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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_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 bool tmpfs_has_children(void *nodep)
  96. {
  97.     return ((tmpfs_dentry_t *) nodep)->child != NULL;
  98. }
  99.  
  100. static void *tmpfs_root_get(void)
  101. {
  102.     return 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.     .create = tmpfs_create_node,
  125.     .destroy = tmpfs_destroy_node,
  126.     .link = tmpfs_link_node,
  127.     .unlink = tmpfs_unlink_node,
  128.     .index_get = tmpfs_index_get,
  129.     .size_get = tmpfs_size_get,
  130.     .lnkcnt_get = tmpfs_lnkcnt_get,
  131.     .has_children = tmpfs_has_children,
  132.     .root_get = tmpfs_root_get,
  133.     .plb_get_char = tmpfs_plb_get_char,
  134.     .is_directory = tmpfs_is_directory,
  135.     .is_file = tmpfs_is_file
  136. };
  137.  
  138. /** Hash table of all directory entries. */
  139. hash_table_t dentries;
  140.  
  141. /* Implementation of hash table interface for the dentries hash table. */
  142. static hash_index_t dentries_hash(unsigned long *key)
  143. {
  144.     return *key % DENTRIES_BUCKETS;
  145. }
  146.  
  147. static int dentries_compare(unsigned long *key, hash_count_t keys,
  148.     link_t *item)
  149. {
  150.     tmpfs_dentry_t *dentry = hash_table_get_instance(item, tmpfs_dentry_t,
  151.         dh_link);
  152.     return dentry->index == *key;
  153. }
  154.  
  155. static void dentries_remove_callback(link_t *item)
  156. {
  157. }
  158.  
  159. /** TMPFS dentries hash table operations. */
  160. hash_table_operations_t dentries_ops = {
  161.     .hash = dentries_hash,
  162.     .compare = dentries_compare,
  163.     .remove_callback = dentries_remove_callback
  164. };
  165.  
  166. fs_index_t tmpfs_next_index = 1;
  167.  
  168. typedef struct {
  169.     char *name;
  170.     tmpfs_dentry_t *parent;
  171.     link_t link;
  172. } tmpfs_name_t;
  173.  
  174. /* Implementation of hash table interface for the names hash table. */
  175. static hash_index_t names_hash(unsigned long *key)
  176. {
  177.     tmpfs_dentry_t *dentry = (tmpfs_dentry_t *) *key;
  178.     return dentry->index % NAMES_BUCKETS;
  179. }
  180.  
  181. static int names_compare(unsigned long *key, hash_count_t keys, link_t *item)
  182. {
  183.     tmpfs_dentry_t *dentry = (tmpfs_dentry_t *) *key;
  184.     tmpfs_name_t *namep = hash_table_get_instance(item, tmpfs_name_t,
  185.         link);
  186.     return dentry == namep->parent;
  187. }
  188.  
  189. static void names_remove_callback(link_t *item)
  190. {
  191.     tmpfs_name_t *namep = hash_table_get_instance(item, tmpfs_name_t,
  192.         link);
  193.     free(namep->name);
  194.     free(namep);
  195. }
  196.  
  197. /** TMPFS node names hash table operations. */
  198. static hash_table_operations_t names_ops = {
  199.     .hash = names_hash,
  200.     .compare = names_compare,
  201.     .remove_callback = names_remove_callback
  202. };
  203.  
  204. static void tmpfs_name_initialize(tmpfs_name_t *namep)
  205. {
  206.     namep->name = NULL;
  207.     namep->parent = NULL;
  208.     link_initialize(&namep->link);
  209. }
  210.  
  211. static bool tmpfs_dentry_initialize(tmpfs_dentry_t *dentry)
  212. {
  213.     dentry->index = 0;
  214.     dentry->sibling = NULL;
  215.     dentry->child = NULL;
  216.     dentry->type = TMPFS_NONE;
  217.     dentry->lnkcnt = 0;
  218.     dentry->size = 0;
  219.     dentry->data = NULL;
  220.     link_initialize(&dentry->dh_link);
  221.     return (bool)hash_table_create(&dentry->names, NAMES_BUCKETS, 1,
  222.         &names_ops);
  223. }
  224.  
  225. static bool tmpfs_init(void)
  226. {
  227.     if (!hash_table_create(&dentries, DENTRIES_BUCKETS, 1, &dentries_ops))
  228.         return false;
  229.     root = (tmpfs_dentry_t *) tmpfs_create_node(L_DIRECTORY);
  230.     if (!root) {
  231.         hash_table_destroy(&dentries);
  232.         return false;
  233.     }
  234.     root->lnkcnt = 1;
  235.     return true;
  236. }
  237.  
