774.         return;
  775.     }
  776.     if (size > dentry->size) {
  777.         size_t delta = size - dentry->size;
  778.         memset(newdata + dentry->size, 0, delta);
  779.     }
  780.     dentry->size = size;
  781.     dentry->data = newdata;
  782.     ipc_answer_0(rid, EOK);
  783. }
  784.  
  785. void tmpfs_destroy(ipc_callid_t rid, ipc_call_t *request)
  786. {
  787.     dev_handle_t dev_handle = (dev_handle_t)IPC_GET_ARG1(*request);
  788.     fs_index_t index = (fs_index_t)IPC_GET_ARG2(*request);
  789.     int rc;
  790.  
  791.     link_t *hlp;
  792.     unsigned long key = index;
  793.     hlp = hash_table_find(&dentries, &key);
  794.     if (!hlp) {
  795.         ipc_answer_0(rid, ENOENT);
  796.         return;
  797.     }
  798.     tmpfs_dentry_t *dentry = hash_table_get_instance(hlp, tmpfs_dentry_t,
  799.         dh_link);
  800.     rc = tmpfs_destroy_node(dentry);
  801.     ipc_answer_0(rid, rc);
  802. }
  803.  
  804. /**
  805.  * @}
  806.  */
  807.