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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 bool tmpfs_match(void *, void *, const char *);
  73. static void *tmpfs_node_get(fs_handle_t, dev_handle_t, fs_index_t);
  74. static void *tmpfs_create_node(int);
  75. static bool tmpfs_link_node(void *, void *, const char *);
  76. static int tmpfs_unlink_node(void *, void *);
  77. static void 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 void *tmpfs_child_get(void *nodep)
  96. {
  97.     return ((tmpfs_dentry_t *) nodep)->child;
  98. }
  99.  
  100. static void *tmpfs_sibling_get(void *nodep)
  101. {
  102.     return ((tmpfs_dentry_t *) nodep)->sibling;
  103. }
  104.  
  105. static void *tmpfs_root_get(void)
  106. {
  107.     return root;
  108. }
  109.  
  110. static char tmpfs_plb_get_char(unsigned pos)
  111. {
  112.     return tmpfs_reg.plb_ro[pos % PLB_SIZE];
  113. }
  114.  
  115. static bool tmpfs_is_directory(void *nodep)
  116. {
  117.     return ((tmpfs_dentry_t *) nodep)->type == TMPFS_DIRECTORY;
  118. }
  119.  
  120. static bool tmpfs_is_file(void *nodep)
  121. {
  122.     return ((tmpfs_dentry_t *) nodep)->type == TMPFS_FILE;
  123. }
  124.  
  125. /** libfs operations */
  126. libfs_ops_t tmpfs_libfs_ops = {
  127.     .match = tmpfs_match,
  128.     .node_get = tmpfs_node_get,
  129.     .create = tmpfs_create_node,
  130.     .destroy = tmpfs_destroy_node,
  131.     .link = tmpfs_link_node,
  132.     .unlink = tmpfs_unlink_node,
  133.     .index_get = tmpfs_index_get,
  134.     .size_get = tmpfs_size_get,
  135.     .lnkcnt_get = tmpfs_lnkcnt_get,
  136.     .child_get = tmpfs_child_get,
  137.     .sibling_get = tmpfs_sibling_get,
  138.     .root_get = tmpfs_root_get,
  139.     .plb_get_char = tmpfs_plb_get_char,
  140.     .is_directory = tmpfs_is_directory,
  141.     .is_file = tmpfs_is_file
  142. };
  143.  
  144. /** Hash table of all directory entries. */
  145. hash_table_t dentries;
  146.  
  147. /* Implementation of hash table interface for the dentries hash table. */
  148. static hash_index_t dentries_hash(unsigned long *key)
  149. {
  150.     return *key % DENTRIES_BUCKETS;
  151. }
  152.  
  153. static int dentries_compare(unsigned long *key, hash_count_t keys,
  154.     link_t *item)
  155. {
  156.     tmpfs_dentry_t *dentry = hash_table_get_instance(item, tmpfs_dentry_t,
  157.         dh_link);
  158.     return dentry->index == *key;
  159. }
  160.  
  161. static void dentries_remove_callback(link_t *item)
  162. {
  163. }
  164.  
  165. /** TMPFS dentries hash table operations. */
  166. hash_table_operations_t dentries_ops = {
  167.     .hash = dentries_hash,
  168.     .compare = dentries_compare,
  169.     .remove_callback = dentries_remove_callback
  170. };
  171.  
  172. fs_index_t tmpfs_next_index = 1;
  173.  
  174. typedef struct {
  175.     char *name;
  176.     tmpfs_dentry_t *parent;
  177.     link_t link;
  178. } tmpfs_name_t;
  179.  
  180. /* Implementation of hash table interface for the names hash table. */
  181. static hash_index_t names_hash(unsigned long *key)
  182. {
  183.     tmpfs_dentry_t *dentry = (tmpfs_dentry_t *) *key;
  184.     return dentry->index % NAMES_BUCKETS;
  185. }
  186.  
