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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. /*
  60.  * For now, we don't distinguish between different dev_handles/instances. All
  61.  * requests resolve to the only instance, rooted in the following variable.
  62.  */
  63. static tmpfs_dentry_t *root;
  64.  
  65. /*
  66.  * Implementation of the libfs interface.
  67.  */
  68.  
  69. /* Forward declarations of static functions. */
  70. static bool tmpfs_match(void *, const char *);
  71. static void *tmpfs_create_node(int);
  72. static bool tmpfs_link_node(void *, void *, const char *);
  73. static int tmpfs_unlink_node(void *);
  74. static void tmpfs_destroy_node(void *);
  75.  
  76. /* Implementation of helper functions. */
  77. static unsigned long tmpfs_index_get(void *nodep)
  78. {
  79.     return ((tmpfs_dentry_t *) nodep)->index;
  80. }
  81.  
  82. static unsigned long tmpfs_size_get(void *nodep)
  83. {
  84.     return ((tmpfs_dentry_t *) nodep)->size;
  85. }
  86.  
  87. static unsigned tmpfs_lnkcnt_get(void *nodep)
  88. {
  89.     return ((tmpfs_dentry_t *) nodep)->lnkcnt;
  90. }
  91.  
  92. static void *tmpfs_child_get(void *nodep)
  93. {
  94.     return ((tmpfs_dentry_t *) nodep)->child;
  95. }
  96.  
  97. static void *tmpfs_sibling_get(void *nodep)
  98. {
  99.     return ((tmpfs_dentry_t *) nodep)->sibling;
  100. }
  101.  
  102. static void *tmpfs_root_get(void)
  103. {
  104.     return root;
  105. }
  106.  
  107. static char tmpfs_plb_get_char(unsigned pos)
  108. {
  109.     return tmpfs_reg.plb_ro[pos % PLB_SIZE];
  110. }
  111.  
  112. static bool tmpfs_is_directory(void *nodep)
  113. {
  114.     return ((tmpfs_dentry_t *) nodep)->type == TMPFS_DIRECTORY;
  115. }
  116.  
  117. static bool tmpfs_is_file(void *nodep)
  118. {
  119.     return ((tmpfs_dentry_t *) nodep)->type == TMPFS_FILE;
  120. }
  121.  
  122. /** libfs operations */
  123. libfs_ops_t tmpfs_libfs_ops = {
  124.     .match = tmpfs_match,
  125.     .create = tmpfs_create_node,
  126.     .destroy = tmpfs_destroy_node,
  127.     .link = tmpfs_link_node,
  128.     .unlink = tmpfs_unlink_node,
  129.     .index_get = tmpfs_index_get,
  130.     .size_get = tmpfs_size_get,
  131.     .lnkcnt_get = tmpfs_lnkcnt_get,
  132.     .child_get = tmpfs_child_get,
  133.     .sibling_get = tmpfs_sibling_get,
  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. */
  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. unsigned tmpfs_next_index = 1;
  169.  
  170. static void tmpfs_dentry_initialize(tmpfs_dentry_t *dentry)
  171. {
  172.     dentry->index = 0;
  173.     dentry->parent = NULL;
  174.     dentry->sibling = NULL;
  175.     dentry->child = NULL;
  176.     dentry->name = NULL;
  177.     dentry->type = TMPFS_NONE;
  178.     dentry->lnkcnt = 0;
  179.     dentry->size = 0;
  180.     dentry->data = NULL;
  181.     link_initialize(&dentry->dh_link);
  182. }
  183.  
  184. static bool tmpfs_init(void)
  185. {
  186.     if (!hash_table_create(&dentries, DENTRIES_BUCKETS, 1, &dentries_ops))
  187.         return false;
  188.     root = (tmpfs_dentry_t *) tmpfs_create_node(L_DIRECTORY);
  189.     root->lnkcnt = 1;
  190.     return root != NULL;
  191. }
  192.  
