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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.     dentry->sibling = NULL;
  208.     dentry->parent = NULL;
  209.  
  210.     return EOK;
  211. }
  212.  
  213. void tmpfs_lookup(ipc_callid_t rid, ipc_call_t *request)
  214. {
  215.     unsigned next = IPC_GET_ARG1(*request);
  216.     unsigned last = IPC_GET_ARG2(*request);
  217.     int dev_handle = IPC_GET_ARG3(*request);
  218.     int lflag = IPC_GET_ARG4(*request);
  219.  
  220.     if (last < next)
  221.         last += PLB_SIZE;
  222.  
  223.     /*
  224.      * Initialize TMPFS.
  225.      */
  226.     if (!root && !tmpfs_init()) {
  227.         ipc_answer_0(rid, ENOMEM);
  228.         return;
  229.     }
  230.  
  231.     tmpfs_dentry_t *dtmp = root->child;
  232.     tmpfs_dentry_t *dcur = root;
  233.  
  234.     if (PLB_GET_CHAR(next) == '/')
  235.         next++;     /* eat slash */
  236.    
  237.     char component[NAME_MAX + 1];
  238.     int len = 0;
  239.     while (dtmp && next <= last) {
  240.  
  241.         /* collect the component */
  242.         if (PLB_GET_CHAR(next) != '/') {
  243.             if (len + 1 == NAME_MAX) {
  244.                 /* comopnent length overflow */
  245.                 ipc_answer_0(rid, ENAMETOOLONG);
  246.                 return;
  247.             }
  248.             component[len++] = PLB_GET_CHAR(next);
  249.             next++; /* process next character */
  250.             if (next <= last)
  251.                 continue;
  252.         }
  253.  
  254.         assert(len);
  255.         component[len] = '\0';
  256.         next++;     /* eat slash */
  257.         len = 0;
  258.  
  259.         /* match the component */
  260.         while (dtmp && !match_component(dtmp, component))
  261.             dtmp = dtmp->sibling;
  262.  
  263.         /* handle miss: match amongst siblings */
  264.         if (!dtmp) {
  265.             if ((next > last) && (lflag & L_CREATE)) {
  266.                 /* no components left and L_CREATE specified */
  267.                 if (dcur->type != TMPFS_DIRECTORY) {
  268.                     ipc_answer_0(rid, ENOTDIR);
  269.                     return;
  270.                 }
  271.                 void *nodep = create_node(dcur,
  272.                     component, lflag);
  273.                 if (nodep) {
  274.                     ipc_answer_5(rid, EOK,
  275.                         tmpfs_reg.fs_handle, dev_handle,
  276.                         TMPFS_GET_INDEX(nodep), 0,
  277.                         TMPFS_GET_LNKCNT(nodep));
  278.                 } else {
  279.                     ipc_answer_0(rid, ENOSPC);
  280.                 }
  281.                 return;
  282.             }
  283.             ipc_answer_0(rid, ENOENT);
  284.             return;
  285.         }
  286.  
  287.         /* descend one level */
  288.         dcur = dtmp;
  289.         dtmp = dtmp->child;
  290.     }
  291.  
  292.     /* handle miss: excessive components */
  293.     if (!dtmp && next <= last) {
  294.         if (lflag & L_CREATE) {
  295.             if (dcur->type != TMPFS_DIRECTORY) {
  296.                 ipc_answer_0(rid, ENOTDIR);
  297.                 return;
  298.             }
  299.  
  300.             /* collect next component */
  301.             while (next <= last) {
  302.                 if (PLB_GET_CHAR(next) == '/') {
  303.                     /* more than one component */
  304.                     ipc_answer_0(rid, ENOENT);
  305.                     return;
  306.                 }
  307.                 if (len + 1 == NAME_MAX) {
  308.                     /* component length overflow */
  309.                     ipc_answer_0(rid, ENAMETOOLONG);
  310.                     return;
  311.                 }
  312.                 component[len++] = PLB_GET_CHAR(next);
  313.                 next++; /* process next character */
  314.             }
  315.             assert(len);
  316.             component[len] = '\0';
  317.             len = 0;
  318.                
  319.             void *nodep = create_node(dcur, component, lflag);
  320.             if (nodep) {
  321.                 ipc_answer_5(rid, EOK, tmpfs_reg.fs_handle,
  322.                     dev_handle, TMPFS_GET_INDEX(nodep), 0,
  323.                     TMPFS_GET_LNKCNT(nodep));
  324.             } else {
  325.                 ipc_answer_0(rid, ENOSPC);
  326.             }
  327.             return;
  328.         }
  329.         ipc_answer_0(rid, ENOENT);
  330.         return;
  331.     }
  332.  