  238. /** Compare one component of path to a directory entry.
  239.  *
  240.  * @param parentp   Pointer to node from which we descended.
  241.  * @param childp    Pointer to node to compare the path component with.
  242.  * @param component Array of characters holding component name.
  243.  *
  244.  * @return      True on match, false otherwise.
  245.  */
  246. static bool
  247. tmpfs_match_one(tmpfs_dentry_t *parentp, tmpfs_dentry_t *childp,
  248.     const char *component)
  249. {
  250.     unsigned long key = (unsigned long) parentp;
  251.     link_t *hlp = hash_table_find(&childp->names, &key);
  252.     assert(hlp);
  253.     tmpfs_name_t *namep = hash_table_get_instance(hlp, tmpfs_name_t, link);
  254.     return !strcmp(namep->name, component);
  255. }
  256.  
  257. void *tmpfs_match(void *prnt, const char *component)
  258. {
  259.     tmpfs_dentry_t *parentp = (tmpfs_dentry_t *) prnt;
  260.     tmpfs_dentry_t *childp = parentp->child;
  261.  
  262.     while (childp && !tmpfs_match_one(parentp, childp, component))
  263.         childp = childp->sibling;
  264.  
  265.     return (void *) childp;
  266. }
  267.  
  268. void *
  269. tmpfs_node_get(dev_handle_t dev_handle, fs_index_t index)
  270. {
  271.     unsigned long key = index;
  272.     link_t *lnk = hash_table_find(&dentries, &key);
  273.     if (!lnk)
  274.         return NULL;
  275.     return hash_table_get_instance(lnk, tmpfs_dentry_t, dh_link);
  276. }
  277.  
  278. void *tmpfs_create_node(int lflag)
  279. {
  280.     assert((lflag & L_FILE) ^ (lflag & L_DIRECTORY));
  281.  
  282.     tmpfs_dentry_t *node = malloc(sizeof(tmpfs_dentry_t));
  283.     if (!node)
  284.         return NULL;
  285.  
  286.     if (!tmpfs_dentry_initialize(node)) {
  287.         free(node);
  288.         return NULL;
  289.     }
  290.     node->index = tmpfs_next_index++;
  291.     if (lflag & L_DIRECTORY)
  292.         node->type = TMPFS_DIRECTORY;
  293.     else
  294.         node->type = TMPFS_FILE;
  295.  
  296.     /* Insert the new node into the dentry hash table. */
  297.     unsigned long key = node->index;
  298.     hash_table_insert(&dentries, &key, &node->dh_link);
  299.     return (void *) node;
  300. }
  301.  
  302. bool tmpfs_link_node(void *prnt, void *chld, const char *nm)
  303. {
  304.     tmpfs_dentry_t *parentp = (tmpfs_dentry_t *) prnt;
  305.     tmpfs_dentry_t *childp = (tmpfs_dentry_t *) chld;
  306.  
  307.     assert(parentp->type == TMPFS_DIRECTORY);
  308.  
  309.     tmpfs_name_t *namep = malloc(sizeof(tmpfs_name_t));
  310.     if (!namep)
  311.         return false;
  312.     tmpfs_name_initialize(namep);
  313.     size_t len = strlen(nm);
  314.     namep->name = malloc(len + 1);
  315.     if (!namep->name) {
  316.         free(namep);
  317.         return false;
  318.     }
  319.     strcpy(namep->name, nm);
  320.     namep->parent = parentp;
  321.    
  322.     childp->lnkcnt++;
  323.  
  324.     unsigned long key = (unsigned long) parentp;
  325.     hash_table_insert(&childp->names, &key, &namep->link);
  326.  
  327.     /* Insert the new node into the namespace. */
  328.     if (parentp->child) {
  329.         tmpfs_dentry_t *tmp = parentp->child;
  330.         while (tmp->sibling)
  331.             tmp = tmp->sibling;
  332.         tmp->sibling = childp;
  333.     } else {
  334.         parentp->child = childp;
  335.     }
  336.  
  337.     return true;
  338. }
  339.  
  340. int tmpfs_unlink_node(void *prnt, void *chld)
  341. {
  342.     tmpfs_dentry_t *parentp = (tmpfs_dentry_t *)prnt;
  343.     tmpfs_dentry_t *childp = (tmpfs_dentry_t *)chld;
  344.  
  345.     if (!parentp)
  346.         return EBUSY;
  347.  
  348.     if (childp->child)
  349.         return ENOTEMPTY;
  350.  
  351.     if (parentp->child == childp) {
  352.         parentp->child = childp->sibling;
  353.     } else {
  354.         /* TODO: consider doubly linked list for organizing siblings. */
  355.         tmpfs_dentry_t *tmp = parentp->child;
  356.         while (tmp->sibling != childp)
  357.             tmp = tmp->sibling;
  358.         tmp->sibling = childp->sibling;
  359.     }
  360.     childp->sibling = NULL;
  361.  
