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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.     return EPERM;
  191. }
  192.  
  193. void tmpfs_lookup(ipc_callid_t rid, ipc_call_t *request)
  194. {
  195.     unsigned next = IPC_GET_ARG1(*request);
  196.     unsigned last = IPC_GET_ARG2(*request);
  197.     int dev_handle = IPC_GET_ARG3(*request);
  198.     int lflag = IPC_GET_ARG4(*request);
  199.  
  200.     if (last < next)
  201.         last += PLB_SIZE;
  202.  
  203.     /*
  204.      * Initialize TMPFS.
  205.      */
  206.     if (!root && !tmpfs_init()) {
  207.         ipc_answer_0(rid, ENOMEM);
  208.         return;
  209.     }
  210.  
  211.     tmpfs_dentry_t *dtmp = root->child;
  212.     tmpfs_dentry_t *dcur = root;
  213.  
  214.     if (PLB_GET_CHAR(next) == '/')
  215.         next++;     /* eat slash */
  216.    
  217.     char component[NAME_MAX + 1];
  218.     int len = 0;
  219.     while (dtmp && next <= last) {
  220.  
  221.         /* collect the component */
  222.         if (PLB_GET_CHAR(next) != '/') {
  223.             if (len + 1 == NAME_MAX) {
  224.                 /* comopnent length overflow */
  225.                 ipc_answer_0(rid, ENAMETOOLONG);
  226.                 return;
  227.             }
  228.             component[len++] = PLB_GET_CHAR(next);
  229.             next++; /* process next character */
  230.             if (next <= last)
  231.                 continue;
  232.         }
  233.  
  234.         assert(len);
  235.         component[len] = '\0';
  236.         next++;     /* eat slash */
  237.         len = 0;
  238.  
  239.         /* match the component */
  240.         while (dtmp && !match_component(dtmp, component))
  241.             dtmp = dtmp->sibling;
  242.  
  243.         /* handle miss: match amongst siblings */
  244.         if (!dtmp) {
  245.             if ((next > last) && (lflag & L_CREATE)) {
  246.                 /* no components left and L_CREATE specified */
  247.                 if (dcur->type != TMPFS_DIRECTORY) {
  248.                     ipc_answer_0(rid, ENOTDIR);
  249.                     return;
  250.                 }
  251.                 void *nodep = create_node(dcur,
  252.                     component, lflag);
  253.                 if (nodep) {
  254.                     ipc_answer_5(rid, EOK,
  255.                         tmpfs_reg.fs_handle, dev_handle,
  256.                         TMPFS_GET_INDEX(nodep), 0,
  257.                         TMPFS_GET_LNKCNT(nodep));
  258.                 } else {
  259.                     ipc_answer_0(rid, ENOSPC);
  260.                 }
  261.                 return;
  262.             }
  263.             ipc_answer_0(rid, ENOENT);
  264.             return;
  265.         }
  266.  
  267.         /* descend one level */
  268.         dcur = dtmp;
  269.         dtmp = dtmp->child;
  270.     }
  271.  
  272.     /* handle miss: excessive components */
  273.     if (!dtmp && next <= last) {
  274.         if (lflag & L_CREATE) {
  275.             if (dcur->type != TMPFS_DIRECTORY) {
  276.                 ipc_answer_0(rid, ENOTDIR);
  277.                 return;
  278.             }
  279.  
  280.             /* collect next component */
  281.             while (next <= last) {
  282.                 if (PLB_GET_CHAR(next) == '/') {
  283.                     /* more than one component */
  284.                     ipc_answer_0(rid, ENOENT);
  285.                     return;
  286.                 }
  287.                 if (len + 1 == NAME_MAX) {
  288.                     /* component length overflow */
  289.                     ipc_answer_0(rid, ENAMETOOLONG);
  290.                     return;
  291.                 }
  292.                 component[len++] = PLB_GET_CHAR(next);
  293.                 next++; /* process next character */
  294.             }
  295.             assert(len);
  296.             component[len] = '\0';
  297.             len = 0;
  298.                
  299.             void *nodep = create_node(dcur, component, lflag);
  300.             if (nodep) {
  301.                 ipc_answer_5(rid, EOK, tmpfs_reg.fs_handle,
  302.                     dev_handle, TMPFS_GET_INDEX(nodep), 0,
  303.                     TMPFS_GET_LNKCNT(nodep));
  304.             } else {
  305.                 ipc_answer_0(rid, ENOSPC);
  306.             }
  307.             return;
  308.         }
  309.         ipc_answer_0(rid, ENOENT);
  310.         return;
  311.     }
  312.  
