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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. /* Forward declarations of static functions. */
  65. static void *create_node(int);
  66. static bool link_node(void *, void *, const char *);
  67. static int unlink_node(void *);
  68. static void destroy_node(void *);
  69.  
  70. /** Hash table of all directory entries. */
  71. hash_table_t dentries;
  72.  
  73. static hash_index_t dentries_hash(unsigned long *key)
  74. {
  75.     return *key % DENTRIES_BUCKETS;
  76. }
  77.  
  78. static int dentries_compare(unsigned long *key, hash_count_t keys,
  79.     link_t *item)
  80. {
  81.     tmpfs_dentry_t *dentry = hash_table_get_instance(item, tmpfs_dentry_t,
  82.         dh_link);
  83.     return dentry->index == *key;
  84. }
  85.  
  86. static void dentries_remove_callback(link_t *item)
  87. {
  88. }
  89.  
  90. /** TMPFS dentries hash table operations. */
  91. hash_table_operations_t dentries_ops = {
  92.     .hash = dentries_hash,
  93.     .compare = dentries_compare,
  94.     .remove_callback = dentries_remove_callback
  95. };
  96.  
  97. unsigned tmpfs_next_index = 1;
  98.  
  99. static void tmpfs_dentry_initialize(tmpfs_dentry_t *dentry)
  100. {
  101.     dentry->index = 0;
  102.     dentry->parent = NULL;
  103.     dentry->sibling = NULL;
  104.     dentry->child = NULL;
  105.     dentry->name = NULL;
  106.     dentry->type = TMPFS_NONE;
  107.     dentry->size = 0;
  108.     dentry->data = NULL;
  109.     link_initialize(&dentry->dh_link);
  110. }
  111.  
  112. /*
  113.  * For now, we don't distinguish between different dev_handles/instances. All
  114.  * requests resolve to the only instance, rooted in the following variable.
  115.  */
  116. static tmpfs_dentry_t *root;
  117.  
  118. static bool tmpfs_init(void)
  119. {
  120.     if (!hash_table_create(&dentries, DENTRIES_BUCKETS, 1, &dentries_ops))
  121.         return false;
  122.     root = (tmpfs_dentry_t *) create_node(L_DIRECTORY);
  123.     return root != NULL;
  124. }
  125.  
  126. /** Compare one component of path to a directory entry.
  127.  *
  128.  * @param nodep     Node to compare the path component with.
  129.  * @param component Array of characters holding component name.
  130.  *
  131.  * @return      True on match, false otherwise.
  132.  */
  133. static bool match_component(void *nodep, const char *component)
  134. {
  135.     tmpfs_dentry_t *dentry = (tmpfs_dentry_t *) nodep;
  136.  
  137.     return !strcmp(dentry->name, component);
  138. }
  139.  
  140. void *create_node(int lflag)
  141. {
  142.     assert((lflag & L_FILE) ^ (lflag & L_DIRECTORY));
  143.  
  144.     tmpfs_dentry_t *node = malloc(sizeof(tmpfs_dentry_t));
  145.     if (!node)
  146.         return NULL;
  147.  
  148.     tmpfs_dentry_initialize(node);
  149.     node->index = tmpfs_next_index++;
  150.     if (lflag & L_DIRECTORY)
  151.         node->type = TMPFS_DIRECTORY;
  152.     else
  153.         node->type = TMPFS_FILE;
  154.  
  155.     /* Insert the new node into the dentry hash table. */
  156.     hash_table_insert(&dentries, &node->index, &node->dh_link);
  157.     return (void *) node;
  158. }
  159.  
  160. bool link_node(void *prnt, void *chld, const char *nm)
  161. {
  162.     tmpfs_dentry_t *parentp = (tmpfs_dentry_t *) prnt;
  163.     tmpfs_dentry_t *childp = (tmpfs_dentry_t *) chld;
  164.  
  165.     assert(parentp->type == TMPFS_DIRECTORY);
  166.  
  167.     size_t len = strlen(nm);
  168.     char *name = malloc(len + 1);
  169.     if (!name)
  170.         return false;
  171.     strcpy(name, nm);
  172.     childp->name = name;
  173.  
  174.     /* Insert the new node into the namespace. */
  175.     if (parentp->child) {
  176.         tmpfs_dentry_t *tmp = parentp->child;
  177.         while (tmp->sibling)
  178.             tmp = tmp->sibling;
  179.         tmp->sibling = childp;
  180.     } else {
  181.         parentp->child = childp;
  182.     }
  183.     childp->parent = parentp;
  184.  
  185.     return true;
  186. }
  187.  
  188. int unlink_node(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.     free(dentry->name);
  211.     dentry->name = NULL;
  212.  