  187. static int names_compare(unsigned long *key, hash_count_t keys, link_t *item)
  188. {
  189.     tmpfs_dentry_t *dentry = (tmpfs_dentry_t *) *key;
  190.     tmpfs_name_t *namep = hash_table_get_instance(item, tmpfs_name_t,
  191.         link);
  192.     return dentry == namep->parent;
  193. }
  194.  
  195. static void names_remove_callback(link_t *item)
  196. {
  197.     tmpfs_name_t *namep = hash_table_get_instance(item, tmpfs_name_t,
  198.         link);
  199.     free(namep->name);
  200.     free(namep);
  201. }
  202.  
  203. /** TMPFS node names hash table operations. */
  204. static hash_table_operations_t names_ops = {
  205.     .hash = names_hash,
  206.     .compare = names_compare,
  207.     .remove_callback = names_remove_callback
  208. };
  209.  
  210. static void tmpfs_name_initialize(tmpfs_name_t *namep)
  211. {
  212.     namep->name = NULL;
  213.     namep->parent = NULL;
  214.     link_initialize(&namep->link);
  215. }
  216.  
  217. static bool tmpfs_dentry_initialize(tmpfs_dentry_t *dentry)
  218. {
  219.     dentry->index = 0;
  220.     dentry->sibling = NULL;
  221.     dentry->child = NULL;
  222.     dentry->type = TMPFS_NONE;
  223.     dentry->lnkcnt = 0;
  224.     dentry->size = 0;
  225.     dentry->data = NULL;
  226.     link_initialize(&dentry->dh_link);
  227.     return (bool)hash_table_create(&dentry->names, NAMES_BUCKETS, 1,
  228.         &names_ops);
  229. }
  230.  
  231. static bool tmpfs_init(void)
  232. {
  233.     if (!hash_table_create(&dentries, DENTRIES_BUCKETS, 1, &dentries_ops))
  234.         return false;
  235.     root = (tmpfs_dentry_t *) tmpfs_create_node(L_DIRECTORY);
  236.     if (!root) {
  237.         hash_table_destroy(&dentries);
  238.         return false;
  239.     }
  240.     root->lnkcnt = 1;
  241.     return true;
  242. }
  243.  
  244. /** Compare one component of path to a directory entry.
  245.  *
  246.  * @param prnt      Node from which we descended.
  247.  * @param chld      Node to compare the path component with.
  248.  * @param component Array of characters holding component name.
  249.  *
  250.  * @return      True on match, false otherwise.
  251.  */
  252. bool tmpfs_match(void *prnt, void *chld, const char *component)
  253. {
  254.     tmpfs_dentry_t *parentp = (tmpfs_dentry_t *) prnt;
  255.     tmpfs_dentry_t *childp = (tmpfs_dentry_t *) chld;
  256.  
  257.     unsigned long key = (unsigned long) parentp;
  258.     link_t *hlp = hash_table_find(&childp->names, &key);
  259.     assert(hlp);
  260.     tmpfs_name_t *namep = hash_table_get_instance(hlp, tmpfs_name_t, link);
  261.  
  262.     return !strcmp(namep->name, component);
  263. }
  264.  
  265. void *
  266. tmpfs_node_get(fs_handle_t fs_handle, dev_handle_t dev_handle, fs_index_t index)
  267. {
  268.     unsigned long key = index;
  269.     link_t *lnk = hash_table_find(&dentries, &key);
  270.     if (!lnk)
  271.         return NULL;
  272.     return hash_table_get_instance(lnk, tmpfs_dentry_t, dh_link);
  273. }
  274.  
  275. void *tmpfs_create_node(int lflag)
  276. {
  277.     assert((lflag & L_FILE) ^ (lflag & L_DIRECTORY));
  278.  
  279.     tmpfs_dentry_t *node = malloc(sizeof(tmpfs_dentry_t));
  280.     if (!node)
  281.         return NULL;
  282.  
  283.     if (!tmpfs_dentry_initialize(node)) {
  284.         free(node);
  285.         return NULL;
  286.     }
  287.     node->index = tmpfs_next_index++;
  288.     if (lflag & L_DIRECTORY)
  289.         node->type = TMPFS_DIRECTORY;
  290.     else
  291.         node->type = TMPFS_FILE;
  292.  