  313.     /* handle hit */
  314.     if (lflag & L_DESTROY) {
  315.         int res = destroy_component(dcur);
  316.         ipc_answer_0(rid, res);
  317.         return;
  318.     }
  319.     if ((lflag & (L_CREATE | L_EXCLUSIVE)) == (L_CREATE | L_EXCLUSIVE)) {
  320.         ipc_answer_0(rid, EEXIST);
  321.         return;
  322.     }
  323.     if ((lflag & L_FILE) && (dcur->type != TMPFS_FILE)) {
  324.         ipc_answer_0(rid, EISDIR);
  325.         return;
  326.     }
  327.     if ((lflag & L_DIRECTORY) && (dcur->type != TMPFS_DIRECTORY)) {
  328.         ipc_answer_0(rid, ENOTDIR);
  329.         return;
  330.     }
  331.  
  332.     ipc_answer_5(rid, EOK, tmpfs_reg.fs_handle, dev_handle, dcur->index,
  333.         dcur->size, TMPFS_GET_LNKCNT(dcur));
  334. }
  335.  
  336. void tmpfs_read(ipc_callid_t rid, ipc_call_t *request)
  337. {
  338.     int dev_handle = IPC_GET_ARG1(*request);
  339.     unsigned long index = IPC_GET_ARG2(*request);
  340.     off_t pos = IPC_GET_ARG3(*request);
  341.  
  342.     /*
  343.      * Lookup the respective dentry.
  344.      */
  345.     link_t *hlp;
  346.     hlp = hash_table_find(&dentries, &index);
  347.     if (!hlp) {
  348.         ipc_answer_0(rid, ENOENT);
  349.         return;
  350.     }
  351.     tmpfs_dentry_t *dentry = hash_table_get_instance(hlp, tmpfs_dentry_t,
  352.         dh_link);
  353.  
  354.     /*
  355.      * Receive the read request.
  356.      */
  357.     ipc_callid_t callid;
  358.     size_t len;
  359.     if (!ipc_data_read_receive(&callid, &len)) {
  360.         ipc_answer_0(callid, EINVAL);  
  361.         ipc_answer_0(rid, EINVAL);
  362.         return;
  363.     }
  364.  
  365.     size_t bytes;
  366.     if (dentry->type == TMPFS_FILE) {
  367.         bytes = max(0, min(dentry->size - pos, len));
  368.         (void) ipc_data_read_finalize(callid, dentry->data + pos,
  369.             bytes);
  370.     } else {
  371.         int i;
  372.         tmpfs_dentry_t *cur = dentry->child;
  373.        
  374.         assert(dentry->type == TMPFS_DIRECTORY);
  375.        
  376.         /*
  377.          * Yes, we really use O(n) algorithm here.
  378.          * If it bothers someone, it could be fixed by introducing a
  379.          * hash table.
  380.          */
  381.         for (i = 0, cur = dentry->child; i < pos && cur; i++,
  382.             cur = cur->sibling)
  383.             ;
  384.  
  385.         if (!cur) {
  386.             ipc_answer_0(callid, ENOENT);
  387.             ipc_answer_1(rid, ENOENT, 0);
  388.             return;
  389.         }
  390.  
  391.         (void) ipc_data_read_finalize(callid, cur->name,
  392.             strlen(cur->name) + 1);
  393.         bytes = 1;
  394.     }
  395.  
  396.     /*
  397.      * Answer the VFS_READ call.
  398.      */
  399.     ipc_answer_1(rid, EOK, bytes);
  400. }
  401.  
  402. void tmpfs_write(ipc_callid_t rid, ipc_call_t *request)
  403. {
  404.     int dev_handle = IPC_GET_ARG1(*request);
  405.     unsigned long index = IPC_GET_ARG2(*request);
  406.     off_t pos = IPC_GET_ARG3(*request);
  407.  
  408.     /*
  409.      * Lookup the respective dentry.
  410.      */
  411.     link_t *hlp;
  412.     hlp = hash_table_find(&dentries, &index);
  413.     if (!hlp) {
  414.         ipc_answer_0(rid, ENOENT);
  415.         return;
  416.     }
  417.     tmpfs_dentry_t *dentry = hash_table_get_instance(hlp, tmpfs_dentry_t,
  418.         dh_link);
  419.  