  213.     return EOK;
  214. }
  215.  
  216. void destroy_node(void *nodep)
  217. {
  218.     tmpfs_dentry_t *dentry = (tmpfs_dentry_t *) nodep;
  219.    
  220.     assert(!dentry->child);
  221.     assert(!dentry->sibling);
  222.  
  223.     unsigned long index = dentry->index;
  224.     hash_table_remove(&dentries, &index, 1);
  225.  
  226.     if (dentry->type == TMPFS_FILE)
  227.         free(dentry->data);
  228.     free(dentry);
  229. }
  230.  
  231. void tmpfs_lookup(ipc_callid_t rid, ipc_call_t *request)
  232. {
  233.     unsigned next = IPC_GET_ARG1(*request);
  234.     unsigned last = IPC_GET_ARG2(*request);
  235.     int dev_handle = IPC_GET_ARG3(*request);
  236.     int lflag = IPC_GET_ARG4(*request);
  237.  
  238.     if (last < next)
  239.         last += PLB_SIZE;
  240.  
  241.     /*
  242.      * Initialize TMPFS.
  243.      */
  244.     if (!root && !tmpfs_init()) {
  245.         ipc_answer_0(rid, ENOMEM);
  246.         return;
  247.     }
  248.  
  249.     tmpfs_dentry_t *dtmp = root->child;
  250.     tmpfs_dentry_t *dcur = root;
  251.  
  252.     if (PLB_GET_CHAR(next) == '/')
  253.         next++;     /* eat slash */
  254.    
  255.     char component[NAME_MAX + 1];
  256.     int len = 0;
  257.     while (dtmp && next <= last) {
  258.  
  259.         /* collect the component */
  260.         if (PLB_GET_CHAR(next) != '/') {
  261.             if (len + 1 == NAME_MAX) {
  262.                 /* comopnent length overflow */
  263.                 ipc_answer_0(rid, ENAMETOOLONG);
  264.                 return;
  265.             }
  266.             component[len++] = PLB_GET_CHAR(next);
  267.             next++; /* process next character */
  268.             if (next <= last)
  269.                 continue;
  270.         }
  271.  
  272.         assert(len);
  273.         component[len] = '\0';
  274.         next++;     /* eat slash */
  275.         len = 0;
  276.  
  277.         /* match the component */
  278.         while (dtmp && !match_component(dtmp, component))
  279.             dtmp = dtmp->sibling;
  280.  
  281.         /* handle miss: match amongst siblings */
  282.         if (!dtmp) {
  283.             if ((next > last) && (lflag & L_CREATE)) {
  284.                 /* no components left and L_CREATE specified */
  285.                 if (dcur->type != TMPFS_DIRECTORY) {
  286.                     ipc_answer_0(rid, ENOTDIR);
  287.                     return;
  288.                 }
  289.                 void *nodep = create_node(lflag);
  290.                 if (nodep) {
  291.                     if (!link_node(dcur, nodep,
  292.                         component)) {
  293.                         destroy_node(nodep);
  294.                         ipc_answer_0(rid, ENOSPC);
  295.                     } else {
  296.                         ipc_answer_5(rid, EOK,
  297.                             tmpfs_reg.fs_handle,
  298.                             dev_handle,
  299.                             TMPFS_GET_INDEX(nodep), 0,
  300.                             TMPFS_GET_LNKCNT(nodep));
  301.                     }
  302.                 } else {
  303.                     ipc_answer_0(rid, ENOSPC);
  304.                 }
  305.                 return;
  306.             }
  307.             ipc_answer_0(rid, ENOENT);
  308.             return;
  309.         }
  310.  
  311.         /* descend one level */
  312.         dcur = dtmp;
  313.         dtmp = dtmp->child;
  314.     }
  315.  
  316.     /* handle miss: excessive components */
  317.     if (!dtmp && next <= last) {
  318.         if (lflag & L_CREATE) {
  319.             if (dcur->type != TMPFS_DIRECTORY) {
  320.                 ipc_answer_0(rid, ENOTDIR);
  321.                 return;
  322.             }
  323.  
  324.             /* collect next component */
  325.             while (next <= last) {
  326.                 if (PLB_GET_CHAR(next) == '/') {
  327.                     /* more than one component */
  328.                     ipc_answer_0(rid, ENOENT);
  329.                     return;
  330.                 }
  331.                 if (len + 1 == NAME_MAX) {
  332.                     /* component length overflow */
  333.                     ipc_answer_0(rid, ENAMETOOLONG);
  334.                     return;
  335.                 }
  336.                 component[len++] = PLB_GET_CHAR(next);
  337.                 next++; /* process next character */
  338.             }
  339.             assert(len);
  340.             component[len] = '\0';
  341.             len = 0;
  342.                