  193. /** Compare one component of path to a directory entry.
  194.  *
  195.  * @param nodep     Node to compare the path component with.
  196.  * @param component Array of characters holding component name.
  197.  *
  198.  * @return      True on match, false otherwise.
  199.  */
  200. bool tmpfs_match(void *nodep, const char *component)
  201. {
  202.     tmpfs_dentry_t *dentry = (tmpfs_dentry_t *) nodep;
  203.  
  204.     return !strcmp(dentry->name, component);
  205. }
  206.  
  207. void *tmpfs_create_node(int lflag)
  208. {
  209.     assert((lflag & L_FILE) ^ (lflag & L_DIRECTORY));
  210.  
  211.     tmpfs_dentry_t *node = malloc(sizeof(tmpfs_dentry_t));
  212.     if (!node)
  213.         return NULL;
  214.  
  215.     tmpfs_dentry_initialize(node);
  216.     node->index = tmpfs_next_index++;
  217.     if (lflag & L_DIRECTORY)
  218.         node->type = TMPFS_DIRECTORY;
  219.     else
  220.         node->type = TMPFS_FILE;
  221.  
  222.     /* Insert the new node into the dentry hash table. */
  223.     hash_table_insert(&dentries, &node->index, &node->dh_link);
  224.     return (void *) node;
  225. }
  226.  
  227. bool tmpfs_link_node(void *prnt, void *chld, const char *nm)
  228. {
  229.     tmpfs_dentry_t *parentp = (tmpfs_dentry_t *) prnt;
  230.     tmpfs_dentry_t *childp = (tmpfs_dentry_t *) chld;
  231.  
  232.     assert(parentp->type == TMPFS_DIRECTORY);
  233.  
  234.     size_t len = strlen(nm);
  235.     char *name = malloc(len + 1);
  236.     if (!name)
  237.         return false;
  238.    
  239.     childp->lnkcnt++;
  240.    
  241.     strcpy(name, nm);
  242.     childp->name = name;
  243.  
  244.     /* Insert the new node into the namespace. */
  245.     if (parentp->child) {
  246.         tmpfs_dentry_t *tmp = parentp->child;
  247.         while (tmp->sibling)
  248.             tmp = tmp->sibling;
  249.         tmp->sibling = childp;
  250.     } else {
  251.         parentp->child = childp;
  252.     }
  253.     childp->parent = parentp;
  254.  
  255.     return true;
  256. }
  257.  
  258. int tmpfs_unlink_node(void *nodeptr)
  259. {
  260.     tmpfs_dentry_t *dentry = (tmpfs_dentry_t *)nodeptr;
  261.  
  262.     if (dentry->child)
  263.         return ENOTEMPTY;
  264.  
  265.     if (!dentry->parent)
  266.         return EBUSY;
  267.  
  268.     if (dentry->parent->child == dentry) {
  269.         dentry->parent->child = dentry->sibling;
  270.     } else {
  271.         /* TODO: consider doubly linked list for organizing siblings. */
  272.         tmpfs_dentry_t *tmp = dentry->parent->child;
  273.         while (tmp->sibling != dentry)
  274.             tmp = tmp->sibling;
  275.         tmp->sibling = dentry->sibling;
  276.     }
  277.     dentry->sibling = NULL;
  278.     dentry->parent = NULL;
  279.  
  280.     free(dentry->name);
  281.     dentry->name = NULL;
  282.  
  283.     dentry->lnkcnt--;
  284.  
  285.     return EOK;
  286. }
  287.  
  288. void tmpfs_destroy_node(void *nodep)
  289. {
  290.     tmpfs_dentry_t *dentry = (tmpfs_dentry_t *) nodep;
  291.    
  292.     assert(!dentry->lnkcnt);
  293.     assert(!dentry->child);
  294.     assert(!dentry->sibling);
  295.  
