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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. #define TMPFS_GET_INDEX(x)  (((tmpfs_dentry_t *)(x))->index)
  62. #define TMPFS_GET_LNKCNT(x) 1
  63.  
  64. /*
  65.  * Hash table of all directory entries.
  66.  */
  67. hash_table_t dentries;
  68.  
  69. static hash_index_t dentries_hash(unsigned long *key)
  70. {
  71.     return *key % DENTRIES_BUCKETS;
  72. }
  73.  
  74. static int dentries_compare(unsigned long *key, hash_count_t keys,
  75.     link_t *item)
  76. {
  77.     tmpfs_dentry_t *dentry = hash_table_get_instance(item, tmpfs_dentry_t,
  78.         dh_link);
  79.     return dentry->index == *key;
  80. }
  81.  
  82. static void dentries_remove_callback(link_t *item)
  83. {
  84. }
  85.  
  86. /** TMPFS dentries hash table operations. */
  87. hash_table_operations_t dentries_ops = {
  88.     .hash = dentries_hash,
  89.     .compare = dentries_compare,
  90.     .remove_callback = dentries_remove_callback
  91. };
  92.  
  93. unsigned tmpfs_next_index = 1;
  94.  
  95. static void tmpfs_dentry_initialize(tmpfs_dentry_t *dentry)
  96. {
  97.     dentry->index = 0;
  98.     dentry->parent = NULL;
  99.     dentry->sibling = NULL;
  100.     dentry->child = NULL;
  101.     dentry->name = NULL;
  102.     dentry->type = TMPFS_NONE;
  103.     dentry->size = 0;
  104.     dentry->data = NULL;
  105.     link_initialize(&dentry->dh_link);
  106. }
  107.  
  108. /*
  109.  * For now, we don't distinguish between different dev_handles/instances. All
  110.  * requests resolve to the only instance, rooted in the following variable.
  111.  */
  112. static tmpfs_dentry_t *root;
  113.  
  114. static bool tmpfs_init(void)
  115. {
  116.     if (!hash_table_create(&dentries, DENTRIES_BUCKETS, 1, &dentries_ops))
  117.         return false;
  118.  
  119.     root = (tmpfs_dentry_t *) malloc(sizeof(tmpfs_dentry_t));
  120.     if (!root)
  121.         return false;
  122.     tmpfs_dentry_initialize(root);
  123.     root->index = tmpfs_next_index++;
  124.     root->name = "";
  125.     root->type = TMPFS_DIRECTORY;
  126.     hash_table_insert(&dentries, &root->index, &root->dh_link);
  127.  
  128.     return true;
  129. }
  130.  
  131. /** Compare one component of path to a directory entry.
  132.  *
  133.  * @param nodep     Node to compare the path component with.
  134.  * @param component Array of characters holding component name.
  135.  *
  136.  * @return      True on match, false otherwise.
  137.  */
  138. static bool match_component(void *nodep, const char *component)
  139. {
  140.     tmpfs_dentry_t *dentry = (tmpfs_dentry_t *) nodep;
  141.  
  142.     return !strcmp(dentry->name, component);
  143. }
  144.  
  145. static void *create_node(void *nodep,
  146.     const char *component, int lflag)
  147. {
  148.     tmpfs_dentry_t *dentry = (tmpfs_dentry_t *) nodep;
  149.  
  150.     assert(dentry->type == TMPFS_DIRECTORY);
  151.     assert((lflag & L_FILE) ^ (lflag & L_DIRECTORY));
  152.  
  153.     tmpfs_dentry_t *node = malloc(sizeof(tmpfs_dentry_t));
  154.     if (!node)
  155.         return NULL;
  156.     size_t len = strlen(component);
  157.     char *name = malloc(len + 1);
  158.     if (!name) {
  159.         free(node);
  160.         return NULL;
  161.     }
  162.     strcpy(name, component);
  163.  
  164.     tmpfs_dentry_initialize(node);
  165.     node->index = tmpfs_next_index++;
  166.     node->name = name;
  167.     node->parent = dentry;
  168.     if (lflag & L_DIRECTORY)
  169.         node->type = TMPFS_DIRECTORY;
  170.     else
  171.         node->type = TMPFS_FILE;
  172.  
  173.     /* Insert the new node into the namespace. */
  174.     if (dentry->child) {
  175.         tmpfs_dentry_t *tmp = dentry->child;
  176.         while (tmp->sibling)
  177.             tmp = tmp->sibling;
  178.         tmp->sibling = node;
  179.     } else {
  180.         dentry->child = node;
  181.     }
  182.  
  183.     /* Insert the new node into the dentry hash table. */
  184.     hash_table_insert(&dentries, &node->index, &node->dh_link);
  185.     return (void *) node;
  186. }
  187.  
