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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.     /*
  126.      * This is only for debugging. Once we can create files and directories
  127.      * using VFS, we can get rid of this.
  128.      */
  129.     tmpfs_dentry_t *d;
  130.     d = (tmpfs_dentry_t *) malloc(sizeof(tmpfs_dentry_t));
  131.     if (!d) {
  132.         free(root);
  133.         root = NULL;
  134.         return false;
  135.     }
  136.     tmpfs_dentry_initialize(d);
  137.     d->index = tmpfs_next_index++;
  138.     root->child = d;
  139.     d->parent = root;
  140.     d->type = TMPFS_DIRECTORY;
  141.     d->name = "dir1";
  142.     hash_table_insert(&dentries, &d->index, &d->dh_link);
  143.  
  144.     d = (tmpfs_dentry_t *) malloc(sizeof(tmpfs_dentry_t));
  145.     if (!d) {
  146.         free(root->child);
  147.         free(root);
  148.         root = NULL;
  149.         return false;
  150.     }
  151.     tmpfs_dentry_initialize(d);
  152.     d->index = tmpfs_next_index++;
  153.     root->child->sibling = d;
  154.     d->parent = root;
  155.     d->type = TMPFS_DIRECTORY;
  156.     d->name = "dir2";
  157.     hash_table_insert(&dentries, &d->index, &d->dh_link);
  158.    
  159.     d = (tmpfs_dentry_t *) malloc(sizeof(tmpfs_dentry_t));
  160.     if (!d) {
  161.         free(root->child->sibling);
  162.         free(root->child);
  163.         free(root);
  164.         root = NULL;
  165.         return false;
  166.     }
  167.     tmpfs_dentry_initialize(d);
  168.     d->index = tmpfs_next_index++;
  169.     root->child->child = d;
  170.     d->parent = root->child;
  171.     d->type = TMPFS_FILE;
  172.     d->name = "file1";
  173.     d->data = "This is the contents of /dir1/file1.\n";
  174.     d->size = strlen(d->data);
  175.     hash_table_insert(&dentries, &d->index, &d->dh_link);
  176.  
  177.     d = (tmpfs_dentry_t *) malloc(sizeof(tmpfs_dentry_t));
  178.     if (!d) {
  179.         free(root->child->sibling);
  180.         free(root->child->child);
  181.         free(root->child);
  182.         free(root);
  183.         root = NULL;
  184.         return false;
  185.     }
  186.     tmpfs_dentry_initialize(d);
  187.     d->index = tmpfs_next_index++;
  188.     root->child->sibling->child = d;
  189.     d->parent = root->child->sibling;
  190.     d->type = TMPFS_FILE;
  191.     d->name = "file2";
  192.     d->data = "This is the contents of /dir2/file2.\n";
  193.     d->size = strlen(d->data);
  194.     hash_table_insert(&dentries, &d->index, &d->dh_link);
  195.  
  196.     return true;
  197. }
  198.  
  199. /** Compare one component of path to a directory entry.
  200.  *
  201.  * @param dentry    Directory entry to compare the path component with.
  202.  * @param component Array of characters holding component name.
  203.  *
  204.  * @return      True on match, false otherwise.
  205.  */
  206. static bool match_component(tmpfs_dentry_t *dentry, const char *component)
  207. {
  208.     return !strcmp(dentry->name, component);
  209. }
  210.  
  211. static unsigned long create_node(tmpfs_dentry_t *dentry,
  212.     const char *component, int lflag)
  213. {
  214.     return 0;
  215. }
  216.  
  217. static int destroy_component(tmpfs_dentry_t *dentry)
  218. {
  219.     return EPERM;
  220. }
  221.  
  222. void tmpfs_lookup(ipc_callid_t rid, ipc_call_t *request)
  223. {
  224.     unsigned next = IPC_GET_ARG1(*request);
  225.     unsigned last = IPC_GET_ARG2(*request);
  226.     int dev_handle = IPC_GET_ARG3(*request);
  227.     int lflag = IPC_GET_ARG4(*request);
  228.  