  296.     unsigned long index = dentry->index;
  297.     hash_table_remove(&dentries, &index, 1);
  298.  
  299.     if (dentry->type == TMPFS_FILE)
  300.         free(dentry->data);
  301.     free(dentry);
  302. }
  303.  
  304. void tmpfs_lookup(ipc_callid_t rid, ipc_call_t *request)
  305. {
  306.     /* Initialize TMPFS. */
  307.     if (!root && !tmpfs_init()) {
  308.         ipc_answer_0(rid, ENOMEM);
  309.         return;
  310.     }
  311.     libfs_lookup(&tmpfs_libfs_ops, tmpfs_reg.fs_handle, rid, request);
  312. }
  313.  
  314. void tmpfs_read(ipc_callid_t rid, ipc_call_t *request)
  315. {
  316.     int dev_handle = IPC_GET_ARG1(*request);
  317.     unsigned long index = IPC_GET_ARG2(*request);
  318.     off_t pos = IPC_GET_ARG3(*request);
  319.  
  320.     /*
  321.      * Lookup the respective dentry.
  322.      */
  323.     link_t *hlp;
  324.     hlp = hash_table_find(&dentries, &index);
  325.     if (!hlp) {
  326.         ipc_answer_0(rid, ENOENT);
  327.         return;
  328.     }
  329.     tmpfs_dentry_t *dentry = hash_table_get_instance(hlp, tmpfs_dentry_t,
  330.         dh_link);
  331.  
  332.     /*
  333.      * Receive the read request.
  334.      */
  335.     ipc_callid_t callid;
  336.     size_t len;
  337.     if (!ipc_data_read_receive(&callid, &len)) {
  338.         ipc_answer_0(callid, EINVAL);  
  339.         ipc_answer_0(rid, EINVAL);
  340.         return;
  341.     }
  342.  
  343.     size_t bytes;
  344.     if (dentry->type == TMPFS_FILE) {
  345.         bytes = max(0, min(dentry->size - pos, len));
  346.         (void) ipc_data_read_finalize(callid, dentry->data + pos,
  347.             bytes);
  348.     } else {
  349.         int i;
  350.         tmpfs_dentry_t *cur;
  351.        
  352.         assert(dentry->type == TMPFS_DIRECTORY);
  353.        
  354.         /*
  355.          * Yes, we really use O(n) algorithm here.
  356.          * If it bothers someone, it could be fixed by introducing a
  357.          * hash table.
  358.          */
  359.         for (i = 0, cur = dentry->child; i < pos && cur; i++,
  360.             cur = cur->sibling)
  361.             ;
  362.  
  363.         if (!cur) {
  364.             ipc_answer_0(callid, ENOENT);
  365.             ipc_answer_1(rid, ENOENT, 0);
  366.             return;
  367.         }
  368.  
  369.         (void) ipc_data_read_finalize(callid, cur->name,
  370.             strlen(cur->name) + 1);
  371.         bytes = 1;
  372.     }
  373.  
  374.     /*
  375.      * Answer the VFS_READ call.
  376.      */
  377.     ipc_answer_1(rid, EOK, bytes);
  378. }
  379.  
  380. void tmpfs_write(ipc_callid_t rid, ipc_call_t *request)
  381. {
  382.     int dev_handle = IPC_GET_ARG1(*request);
  383.     unsigned long index = IPC_GET_ARG2(*request);
  384.     off_t pos = IPC_GET_ARG3(*request);
  385.  
  386.     /*
  387.      * Lookup the respective dentry.
  388.      */
  389.     link_t *hlp;
  390.     hlp = hash_table_find(&dentries, &index);
  391.     if (!hlp) {
  392.         ipc_answer_0(rid, ENOENT);
  393.         return;
  394.     }
  395.     tmpfs_dentry_t *dentry = hash_table_get_instance(hlp, tmpfs_dentry_t,
  396.         dh_link);
  397.  
  398.     /*
  399.      * Receive the write request.
