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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_create_node(int);
  74. static bool tmpfs_link_node(void *, void *, const char *);
  75. static int tmpfs_unlink_node(void *, void *);
  76. static void tmpfs_destroy_node(void *);
  77.  
  78. /* Implementation of helper functions. */
  79. static unsigned long tmpfs_index_get(void *nodep)
  80. {
  81.     return ((tmpfs_dentry_t *) nodep)->index;
  82. }
  83.  
  84. static unsigned long tmpfs_size_get(void *nodep)
  85. {
  86.     return ((tmpfs_dentry_t *) nodep)->size;
  87. }
  88.  
  89. static unsigned tmpfs_lnkcnt_get(void *nodep)
  90. {
  91.     return ((tmpfs_dentry_t *) nodep)->lnkcnt;
  92. }
  93.  
  94. static void *tmpfs_child_get(void *nodep)
  95. {
  96.     return ((tmpfs_dentry_t *) nodep)->child;
  97. }
  98.  
  99. static void *tmpfs_sibling_get(void *nodep)
  100. {
  101.     return ((tmpfs_dentry_t *) nodep)->sibling;
  102. }
  103.  
  104. static void *tmpfs_root_get(void)
  105. {
  106.     return root;
  107. }
  108.  
  109. static char tmpfs_plb_get_char(unsigned pos)
  110. {
  111.     return tmpfs_reg.plb_ro[pos % PLB_SIZE];
  112. }
  113.  
  114. static bool tmpfs_is_directory(void *nodep)
  115. {
  116.     return ((tmpfs_dentry_t *) nodep)->type == TMPFS_DIRECTORY;
  117. }
  118.  
  119. static bool tmpfs_is_file(void *nodep)
  120. {
  121.     return ((tmpfs_dentry_t *) nodep)->type == TMPFS_FILE;
  122. }
  123.  
  124. /** libfs operations */
  125. libfs_ops_t tmpfs_libfs_ops = {
  126.     .match = tmpfs_match,
  127.     .create = tmpfs_create_node,
  128.     .destroy = tmpfs_destroy_node,
  129.     .link = tmpfs_link_node,
  130.     .unlink = tmpfs_unlink_node,
  131.     .index_get = tmpfs_index_get,
  132.     .size_get = tmpfs_size_get,
  133.     .lnkcnt_get = tmpfs_lnkcnt_get,
  134.     .child_get = tmpfs_child_get,
  135.     .sibling_get = tmpfs_sibling_get,
  136.     .root_get = tmpfs_root_get,
  137.     .plb_get_char = tmpfs_plb_get_char,
  138.     .is_directory = tmpfs_is_directory,
  139.     .is_file = tmpfs_is_file
  140. };
  141.  
  142. /** Hash table of all directory entries. */
  143. hash_table_t dentries;
  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_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;
  157. }
  158.  
  159. static void dentries_remove_callback(link_t *item)
  160. {
  161. }
  162.  
  163. /** TMPFS dentries hash table operations. */
  164. hash_table_operations_t dentries_ops = {
  165.     .hash = dentries_hash,
  166.     .compare = dentries_compare,
  167.     .remove_callback = dentries_remove_callback
  168. };
  169.  
  170. unsigned tmpfs_next_index = 1;
  171.  
  172. typedef struct {
  173.     char *name;
  174.     tmpfs_dentry_t *parent;
  175.     link_t link;
  176. } tmpfs_name_t;
  177.  
  178. /* Implementation of hash table interface for the names hash table. */
  179. static hash_index_t names_hash(unsigned long *key)
  180. {
  181.     tmpfs_dentry_t *dentry = (tmpfs_dentry_t *) *key;
  182.     return dentry->index % NAMES_BUCKETS;
  183. }
  184.  
  185. static int names_compare(unsigned long *key, hash_count_t keys, link_t *item)
  186. {
  187.     tmpfs_dentry_t *dentry = (tmpfs_dentry_t *) *key;
  188.     tmpfs_name_t *namep = hash_table_get_instance(item, tmpfs_name_t,
  189.         link);
  190.     return dentry == namep->parent;
  191. }
  192.  
  193. static void names_remove_callback(link_t *item)
  194. {
  195.     tmpfs_name_t *namep = hash_table_get_instance(item, tmpfs_name_t,
  196.         link);
  197.     free(namep->name);
  198.     free(namep);
  199. }
  200.  
  201. /** TMPFS node names hash table operations. */
  202. static hash_table_operations_t names_ops = {
  203.     .hash = names_hash,
  204.     .compare = names_compare,
  205.     .remove_callback = names_remove_callback
  206. };
  207.  