  293.     /* Insert the new node into the dentry hash table. */
  294.     unsigned long key = node->index;
  295.     hash_table_insert(&dentries, &key, &node->dh_link);
  296.     return (void *) node;
  297. }
  298.  
  299. bool tmpfs_link_node(void *prnt, void *chld, const char *nm)
  300. {
  301.     tmpfs_dentry_t *parentp = (tmpfs_dentry_t *) prnt;
  302.     tmpfs_dentry_t *childp = (tmpfs_dentry_t *) chld;
  303.  
  304.     assert(parentp->type == TMPFS_DIRECTORY);
  305.  
  306.     tmpfs_name_t *namep = malloc(sizeof(tmpfs_name_t));
  307.     if (!namep)
  308.         return false;
  309.     tmpfs_name_initialize(namep);
  310.     size_t len = strlen(nm);
  311.     namep->name = malloc(len + 1);
  312.     if (!namep->name) {
  313.         free(namep);
  314.         return false;
  315.     }
  316.     strcpy(namep->name, nm);
  317.     namep->parent = parentp;
  318.    
  319.     childp->lnkcnt++;
  320.  
  321.     unsigned long key = (unsigned long) parentp;
  322.     hash_table_insert(&childp->names, &key, &namep->link);
  323.  
  324.     /* Insert the new node into the namespace. */
  325.     if (parentp->child) {
  326.         tmpfs_dentry_t *tmp = parentp->child;
  327.         while (tmp->sibling)
  328.             tmp = tmp->sibling;
  329.         tmp->sibling = childp;
  330.     } else {
  331.         parentp->child = childp;
  332.     }
  333.  
  334.     return true;
  335. }
  336.  
  337. int tmpfs_unlink_node(void *prnt, void *chld)
  338. {
  339.     tmpfs_dentry_t *parentp = (tmpfs_dentry_t *)prnt;
  340.     tmpfs_dentry_t *childp = (tmpfs_dentry_t *)chld;
  341.  
  342.     if (!parentp)
  343.         return EBUSY;
  344.  
  345.     if (childp->child)
  346.         return ENOTEMPTY;
  347.  
  348.     if (parentp->child == childp) {
  349.         parentp->child = childp->sibling;
  350.     } else {
  351.         /* TODO: consider doubly linked list for organizing siblings. */
  352.         tmpfs_dentry_t *tmp = parentp->child;
  353.         while (tmp->sibling != childp)
  354.             tmp = tmp->sibling;
  355.         tmp->sibling = childp->sibling;
  356.     }
  357.     childp->sibling = NULL;
  358.  
  359.     unsigned long key = (unsigned long) parentp;
  360.     hash_table_remove(&childp->names, &key, 1);
  361.  
  362.     childp->lnkcnt--;
  363.  
  364.     return EOK;
  365. }
  366.  
  367. void tmpfs_destroy_node(void *nodep)
  368. {
  369.     tmpfs_dentry_t *dentry = (tmpfs_dentry_t *) nodep;
  370.    
  371.     assert(!dentry->lnkcnt);
  372.     assert(!dentry->child);
  373.     assert(!dentry->sibling);
  374.  
  375.     unsigned long key = dentry->index;
  376.     hash_table_remove(&dentries, &key, 1);
  377.  
  378.     hash_table_destroy(&dentry->names);
  379.  
  380.     if (dentry->type == TMPFS_FILE)
  381.         free(dentry->data);
  382.     free(dentry);
  383. }
  384.  
  385. void tmpfs_lookup(ipc_callid_t rid, ipc_call_t *request)
  386. {
  387.     /* Initialize TMPFS. */
  388.     if (!root && !tmpfs_init()) {
  389.         ipc_answer_0(rid, ENOMEM);
  390.         return;
  391.     }
  392.     libfs_lookup(&tmpfs_libfs_ops, tmpfs_reg.fs_handle, rid, request);
  393. }
  394.  