  333.     /* handle hit */
  334.     if (lflag & L_DESTROY) {
  335.         unsigned old_lnkcnt = TMPFS_GET_LNKCNT(dcur);
  336.         int res = destroy_component(dcur);
  337.         ipc_answer_5(rid, (ipcarg_t)res, tmpfs_reg.fs_handle,
  338.             dev_handle, dcur->index, dcur->size, old_lnkcnt);
  339.         return;
  340.     }
  341.     if ((lflag & (L_CREATE | L_EXCLUSIVE)) == (L_CREATE | L_EXCLUSIVE)) {
  342.         ipc_answer_0(rid, EEXIST);
  343.         return;
  344.     }
  345.     if ((lflag & L_FILE) && (dcur->type != TMPFS_FILE)) {
  346.         ipc_answer_0(rid, EISDIR);
  347.         return;
  348.     }
  349.     if ((lflag & L_DIRECTORY) && (dcur->type != TMPFS_DIRECTORY)) {
  350.         ipc_answer_0(rid, ENOTDIR);
  351.         return;
  352.     }
  353.  
  354.     ipc_answer_5(rid, EOK, tmpfs_reg.fs_handle, dev_handle, dcur->index,
  355.         dcur->size, TMPFS_GET_LNKCNT(dcur));
  356. }
  357.  
  358. void tmpfs_read(ipc_callid_t rid, ipc_call_t *request)
  359. {
  360.     int dev_handle = IPC_GET_ARG1(*request);
  361.     unsigned long index = IPC_GET_ARG2(*request);
  362.     off_t pos = IPC_GET_ARG3(*request);
  363.  
  364.     /*
  365.      * Lookup the respective dentry.
  366.      */
  367.     link_t *hlp;
  368.     hlp = hash_table_find(&dentries, &index);
  369.     if (!hlp) {
  370.         ipc_answer_0(rid, ENOENT);
  371.         return;
  372.     }
  373.     tmpfs_dentry_t *dentry = hash_table_get_instance(hlp, tmpfs_dentry_t,
  374.         dh_link);
  375.  
  376.     /*
  377.      * Receive the read request.
  378.      */
  379.     ipc_callid_t callid;
  380.     size_t len;
  381.     if (!ipc_data_read_receive(&callid, &len)) {
  382.         ipc_answer_0(callid, EINVAL);  
  383.         ipc_answer_0(rid, EINVAL);
  384.         return;
  385.     }
  386.  
  387.     size_t bytes;
  388.     if (dentry->type == TMPFS_FILE) {
  389.         bytes = max(0, min(dentry->size - pos, len));
  390.         (void) ipc_data_read_finalize(callid, dentry->data + pos,
  391.             bytes);
  392.     } else {
  393.         int i;
  394.         tmpfs_dentry_t *cur;
  395.        
  396.         assert(dentry->type == TMPFS_DIRECTORY);
  397.        
  398.         /*
  399.          * Yes, we really use O(n) algorithm here.
  400.          * If it bothers someone, it could be fixed by introducing a
  401.          * hash table.
  402.          */
  403.         for (i = 0, cur = dentry->child; i < pos && cur; i++,
  404.             cur = cur->sibling)
  405.             ;
  406.  
  407.         if (!cur) {
  408.             ipc_answer_0(callid, ENOENT);
  409.             ipc_answer_1(rid, ENOENT, 0);
  410.             return;
  411.         }
  412.  
  413.         (void) ipc_data_read_finalize(callid, cur->name,
  414.             strlen(cur->name) + 1);
  415.         bytes = 1;
  416.     }
  417.  
  418.     /*
  419.      * Answer the VFS_READ call.
  420.      */
  421.     ipc_answer_1(rid, EOK, bytes);
  422. }
  423.  
  424. void tmpfs_write(ipc_callid_t rid, ipc_call_t *request)
  425. {
  426.     int dev_handle = IPC_GET_ARG1(*request);
  427.     unsigned long index = IPC_GET_ARG2(*request);
  428.     off_t pos = IPC_GET_ARG3(*request);
  429.  
  430.     /*
  431.      * Lookup the respective dentry.