  208. static void tmpfs_name_initialize(tmpfs_name_t *namep)
  209. {
  210.     namep->name = NULL;
  211.     namep->parent = NULL;
  212.     link_initialize(&namep->link);
  213. }
  214.  
  215. static bool tmpfs_dentry_initialize(tmpfs_dentry_t *dentry)
  216. {
  217.     dentry->index = 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. static bool tmpfs_init(void)
  230. {
  231.     if (!hash_table_create(&dentries, DENTRIES_BUCKETS, 1, &dentries_ops))
  232.         return false;
  233.     root = (tmpfs_dentry_t *) tmpfs_create_node(L_DIRECTORY);
  234.     if (!root) {
  235.         hash_table_destroy(&dentries);
  236.         return false;
  237.     }
  238.     root->lnkcnt = 1;
  239.     return true;
  240. }
  241.  
  242. /** Compare one component of path to a directory entry.
  243.  *
  244.  * @param prnt      Node from which we descended.
  245.  * @param chld      Node to compare the path component with.
  246.  * @param component Array of characters holding component name.
  247.  *
  248.  * @return      True on match, false otherwise.
  249.  */
  250. bool tmpfs_match(void *prnt, void *chld, const char *component)
  251. {
  252.     tmpfs_dentry_t *parentp = (tmpfs_dentry_t *) prnt;
  253.     tmpfs_dentry_t *childp = (tmpfs_dentry_t *) chld;
  254.  
  255.     unsigned long key = (unsigned long) parentp;
  256.     link_t *hlp = hash_table_find(&childp->names, &key);
  257.     assert(hlp);
  258.     tmpfs_name_t *namep = hash_table_get_instance(hlp, tmpfs_name_t, link);
  259.  
  260.     return !strcmp(namep->name, component);
  261. }
  262.  
  263. void *tmpfs_create_node(int lflag)
  264. {
  265.     assert((lflag & L_FILE) ^ (lflag & L_DIRECTORY));
  266.  
  267.     tmpfs_dentry_t *node = malloc(sizeof(tmpfs_dentry_t));
  268.     if (!node)
  269.         return NULL;
  270.  
  271.     if (!tmpfs_dentry_initialize(node)) {
  272.         free(node);
  273.         return NULL;
  274.     }
  275.     node->index = tmpfs_next_index++;
  276.     if (lflag & L_DIRECTORY)
  277.         node->type = TMPFS_DIRECTORY;
  278.     else
  279.         node->type = TMPFS_FILE;
  280.  
  281.     /* Insert the new node into the dentry hash table. */
  282.     hash_table_insert(&dentries, &node->index, &node->dh_link);
  283.     return (void *) node;
  284. }
  285.  
  286. bool tmpfs_link_node(void *prnt, void *chld, const char *nm)
  287. {
  288.     tmpfs_dentry_t *parentp = (tmpfs_dentry_t *) prnt;
  289.     tmpfs_dentry_t *childp = (tmpfs_dentry_t *) chld;
  290.  
  291.     assert(parentp->type == TMPFS_DIRECTORY);
  292.  
  293.     tmpfs_name_t *namep = malloc(sizeof(tmpfs_name_t));
  294.     if (!namep)
  295.         return false;
  296.     tmpfs_name_initialize(namep);
  297.     size_t len = strlen(nm);
  298.     namep->name = malloc(len + 1);
  299.     if (!namep->name) {
  300.         free(namep);
  301.         return false;
  302.     }
  303.     strcpy(namep->name, nm);
  304.     namep->parent = parentp;
  305.    
  306.     childp->lnkcnt++;
  307.  
  308.     unsigned long key = (unsigned long) parentp;
  309.     hash_table_insert(&childp->names, &key, &namep->link);
  310.  
  311.     /* Insert the new node into the namespace. */
  312.     if (parentp->child) {
  313.         tmpfs_dentry_t *tmp = parentp->child;
  314.         while (tmp->sibling)
  315.             tmp = tmp->sibling;
  316.         tmp->sibling = childp;
  317.     } else {
  318.         parentp->child = childp;
  319.     }
  320.  
  321.     return true;
  322. }
  323.  
  324. int tmpfs_unlink_node(void *prnt, void *chld)
  325. {
  326.     tmpfs_dentry_t *parentp = (tmpfs_dentry_t *)prnt;
  327.     tmpfs_dentry_t *childp = (tmpfs_dentry_t *)chld;
  328.  
  329.     if (!parentp)
  330.         return EBUSY;
  331.  
  332.     if (childp->child)
  333.         return ENOTEMPTY;
  334.  