  420.     /*
  421.      * Receive the write request.
  422.      */
  423.     ipc_callid_t callid;
  424.     size_t len;
  425.     if (!ipc_data_write_receive(&callid, &len)) {
  426.         ipc_answer_0(callid, EINVAL);  
  427.         ipc_answer_0(rid, EINVAL);
  428.         return;
  429.     }
  430.  
  431.     /*
  432.      * Check whether the file needs to grow.
  433.      */
  434.     if (pos + len <= dentry->size) {
  435.         /* The file size is not changing. */
  436.         (void) ipc_data_write_finalize(callid, dentry->data + pos, len);
  437.         ipc_answer_2(rid, EOK, len, dentry->size);
  438.         return;
  439.     }
  440.     size_t delta = (pos + len) - dentry->size;
  441.     /*
  442.      * At this point, we are deliberately extremely straightforward and
  443.      * simply realloc the contents of the file on every write that grows the
  444.      * file. In the end, the situation might not be as bad as it may look:
  445.      * our heap allocator can save us and just grow the block whenever
  446.      * possible.
  447.      */
  448.     void *newdata = realloc(dentry->data, dentry->size + delta);
  449.     if (!newdata) {
  450.         ipc_answer_0(callid, ENOMEM);
  451.         ipc_answer_2(rid, EOK, 0, dentry->size);
  452.         return;
  453.     }
  454.     /* Clear any newly allocated memory in order to emulate gaps. */
  455.     memset(newdata + dentry->size, 0, delta);
  456.     dentry->size += delta;
  457.     dentry->data = newdata;
  458.     (void) ipc_data_write_finalize(callid, dentry->data + pos, len);
  459.     ipc_answer_2(rid, EOK, len, dentry->size);
  460. }
  461.  
  462. void tmpfs_truncate(ipc_callid_t rid, ipc_call_t *request)
  463. {
  464.     int dev_handle = IPC_GET_ARG1(*request);
  465.     unsigned long index = IPC_GET_ARG2(*request);
  466.     size_t size = IPC_GET_ARG3(*request);
  467.  
  468.     /*
  469.      * Lookup the respective dentry.
  470.      */
  471.     link_t *hlp;
  472.     hlp = hash_table_find(&dentries, &index);
  473.     if (!hlp) {
  474.         ipc_answer_0(rid, ENOENT);
  475.         return;
  476.     }
  477.     tmpfs_dentry_t *dentry = hash_table_get_instance(hlp, tmpfs_dentry_t,
  478.         dh_link);
  479.  
  480.     if (size == dentry->size) {
  481.         ipc_answer_0(rid, EOK);
  482.         return;
  483.     }
  484.  
  485.     void *newdata = realloc(dentry->data, size);
  486.     if (!newdata) {
  487.         ipc_answer_0(rid, ENOMEM);
  488.         return;
  489.     }
  490.     if (size > dentry->size) {
  491.         size_t delta = size - dentry->size;
  492.         memset(newdata + dentry->size, 0, delta);
  493.     }
  494.     dentry->size = size;
  495.     dentry->data = newdata;
  496.     ipc_answer_0(rid, EOK);
  497. }
  498.  
  499. void tmpfs_free(ipc_callid_t rid, ipc_call_t *request)
  500. {
  501.     int dev_handle = IPC_GET_ARG1(*request);
  502.     unsigned long index = IPC_GET_ARG2(*request);
  503.  
  504.     link_t *hlp;
  505.     hlp = hash_table_find(&dentries, &index);
  506.     if (!hlp) {
  507.         ipc_answer_0(rid, ENOENT);
  508.         return;
  509.     }
  510.     tmpfs_dentry_t *dentry = hash_table_get_instance(hlp, tmpfs_dentry_t,
  511.         dh_link);
  512.    
  513.     assert(!dentry->parent);
  514.     assert(!dentry->child);
  515.     assert(!dentry->sibling);
  516.  
  517.     hash_table_remove(&dentries, &index, 1);
  518.  
  519.     if (dentry->type == TMPFS_FILE)
  520.         free(dentry->data);
  521.     free(dentry->name);
  522.     free(dentry);
  523.  
  524.     ipc_answer_0(rid, EOK);
  525. }
  526.  
  527. /**
  528.  * @}
  529.  */
  530.