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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.     return root != NULL;
  190. }
  191.  
  192. /** Compare one component of path to a directory entry.
  193.  *
  194.  * @param nodep     Node to compare the path component with.
  195.  * @param component Array of characters holding component name.
  196.  *
  197.  * @return      True on match, false otherwise.
  198.  */
  199. bool tmpfs_match(void *nodep, const char *component)
  200. {
  201.     tmpfs_dentry_t *dentry = (tmpfs_dentry_t *) nodep;
  202.  
  203.     return !strcmp(dentry->name, component);
  204. }
  205.  
  206. void *tmpfs_create_node(int lflag)
  207. {
  208.     assert((lflag & L_FILE) ^ (lflag & L_DIRECTORY));
  209.  
  210.     tmpfs_dentry_t *node = malloc(sizeof(tmpfs_dentry_t));
  211.     if (!node)
  212.         return NULL;
  213.  
  214.     tmpfs_dentry_initialize(node);
  215.     node->index = tmpfs_next_index++;
  216.     if (lflag & L_DIRECTORY)
  217.         node->type = TMPFS_DIRECTORY;
  218.     else
  219.         node->type = TMPFS_FILE;
  220.  
  221.     /* Insert the new node into the dentry hash table. */
  222.     hash_table_insert(&dentries, &node->index, &node->dh_link);
  223.     return (void *) node;
  224. }
  225.  
  226. bool tmpfs_link_node(void *prnt, void *chld, const char *nm)
  227. {
  228.     tmpfs_dentry_t *parentp = (tmpfs_dentry_t *) prnt;
  229.     tmpfs_dentry_t *childp = (tmpfs_dentry_t *) chld;
  230.  
  231.     assert(parentp->type == TMPFS_DIRECTORY);
  232.  
  233.     size_t len = strlen(nm);
  234.     char *name = malloc(len + 1);
  235.     if (!name)
  236.         return false;
  237.    
  238.     childp->lnkcnt++;
  239.    
  240.     strcpy(name, nm);
  241.     childp->name = name;
  242.  
  243.     /* Insert the new node into the namespace. */
  244.     if (parentp->child) {
  245.         tmpfs_dentry_t *tmp = parentp->child;
  246.         while (tmp->sibling)
  247.             tmp = tmp->sibling;
  248.         tmp->sibling = childp;
  249.     } else {
  250.         parentp->child = childp;
  251.     }
  252.     childp->parent = parentp;
  253.  
  254.     return true;
  255. }
  256.  
  257. int tmpfs_unlink_node(void *nodeptr)
  258. {
  259.     tmpfs_dentry_t *dentry = (tmpfs_dentry_t *)nodeptr;
  260.  
  261.     if (dentry->child)
  262.         return ENOTEMPTY;
  263.  
  264.     if (!dentry->parent)
  265.         return EBUSY;
  266.  
  267.     if (dentry->parent->child == dentry) {
  268.         dentry->parent->child = dentry->sibling;
  269.     } else {
  270.         /* TODO: consider doubly linked list for organizing siblings. */
  271.         tmpfs_dentry_t *tmp = dentry->parent->child;
  272.         while (tmp->sibling != dentry)
  273.             tmp = tmp->sibling;
  274.         tmp->sibling = dentry->sibling;
  275.     }
  276.     dentry->sibling = NULL;
  277.     dentry->parent = NULL;
  278.  
  279.     free(dentry->name);
  280.     dentry->name = NULL;
  281.  
  282.     dentry->lnkcnt--;
  283.  
  284.     return EOK;
  285. }
  286.  
  287. void tmpfs_destroy_node(void *nodep)
  288. {
  289.     tmpfs_dentry_t *dentry = (tmpfs_dentry_t *) nodep;
  290.    
  291.     assert(!dentry->lnkcnt);
  292.     assert(!dentry->child);
  293.     assert(!dentry->sibling);
  294.  
  295.     unsigned long index = dentry->index;
  296.     hash_table_remove(&dentries, &index, 1);
  297.  
  298.     if (dentry->type == TMPFS_FILE)
  299.         free(dentry->data);
  300.     free(dentry);
  301. }
  302.  
  303. void tmpfs_lookup(ipc_callid_t rid, ipc_call_t *request)
  304. {
  305.     /* Initialize TMPFS. */
  306.     if (!root && !tmpfs_init()) {
  307.         ipc_answer_0(rid, ENOMEM);
  308.         return;
  309.     }
  310.     libfs_lookup(&tmpfs_libfs_ops, tmpfs_reg.fs_handle, rid, request);
  311. }
  312.  
  313. void tmpfs_read(ipc_callid_t rid, ipc_call_t *request)
  314. {
  315.     int dev_handle = IPC_GET_ARG1(*request);
  316.     unsigned long index = IPC_GET_ARG2(*request);
  317.     off_t pos = IPC_GET_ARG3(*request);
  318.  
  319.     /*
  320.      * Lookup the respective dentry.
  321.      */
  322.     link_t *hlp;
  323.     hlp = hash_table_find(&dentries, &index);
  324.     if (!hlp) {
  325.         ipc_answer_0(rid, ENOENT);
  326.         return;
  327.     }
  328.     tmpfs_dentry_t *dentry = hash_table_get_instance(hlp, tmpfs_dentry_t,
  329.         dh_link);
  330.  
  331.     /*
  332.      * Receive the read request.
  333.      */
  334.     ipc_callid_t callid;
  335.     size_t len;
  336.     if (!ipc_data_read_receive(&callid, &len)) {
  337.         ipc_answer_0(callid, EINVAL);  
  338.         ipc_answer_0(rid, EINVAL);
  339.         return;
  340.     }
  341.  
