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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 <dirent.h>
  49. #include <assert.h>
  50. #include <sys/types.h>
  51. #include <libadt/hash_table.h>
  52. #include <as.h>
  53.  
  54. #define min(a, b)       ((a) < (b) ? (a) : (b))
  55. #define max(a, b)       ((a) > (b) ? (a) : (b))
  56.  
  57. #define PLB_GET_CHAR(i)     (tmpfs_reg.plb_ro[(i) % PLB_SIZE])
  58.  
  59. #define DENTRIES_BUCKETS    256
  60.  
  61. /*
  62.  * Hash table of all directory entries.
  63.  */
  64. hash_table_t dentries;
  65.  
  66. static hash_index_t dentries_hash(unsigned long *key)
  67. {
  68.     return *key % DENTRIES_BUCKETS;
  69. }
  70.  
  71. static int dentries_compare(unsigned long *key, hash_count_t keys,
  72.     link_t *item)
  73. {
  74.     tmpfs_dentry_t *dentry = hash_table_get_instance(item, tmpfs_dentry_t,
  75.         dh_link);
  76.     return dentry->index == *key;
  77. }
  78.  
  79. static void dentries_remove_callback(link_t *item)
  80. {
  81. }
  82.  
  83. /** TMPFS dentries hash table operations. */
  84. hash_table_operations_t dentries_ops = {
  85.     .hash = dentries_hash,
  86.     .compare = dentries_compare,
  87.     .remove_callback = dentries_remove_callback
  88. };
  89.  
  90. unsigned tmpfs_next_index = 1;
  91.  
  92. static void tmpfs_dentry_initialize(tmpfs_dentry_t *dentry)
  93. {
  94.     dentry->index = 0;
  95.     dentry->parent = NULL;
  96.     dentry->sibling = NULL;
  97.     dentry->child = NULL;
  98.     dentry->name = NULL;
  99.     dentry->type = TMPFS_NONE;
  100.     dentry->size = 0;
  101.     dentry->data = NULL;
  102.     link_initialize(&dentry->dh_link);
  103. }
  104.  
  105. /*
  106.  * For now, we don't distinguish between different dev_handles/instances. All
  107.  * requests resolve to the only instance, rooted in the following variable.
  108.  */
  109. static tmpfs_dentry_t *root;
  110.  
  111. static bool tmpfs_init(void)
  112. {
  113.     if (!hash_table_create(&dentries, DENTRIES_BUCKETS, 1, &dentries_ops))
  114.         return false;
  115.  
  116.     root = (tmpfs_dentry_t *) malloc(sizeof(tmpfs_dentry_t));
  117.     if (!root)
  118.         return false;
  119.     tmpfs_dentry_initialize(root);
  120.     root->index = tmpfs_next_index++;
  121.     root->name = "";
  122.     root->type = TMPFS_DIRECTORY;
  123.     hash_table_insert(&dentries, &root->index, &root->dh_link);
  124.  
  125.     return true;
  126. }
  127.  
  128. /** Compare one component of path to a directory entry.
  129.  *
  130.  * @param dentry    Directory entry to compare the path component with.
  131.  * @param component Array of characters holding component name.
  132.  *
  133.  * @return      True on match, false otherwise.
  134.  */
  135. static bool match_component(tmpfs_dentry_t *dentry, const char *component)
  136. {
  137.     return !strcmp(dentry->name, component);
  138. }
  139.  
  140. static unsigned long create_node(tmpfs_dentry_t *dentry,
  141.     const char *component, int lflag)
  142. {
  143.     assert(dentry->type == TMPFS_DIRECTORY);
  144.     assert((lflag & L_FILE) ^ (lflag & L_DIRECTORY));
  145.  
  146.     tmpfs_dentry_t *node = malloc(sizeof(tmpfs_dentry_t));
  147.     if (!node)
  148.         return 0;
  149.     size_t len = strlen(component);
  150.     char *name = malloc(len + 1);
  151.     if (!name) {
  152.         free(node);
  153.         return 0;
  154.     }
  155.     strcpy(name, component);
  156.  