  343.             void *nodep = create_node(lflag);
  344.             if (nodep) {
  345.                 if (!link_node(dcur, nodep, component)) {
  346.                     destroy_node(nodep);
  347.                     ipc_answer_0(rid, ENOSPC);
  348.                 } else {
  349.                     ipc_answer_5(rid, EOK,
  350.                         tmpfs_reg.fs_handle,
  351.                         dev_handle, TMPFS_GET_INDEX(nodep),
  352.                         0, TMPFS_GET_LNKCNT(nodep));
  353.                 }
  354.             } else {
  355.                 ipc_answer_0(rid, ENOSPC);
  356.             }
  357.             return;
  358.         }
  359.         ipc_answer_0(rid, ENOENT);
  360.         return;
  361.     }
  362.  
  363.     /* handle hit */
  364.     if (lflag & L_DESTROY) {
  365.         unsigned old_lnkcnt = TMPFS_GET_LNKCNT(dcur);
  366.         int res = unlink_node(dcur);
  367.         ipc_answer_5(rid, (ipcarg_t)res, tmpfs_reg.fs_handle,
  368.             dev_handle, dcur->index, dcur->size, old_lnkcnt);
  369.         return;
  370.     }
  371.     if ((lflag & (L_CREATE | L_EXCLUSIVE)) == (L_CREATE | L_EXCLUSIVE)) {
  372.         ipc_answer_0(rid, EEXIST);
  373.         return;
  374.     }
  375.     if ((lflag & L_FILE) && (dcur->type != TMPFS_FILE)) {
  376.         ipc_answer_0(rid, EISDIR);
  377.         return;
  378.     }
  379.     if ((lflag & L_DIRECTORY) && (dcur->type != TMPFS_DIRECTORY)) {
  380.         ipc_answer_0(rid, ENOTDIR);
  381.         return;
  382.     }
  383.  
  384.     ipc_answer_5(rid, EOK, tmpfs_reg.fs_handle, dev_handle, dcur->index,
  385.         dcur->size, TMPFS_GET_LNKCNT(dcur));
  386. }
  387.  
  388. void tmpfs_read(ipc_callid_t rid, ipc_call_t *request)
  389. {
  390.     int dev_handle = IPC_GET_ARG1(*request);
  391.     unsigned long index = IPC_GET_ARG2(*request);
  392.     off_t pos = IPC_GET_ARG3(*request);
  393.  
  394.     /*
  395.      * Lookup the respective dentry.
  396.      */
  397.     link_t *hlp;
  398.     hlp = hash_table_find(&dentries, &index);
  399.     if (!hlp) {
  400.         ipc_answer_0(rid, ENOENT);
  401.         return;
  402.     }
  403.     tmpfs_dentry_t *dentry = hash_table_get_instance(hlp, tmpfs_dentry_t,
  404.         dh_link);
  405.  
  406.     /*
  407.      * Receive the read request.
  408.      */
  409.     ipc_callid_t callid;
  410.     size_t len;
  411.     if (!ipc_data_read_receive(&callid, &len)) {
  412.         ipc_answer_0(callid, EINVAL);  
  413.         ipc_answer_0(rid, EINVAL);
  414.         return;
  415.     }
  416.  
  417.     size_t bytes;
  418.     if (dentry->type == TMPFS_FILE) {
  419.         bytes = max(0, min(dentry->size - pos, len));
  420.         (void) ipc_data_read_finalize(callid, dentry->data + pos,
  421.             bytes);
  422.     } else {
  423.         int i;
  424.         tmpfs_dentry_t *cur;
  425.        
  426.         assert(dentry->type == TMPFS_DIRECTORY);
  427.        
  428.         /*
  429.          * Yes, we really use O(n) algorithm here.
  430.          * If it bothers someone, it could be fixed by introducing a
  431.          * hash table.
  432.          */
  433.         for (i = 0, cur = dentry->child; i < pos && cur; i++,
  434.             cur = cur->sibling)
  435.             ;
  436.  
  437.         if (!cur) {
  438.             ipc_answer_0(callid, ENOENT);
  439.             ipc_answer_1(rid, ENOENT, 0);
  440.             return;
  441.         }
  442.  
  443.         (void) ipc_data_read_finalize(callid, cur->name,
  444.             strlen(cur->name) + 1);
  445.         bytes = 1;
  446.     }
  447.  
  448.     /*
  449.      * Answer the VFS_READ call.
  450.      */
  451.     ipc_answer_1(rid, EOK, bytes);
  452. }
  453.  