  229.     if (last < next)
  230.         last += PLB_SIZE;
  231.  
  232.     /*
  233.      * Initialize TMPFS.
  234.      */
  235.     if (!root && !tmpfs_init()) {
  236.         ipc_answer_0(rid, ENOMEM);
  237.         return;
  238.     }
  239.  
  240.     tmpfs_dentry_t *dtmp = root->child;
  241.     tmpfs_dentry_t *dcur = root;
  242.  
  243.     if (PLB_GET_CHAR(next) == '/')
  244.         next++;     /* eat slash */
  245.    
  246.     char component[NAME_MAX + 1];
  247.     int len = 0;
  248.     while (next <= last) {
  249.  
  250.         /* collect the component */
  251.         if (PLB_GET_CHAR(next) != '/') {
  252.             if (len + 1 == NAME_MAX) {
  253.                 /* comopnent length overflow */
  254.                 ipc_answer_0(rid, ENAMETOOLONG);
  255.                 return;
  256.             }
  257.             component[len++] = PLB_GET_CHAR(next);
  258.             next++; /* process next character */
  259.             if (next <= last)
  260.                 continue;
  261.         }
  262.  
  263.         assert(len);
  264.         component[len] = '\0';
  265.         next++;     /* eat slash */
  266.         len = 0;
  267.  
  268.         /* match the component */
  269.         while (dtmp && !match_component(dtmp, component))
  270.             dtmp = dtmp->sibling;
  271.  
  272.         /* handle miss: match amongst siblings */
  273.         if (!dtmp) {
  274.             if ((next > last) && (lflag & L_CREATE)) {
  275.                 /* no components left and L_CREATE specified */
  276.                 if (dcur->type != TMPFS_DIRECTORY) {
  277.                     ipc_answer_0(rid, ENOTDIR);
  278.                     return;
  279.                 }
  280.                 unsigned long index = create_node(dcur,
  281.                     component, lflag);
  282.                 if (index) {
  283.                     ipc_answer_4(rid, EOK,
  284.                         tmpfs_reg.fs_handle, dev_handle,
  285.                         index, 0);
  286.                 } else {
  287.                     ipc_answer_0(rid, ENOSPC);
  288.                 }
  289.                 return;
  290.             }
  291.             ipc_answer_0(rid, ENOENT);
  292.             return;
  293.         }
  294.  
  295.         /* descent one level */
  296.         dcur = dtmp;
  297.         dtmp = dtmp->child;
  298.  
  299.         /* handle miss: excessive components */
  300.         if (!dtmp && next <= last) {
  301.             if (lflag & L_CREATE) {
  302.                 if (dcur->type != TMPFS_DIRECTORY) {
  303.                     ipc_answer_0(rid, ENOTDIR);
  304.                     return;
  305.                 }
  306.  
  307.                 /* collect next component */
  308.                 while (next <= last) {
  309.                     if (PLB_GET_CHAR(next) == '/') {
  310.                         /* more than one component */
  311.                         ipc_answer_0(rid, ENOENT);
  312.                         return;
  313.                     }
  314.                     if (len + 1 == NAME_MAX) {
  315.                         /* component length overflow */
  316.                         ipc_answer_0(rid, ENAMETOOLONG);
  317.                         return;
  318.                     }
  319.                     component[len++] = PLB_GET_CHAR(next);
  320.                     next++; /* process next character */
  321.                 }
  322.                 assert(len);
  323.                 component[len] = '\0';
  324.                 len = 0;
  325.                