  362.     unsigned long key = (unsigned long) parentp;
  363.     hash_table_remove(&childp->names, &key, 1);
  364.  
  365.     childp->lnkcnt--;
  366.  
  367.     return EOK;
  368. }
  369.  
  370. void tmpfs_destroy_node(void *nodep)
  371. {
  372.     tmpfs_dentry_t *dentry = (tmpfs_dentry_t *) nodep;
  373.    
  374.     assert(!dentry->lnkcnt);
  375.     assert(!dentry->child);
  376.     assert(!dentry->sibling);
  377.  
  378.     unsigned long key = dentry->index;
  379.     hash_table_remove(&dentries, &key, 1);
  380.  
  381.     hash_table_destroy(&dentry->names);
  382.  
  383.     if (dentry->type == TMPFS_FILE)
  384.         free(dentry->data);
  385.     free(dentry);
  386. }
  387.  
  388. void tmpfs_lookup(ipc_callid_t rid, ipc_call_t *request)
  389. {
  390.     /* Initialize TMPFS. */
  391.     if (!root && !tmpfs_init()) {
  392.         ipc_answer_0(rid, ENOMEM);
  393.         return;
  394.     }
  395.     libfs_lookup(&tmpfs_libfs_ops, tmpfs_reg.fs_handle, rid, request);
  396. }
  397.  
  398. void tmpfs_read(ipc_callid_t rid, ipc_call_t *request)
  399. {
  400.     dev_handle_t dev_handle = (dev_handle_t)IPC_GET_ARG1(*request);
  401.     fs_index_t index = (fs_index_t)IPC_GET_ARG2(*request);
  402.     off_t pos = (off_t)IPC_GET_ARG3(*request);
  403.  
  404.     /*
  405.      * Lookup the respective dentry.
  406.      */
  407.     link_t *hlp;
  408.     unsigned long key = index;
  409.     hlp = hash_table_find(&dentries, &key);
  410.     if (!hlp) {
  411.         ipc_answer_0(rid, ENOENT);
  412.         return;
  413.     }
  414.     tmpfs_dentry_t *dentry = hash_table_get_instance(hlp, tmpfs_dentry_t,
  415.         dh_link);
  416.  
  417.     /*
  418.      * Receive the read request.
  419.      */
  420.     ipc_callid_t callid;
  421.     size_t len;
  422.     if (!ipc_data_read_receive(&callid, &len)) {
  423.         ipc_answer_0(callid, EINVAL);  
  424.         ipc_answer_0(rid, EINVAL);
  425.         return;
  426.     }
  427.  
  428.     size_t bytes;
  429.     if (dentry->type == TMPFS_FILE) {
  430.         bytes = max(0, min(dentry->size - pos, len));
  431.         (void) ipc_data_read_finalize(callid, dentry->data + pos,
  432.             bytes);
  433.     } else {
  434.         int i;
  435.         tmpfs_dentry_t *cur;
  436.        
  437.         assert(dentry->type == TMPFS_DIRECTORY);
  438.        
  439.         /*
  440.          * Yes, we really use O(n) algorithm here.
  441.          * If it bothers someone, it could be fixed by introducing a
  442.          * hash table.
  443.          */
  444.         for (i = 0, cur = dentry->child; i < pos && cur; i++,
  445.             cur = cur->sibling)
  446.             ;
  447.  
  448.         if (!cur) {
  449.             ipc_answer_0(callid, ENOENT);
  450.             ipc_answer_1(rid, ENOENT, 0);
  451.             return;
  452.         }
  453.  
  454.         unsigned long key = (unsigned long) dentry;
  455.         link_t *hlp = hash_table_find(&cur->names, &key);
  456.         assert(hlp);
  457.         tmpfs_name_t *namep = hash_table_get_instance(hlp, tmpfs_name_t,
  458.             link);
  459.  
  460.         (void) ipc_data_read_finalize(callid, namep->name,
  461.             strlen(namep->name) + 1);
  462.         bytes = 1;
  463.     }
  464.  
  465.     /*
  466.      * Answer the VFS_READ call.
  467.      */
  468.     ipc_answer_1(rid, EOK, bytes);
  469. }
  470.  
  471. void tmpfs_write(ipc_callid_t rid, ipc_call_t *request)
  472. {
  473.     dev_handle_t dev_handle = (dev_handle_t)IPC_GET_ARG1(*request);
  474.     fs_index_t index = (fs_index_t)IPC_GET_ARG2(*request);
  475.     off_t pos = (off_t)IPC_GET_ARG3(*request);
  476.  