  400.      */
  401.     ipc_callid_t callid;
  402.     size_t len;
  403.     if (!ipc_data_write_receive(&callid, &len)) {
  404.         ipc_answer_0(callid, EINVAL);  
  405.         ipc_answer_0(rid, EINVAL);
  406.         return;
  407.     }
  408.  
  409.     /*
  410.      * Check whether the file needs to grow.
  411.      */
  412.     if (pos + len <= dentry->size) {
  413.         /* The file size is not changing. */
  414.         (void) ipc_data_write_finalize(callid, dentry->data + pos, len);
  415.         ipc_answer_2(rid, EOK, len, dentry->size);
  416.         return;
  417.     }
  418.     size_t delta = (pos + len) - dentry->size;
  419.     /*
  420.      * At this point, we are deliberately extremely straightforward and
  421.      * simply realloc the contents of the file on every write that grows the
  422.      * file. In the end, the situation might not be as bad as it may look:
  423.      * our heap allocator can save us and just grow the block whenever
  424.      * possible.
  425.      */
  426.     void *newdata = realloc(dentry->data, dentry->size + delta);
  427.     if (!newdata) {
  428.         ipc_answer_0(callid, ENOMEM);
  429.         ipc_answer_2(rid, EOK, 0, dentry->size);
  430.         return;
  431.     }
  432.     /* Clear any newly allocated memory in order to emulate gaps. */
  433.     memset(newdata + dentry->size, 0, delta);
  434.     dentry->size += delta;
  435.     dentry->data = newdata;
  436.     (void) ipc_data_write_finalize(callid, dentry->data + pos, len);
  437.     ipc_answer_2(rid, EOK, len, dentry->size);
  438. }
  439.  
  440. void tmpfs_truncate(ipc_callid_t rid, ipc_call_t *request)
  441. {
  442.     int dev_handle = IPC_GET_ARG1(*request);
  443.     unsigned long index = IPC_GET_ARG2(*request);
  444.     size_t size = IPC_GET_ARG3(*request);
  445.  
  446.     /*
  447.      * Lookup the respective dentry.
  448.      */
  449.     link_t *hlp;
  450.     hlp = hash_table_find(&dentries, &index);
  451.     if (!hlp) {
  452.         ipc_answer_0(rid, ENOENT);
  453.         return;
  454.     }
  455.     tmpfs_dentry_t *dentry = hash_table_get_instance(hlp, tmpfs_dentry_t,
  456.         dh_link);
  457.  
  458.     if (size == dentry->size) {
  459.         ipc_answer_0(rid, EOK);
  460.         return;
  461.     }
  462.  
  463.     void *newdata = realloc(dentry->data, size);
  464.     if (!newdata) {
  465.         ipc_answer_0(rid, ENOMEM);
  466.         return;
  467.     }
  468.     if (size > dentry->size) {
  469.         size_t delta = size - dentry->size;
  470.         memset(newdata + dentry->size, 0, delta);
  471.     }
  472.     dentry->size = size;
  473.     dentry->data = newdata;
  474.     ipc_answer_0(rid, EOK);
  475. }
  476.  
  477. void tmpfs_destroy(ipc_callid_t rid, ipc_call_t *request)
  478. {
  479.     int dev_handle = IPC_GET_ARG1(*request);
  480.     unsigned long index = IPC_GET_ARG2(*request);
  481.  
  482.     link_t *hlp;
  483.     hlp = hash_table_find(&dentries, &index);
  484.     if (!hlp) {
  485.         ipc_answer_0(rid, ENOENT);
  486.         return;
  487.     }
  488.     tmpfs_dentry_t *dentry = hash_table_get_instance(hlp, tmpfs_dentry_t,
  489.         dh_link);
  490.     tmpfs_destroy_node(dentry);
  491.     ipc_answer_0(rid, EOK);
  492. }
  493.  
  494. /**
  495.  * @}
  496.  */
  497.