  326.                 unsigned long index;
  327.                 index = create_node(dcur, component, lflag);
  328.                 if (index) {
  329.                     ipc_answer_4(rid, EOK,
  330.                         tmpfs_reg.fs_handle, dev_handle,
  331.                         index, 0);
  332.                 } else {
  333.                     ipc_answer_0(rid, ENOSPC);
  334.                 }
  335.                 return;
  336.             }
  337.             ipc_answer_0(rid, ENOENT);
  338.             return;
  339.         }
  340.    
  341.     }
  342.  
  343.     /* handle hit */
  344.     if (lflag & L_DESTROY) {
  345.         int res = destroy_component(dcur);
  346.         ipc_answer_0(rid, res);
  347.         return;
  348.     }
  349.     if ((lflag & (L_CREATE | L_EXCLUSIVE)) == (L_CREATE | L_EXCLUSIVE)) {
  350.         ipc_answer_0(rid, EEXIST);
  351.         return;
  352.     }
  353.     if ((lflag & L_FILE) && (dcur->type != TMPFS_FILE)) {
  354.         ipc_answer_0(rid, EISDIR);
  355.         return;
  356.     }
  357.     if ((lflag & L_DIRECTORY) && (dcur->type != TMPFS_DIRECTORY)) {
  358.         ipc_answer_0(rid, ENOTDIR);
  359.         return;
  360.     }
  361.  
  362.     ipc_answer_4(rid, EOK, tmpfs_reg.fs_handle, dev_handle, dcur->index,
  363.         dcur->size);
  364. }
  365.  
  366. void tmpfs_read(ipc_callid_t rid, ipc_call_t *request)
  367. {
  368.     int dev_handle = IPC_GET_ARG1(*request);
  369.     unsigned long index = IPC_GET_ARG2(*request);
  370.     off_t pos = IPC_GET_ARG3(*request);
  371.  
  372.     /*
  373.      * Lookup the respective dentry.
  374.      */
  375.     link_t *hlp;
  376.     hlp = hash_table_find(&dentries, &index);
  377.     if (!hlp) {
  378.         ipc_answer_0(rid, ENOENT);
  379.         return;
  380.     }
  381.     tmpfs_dentry_t *dentry = hash_table_get_instance(hlp, tmpfs_dentry_t,
  382.         dh_link);
  383.  
  384.     /*
  385.      * Receive the read request.
  386.      */
  387.     ipc_callid_t callid;
  388.     size_t len;
  389.     if (!ipc_data_read_receive(&callid, &len)) {
  390.         ipc_answer_0(callid, EINVAL);  
  391.         ipc_answer_0(rid, EINVAL);
  392.         return;
  393.     }
  394.  
  395.     size_t bytes;
  396.     if (dentry->type == TMPFS_FILE) {
  397.         bytes = max(0, min(dentry->size - pos, len));
  398.         (void) ipc_data_read_finalize(callid, dentry->data + pos,
  399.             bytes);
  400.     } else {
  401.         int i;
  402.         tmpfs_dentry_t *cur = dentry->child;
  403.        
  404.         assert(dentry->type == TMPFS_DIRECTORY);
  405.        
  406.         /*
  407.          * Yes, we really use O(n) algorithm here.
  408.          * If it bothers someone, it could be fixed by introducing a
  409.          * hash table.
  410.          */
  411.         for (i = 0, cur = dentry->child; i < pos && cur; i++,
  412.             cur = cur->sibling)
  413.             ;
  414.  
  415.         if (!cur) {
  416.             ipc_answer_0(callid, ENOENT);
  417.             ipc_answer_1(rid, ENOENT, 0);
  418.             return;
  419.         }
  420.  
  421.         (void) ipc_data_read_finalize(callid, cur->name,
  422.             strlen(cur->name) + 1);
  423.         bytes = 1;
  424.     }
  425.  
  426.     /*
  427.      * Answer the VFS_READ call.
  428.      */
  429.     ipc_answer_1(rid, EOK, bytes);
  430. }
  431.  