  335.     if (parentp->child == childp) {
  336.         parentp->child = childp->sibling;
  337.     } else {
  338.         /* TODO: consider doubly linked list for organizing siblings. */
  339.         tmpfs_dentry_t *tmp = parentp->child;
  340.         while (tmp->sibling != childp)
  341.             tmp = tmp->sibling;
  342.         tmp->sibling = childp->sibling;
  343.     }
  344.     childp->sibling = NULL;
  345.  
  346.     unsigned long key = (unsigned long) parentp;
  347.     hash_table_remove(&childp->names, &key, 1);
  348.  
  349.     childp->lnkcnt--;
  350.  
  351.     return EOK;
  352. }
  353.  
  354. void tmpfs_destroy_node(void *nodep)
  355. {
  356.     tmpfs_dentry_t *dentry = (tmpfs_dentry_t *) nodep;
  357.    
  358.     assert(!dentry->lnkcnt);
  359.     assert(!dentry->child);
  360.     assert(!dentry->sibling);
  361.  
  362.     unsigned long index = dentry->index;
  363.     hash_table_remove(&dentries, &index, 1);
  364.  
  365.     hash_table_destroy(&dentry->names);
  366.  
  367.     if (dentry->type == TMPFS_FILE)
  368.         free(dentry->data);
  369.     free(dentry);
  370. }
  371.  
  372. void tmpfs_lookup(ipc_callid_t rid, ipc_call_t *request)
  373. {
  374.     /* Initialize TMPFS. */
  375.     if (!root && !tmpfs_init()) {
  376.         ipc_answer_0(rid, ENOMEM);
  377.         return;
  378.     }
  379.     libfs_lookup(&tmpfs_libfs_ops, tmpfs_reg.fs_handle, rid, request);
  380. }
  381.  
  382. void tmpfs_read(ipc_callid_t rid, ipc_call_t *request)
  383. {
  384.     int dev_handle = IPC_GET_ARG1(*request);
  385.     unsigned long index = IPC_GET_ARG2(*request);
  386.     off_t pos = IPC_GET_ARG3(*request);
  387.  
  388.     /*
  389.      * Lookup the respective dentry.
  390.      */
  391.     link_t *hlp;
  392.     hlp = hash_table_find(&dentries, &index);
  393.     if (!hlp) {
  394.         ipc_answer_0(rid, ENOENT);
  395.         return;
  396.     }
  397.     tmpfs_dentry_t *dentry = hash_table_get_instance(hlp, tmpfs_dentry_t,
  398.         dh_link);
  399.  
  400.     /*
  401.      * Receive the read request.
  402.      */
  403.     ipc_callid_t callid;
  404.     size_t len;
  405.     if (!ipc_data_read_receive(&callid, &len)) {
  406.         ipc_answer_0(callid, EINVAL);  
  407.         ipc_answer_0(rid, EINVAL);
  408.         return;
  409.     }
  410.  
  411.     size_t bytes;
  412.     if (dentry->type == TMPFS_FILE) {
  413.         bytes = max(0, min(dentry->size - pos, len));
  414.         (void) ipc_data_read_finalize(callid, dentry->data + pos,
  415.             bytes);
  416.     } else {
  417.         int i;
  418.         tmpfs_dentry_t *cur;
  419.        
  420.         assert(dentry->type == TMPFS_DIRECTORY);
  421.        
  422.         /*
  423.          * Yes, we really use O(n) algorithm here.
  424.          * If it bothers someone, it could be fixed by introducing a
  425.          * hash table.
  426.          */
  427.         for (i = 0, cur = dentry->child; i < pos && cur; i++,
  428.             cur = cur->sibling)
  429.             ;
  430.  
  431.         if (!cur) {
  432.             ipc_answer_0(callid, ENOENT);
  433.             ipc_answer_1(rid, ENOENT, 0);
  434.             return;
  435.         }
  436.  
  437.         unsigned long key = (unsigned long) dentry;
  438.         link_t *hlp = hash_table_find(&cur->names, &key);
  439.         assert(hlp);
  440.         tmpfs_name_t *namep = hash_table_get_instance(hlp, tmpfs_name_t,
  441.             link);
  442.  
  443.         (void) ipc_data_read_finalize(callid, namep->name,
  444.             strlen(namep->name) + 1);
  445.         bytes = 1;
  446.     }
  447.  
  448.     /*
  449.      * Answer the VFS_READ call.
  450.      */
  451.     ipc_answer_1(rid, EOK, bytes);
  452. }
  453.  
