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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 <assert.h>
  49. #include <sys/types.h>
  50. #include <libadt/hash_table.h>
  51. #include <as.h>
  52.  
  53. #define min(a, b)       ((a) < (b) ? (a) : (b))
  54. #define max(a, b)       ((a) > (b) ? (a) : (b))
  55.  
  56. #define PLB_GET_CHAR(i)     (tmpfs_reg.plb_ro[(i) % PLB_SIZE])
  57.  
  58. #define DENTRIES_BUCKETS    256
  59.  
  60. /*
  61.  * Hash table of all directory entries.
  62.  */
  63. hash_table_t dentries;
  64.  
  65. static hash_index_t dentries_hash(unsigned long *key)
  66. {
  67.     return *key % DENTRIES_BUCKETS;
  68. }
  69.  
  70. static int dentries_compare(unsigned long *key, hash_count_t keys,
  71.     link_t *item)
  72. {
  73.     tmpfs_dentry_t *dentry = hash_table_get_instance(item, tmpfs_dentry_t,
  74.         dh_link);
  75.     return dentry->index == *key;
  76. }
  77.  
  78. static void dentries_remove_callback(link_t *item)
  79. {
  80. }
  81.  
  82. /** TMPFS dentries hash table operations. */
  83. hash_table_operations_t dentries_ops = {
  84.     .hash = dentries_hash,
  85.     .compare = dentries_compare,
  86.     .remove_callback = dentries_remove_callback
  87. };
  88.  
  89. unsigned tmpfs_next_index = 1;
  90.  
  91. static void tmpfs_dentry_initialize(tmpfs_dentry_t *dentry)
  92. {
  93.     dentry->index = 0;
  94.     dentry->parent = NULL;
  95.     dentry->sibling = NULL;
  96.     dentry->child = NULL;
  97.     dentry->name = NULL;
  98.     dentry->type = TMPFS_NONE;
  99.     dentry->size = 0;
  100.     dentry->data = NULL;
  101.     link_initialize(&dentry->dh_link);
  102. }
  103.  
  104. /*
  105.  * For now, we don't distinguish between different dev_handles/instances. All
  106.  * requests resolve to the only instance, rooted in the following variable.
  107.  */
  108. static tmpfs_dentry_t *root;
  109.  
  110. static bool tmpfs_init(void)
  111. {
  112.     if (!hash_table_create(&dentries, DENTRIES_BUCKETS, 1, &dentries_ops))
  113.         return false;
  114.  
  115.     root = (tmpfs_dentry_t *) malloc(sizeof(tmpfs_dentry_t));
  116.     if (!root)
  117.         return false;
  118.     tmpfs_dentry_initialize(root);
  119.     root->index = tmpfs_next_index++;
  120.     root->name = "";
  121.     root->type = TMPFS_DIRECTORY;
  122.     hash_table_insert(&dentries, &root->index, &root->dh_link);
  123.  
  124.     /*
  125.      * This is only for debugging. Once we can create files and directories
  126.      * using VFS, we can get rid of this.
  127.      */
  128.     tmpfs_dentry_t *d;
  129.     d = (tmpfs_dentry_t *) malloc(sizeof(tmpfs_dentry_t));
  130.     if (!d) {
  131.         free(root);
  132.         root = NULL;
  133.         return false;
  134.     }
  135.     tmpfs_dentry_initialize(d);
  136.     d->index = tmpfs_next_index++;
  137.     root->child = d;
  138.     d->parent = root;
  139.     d->type = TMPFS_DIRECTORY;
  140.     d->name = "dir1";
  141.     hash_table_insert(&dentries, &d->index, &d->dh_link);
  142.  
  143.     d = (tmpfs_dentry_t *) malloc(sizeof(tmpfs_dentry_t));
  144.     if (!d) {
  145.         free(root->child);
  146.         free(root);
  147.         root = NULL;
  148.         return false;
  149.     }
  150.     tmpfs_dentry_initialize(d);
  151.     d->index = tmpfs_next_index++;
  152.     root->child->sibling = d;
  153.     d->parent = root;
  154.     d->type = TMPFS_DIRECTORY;
  155.     d->name = "dir2";
  156.     hash_table_insert(&dentries, &d->index, &d->dh_link);
  157.    
  158.     d = (tmpfs_dentry_t *) malloc(sizeof(tmpfs_dentry_t));
  159.     if (!d) {
  160.         free(root->child->sibling);
  161.         free(root->child);
  162.         free(root);
  163.         root = NULL;
  164.         return false;
  165.     }
  166.     tmpfs_dentry_initialize(d);
  167.     d->index = tmpfs_next_index++;
  168.     root->child->child = d;
  169.     d->parent = root->child;
  170.     d->type = TMPFS_FILE;
  171.     d->name = "file1";
  172.     d->data = "This is the contents of /dir1/file1.\n";
  173.     d->size = strlen(d->data);
  174.     hash_table_insert(&dentries, &d->index, &d->dh_link);
  175.  
