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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 (dtmp && 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.  
  300.     /* handle miss: excessive components */
  301.     if (!dtmp && next <= last) {
  302.         if (lflag & L_CREATE) {
  303.             if (dcur->type != TMPFS_DIRECTORY) {
  304.                 ipc_answer_0(rid, ENOTDIR);
  305.                 return;
  306.             }
  307.  
  308.             /* collect next component */
  309.             while (next <= last) {
  310.                 if (PLB_GET_CHAR(next) == '/') {
  311.                     /* more than one component */
  312.                     ipc_answer_0(rid, ENOENT);
  313.                     return;
  314.                 }
  315.                 if (len + 1 == NAME_MAX) {
  316.                     /* component length overflow */
  317.                     ipc_answer_0(rid, ENAMETOOLONG);
  318.                     return;
  319.                 }
  320.                 component[len++] = PLB_GET_CHAR(next);
  321.                 next++; /* process next character */
  322.             }
  323.             assert(len);
  324.             component[len] = '\0';
  325.             len = 0;
  326.                
  327.             unsigned long index;
  328.             index = create_node(dcur, component, lflag);
  329.             if (index) {
  330.                 ipc_answer_4(rid, EOK, tmpfs_reg.fs_handle,
  331.                     dev_handle, 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.     /* handle hit */
  342.     if (lflag & L_DESTROY) {
  343.         int res = destroy_component(dcur);
  344.         ipc_answer_0(rid, res);
  345.         return;
  346.     }
  347.     if ((lflag & (L_CREATE | L_EXCLUSIVE)) == (L_CREATE | L_EXCLUSIVE)) {
  348.         ipc_answer_0(rid, EEXIST);
  349.         return;
  350.     }
  351.     if ((lflag & L_FILE) && (dcur->type != TMPFS_FILE)) {
  352.         ipc_answer_0(rid, EISDIR);
  353.         return;
  354.     }
  355.     if ((lflag & L_DIRECTORY) && (dcur->type != TMPFS_DIRECTORY)) {
  356.         ipc_answer_0(rid, ENOTDIR);
  357.         return;
  358.     }
  359.  
  360.     ipc_answer_4(rid, EOK, tmpfs_reg.fs_handle, dev_handle, dcur->index,
  361.         dcur->size);
  362. }
  363.  
  364. void tmpfs_read(ipc_callid_t rid, ipc_call_t *request)
  365. {
  366.     int dev_handle = IPC_GET_ARG1(*request);
  367.     unsigned long index = IPC_GET_ARG2(*request);
  368.     off_t pos = IPC_GET_ARG3(*request);
  369.  
  370.     /*
  371.      * Lookup the respective dentry.
  372.      */
  373.     link_t *hlp;
  374.     hlp = hash_table_find(&dentries, &index);
  375.     if (!hlp) {
  376.         ipc_answer_0(rid, ENOENT);
  377.         return;
  378.     }
  379.     tmpfs_dentry_t *dentry = hash_table_get_instance(hlp, tmpfs_dentry_t,
  380.         dh_link);
  381.  
  382.     /*
  383.      * Receive the read request.
  384.      */
  385.     ipc_callid_t callid;
  386.     size_t len;
  387.     if (!ipc_data_read_receive(&callid, &len)) {
  388.         ipc_answer_0(callid, EINVAL);  
  389.         ipc_answer_0(rid, EINVAL);
  390.         return;
  391.     }
  392.  
  393.     size_t bytes;
  394.     if (dentry->type == TMPFS_FILE) {
  395.         bytes = max(0, min(dentry->size - pos, len));
  396.         (void) ipc_data_read_finalize(callid, dentry->data + pos,
  397.             bytes);
  398.     } else {
  399.         int i;
  400.         tmpfs_dentry_t *cur = dentry->child;
  401.        
  402.         assert(dentry->type == TMPFS_DIRECTORY);
  403.        
  404.         /*
  405.          * Yes, we really use O(n) algorithm here.
  406.          * If it bothers someone, it could be fixed by introducing a
  407.          * hash table.
  408.          */
  409.         for (i = 0, cur = dentry->child; i < pos && cur; i++,
  410.             cur = cur->sibling)
  411.             ;
  412.  
  413.         if (!cur) {
  414.             ipc_answer_0(callid, ENOENT);
  415.             ipc_answer_1(rid, ENOENT, 0);
  416.             return;
  417.         }
  418.  