  395. void tmpfs_read(ipc_callid_t rid, ipc_call_t *request)
  396. {
  397.     dev_handle_t dev_handle = (dev_handle_t)IPC_GET_ARG1(*request);
  398.     fs_index_t index = (fs_index_t)IPC_GET_ARG2(*request);
  399.     off_t pos = (off_t)IPC_GET_ARG3(*request);
  400.  
  401.     /*
  402.      * Lookup the respective dentry.
  403.      */
  404.     link_t *hlp;
  405.     unsigned long key = index;
  406.     hlp = hash_table_find(&dentries, &key);
  407.     if (!hlp) {
  408.         ipc_answer_0(rid, ENOENT);
  409.         return;
  410.     }
  411.     tmpfs_dentry_t *dentry = hash_table_get_instance(hlp, tmpfs_dentry_t,
  412.         dh_link);
  413.  
  414.     /*
  415.      * Receive the read request.
  416.      */
  417.     ipc_callid_t callid;
  418.     size_t len;
  419.     if (!ipc_data_read_receive(&callid, &len)) {
  420.         ipc_answer_0(callid, EINVAL);  
  421.         ipc_answer_0(rid, EINVAL);
  422.         return;
  423.     }
  424.  
  425.     size_t bytes;
  426.     if (dentry->type == TMPFS_FILE) {
  427.         bytes = max(0, min(dentry->size - pos, len));
  428.         (void) ipc_data_read_finalize(callid, dentry->data + pos,
  429.             bytes);
  430.     } else {
  431.         int i;
  432.         tmpfs_dentry_t *cur;
  433.        
  434.         assert(dentry->type == TMPFS_DIRECTORY);
  435.        
  436.         /*
  437.          * Yes, we really use O(n) algorithm here.
  438.          * If it bothers someone, it could be fixed by introducing a
  439.          * hash table.
  440.          */
  441.         for (i = 0, cur = dentry->child; i < pos && cur; i++,
  442.             cur = cur->sibling)
  443.             ;
  444.  
  445.         if (!cur) {
  446.             ipc_answer_0(callid, ENOENT);
  447.             ipc_answer_1(rid, ENOENT, 0);
  448.             return;
  449.         }
  450.  
  451.         unsigned long key = (unsigned long) dentry;
  452.         link_t *hlp = hash_table_find(&cur->names, &key);
  453.         assert(hlp);
  454.         tmpfs_name_t *namep = hash_table_get_instance(hlp, tmpfs_name_t,
  455.             link);
  456.  
  457.         (void) ipc_data_read_finalize(callid, namep->name,
  458.             strlen(namep->name) + 1);
  459.         bytes = 1;
  460.     }
  461.  
  462.     /*
  463.      * Answer the VFS_READ call.
  464.      */
  465.     ipc_answer_1(rid, EOK, bytes);
  466. }
  467.  
  468. void tmpfs_write(ipc_callid_t rid, ipc_call_t *request)
  469. {
  470.     dev_handle_t dev_handle = (dev_handle_t)IPC_GET_ARG1(*request);
  471.     fs_index_t index = (fs_index_t)IPC_GET_ARG2(*request);
  472.     off_t pos = (off_t)IPC_GET_ARG3(*request);
  473.  
  474.     /*
  475.      * Lookup the respective dentry.
  476.      */
  477.     link_t *hlp;
  478.     unsigned long key = index;
  479.     hlp = hash_table_find(&dentries, &key);
  480.     if (!hlp) {
  481.         ipc_answer_0(rid, ENOENT);
  482.         return;
  483.     }
  484.     tmpfs_dentry_t *dentry = hash_table_get_instance(hlp, tmpfs_dentry_t,
  485.         dh_link);
  486.  
  487.     /*
  488.      * Receive the write request.