  188. static int destroy_component(void *nodeptr)
  189. {
  190.     tmpfs_dentry_t *dentry = (tmpfs_dentry_t *)nodeptr;
  191.  
  192.     if (dentry->child)
  193.         return ENOTEMPTY;
  194.  
  195.     if (!dentry->parent)
  196.         return EBUSY;
  197.  
  198.     if (dentry->parent->child == dentry) {
  199.         dentry->parent->child = dentry->sibling;
  200.     } else {
  201.         /* TODO: consider doubly linked list for organizing siblings. */
  202.         tmpfs_dentry_t *tmp = dentry->parent->child;
  203.         while (tmp->sibling != dentry)
  204.             tmp = tmp->sibling;
  205.         tmp->sibling = dentry->sibling;
  206.     }
  207.  
  208.     return EOK;
  209. }
  210.  
  211. void tmpfs_lookup(ipc_callid_t rid, ipc_call_t *request)
  212. {
  213.     unsigned next = IPC_GET_ARG1(*request);
  214.     unsigned last = IPC_GET_ARG2(*request);
  215.     int dev_handle = IPC_GET_ARG3(*request);
  216.     int lflag = IPC_GET_ARG4(*request);
  217.  
  218.     if (last < next)
  219.         last += PLB_SIZE;
  220.  
  221.     /*
  222.      * Initialize TMPFS.
  223.      */
  224.     if (!root && !tmpfs_init()) {
  225.         ipc_answer_0(rid, ENOMEM);
  226.         return;
  227.     }
  228.  
  229.     tmpfs_dentry_t *dtmp = root->child;
  230.     tmpfs_dentry_t *dcur = root;
  231.  
  232.     if (PLB_GET_CHAR(next) == '/')
  233.         next++;     /* eat slash */
  234.    
  235.     char component[NAME_MAX + 1];
  236.     int len = 0;
  237.     while (dtmp && next <= last) {
  238.  
  239.         /* collect the component */
  240.         if (PLB_GET_CHAR(next) != '/') {
  241.             if (len + 1 == NAME_MAX) {
  242.                 /* comopnent length overflow */
  243.                 ipc_answer_0(rid, ENAMETOOLONG);
  244.                 return;
  245.             }
  246.             component[len++] = PLB_GET_CHAR(next);
  247.             next++; /* process next character */
  248.             if (next <= last)
  249.                 continue;
  250.         }
  251.  
  252.         assert(len);
  253.         component[len] = '\0';
  254.         next++;     /* eat slash */
  255.         len = 0;
  256.  
  257.         /* match the component */
  258.         while (dtmp && !match_component(dtmp, component))
  259.             dtmp = dtmp->sibling;
  260.  
  261.         /* handle miss: match amongst siblings */
  262.         if (!dtmp) {
  263.             if ((next > last) && (lflag & L_CREATE)) {
  264.                 /* no components left and L_CREATE specified */
  265.                 if (dcur->type != TMPFS_DIRECTORY) {
  266.                     ipc_answer_0(rid, ENOTDIR);
  267.                     return;
  268.                 }
  269.                 void *nodep = create_node(dcur,
  270.                     component, lflag);
  271.                 if (nodep) {
  272.                     ipc_answer_5(rid, EOK,
  273.                         tmpfs_reg.fs_handle, dev_handle,
  274.                         TMPFS_GET_INDEX(nodep), 0,
  275.                         TMPFS_GET_LNKCNT(nodep));
  276.                 } else {
  277.                     ipc_answer_0(rid, ENOSPC);
  278.                 }
  279.                 return;
  280.             }
  281.             ipc_answer_0(rid, ENOENT);
  282.             return;
  283.         }
  284.  
  285.         /* descend one level */
  286.         dcur = dtmp;
  287.         dtmp = dtmp->child;
  288.     }
  289.  
  290.     /* handle miss: excessive components */
  291.     if (!dtmp && next <= last) {
  292.         if (lflag & L_CREATE) {
  293.             if (dcur->type != TMPFS_DIRECTORY) {
  294.                 ipc_answer_0(rid, ENOTDIR);
  295.                 return;
  296.             }
  297.  
  298.             /* collect next component */
  299.             while (next <= last) {
  300.                 if (PLB_GET_CHAR(next) == '/') {
  301.                     /* more than one component */
  302.                     ipc_answer_0(rid, ENOENT);
  303.                     return;
  304.                 }
  305.                 if (len + 1 == NAME_MAX) {
  306.                     /* component length overflow */
  307.                     ipc_answer_0(rid, ENAMETOOLONG);
  308.                     return;
  309.                 }
  310.                 component[len++] = PLB_GET_CHAR(next);
  311.                 next++; /* process next character */
  312.             }
  313.             assert(len);
  314.             component[len] = '\0';
  315.             len = 0;
  316.                