  432. void tmpfs_write(ipc_callid_t rid, ipc_call_t *request)
  433. {
  434.     int dev_handle = IPC_GET_ARG1(*request);
  435.     unsigned long index = IPC_GET_ARG2(*request);
  436.     off_t pos = IPC_GET_ARG3(*request);
  437.  
  438.     /*
  439.      * Lookup the respective dentry.
  440.      */
  441.     link_t *hlp;
  442.     hlp = hash_table_find(&dentries, &index);
  443.     if (!hlp) {
  444.         ipc_answer_0(rid, ENOENT);
  445.         return;
  446.     }
  447.     tmpfs_dentry_t *dentry = hash_table_get_instance(hlp, tmpfs_dentry_t,
  448.         dh_link);
  449.  
  450.     /*
  451.      * Receive the write request.
  452.      */
  453.     ipc_callid_t callid;
  454.     size_t len;
  455.     if (!ipc_data_write_receive(&callid, &len)) {
  456.         ipc_answer_0(callid, EINVAL);  
  457.         ipc_answer_0(rid, EINVAL);
  458.         return;
  459.     }
  460.  
  461.     /*
  462.      * Check whether the file needs to grow.
  463.      */
  464.     if (pos + len <= dentry->size) {
  465.         /* The file size is not changing. */
  466.         (void) ipc_data_write_finalize(callid, dentry->data + pos, len);
  467.         ipc_answer_1(rid, EOK, len);
  468.         return;
  469.     }
  470.     size_t delta = (pos + len) - dentry->size;
  471.     /*
  472.      * At this point, we are deliberately extremely straightforward and
  473.      * simply realloc the contents of the file on every write that grows the
  474.      * file. In the end, the situation might not be as bad as it may look:
  475.      * our heap allocator can save us and just grow the block whenever
  476.      * possible.
  477.      */
  478.     void *newdata = realloc(dentry->data, dentry->size + delta);
  479.     if (!newdata) {
  480.         ipc_answer_0(callid, ENOMEM);
  481.         ipc_answer_1(rid, EOK, 0);
  482.         return;
  483.     }
  484.     /* Clear any newly allocated memory in order to emulate gaps. */
  485.     memset(newdata + dentry->size, 0, delta);
  486.     dentry->size += delta;
  487.     dentry->data = newdata;
  488.     (void) ipc_data_write_finalize(callid, dentry->data + pos, len);
  489.     ipc_answer_2(rid, EOK, len, dentry->size);
  490. }
  491.  
  492. void tmpfs_truncate(ipc_callid_t rid, ipc_call_t *request)
  493. {
  494.     int dev_handle = IPC_GET_ARG1(*request);
  495.     unsigned long index = IPC_GET_ARG2(*request);
  496.     size_t size = IPC_GET_ARG3(*request);
  497.  
  498.     /*
  499.      * Lookup the respective dentry.
  500.      */
  501.     link_t *hlp;
  502.     hlp = hash_table_find(&dentries, &index);
  503.     if (!hlp) {
  504.         ipc_answer_0(rid, ENOENT);
  505.         return;
  506.     }
  507.     tmpfs_dentry_t *dentry = hash_table_get_instance(hlp, tmpfs_dentry_t,
  508.         dh_link);
  509.  
  510.     if (size == dentry->size) {
  511.         ipc_answer_0(rid, EOK);
  512.         return;
  513.     }
  514.  
  515.     void *newdata = realloc(dentry->data, size);
  516.     if (!newdata) {
  517.         ipc_answer_0(rid, ENOMEM);
  518.         return;
  519.     }
  520.     if (size > dentry->size) {
  521.         size_t delta = size - dentry->size;
  522.         memset(newdata + dentry->size, 0, delta);
  523.     }
  524.     dentry->size = size;
  525.     dentry->data = newdata;
  526.     ipc_answer_0(rid, EOK);
  527. }
  528.  
  529. /**
  530.  * @}
  531.  */
  532.