  489.      */
  490.     ipc_callid_t callid;
  491.     size_t len;
  492.     if (!ipc_data_write_receive(&callid, &len)) {
  493.         ipc_answer_0(callid, EINVAL);  
  494.         ipc_answer_0(rid, EINVAL);
  495.         return;
  496.     }
  497.  
  498.     /*
  499.      * Check whether the file needs to grow.
  500.      */
  501.     if (pos + len <= dentry->size) {
  502.         /* The file size is not changing. */
  503.         (void) ipc_data_write_finalize(callid, dentry->data + pos, len);
  504.         ipc_answer_2(rid, EOK, len, dentry->size);
  505.         return;
  506.     }
  507.     size_t delta = (pos + len) - dentry->size;
  508.     /*
  509.      * At this point, we are deliberately extremely straightforward and
  510.      * simply realloc the contents of the file on every write that grows the
  511.      * file. In the end, the situation might not be as bad as it may look:
  512.      * our heap allocator can save us and just grow the block whenever
  513.      * possible.
  514.      */
  515.     void *newdata = realloc(dentry->data, dentry->size + delta);
  516.     if (!newdata) {
  517.         ipc_answer_0(callid, ENOMEM);
  518.         ipc_answer_2(rid, EOK, 0, dentry->size);
  519.         return;
  520.     }
  521.     /* Clear any newly allocated memory in order to emulate gaps. */
  522.     memset(newdata + dentry->size, 0, delta);
  523.     dentry->size += delta;
  524.     dentry->data = newdata;
  525.     (void) ipc_data_write_finalize(callid, dentry->data + pos, len);
  526.     ipc_answer_2(rid, EOK, len, dentry->size);
  527. }
  528.  
  529. void tmpfs_truncate(ipc_callid_t rid, ipc_call_t *request)
  530. {
  531.     dev_handle_t dev_handle = (dev_handle_t)IPC_GET_ARG1(*request);
  532.     fs_index_t index = (fs_index_t)IPC_GET_ARG2(*request);
  533.     size_t size = (off_t)IPC_GET_ARG3(*request);
  534.  
  535.     /*
  536.      * Lookup the respective dentry.
  537.      */
  538.     link_t *hlp;
  539.     unsigned long key = index;
  540.     hlp = hash_table_find(&dentries, &key);
  541.     if (!hlp) {
  542.         ipc_answer_0(rid, ENOENT);
  543.         return;
  544.     }
  545.     tmpfs_dentry_t *dentry = hash_table_get_instance(hlp, tmpfs_dentry_t,
  546.         dh_link);
  547.  
  548.     if (size == dentry->size) {
  549.         ipc_answer_0(rid, EOK);
  550.         return;
  551.     }
  552.  
  553.     void *newdata = realloc(dentry->data, size);
  554.     if (!newdata) {
  555.         ipc_answer_0(rid, ENOMEM);
  556.         return;
  557.     }
  558.     if (size > dentry->size) {
  559.         size_t delta = size - dentry->size;
  560.         memset(newdata + dentry->size, 0, delta);
  561.     }
  562.     dentry->size = size;
  563.     dentry->data = newdata;
  564.     ipc_answer_0(rid, EOK);
  565. }
  566.  
  567. void tmpfs_destroy(ipc_callid_t rid, ipc_call_t *request)
  568. {
  569.     dev_handle_t dev_handle = (dev_handle_t)IPC_GET_ARG1(*request);
  570.     fs_index_t index = (fs_index_t)IPC_GET_ARG2(*request);
  571.  
  572.     link_t *hlp;
  573.     unsigned long key = index;
  574.     hlp = hash_table_find(&dentries, &key);
  575.     if (!hlp) {
  576.         ipc_answer_0(rid, ENOENT);
  577.         return;
  578.     }
  579.     tmpfs_dentry_t *dentry = hash_table_get_instance(hlp, tmpfs_dentry_t,
  580.         dh_link);
  581.     tmpfs_destroy_node(dentry);
  582.     ipc_answer_0(rid, EOK);
  583. }
  584.  
  585. /**
  586.  * @}
  587.  */
  588.