  317.             void *nodep = create_node(dcur, component, lflag);
  318.             if (nodep) {
  319.                 ipc_answer_5(rid, EOK, tmpfs_reg.fs_handle,
  320.                     dev_handle, TMPFS_GET_INDEX(nodep), 0,
  321.                     TMPFS_GET_LNKCNT(nodep));
  322.             } else {
  323.                 ipc_answer_0(rid, ENOSPC);
  324.             }
  325.             return;
  326.         }
  327.         ipc_answer_0(rid, ENOENT);
  328.         return;
  329.     }
  330.  
  331.     /* handle hit */
  332.     if (lflag & L_DESTROY) {
  333.         int res = destroy_component(dcur);
  334.         unsigned lnkcnt = (res == EOK) ? 0 : TMPFS_GET_LNKCNT(dcur);
  335.         ipc_answer_5(rid, (ipcarg_t)res, tmpfs_reg.fs_handle,
  336.             dev_handle, dcur->index, dcur->size, lnkcnt);
  337.         return;
  338.     }
  339.     if ((lflag & (L_CREATE | L_EXCLUSIVE)) == (L_CREATE | L_EXCLUSIVE)) {
  340.         ipc_answer_0(rid, EEXIST);
  341.         return;
  342.     }
  343.     if ((lflag & L_FILE) && (dcur->type != TMPFS_FILE)) {
  344.         ipc_answer_0(rid, EISDIR);
  345.         return;
  346.     }
  347.     if ((lflag & L_DIRECTORY) && (dcur->type != TMPFS_DIRECTORY)) {
  348.         ipc_answer_0(rid, ENOTDIR);
  349.         return;
  350.     }
  351.  
  352.     ipc_answer_5(rid, EOK, tmpfs_reg.fs_handle, dev_handle, dcur->index,
  353.         dcur->size, TMPFS_GET_LNKCNT(dcur));
  354. }
  355.  
  356. void tmpfs_read(ipc_callid_t rid, ipc_call_t *request)
  357. {
  358.     int dev_handle = IPC_GET_ARG1(*request);
  359.     unsigned long index = IPC_GET_ARG2(*request);
  360.     off_t pos = IPC_GET_ARG3(*request);
  361.  
  362.     /*
  363.      * Lookup the respective dentry.
  364.      */
  365.     link_t *hlp;
  366.     hlp = hash_table_find(&dentries, &index);
  367.     if (!hlp) {
  368.         ipc_answer_0(rid, ENOENT);
  369.         return;
  370.     }
  371.     tmpfs_dentry_t *dentry = hash_table_get_instance(hlp, tmpfs_dentry_t,
  372.         dh_link);
  373.  
  374.     /*
  375.      * Receive the read request.
  376.      */
  377.     ipc_callid_t callid;
  378.     size_t len;
  379.     if (!ipc_data_read_receive(&callid, &len)) {
  380.         ipc_answer_0(callid, EINVAL);  
  381.         ipc_answer_0(rid, EINVAL);
  382.         return;
  383.     }
  384.  
  385.     size_t bytes;
  386.     if (dentry->type == TMPFS_FILE) {
  387.         bytes = max(0, min(dentry->size - pos, len));
  388.         (void) ipc_data_read_finalize(callid, dentry->data + pos,
  389.             bytes);
  390.     } else {
  391.         int i;
  392.         tmpfs_dentry_t *cur = dentry->child;
  393.        
  394.         assert(dentry->type == TMPFS_DIRECTORY);
  395.        
  396.         /*
  397.          * Yes, we really use O(n) algorithm here.
  398.          * If it bothers someone, it could be fixed by introducing a
  399.          * hash table.
  400.          */
  401.         for (i = 0, cur = dentry->child; i < pos && cur; i++,
  402.             cur = cur->sibling)
  403.             ;
  404.  
  405.         if (!cur) {
  406.             ipc_answer_0(callid, ENOENT);
  407.             ipc_answer_1(rid, ENOENT, 0);
  408.             return;
  409.         }
  410.  
  411.         (void) ipc_data_read_finalize(callid, cur->name,
  412.             strlen(cur->name) + 1);
  413.         bytes = 1;
  414.     }
  415.  
  416.     /*
  417.      * Answer the VFS_READ call.
  418.      */
  419.     ipc_answer_1(rid, EOK, bytes);
  420. }
  421.  
  422. void tmpfs_write(ipc_callid_t rid, ipc_call_t *request)
  423. {
  424.     int dev_handle = IPC_GET_ARG1(*request);
  425.     unsigned long index = IPC_GET_ARG2(*request);
  426.     off_t pos = IPC_GET_ARG3(*request);
  427.  