  419.         (void) ipc_data_read_finalize(callid, cur->name,
  420.             strlen(cur->name) + 1);
  421.         bytes = 1;
  422.     }
  423.  
  424.     /*
  425.      * Answer the VFS_READ call.
  426.      */
  427.     ipc_answer_1(rid, EOK, bytes);
  428. }
  429.  
  430. void tmpfs_write(ipc_callid_t rid, ipc_call_t *request)
  431. {
  432.     int dev_handle = IPC_GET_ARG1(*request);
  433.     unsigned long index = IPC_GET_ARG2(*request);
  434.     off_t pos = IPC_GET_ARG3(*request);
  435.  
  436.     /*
  437.      * Lookup the respective dentry.
  438.      */
  439.     link_t *hlp;
  440.     hlp = hash_table_find(&dentries, &index);
  441.     if (!hlp) {
  442.         ipc_answer_0(rid, ENOENT);
  443.         return;
  444.     }
  445.     tmpfs_dentry_t *dentry = hash_table_get_instance(hlp, tmpfs_dentry_t,
  446.         dh_link);
  447.  
  448.     /*
  449.      * Receive the write request.
  450.      */
  451.     ipc_callid_t callid;
  452.     size_t len;
  453.     if (!ipc_data_write_receive(&callid, &len)) {
  454.         ipc_answer_0(callid, EINVAL);  
  455.         ipc_answer_0(rid, EINVAL);
  456.         return;
  457.     }
  458.  
  459.     /*
  460.      * Check whether the file needs to grow.
  461.      */
  462.     if (pos + len <= dentry->size) {
  463.         /* The file size is not changing. */
  464.         (void) ipc_data_write_finalize(callid, dentry->data + pos, len);
  465.         ipc_answer_1(rid, EOK, len);
  466.         return;
  467.     }
  468.     size_t delta = (pos + len) - dentry->size;
  469.     /*
  470.      * At this point, we are deliberately extremely straightforward and
  471.      * simply realloc the contents of the file on every write that grows the
  472.      * file. In the end, the situation might not be as bad as it may look:
  473.      * our heap allocator can save us and just grow the block whenever
  474.      * possible.
  475.      */
  476.     void *newdata = realloc(dentry->data, dentry->size + delta);
  477.     if (!newdata) {
  478.         ipc_answer_0(callid, ENOMEM);
  479.         ipc_answer_1(rid, EOK, 0);
  480.         return;
  481.     }
  482.     /* Clear any newly allocated memory in order to emulate gaps. */
  483.     memset(newdata + dentry->size, 0, delta);
  484.     dentry->size += delta;
  485.     dentry->data = newdata;
  486.     (void) ipc_data_write_finalize(callid, dentry->data + pos, len);
  487.     ipc_answer_2(rid, EOK, len, dentry->size);
  488. }
  489.  
  490. void tmpfs_truncate(ipc_callid_t rid, ipc_call_t *request)
  491. {
  492.     int dev_handle = IPC_GET_ARG1(*request);
  493.     unsigned long index = IPC_GET_ARG2(*request);
  494.     size_t size = IPC_GET_ARG3(*request);
  495.  
  496.     /*
  497.      * Lookup the respective dentry.
  498.      */
  499.     link_t *hlp;
  500.     hlp = hash_table_find(&dentries, &index);
  501.     if (!hlp) {
  502.         ipc_answer_0(rid, ENOENT);
  503.         return;
  504.     }
  505.     tmpfs_dentry_t *dentry = hash_table_get_instance(hlp, tmpfs_dentry_t,
  506.         dh_link);
  507.  
  508.     if (size == dentry->size) {
  509.         ipc_answer_0(rid, EOK);
  510.         return;
  511.     }
  512.  
  513.     void *newdata = realloc(dentry->data, size);
  514.     if (!newdata) {
  515.         ipc_answer_0(rid, ENOMEM);
  516.         return;
  517.     }
  518.     if (size > dentry->size) {
  519.         size_t delta = size - dentry->size;
  520.         memset(newdata + dentry->size, 0, delta);
  521.     }
  522.     dentry->size = size;
  523.     dentry->data = newdata;
  524.     ipc_answer_0(rid, EOK);
  525. }
  526.  
  527. /**
  528.  * @}
  529.  */
  530.