  176.     d = (tmpfs_dentry_t *) malloc(sizeof(tmpfs_dentry_t));
  177.     if (!d) {
  178.         free(root->child->sibling);
  179.         free(root->child->child);
  180.         free(root->child);
  181.         free(root);
  182.         root = NULL;
  183.         return false;
  184.     }
  185.     tmpfs_dentry_initialize(d);
  186.     d->index = tmpfs_next_index++;
  187.     root->child->sibling->child = d;
  188.     d->parent = root->child->sibling;
  189.     d->type = TMPFS_FILE;
  190.     d->name = "file2";
  191.     d->data = "This is the contents of /dir2/file2.\n";
  192.     d->size = strlen(d->data);
  193.     hash_table_insert(&dentries, &d->index, &d->dh_link);
  194.  
  195.     return true;
  196. }
  197.  
  198. /** Compare one component of path to a directory entry.
  199.  *
  200.  * @param dentry    Directory entry to compare the path component with.
  201.  * @param start     Index into PLB where the path component starts.
  202.  * @param last      Index of the last character of the path in PLB.
  203.  *
  204.  * @return      Zero on failure or delta such that (index + delta) %
  205.  *          PLB_SIZE points to the first unprocessed character in
  206.  *          PLB which comprises the path.
  207.  */
  208. static unsigned match_path_component(tmpfs_dentry_t *dentry, unsigned start,
  209.     unsigned last)
  210. {
  211.     int i, j;
  212.     size_t namelen;
  213.  
  214.     namelen = strlen(dentry->name);
  215.  
  216.     if (last < start)
  217.         last += PLB_SIZE;
  218.  
  219.     for (i = 0, j = start; i < namelen && j <= last; i++, j++) {
  220.         if (dentry->name[i] != PLB_GET_CHAR(j))
  221.             return 0;
  222.     }
  223.    
  224.     if (i != namelen)
  225.         return 0;
  226.     if (j < last && PLB_GET_CHAR(j) != '/')
  227.         return 0;
  228.     if (j == last)
  229.             return 0;
  230.    
  231.     return (j - start);
  232. }
  233.  
  234. void tmpfs_lookup(ipc_callid_t rid, ipc_call_t *request)
  235. {
  236.     unsigned next = IPC_GET_ARG1(*request);
  237.     unsigned last = IPC_GET_ARG2(*request);
  238.     int dev_handle = IPC_GET_ARG3(*request);
  239.  
  240.     if (last < next)
  241.         last += PLB_SIZE;
  242.  
  243.     if (!root && !tmpfs_init()) {
  244.         ipc_answer_0(rid, ENOMEM);
  245.         return;
  246.     }
  247.  
  248.     tmpfs_dentry_t *dtmp = root->child;
  249.     tmpfs_dentry_t *dcur = root;
  250.  
  251.     bool hit = true;
  252.    
  253.     if (PLB_GET_CHAR(next) == '/')
  254.         next++;     /* eat slash */
  255.    
  256.     while (next <= last) {
  257.         unsigned delta;
  258.         hit = false;
  259.         do {
  260.             delta = match_path_component(dtmp, next, last);
  261.             if (!delta) {
  262.                 dtmp = dtmp->sibling;
  263.             } else {
  264.                 hit = true;
  265.                 next += delta;
  266.                 next++;     /* eat slash */
  267.                 dcur = dtmp;
  268.                 dtmp = dtmp->child;
  269.             }  
  270.         } while (delta == 0 && dtmp);
  271.         if (!hit) {
  272.             ipc_answer_3(rid, ENOENT, tmpfs_reg.fs_handle,
  273.                 dev_handle, dcur->index);
  274.             return;
  275.         }
  276.     }
  277.  
  278.     ipc_answer_4(rid, EOK, tmpfs_reg.fs_handle, dev_handle, dcur->index,
  279.         dcur->size);
  280. }
  281.  
  282. void tmpfs_read(ipc_callid_t rid, ipc_call_t *request)
  283. {
  284.     int dev_handle = IPC_GET_ARG1(*request);
  285.     unsigned long index = IPC_GET_ARG2(*request);
  286.     off_t pos = IPC_GET_ARG3(*request);
  287.  
  288.     /*
  289.      * Lookup the respective dentry.
  290.      */
  291.     link_t *hlp;
  292.     hlp = hash_table_find(&dentries, &index);
  293.     if (!hlp) {
  294.         ipc_answer_0(rid, ENOENT);
  295.         return;
  296.     }
  297.     tmpfs_dentry_t *dentry = hash_table_get_instance(hlp, tmpfs_dentry_t,
  298.         dh_link);
  299.  
  300.     /*
  301.      * Receive the read request.
  302.      */
  303.     ipc_callid_t callid;
  304.     size_t len;
  305.     if (!ipc_data_read_receive(&callid, &len)) {
  306.         ipc_answer_0(callid, EINVAL);  
  307.         ipc_answer_0(rid, EINVAL);
  308.         return;
  309.     }
  310.  