  342.     size_t bytes;
  343.     if (dentry->type == TMPFS_FILE) {
  344.         bytes = max(0, min(dentry->size - pos, len));
  345.         (void) ipc_data_read_finalize(callid, dentry->data + pos,
  346.             bytes);
  347.     } else {
  348.         int i;
  349.         tmpfs_dentry_t *cur;
  350.        
  351.         assert(dentry->type == TMPFS_DIRECTORY);
  352.        
  353.         /*
  354.          * Yes, we really use O(n) algorithm here.
  355.          * If it bothers someone, it could be fixed by introducing a
  356.          * hash table.
  357.          */
  358.         for (i = 0, cur = dentry->child; i < pos && cur; i++,
  359.             cur = cur->sibling)
  360.             ;
  361.  
  362.         if (!cur) {
  363.             ipc_answer_0(callid, ENOENT);
  364.             ipc_answer_1(rid, ENOENT, 0);
  365.             return;
  366.         }
  367.  
  368.         (void) ipc_data_read_finalize(callid, cur->name,
  369.             strlen(cur->name) + 1);
  370.         bytes = 1;
  371.     }
  372.  
  373.     /*
  374.      * Answer the VFS_READ call.
  375.      */
  376.     ipc_answer_1(rid, EOK, bytes);
  377. }
  378.  
  379. void tmpfs_write(ipc_callid_t rid, ipc_call_t *request)
  380. {
  381.     int dev_handle = IPC_GET_ARG1(*request);
  382.     unsigned long index = IPC_GET_ARG2(*request);
  383.     off_t pos = IPC_GET_ARG3(*request);
  384.  
  385.     /*
  386.      * Lookup the respective dentry.
  387.      */
  388.     link_t *hlp;
  389.     hlp = hash_table_find(&dentries, &index);
  390.     if (!hlp) {
  391.         ipc_answer_0(rid, ENOENT);
  392.         return;
  393.     }
  394.     tmpfs_dentry_t *dentry = hash_table_get_instance(hlp, tmpfs_dentry_t,
  395.         dh_link);
  396.  
  397.     /*
  398.      * Receive the write request.
  399.      */
  400.     ipc_callid_t callid;
  401.     size_t len;
  402.     if (!ipc_data_write_receive(&callid, &len)) {
  403.         ipc_answer_0(callid, EINVAL);  
  404.         ipc_answer_0(rid, EINVAL);
  405.         return;
  406.     }
  407.  
  408.     /*
  409.      * Check whether the file needs to grow.
  410.      */
  411.     if (pos + len <= dentry->size) {
  412.         /* The file size is not changing. */
  413.         (void) ipc_data_write_finalize(callid, dentry->data + pos, len);
  414.         ipc_answer_2(rid, EOK, len, dentry->size);
  415.         return;
  416.     }
  417.     size_t delta = (pos + len) - dentry->size;
  418.     /*
  419.      * At this point, we are deliberately extremely straightforward and
  420.      * simply realloc the contents of the file on every write that grows the
  421.      * file. In the end, the situation might not be as bad as it may look:
  422.      * our heap allocator can save us and just grow the block whenever
  423.      * possible.
  424.      */
  425.     void *newdata = realloc(dentry->data, dentry->size + delta);
  426.     if (!newdata) {
  427.         ipc_answer_0(callid, ENOMEM);
  428.         ipc_answer_2(rid, EOK, 0, dentry->size);
  429.         return;
  430.     }
  431.     /* Clear any newly allocated memory in order to emulate gaps. */
  432.     memset(newdata + dentry->size, 0, delta);
  433.     dentry->size += delta;
  434.     dentry->data = newdata;
  435.     (void) ipc_data_write_finalize(callid, dentry->data + pos, len);
  436.     ipc_answer_2(rid, EOK, len, dentry->size);
  437. }
  438.  
  439. void tmpfs_truncate(ipc_callid_t rid, ipc_call_t *request)
  440. {
  441.     int dev_handle = IPC_GET_ARG1(*request);
  442.     unsigned long index = IPC_GET_ARG2(*request);
  443.     size_t size = IPC_GET_ARG3(*request);
  444.  
  445.     /*
  446.      * Lookup the respective dentry.
  447.      */
  448.     link_t *hlp;
  449.     hlp = hash_table_find(&dentries, &index);
  450.     if (!hlp) {
  451.         ipc_answer_0(rid, ENOENT);
  452.         return;
  453.     }
  454.     tmpfs_dentry_t *dentry = hash_table_get_instance(hlp, tmpfs_dentry_t,
  455.         dh_link);
  456.  
  457.     if (size == dentry->size) {
  458.         ipc_answer_0(rid, EOK);
  459.         return;
  460.     }
  461.  
  462.     void *newdata = realloc(dentry->data, size);
  463.     if (!newdata) {
  464.         ipc_answer_0(rid, ENOMEM);
  465.         return;
  466.     }
  467.     if (size > dentry->size) {
  468.         size_t delta = size - dentry->size;
  469.         memset(newdata + dentry->size, 0, delta);
  470.     }
  471.     dentry->size = size;
  472.     dentry->data = newdata;
  473.     ipc_answer_0(rid, EOK);
  474. }
  475.  
  476. void tmpfs_destroy(ipc_callid_t rid, ipc_call_t *request)
  477. {
  478.     int dev_handle = IPC_GET_ARG1(*request);
  479.     unsigned long index = IPC_GET_ARG2(*request);
  480.  
  481.     link_t *hlp;
  482.     hlp = hash_table_find(&dentries, &index);
  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.     tmpfs_destroy_node(dentry);
  490.     ipc_answer_0(rid, EOK);
  491. }
  492.  
  493. /**
  494.  * @}
  495.  */
  496.