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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    fat_ops.c
  35.  * @brief   Implementation of VFS operations for the FAT file system server.
  36.  */
  37.  
  38. #include "fat.h"
  39. #include "fat_dentry.h"
  40. #include "fat_fat.h"
  41. #include "../../vfs/vfs.h"
  42. #include <libfs.h>
  43. #include <libblock.h>
  44. #include <ipc/ipc.h>
  45. #include <ipc/services.h>
  46. #include <ipc/devmap.h>
  47. #include <async.h>
  48. #include <errno.h>
  49. #include <string.h>
  50. #include <byteorder.h>
  51. #include <libadt/hash_table.h>
  52. #include <libadt/list.h>
  53. #include <assert.h>
  54. #include <futex.h>
  55. #include <sys/mman.h>
  56. #include <align.h>
  57.  
  58. /** Futex protecting the list of cached free FAT nodes. */
  59. static futex_t ffn_futex = FUTEX_INITIALIZER;
  60.  
  61. /** List of cached free FAT nodes. */
  62. static LIST_INITIALIZE(ffn_head);
  63.  
  64. static void fat_node_initialize(fat_node_t *node)
  65. {
  66.     futex_initialize(&node->lock, 1);
  67.     node->idx = NULL;
  68.     node->type = 0;
  69.     link_initialize(&node->ffn_link);
  70.     node->size = 0;
  71.     node->lnkcnt = 0;
  72.     node->refcnt = 0;
  73.     node->dirty = false;
  74. }
  75.  
  76. static void fat_node_sync(fat_node_t *node)
  77. {
  78.     block_t *b;
  79.     fat_bs_t *bs;
  80.     fat_dentry_t *d;
  81.     uint16_t bps;
  82.     unsigned dps;
  83.    
  84.     assert(node->dirty);
  85.  
  86.     bs = block_bb_get(node->idx->dev_handle);
  87.     bps = uint16_t_le2host(bs->bps);
  88.     dps = bps / sizeof(fat_dentry_t);
  89.    
  90.     /* Read the block that contains the dentry of interest. */
  91.     b = _fat_block_get(bs, node->idx->dev_handle, node->idx->pfc,
  92.         (node->idx->pdi * sizeof(fat_dentry_t)) / bps, BLOCK_FLAGS_NONE);
  93.  
  94.     d = ((fat_dentry_t *)b->data) + (node->idx->pdi % dps);
  95.  
  96.     d->firstc = host2uint16_t_le(node->firstc);
  97.     if (node->type == FAT_FILE) {
  98.         d->size = host2uint32_t_le(node->size);
  99.     } else if (node->type == FAT_DIRECTORY) {
  100.         d->attr = FAT_ATTR_SUBDIR;
  101.     }
  102.    
  103.     /* TODO: update other fields? (e.g time fields) */
  104.    
  105.     b->dirty = true;        /* need to sync block */
  106.     block_put(b);
  107. }
  108.  
  109. static fat_node_t *fat_node_get_new(void)
  110. {
  111.     fat_node_t *nodep;
  112.  
  113.     futex_down(&ffn_futex);
  114.     if (!list_empty(&ffn_head)) {
  115.         /* Try to use a cached free node structure. */
  116.         fat_idx_t *idxp_tmp;
  117.         nodep = list_get_instance(ffn_head.next, fat_node_t, ffn_link);
  118.         if (futex_trydown(&nodep->lock) == ESYNCH_WOULD_BLOCK)
  119.             goto skip_cache;
  120.         idxp_tmp = nodep->idx;
  121.         if (futex_trydown(&idxp_tmp->lock) == ESYNCH_WOULD_BLOCK) {
  122.             futex_up(&nodep->lock);
  123.             goto skip_cache;
  124.         }
  125.         list_remove(&nodep->ffn_link);
  126.         futex_up(&ffn_futex);
  127.         if (nodep->dirty)
  128.             fat_node_sync(nodep);
  129.         idxp_tmp->nodep = NULL;
  130.         futex_up(&nodep->lock);
  131.         futex_up(&idxp_tmp->lock);
  132.     } else {
  133. skip_cache:
  134.         /* Try to allocate a new node structure. */
  135.         futex_up(&ffn_futex);
  136.         nodep = (fat_node_t *)malloc(sizeof(fat_node_t));
  137.         if (!nodep)
  138.             return NULL;
  139.     }
  140.     fat_node_initialize(nodep);
  141.    
  142.     return nodep;
  143. }
  144.  
  145. /** Internal version of fat_node_get().
  146.  *
  147.  * @param idxp      Locked index structure.
  148.  */
  149. static void *fat_node_get_core(fat_idx_t *idxp)
  150. {
  151.     block_t *b;
  152.     fat_bs_t *bs;
  153.     fat_dentry_t *d;
  154.     fat_node_t *nodep = NULL;
  155.     unsigned bps;
  156.     unsigned spc;
  157.     unsigned dps;
  158.  
  159.     if (idxp->nodep) {
  160.         /*
  161.          * We are lucky.
  162.          * The node is already instantiated in memory.
  163.          */
  164.         futex_down(&idxp->nodep->lock);
  165.         if (!idxp->nodep->refcnt++)
  166.             list_remove(&idxp->nodep->ffn_link);
  167.         futex_up(&idxp->nodep->lock);
  168.         return idxp->nodep;
  169.     }
  170.  
  171.     /*
  172.      * We must instantiate the node from the file system.
  173.      */
  174.    
  175.     assert(idxp->pfc);
  176.  
  177.     nodep = fat_node_get_new();
  178.     if (!nodep)
  179.         return NULL;
  180.  