  311.     size_t bytes;
  312.     if (dentry->type == TMPFS_FILE) {
  313.         bytes = max(0, min(dentry->size - pos, len));
  314.         (void) ipc_data_read_finalize(callid, dentry->data + pos,
  315.             bytes);
  316.     } else {
  317.         int i;
  318.         tmpfs_dentry_t *cur = dentry->child;
  319.        
  320.         assert(dentry->type == TMPFS_DIRECTORY);
  321.        
  322.         /*
  323.          * Yes, we really use O(n) algorithm here.
  324.          * If it bothers someone, it could be fixed by introducing a
  325.          * hash table.
  326.          */
  327.         for (i = 0, cur = dentry->child; i < pos && cur; i++,
  328.             cur = cur->sibling)
  329.             ;
  330.  
  331.         if (!cur) {
  332.             ipc_answer_0(callid, ENOENT);
  333.             ipc_answer_1(rid, ENOENT, 0);
  334.             return;
  335.         }
  336.  
  337.         (void) ipc_data_read_finalize(callid, cur->name,
  338.             strlen(cur->name) + 1);
  339.         bytes = 1;
  340.     }
  341.  
  342.     /*
  343.      * Answer the VFS_READ call.
  344.      */
  345.     ipc_answer_1(rid, EOK, bytes);
  346. }
  347.  
  348. void tmpfs_write(ipc_callid_t rid, ipc_call_t *request)
  349. {
  350.     int dev_handle = IPC_GET_ARG1(*request);
  351.     unsigned long index = IPC_GET_ARG2(*request);
  352.     off_t pos = IPC_GET_ARG3(*request);
  353.  
  354.     /*
  355.      * Lookup the respective dentry.
  356.      */
  357.     link_t *hlp;
  358.     hlp = hash_table_find(&dentries, &index);
  359.     if (!hlp) {
  360.         ipc_answer_0(rid, ENOENT);
  361.         return;
  362.     }
  363.     tmpfs_dentry_t *dentry = hash_table_get_instance(hlp, tmpfs_dentry_t,
  364.         dh_link);
  365.  
  366.     /*
  367.      * Receive the write request.
  368.      */
  369.     ipc_callid_t callid;
  370.     size_t len;
  371.     if (!ipc_data_write_receive(&callid, &len)) {
  372.         ipc_answer_0(callid, EINVAL);  
  373.         ipc_answer_0(rid, EINVAL);
  374.         return;
  375.     }
  376.  
  377.     /*
  378.      * Check whether the file needs to grow.
  379.      */
  380.     if (pos + len <= dentry->size) {
  381.         /* The file size is not changing. */
  382.         (void) ipc_data_write_finalize(callid, dentry->data + pos, len);
  383.         ipc_answer_1(rid, EOK, len);
  384.         return;
  385.     }
  386.     size_t delta = (pos + len) - dentry->size;
  387.     /*
  388.      * At this point, we are deliberately extremely straightforward and
  389.      * simply realloc the contents of the file on every write that grows the
  390.      * file. In the end, the situation might not be as bad as it may look:
  391.      * our heap allocator can save us and just grow the block whenever
  392.      * possible.
  393.      */
  394.     void *newdata = realloc(dentry->data, dentry->size + delta);
  395.     if (!newdata) {
  396.         ipc_answer_0(callid, ENOMEM);
  397.         ipc_answer_1(rid, EOK, 0);
  398.         return;
  399.     }
  400.     /* Clear any newly allocated memory in order to emulate gaps. */
  401.     memset(newdata + dentry->size, 0, delta);
  402.     dentry->size += delta;
  403.     dentry->data = newdata;
  404.     (void) ipc_data_write_finalize(callid, dentry->data + pos, len);
  405.     ipc_answer_2(rid, EOK, len, dentry->size);
  406. }
  407.  
  408. void tmpfs_truncate(ipc_callid_t rid, ipc_call_t *request)
  409. {
  410.     int dev_handle = IPC_GET_ARG1(*request);
  411.     unsigned long index = IPC_GET_ARG2(*request);
  412.     size_t size = IPC_GET_ARG3(*request);
  413.  
  414.     /*
  415.      * Lookup the respective dentry.
  416.      */
  417.     link_t *hlp;
  418.     hlp = hash_table_find(&dentries, &index);
  419.     if (!hlp) {
  420.         ipc_answer_0(rid, ENOENT);
  421.         return;
  422.     }
  423.     tmpfs_dentry_t *dentry = hash_table_get_instance(hlp, tmpfs_dentry_t,
  424.         dh_link);
  425.  
  426.     if (size == dentry->size) {
  427.         ipc_answer_0(rid, EOK);
  428.         return;
  429.     }
  430.  
  431.     void *newdata = realloc(dentry->data, size);
  432.     if (!newdata) {
  433.         ipc_answer_0(rid, ENOMEM);
  434.         return;
  435.     }
  436.     if (size > dentry->size) {
  437.         size_t delta = size - dentry->size;
  438.         memset(newdata + dentry->size, 0, delta);
  439.     }
  440.     dentry->size = size;
  441.     dentry->data = newdata;
  442.     ipc_answer_0(rid, EOK);
  443. }
  444.  
  445. /**
  446.  * @}
  447.  */
  448.