  454. void tmpfs_write(ipc_callid_t rid, ipc_call_t *request)
  455. {
  456.     int dev_handle = IPC_GET_ARG1(*request);
  457.     unsigned long index = IPC_GET_ARG2(*request);
  458.     off_t pos = IPC_GET_ARG3(*request);
  459.  
  460.     /*
  461.      * Lookup the respective dentry.
  462.      */
  463.     link_t *hlp;
  464.     hlp = hash_table_find(&dentries, &index);
  465.     if (!hlp) {
  466.         ipc_answer_0(rid, ENOENT);
  467.         return;
  468.     }
  469.     tmpfs_dentry_t *dentry = hash_table_get_instance(hlp, tmpfs_dentry_t,
  470.         dh_link);
  471.  
  472.     /*
  473.      * Receive the write request.
  474.      */
  475.     ipc_callid_t callid;
  476.     size_t len;
  477.     if (!ipc_data_write_receive(&callid, &len)) {
  478.         ipc_answer_0(callid, EINVAL);  
  479.         ipc_answer_0(rid, EINVAL);
  480.         return;
  481.     }
  482.  
  483.     /*
  484.      * Check whether the file needs to grow.
  485.      */
  486.     if (pos + len <= dentry->size) {
  487.         /* The file size is not changing. */
  488.         (void) ipc_data_write_finalize(callid, dentry->data + pos, len);
  489.         ipc_answer_2(rid, EOK, len, dentry->size);
  490.         return;
  491.     }
  492.     size_t delta = (pos + len) - dentry->size;
  493.     /*
  494.      * At this point, we are deliberately extremely straightforward and
  495.      * simply realloc the contents of the file on every write that grows the
  496.      * file. In the end, the situation might not be as bad as it may look:
  497.      * our heap allocator can save us and just grow the block whenever
  498.      * possible.
  499.      */
  500.     void *newdata = realloc(dentry->data, dentry->size + delta);
  501.     if (!newdata) {
  502.         ipc_answer_0(callid, ENOMEM);
  503.         ipc_answer_2(rid, EOK, 0, dentry->size);
  504.         return;
  505.     }
  506.     /* Clear any newly allocated memory in order to emulate gaps. */
  507.     memset(newdata + dentry->size, 0, delta);
  508.     dentry->size += delta;
  509.     dentry->data = newdata;
  510.     (void) ipc_data_write_finalize(callid, dentry->data + pos, len);
  511.     ipc_answer_2(rid, EOK, len, dentry->size);
  512. }
  513.  
  514. void tmpfs_truncate(ipc_callid_t rid, ipc_call_t *request)
  515. {
  516.     int dev_handle = IPC_GET_ARG1(*request);
  517.     unsigned long index = IPC_GET_ARG2(*request);
  518.     size_t size = IPC_GET_ARG3(*request);
  519.  
  520.     /*
  521.      * Lookup the respective dentry.
  522.      */
  523.     link_t *hlp;
  524.     hlp = hash_table_find(&dentries, &index);
  525.     if (!hlp) {
  526.         ipc_answer_0(rid, ENOENT);
  527.         return;
  528.     }
  529.     tmpfs_dentry_t *dentry = hash_table_get_instance(hlp, tmpfs_dentry_t,
  530.         dh_link);
  531.  
  532.     if (size == dentry->size) {
  533.         ipc_answer_0(rid, EOK);
  534.         return;
  535.     }
  536.  
  537.     void *newdata = realloc(dentry->data, size);
  538.     if (!newdata) {
  539.         ipc_answer_0(rid, ENOMEM);
  540.         return;
  541.     }
  542.     if (size > dentry->size) {
  543.         size_t delta = size - dentry->size;
  544.         memset(newdata + dentry->size, 0, delta);
  545.     }
  546.     dentry->size = size;
  547.     dentry->data = newdata;
  548.     ipc_answer_0(rid, EOK);
  549. }
  550.  
  551. void tmpfs_destroy(ipc_callid_t rid, ipc_call_t *request)
  552. {
  553.     int dev_handle = IPC_GET_ARG1(*request);
  554.     unsigned long index = IPC_GET_ARG2(*request);
  555.  
  556.     link_t *hlp;
  557.     hlp = hash_table_find(&dentries, &index);
  558.     if (!hlp) {
  559.         ipc_answer_0(rid, ENOENT);
  560.         return;
  561.     }
  562.     tmpfs_dentry_t *dentry = hash_table_get_instance(hlp, tmpfs_dentry_t,
  563.         dh_link);
  564.     tmpfs_destroy_node(dentry);
  565.     ipc_answer_0(rid, EOK);
  566. }
  567.  
  568. /**
  569.  * @}
  570.  */
  571.