  428.     /*
  429.      * Lookup the respective dentry.
  430.      */
  431.     link_t *hlp;
  432.     hlp = hash_table_find(&dentries, &index);
  433.     if (!hlp) {
  434.         ipc_answer_0(rid, ENOENT);
  435.         return;
  436.     }
  437.     tmpfs_dentry_t *dentry = hash_table_get_instance(hlp, tmpfs_dentry_t,
  438.         dh_link);
  439.  
  440.     /*
  441.      * Receive the write request.
  442.      */
  443.     ipc_callid_t callid;
  444.     size_t len;
  445.     if (!ipc_data_write_receive(&callid, &len)) {
  446.         ipc_answer_0(callid, EINVAL);  
  447.         ipc_answer_0(rid, EINVAL);
  448.         return;
  449.     }
  450.  
  451.     /*
  452.      * Check whether the file needs to grow.
  453.      */
  454.     if (pos + len <= dentry->size) {
  455.         /* The file size is not changing. */
  456.         (void) ipc_data_write_finalize(callid, dentry->data + pos, len);
  457.         ipc_answer_2(rid, EOK, len, dentry->size);
  458.         return;
  459.     }
  460.     size_t delta = (pos + len) - dentry->size;
  461.     /*
  462.      * At this point, we are deliberately extremely straightforward and
  463.      * simply realloc the contents of the file on every write that grows the
  464.      * file. In the end, the situation might not be as bad as it may look:
  465.      * our heap allocator can save us and just grow the block whenever
  466.      * possible.
  467.      */
  468.     void *newdata = realloc(dentry->data, dentry->size + delta);
  469.     if (!newdata) {
  470.         ipc_answer_0(callid, ENOMEM);
  471.         ipc_answer_2(rid, EOK, 0, dentry->size);
  472.         return;
  473.     }
  474.     /* Clear any newly allocated memory in order to emulate gaps. */
  475.     memset(newdata + dentry->size, 0, delta);
  476.     dentry->size += delta;
  477.     dentry->data = newdata;
  478.     (void) ipc_data_write_finalize(callid, dentry->data + pos, len);
  479.     ipc_answer_2(rid, EOK, len, dentry->size);
  480. }
  481.  
  482. void tmpfs_truncate(ipc_callid_t rid, ipc_call_t *request)
  483. {
  484.     int dev_handle = IPC_GET_ARG1(*request);
  485.     unsigned long index = IPC_GET_ARG2(*request);
  486.     size_t size = IPC_GET_ARG3(*request);
  487.  
  488.     /*
  489.      * Lookup the respective dentry.
  490.      */
  491.     link_t *hlp;
  492.     hlp = hash_table_find(&dentries, &index);
  493.     if (!hlp) {
  494.         ipc_answer_0(rid, ENOENT);
  495.         return;
  496.     }
  497.     tmpfs_dentry_t *dentry = hash_table_get_instance(hlp, tmpfs_dentry_t,
  498.         dh_link);
  499.  
  500.     if (size == dentry->size) {
  501.         ipc_answer_0(rid, EOK);
  502.         return;
  503.     }
  504.  
  505.     void *newdata = realloc(dentry->data, size);
  506.     if (!newdata) {
  507.         ipc_answer_0(rid, ENOMEM);
  508.         return;
  509.     }
  510.     if (size > dentry->size) {
  511.         size_t delta = size - dentry->size;
  512.         memset(newdata + dentry->size, 0, delta);
  513.     }
  514.     dentry->size = size;
  515.     dentry->data = newdata;
  516.     ipc_answer_0(rid, EOK);
  517. }
  518.  
  519. void tmpfs_free(ipc_callid_t rid, ipc_call_t *request)
  520. {
  521.     int dev_handle = IPC_GET_ARG1(*request);
  522.     unsigned long index = IPC_GET_ARG2(*request);
  523.  
  524.     link_t *hlp;
  525.     hlp = hash_table_find(&dentries, &index);
  526.     if (!hlp) {
  527.         ipc_answer_0(rid, ENOENT);
  528.         return;
  529.     }
  530.     tmpfs_dentry_t *dentry = hash_table_get_instance(hlp, tmpfs_dentry_t,
  531.         dh_link);
  532.    
  533.     assert(!dentry->parent);
  534.     assert(!dentry->child);
  535.     assert(!dentry->sibling);
  536.  
  537.     hash_table_remove(&dentries, &index, 1);
  538.  
  539.     if (dentry->type == TMPFS_FILE)
  540.         free(dentry->data);
  541.     free(dentry->name);
  542.     free(dentry);
  543.  
  544.     ipc_answer_0(rid, EOK);
  545. }
  546.  
  547. /**
  548.  * @}
  549.  */
  550.