  477.     /*
  478.      * Lookup the respective dentry.
  479.      */
  480.     link_t *hlp;
  481.     unsigned long key = index;
  482.     hlp = hash_table_find(&dentries, &key);
  483.     if (!hlp) {
  484.         ipc_answer_0(rid, ENOENT);
  485.         return;
  486.     }
  487.     tmpfs_dentry_t *dentry = hash_table_get_instance(hlp, tmpfs_dentry_t,
  488.         dh_link);
  489.  
  490.     /*
  491.      * Receive the write request.
  492.      */
  493.     ipc_callid_t callid;
  494.     size_t len;
  495.     if (!ipc_data_write_receive(&callid, &len)) {
  496.         ipc_answer_0(callid, EINVAL);  
  497.         ipc_answer_0(rid, EINVAL);
  498.         return;
  499.     }
  500.  
  501.     /*
  502.      * Check whether the file needs to grow.
  503.      */
  504.     if (pos + len <= dentry->size) {
  505.         /* The file size is not changing. */
  506.         (void) ipc_data_write_finalize(callid, dentry->data + pos, len);
  507.         ipc_answer_2(rid, EOK, len, dentry->size);
  508.         return;
  509.     }
  510.     size_t delta = (pos + len) - dentry->size;
  511.     /*
  512.      * At this point, we are deliberately extremely straightforward and
  513.      * simply realloc the contents of the file on every write that grows the
  514.      * file. In the end, the situation might not be as bad as it may look:
  515.      * our heap allocator can save us and just grow the block whenever
  516.      * possible.
  517.      */
  518.     void *newdata = realloc(dentry->data, dentry->size + delta);
  519.     if (!newdata) {
  520.         ipc_answer_0(callid, ENOMEM);
  521.         ipc_answer_2(rid, EOK, 0, dentry->size);
  522.         return;
  523.     }
  524.     /* Clear any newly allocated memory in order to emulate gaps. */
  525.     memset(newdata + dentry->size, 0, delta);
  526.     dentry->size += delta;
  527.     dentry->data = newdata;
  528.     (void) ipc_data_write_finalize(callid, dentry->data + pos, len);
  529.     ipc_answer_2(rid, EOK, len, dentry->size);
  530. }
  531.  
  532. void tmpfs_truncate(ipc_callid_t rid, ipc_call_t *request)
  533. {
  534.     dev_handle_t dev_handle = (dev_handle_t)IPC_GET_ARG1(*request);
  535.     fs_index_t index = (fs_index_t)IPC_GET_ARG2(*request);
  536.     size_t size = (off_t)IPC_GET_ARG3(*request);
  537.  
  538.     /*
  539.      * Lookup the respective dentry.
  540.      */
  541.     link_t *hlp;
  542.     unsigned long key = index;
  543.     hlp = hash_table_find(&dentries, &key);
  544.     if (!hlp) {
  545.         ipc_answer_0(rid, ENOENT);
  546.         return;
  547.     }
  548.     tmpfs_dentry_t *dentry = hash_table_get_instance(hlp, tmpfs_dentry_t,
  549.         dh_link);
  550.  
  551.     if (size == dentry->size) {
  552.         ipc_answer_0(rid, EOK);
  553.         return;
  554.     }
  555.  
  556.     void *newdata = realloc(dentry->data, size);
  557.     if (!newdata) {
  558.         ipc_answer_0(rid, ENOMEM);
  559.         return;
  560.     }
  561.     if (size > dentry->size) {
  562.         size_t delta = size - dentry->size;
  563.         memset(newdata + dentry->size, 0, delta);
  564.     }
  565.     dentry->size = size;
  566.     dentry->data = newdata;
  567.     ipc_answer_0(rid, EOK);
  568. }
  569.  
  570. void tmpfs_destroy(ipc_callid_t rid, ipc_call_t *request)
  571. {
  572.     dev_handle_t dev_handle = (dev_handle_t)IPC_GET_ARG1(*request);
  573.     fs_index_t index = (fs_index_t)IPC_GET_ARG2(*request);
  574.  
  575.     link_t *hlp;
  576.     unsigned long key = index;
  577.     hlp = hash_table_find(&dentries, &key);
  578.     if (!hlp) {
  579.         ipc_answer_0(rid, ENOENT);
  580.         return;
  581.     }
  582.     tmpfs_dentry_t *dentry = hash_table_get_instance(hlp, tmpfs_dentry_t,
  583.         dh_link);
  584.     tmpfs_destroy_node(dentry);
  585.     ipc_answer_0(rid, EOK);
  586. }
  587.  
  588. /**
  589.  * @}
  590.  */
  591.