  157.     tmpfs_dentry_initialize(node);
  158.     node->index = tmpfs_next_index++;
  159.     node->name = name;
  160.     node->parent = dentry;
  161.     if (lflag & L_DIRECTORY)
  162.         node->type = TMPFS_DIRECTORY;
  163.     else
  164.         node->type = TMPFS_FILE;
  165.  
  166.     /* Insert the new node into the namespace. */
  167.     if (dentry->child) {
  168.         tmpfs_dentry_t *tmp = dentry->child;
  169.         while (tmp->sibling)
  170.             tmp = tmp->sibling;
  171.         tmp->sibling = node;
  172.     } else {
  173.         dentry->child = node;
  174.     }
  175.  
  176.     /* Insert the new node into the dentry hash table. */
  177.     hash_table_insert(&dentries, &node->index, &node->dh_link);
  178.     return node->index;
  179. }
  180.  
  181. static int destroy_component(tmpfs_dentry_t *dentry)
  182. {
  183.     return EPERM;
  184. }
  185.  
  186. void tmpfs_lookup(ipc_callid_t rid, ipc_call_t *request)
  187. {
  188.     unsigned next = IPC_GET_ARG1(*request);
  189.     unsigned last = IPC_GET_ARG2(*request);
  190.     int dev_handle = IPC_GET_ARG3(*request);
  191.     int lflag = IPC_GET_ARG4(*request);
  192.  
  193.     if (last < next)
  194.         last += PLB_SIZE;
  195.  
  196.     /*
  197.      * Initialize TMPFS.
  198.      */
  199.     if (!root && !tmpfs_init()) {
  200.         ipc_answer_0(rid, ENOMEM);
  201.         return;
  202.     }
  203.  
  204.     tmpfs_dentry_t *dtmp = root->child;
  205.     tmpfs_dentry_t *dcur = root;
  206.  
  207.     if (PLB_GET_CHAR(next) == '/')
  208.         next++;     /* eat slash */
  209.    
  210.     char component[NAME_MAX + 1];
  211.     int len = 0;
  212.     while (dtmp && next <= last) {
  213.  
  214.         /* collect the component */
  215.         if (PLB_GET_CHAR(next) != '/') {
  216.             if (len + 1 == NAME_MAX) {
  217.                 /* comopnent length overflow */
  218.                 ipc_answer_0(rid, ENAMETOOLONG);
  219.                 return;
  220.             }
  221.             component[len++] = PLB_GET_CHAR(next);
  222.             next++; /* process next character */
  223.             if (next <= last)
  224.                 continue;
  225.         }
  226.  
  227.         assert(len);
  228.         component[len] = '\0';
  229.         next++;     /* eat slash */
  230.         len = 0;
  231.  
  232.         /* match the component */
  233.         while (dtmp && !match_component(dtmp, component))
  234.             dtmp = dtmp->sibling;
  235.  
  236.         /* handle miss: match amongst siblings */
  237.         if (!dtmp) {
  238.             if ((next > last) && (lflag & L_CREATE)) {
  239.                 /* no components left and L_CREATE specified */
  240.                 if (dcur->type != TMPFS_DIRECTORY) {
  241.                     ipc_answer_0(rid, ENOTDIR);
  242.                     return;
  243.                 }
  244.                 unsigned long index = create_node(dcur,
  245.                     component, lflag);
  246.                 if (index > 0) {
  247.                     ipc_answer_4(rid, EOK,
  248.                         tmpfs_reg.fs_handle, dev_handle,
  249.                         index, 0);
  250.                 } else {
  251.                     ipc_answer_0(rid, ENOSPC);
  252.                 }
  253.                 return;
  254.             }
  255.             ipc_answer_0(rid, ENOENT);
  256.             return;
  257.         }
  258.  
  259.         /* descent one level */
  260.         dcur = dtmp;
  261.         dtmp = dtmp->child;
  262.     }
  263.  