  432.      */
  433.     link_t *hlp;
  434.     hlp = hash_table_find(&dentries, &index);
  435.     if (!hlp) {
  436.         ipc_answer_0(rid, ENOENT);
  437.         return;
  438.     }
  439.     tmpfs_dentry_t *dentry = hash_table_get_instance(hlp, tmpfs_dentry_t,
  440.         dh_link);
  441.  
  442.     /*
  443.      * Receive the write request.
  444.      */
  445.     ipc_callid_t callid;
  446.     size_t len;
  447.     if (!ipc_data_write_receive(&callid, &len)) {
  448.         ipc_answer_0(callid, EINVAL);  
  449.         ipc_answer_0(rid, EINVAL);
  450.         return;
  451.     }
  452.  
  453.     /*
  454.      * Check whether the file needs to grow.
  455.      */
  456.     if (pos + len <= dentry->size) {
  457.         /* The file size is not changing. */
  458.         (void) ipc_data_write_finalize(callid, dentry->data + pos, len);
  459.         ipc_answer_2(rid, EOK, len, dentry->size);
  460.         return;
  461.     }
  462.     size_t delta = (pos + len) - dentry->size;
  463.     /*
  464.      * At this point, we are deliberately extremely straightforward and
  465.      * simply realloc the contents of the file on every write that grows the
  466.      * file. In the end, the situation might not be as bad as it may look:
  467.      * our heap allocator can save us and just grow the block whenever
  468.      * possible.
  469.      */
  470.     void *newdata = realloc(dentry->data, dentry->size + delta);
  471.     if (!newdata) {
  472.         ipc_answer_0(callid, ENOMEM);
  473.         ipc_answer_2(rid, EOK, 0, dentry->size);
  474.         return;
  475.     }
  476.     /* Clear any newly allocated memory in order to emulate gaps. */
  477.     memset(newdata + dentry->size, 0, delta);
  478.     dentry->size += delta;
  479.     dentry->data = newdata;
  480.     (void) ipc_data_write_finalize(callid, dentry->data + pos, len);
  481.     ipc_answer_2(rid, EOK, len, dentry->size);
  482. }
  483.  
  484. void tmpfs_truncate(ipc_callid_t rid, ipc_call_t *request)
  485. {
  486.     int dev_handle = IPC_GET_ARG1(*request);
  487.     unsigned long index = IPC_GET_ARG2(*request);
  488.     size_t size = IPC_GET_ARG3(*request);
  489.  
  490.     /*
  491.      * Lookup the respective dentry.
  492.      */
  493.     link_t *hlp;
  494.     hlp = hash_table_find(&dentries, &index);
  495.     if (!hlp) {
  496.         ipc_answer_0(rid, ENOENT);
  497.         return;
  498.     }
  499.     tmpfs_dentry_t *dentry = hash_table_get_instance(hlp, tmpfs_dentry_t,
  500.         dh_link);
  501.  
  502.     if (size == dentry->size) {
  503.         ipc_answer_0(rid, EOK);
  504.         return;
  505.     }
  506.  
  507.     void *newdata = realloc(dentry->data, size);
  508.     if (!newdata) {
  509.         ipc_answer_0(rid, ENOMEM);
  510.         return;
  511.     }
  512.     if (size > dentry->size) {
  513.         size_t delta = size - dentry->size;
  514.         memset(newdata + dentry->size, 0, delta);
  515.     }
  516.     dentry->size = size;
  517.     dentry->data = newdata;
  518.     ipc_answer_0(rid, EOK);
  519. }
  520.  
  521. void tmpfs_free(ipc_callid_t rid, ipc_call_t *request)
  522. {
  523.     int dev_handle = IPC_GET_ARG1(*request);
  524.     unsigned long index = IPC_GET_ARG2(*request);
  525.  
  526.     link_t *hlp;
  527.     hlp = hash_table_find(&dentries, &index);
  528.     if (!hlp) {
  529.         ipc_answer_0(rid, ENOENT);
  530.         return;
  531.     }
  532.     tmpfs_dentry_t *dentry = hash_table_get_instance(hlp, tmpfs_dentry_t,
  533.         dh_link);
  534.    
  535.     assert(!dentry->parent);
  536.     assert(!dentry->child);
  537.     assert(!dentry->sibling);
  538.  
  539.     hash_table_remove(&dentries, &index, 1);
  540.  
  541.     if (dentry->type == TMPFS_FILE)
  542.         free(dentry->data);
  543.     free(dentry->name);
  544.     free(dentry);
  545.  
  546.     ipc_answer_0(rid, EOK);
  547. }
  548.  
  549. /**
  550.  * @}
  551.  */
  552.