  454. void tmpfs_write(ipc_callid_t rid, ipc_call_t *request)
  455. {
  456.     int dev_handle = IPC_GET_ARG1(*request);
  457.     unsigned long index = IPC_GET_ARG2(*request);
  458.     off_t pos = IPC_GET_ARG3(*request);
  459.  
  460.     /*
  461.      * Lookup the respective dentry.
  462.      */
  463.     link_t *hlp;
  464.     hlp = hash_table_find(&dentries, &index);
  465.     if (!hlp) {
  466.         ipc_answer_0(rid, ENOENT);
  467.         return;
  468.     }
  469.     tmpfs_dentry_t *dentry = hash_table_get_instance(hlp, tmpfs_dentry_t,
  470.         dh_link);
  471.  
  472.     /*
  473.      * Receive the write request.
  474.      */
  475.     ipc_callid_t callid;
  476.     size_t len;
  477.     if (!ipc_data_write_receive(&callid, &len)) {
  478.         ipc_answer_0(callid, EINVAL);  
  479.         ipc_answer_0(rid, EINVAL);
  480.         return;
  481.     }
  482.  
  483.     /*
  484.      * Check whether the file needs to grow.
  485.      */
  486.     if (pos + len <= dentry->size) {
  487.         /* The file size is not changing. */
  488.         (void) ipc_data_write_finalize(callid, dentry->data + pos, len);
  489.         ipc_answer_2(rid, EOK, len, dentry->size);
  490.         return;
  491.     }
  492.     size_t delta = (pos + len) - dentry->size;
  493.     /*
  494.      * At this point, we are deliberately extremely straightforward and
  495.      * simply realloc the contents of the file on every write that grows the
  496.      * file. In the end, the situation might not be as bad as it may look:
  497.      * our heap allocator can save us and just grow the block whenever
  498.      * possible.
  499.      */
  500.     void *newdata = realloc(dentry->data, dentry->size + delta);
  501.     if (!newdata) {
  502.         ipc_answer_0(callid, ENOMEM);
  503.         ipc_answer_2(rid, EOK, 0, dentry->size);
  504.         return;
  505.     }
  506.     /* Clear any newly allocated memory in order to emulate gaps. */
  507.     memset(newdata + dentry->size, 0, delta);
  508.     dentry->size += delta;
  509.     dentry->data = newdata;
  510.     (void) ipc_data_write_finalize(callid, dentry->data + pos, len);
  511.     ipc_answer_2(rid, EOK, len, dentry->size);
  512. }
  513.  
  514. void tmpfs_truncate(ipc_callid_t rid, ipc_call_t *request)
  515. {
  516.     int dev_handle = IPC_GET_ARG1(*request);
  517.     unsigned long index = IPC_GET_ARG2(*request);
  518.     size_t size = IPC_GET_ARG3(*request);
  519.  
  520.     /*
  521.      * Lookup the respective dentry.
  522.      */
  523.     link_t *hlp;
  524.     hlp = hash_table_find(&dentries, &index);
  525.     if (!hlp) {
  526.         ipc_answer_0(rid, ENOENT);
  527.         return;
  528.     }
  529.     tmpfs_dentry_t *dentry = hash_table_get_instance(hlp, tmpfs_dentry_t,
  530.         dh_link);
  531.  
  532.     if (size == dentry->size) {
  533.         ipc_answer_0(rid, EOK);
  534.         return;
  535.     }
  536.  
  537.     void *newdata = realloc(dentry->data, size);
  538.     if (!newdata) {
  539.         ipc_answer_0(rid, ENOMEM);
  540.         return;
  541.     }
  542.     if (size > dentry->size) {
  543.         size_t delta = size - dentry->size;
  544.         memset(newdata + dentry->size, 0, delta);
  545.     }
  546.     dentry->size = size;
  547.     dentry->data = newdata;
  548.     ipc_answer_0(rid, EOK);
  549. }
  550.  
  551. void tmpfs_destroy(ipc_callid_t rid, ipc_call_t *request)
  552. {
  553.     int dev_handle = IPC_GET_ARG1(*request);
  554.     unsigned long index = IPC_GET_ARG2(*request);
  555.  
  556.     link_t *hlp;
  557.     hlp = hash_table_find(&dentries, &index);
  558.     if (!hlp) {
  559.         ipc_answer_0(rid, ENOENT);
  560.         return;
  561.     }
  562.     tmpfs_dentry_t *dentry = hash_table_get_instance(hlp, tmpfs_dentry_t,
  563.         dh_link);
  564.     destroy_node(dentry);
  565.     ipc_answer_0(rid, EOK);
  566. }
  567.  
  568. /**
  569.  * @}
  570.  */
  571.