  264.     /* handle miss: excessive components */
  265.     if (!dtmp && next <= last) {
  266.         if (lflag & L_CREATE) {
  267.             if (dcur->type != TMPFS_DIRECTORY) {
  268.                 ipc_answer_0(rid, ENOTDIR);
  269.                 return;
  270.             }
  271.  
  272.             /* collect next component */
  273.             while (next <= last) {
  274.                 if (PLB_GET_CHAR(next) == '/') {
  275.                     /* more than one component */
  276.                     ipc_answer_0(rid, ENOENT);
  277.                     return;
  278.                 }
  279.                 if (len + 1 == NAME_MAX) {
  280.                     /* component length overflow */
  281.                     ipc_answer_0(rid, ENAMETOOLONG);
  282.                     return;
  283.                 }
  284.                 component[len++] = PLB_GET_CHAR(next);
  285.                 next++; /* process next character */
  286.             }
  287.             assert(len);
  288.             component[len] = '\0';
  289.             len = 0;
  290.                
  291.             unsigned long index;
  292.             index = create_node(dcur, component, lflag);
  293.             if (index) {
  294.                 ipc_answer_4(rid, EOK, tmpfs_reg.fs_handle,
  295.                     dev_handle, index, 0);
  296.             } else {
  297.                 ipc_answer_0(rid, ENOSPC);
  298.             }
  299.             return;
  300.         }
  301.         ipc_answer_0(rid, ENOENT);
  302.         return;
  303.     }
  304.  
  305.     /* handle hit */
  306.     if (lflag & L_DESTROY) {
  307.         int res = destroy_component(dcur);
  308.         ipc_answer_0(rid, res);
  309.         return;
  310.     }
  311.     if ((lflag & (L_CREATE | L_EXCLUSIVE)) == (L_CREATE | L_EXCLUSIVE)) {
  312.         ipc_answer_0(rid, EEXIST);
  313.         return;
  314.     }
  315.     if ((lflag & L_FILE) && (dcur->type != TMPFS_FILE)) {
  316.         ipc_answer_0(rid, EISDIR);
  317.         return;
  318.     }
  319.     if ((lflag & L_DIRECTORY) && (dcur->type != TMPFS_DIRECTORY)) {
  320.         ipc_answer_0(rid, ENOTDIR);
  321.         return;
  322.     }
  323.  
  324.     ipc_answer_4(rid, EOK, tmpfs_reg.fs_handle, dev_handle, dcur->index,
  325.         dcur->size);
  326. }
  327.  
  328. void tmpfs_read(ipc_callid_t rid, ipc_call_t *request)
  329. {
  330.     int dev_handle = IPC_GET_ARG1(*request);
  331.     unsigned long index = IPC_GET_ARG2(*request);
  332.     off_t pos = IPC_GET_ARG3(*request);
  333.  
  334.     /*
  335.      * Lookup the respective dentry.
  336.      */
  337.     link_t *hlp;
  338.     hlp = hash_table_find(&dentries, &index);
  339.     if (!hlp) {
  340.         ipc_answer_0(rid, ENOENT);
  341.         return;
  342.     }
  343.     tmpfs_dentry_t *dentry = hash_table_get_instance(hlp, tmpfs_dentry_t,
  344.         dh_link);
  345.  
  346.     /*
  347.      * Receive the read request.
  348.      */
  349.     ipc_callid_t callid;
  350.     size_t len;
  351.     if (!ipc_data_read_receive(&callid, &len)) {
  352.         ipc_answer_0(callid, EINVAL);  
  353.         ipc_answer_0(rid, EINVAL);
  354.         return;
  355.     }
  356.  
  357.     size_t bytes;
  358.     if (dentry->type == TMPFS_FILE) {
  359.         bytes = max(0, min(dentry->size - pos, len));
  360.         (void) ipc_data_read_finalize(callid, dentry->data + pos,
  361.             bytes);
  362.     } else {
  363.         int i;
  364.         tmpfs_dentry_t *cur = dentry->child;
  365.        
  366.         assert(dentry->type == TMPFS_DIRECTORY);
  367.        
  368.         /*
  369.          * Yes, we really use O(n) algorithm here.
