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