  370.          * If it bothers someone, it could be fixed by introducing a
  371.          * hash table.
  372.          */
  373.         for (i = 0, cur = dentry->child; i < pos && cur; i++,
  374.             cur = cur->sibling)
  375.             ;
  376.  
  377.         if (!cur) {
  378.             ipc_answer_0(callid, ENOENT);
  379.             ipc_answer_1(rid, ENOENT, 0);
  380.             return;
  381.         }
  382.  
  383.         (void) ipc_data_read_finalize(callid, cur->name,
  384.             strlen(cur->name) + 1);
  385.         bytes = 1;
  386.     }
  387.  
  388.     /*
  389.      * Answer the VFS_READ call.
  390.      */
  391.     ipc_answer_1(rid, EOK, bytes);
  392. }
  393.  
  394. void tmpfs_write(ipc_callid_t rid, ipc_call_t *request)
  395. {
  396.     int dev_handle = IPC_GET_ARG1(*request);
  397.     unsigned long index = IPC_GET_ARG2(*request);
  398.     off_t pos = IPC_GET_ARG3(*request);
  399.  
  400.     /*
  401.      * Lookup the respective dentry.
  402.      */
  403.     link_t *hlp;
  404.     hlp = hash_table_find(&dentries, &index);
  405.     if (!hlp) {
  406.         ipc_answer_0(rid, ENOENT);
  407.         return;
  408.     }
  409.     tmpfs_dentry_t *dentry = hash_table_get_instance(hlp, tmpfs_dentry_t,
  410.         dh_link);
  411.  
  412.     /*
  413.      * Receive the write request.
  414.      */
  415.     ipc_callid_t callid;
  416.     size_t len;
  417.     if (!ipc_data_write_receive(&callid, &len)) {
  418.         ipc_answer_0(callid, EINVAL);  
  419.         ipc_answer_0(rid, EINVAL);
  420.         return;
  421.     }
  422.  
  423.     /*
  424.      * Check whether the file needs to grow.
  425.      */
  426.     if (pos + len <= dentry->size) {
  427.         /* The file size is not changing. */
  428.         (void) ipc_data_write_finalize(callid, dentry->data + pos, len);
  429.         ipc_answer_2(rid, EOK, len, dentry->size);
  430.         return;
  431.     }
  432.     size_t delta = (pos + len) - dentry->size;
  433.     /*
  434.      * At this point, we are deliberately extremely straightforward and
  435.      * simply realloc the contents of the file on every write that grows the
  436.      * file. In the end, the situation might not be as bad as it may look:
  437.      * our heap allocator can save us and just grow the block whenever
  438.      * possible.
  439.      */
  440.     void *newdata = realloc(dentry->data, dentry->size + delta);
  441.     if (!newdata) {
  442.         ipc_answer_0(callid, ENOMEM);
  443.         ipc_answer_2(rid, EOK, 0, dentry->size);
  444.         return;
  445.     }
  446.     /* Clear any newly allocated memory in order to emulate gaps. */
  447.     memset(newdata + dentry->size, 0, delta);
  448.     dentry->size += delta;
  449.     dentry->data = newdata;
  450.     (void) ipc_data_write_finalize(callid, dentry->data + pos, len);
  451.     ipc_answer_2(rid, EOK, len, dentry->size);
  452. }
  453.  
  454. void tmpfs_truncate(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.     size_t size = 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.     if (size == dentry->size) {
  473.         ipc_answer_0(rid, EOK);
  474.         return;
  475.     }
  476.  
  477.     void *newdata = realloc(dentry->data, size);
  478.     if (!newdata) {
  479.         ipc_answer_0(rid, ENOMEM);
  480.         return;
  481.     }
  482.     if (size > dentry->size) {
  483.         size_t delta = size - dentry->size;
  484.         memset(newdata + dentry->size, 0, delta);
  485.     }
  486.     dentry->size = size;
  487.     dentry->data = newdata;
  488.     ipc_answer_0(rid, EOK);
  489. }
  490.  
  491. /**
  492.  * @}
  493.  */
  494.