  181.     bs = block_bb_get(idxp->dev_handle);
  182.     bps = uint16_t_le2host(bs->bps);
  183.     spc = bs->spc;
  184.     dps = bps / sizeof(fat_dentry_t);
  185.  
  186.     /* Read the block that contains the dentry of interest. */
  187.     b = _fat_block_get(bs, idxp->dev_handle, idxp->pfc,
  188.         (idxp->pdi * sizeof(fat_dentry_t)) / bps, BLOCK_FLAGS_NONE);
  189.     assert(b);
  190.  
  191.     d = ((fat_dentry_t *)b->data) + (idxp->pdi % dps);
  192.     if (d->attr & FAT_ATTR_SUBDIR) {
  193.         /*
  194.          * The only directory which does not have this bit set is the
  195.          * root directory itself. The root directory node is handled
  196.          * and initialized elsewhere.
  197.          */
  198.         nodep->type = FAT_DIRECTORY;
  199.         /*
  200.          * Unfortunately, the 'size' field of the FAT dentry is not
  201.          * defined for the directory entry type. We must determine the
  202.          * size of the directory by walking the FAT.
  203.          */
  204.         nodep->size = bps * spc * fat_clusters_get(bs, idxp->dev_handle,
  205.             uint16_t_le2host(d->firstc));
  206.     } else {
  207.         nodep->type = FAT_FILE;
  208.         nodep->size = uint32_t_le2host(d->size);
  209.     }
  210.     nodep->firstc = uint16_t_le2host(d->firstc);
  211.     nodep->lnkcnt = 1;
  212.     nodep->refcnt = 1;
  213.  
  214.     block_put(b);
  215.  
  216.     /* Link the idx structure with the node structure. */
  217.     nodep->idx = idxp;
  218.     idxp->nodep = nodep;
  219.  
  220.     return nodep;
  221. }
  222.  
  223. /*
  224.  * Forward declarations of FAT libfs operations.
  225.  */
  226. static void *fat_node_get(dev_handle_t, fs_index_t);
  227. static void fat_node_put(void *);
  228. static void *fat_create_node(dev_handle_t, int);
  229. static int fat_destroy_node(void *);
  230. static int fat_link(void *, void *, const char *);
  231. static int fat_unlink(void *, void *);
  232. static void *fat_match(void *, const char *);
  233. static fs_index_t fat_index_get(void *);
  234. static size_t fat_size_get(void *);
  235. static unsigned fat_lnkcnt_get(void *);
  236. static bool fat_has_children(void *);
  237. static void *fat_root_get(dev_handle_t);
  238. static char fat_plb_get_char(unsigned);
  239. static bool fat_is_directory(void *);
  240. static bool fat_is_file(void *node);
  241.  
  242. /*
  243.  * FAT libfs operations.
  244.  */
  245.  
  246. /** Instantiate a FAT in-core node. */
  247. void *fat_node_get(dev_handle_t dev_handle, fs_index_t index)
  248. {
  249.     void *node;
  250.     fat_idx_t *idxp;
  251.  
  252.     idxp = fat_idx_get_by_index(dev_handle, index);
  253.     if (!idxp)
  254.         return NULL;
  255.     /* idxp->lock held */
  256.     node = fat_node_get_core(idxp);
  257.     futex_up(&idxp->lock);
  258.     return node;
  259. }
  260.  
  261. void fat_node_put(void *node)
  262. {
  263.     fat_node_t *nodep = (fat_node_t *)node;
  264.     bool destroy = false;
  265.  
  266.     futex_down(&nodep->lock);
  267.     if (!--nodep->refcnt) {
  268.         if (nodep->idx) {
  269.             futex_down(&ffn_futex);
  270.             list_append(&nodep->ffn_link, &ffn_head);
  271.             futex_up(&ffn_futex);
  272.         } else {
  273.             /*
  274.              * The node does not have any index structure associated
  275.              * with itself. This can only mean that we are releasing
  276.              * the node after a failed attempt to allocate the index
  277.              * structure for it.
  278.              */
  279.             destroy = true;
  280.         }
  281.     }
  282.     futex_up(&nodep->lock);
  283.     if (destroy)
  284.         free(node);
  285. }
  286.  
  287. void *fat_create_node(dev_handle_t dev_handle, int flags)
  288. {
  289.     fat_idx_t *idxp;
  290.     fat_node_t *nodep;
  291.     fat_bs_t *bs;
  292.     fat_cluster_t mcl, lcl;
  293.     uint16_t bps;
  294.     int rc;
  295.  
  296.     bs = block_bb_get(dev_handle);
  297.     bps = uint16_t_le2host(bs->bps);
  298.     if (flags & L_DIRECTORY) {
  299.         /* allocate a cluster */
  300.         rc = fat_alloc_clusters(bs, dev_handle, 1, &mcl, &lcl);
  301.         if (rc != EOK)
  302.             return NULL;
  303.     }
  304.  
  305.     nodep = fat_node_get_new();
  306.     if (!nodep) {
  307.         fat_free_clusters(bs, dev_handle, mcl);
  308.         return NULL;
  309.     }
  310.     idxp = fat_idx_get_new(dev_handle);
  311.     if (!idxp) {
  312.         fat_free_clusters(bs, dev_handle, mcl);
  313.         fat_node_put(nodep);
  314.         return NULL;
  315.     }
  316.     /* idxp->lock held */
  317.     if (flags & L_DIRECTORY) {
  318.         int i;
  319.         block_t *b;
  320.  
  321.         /*
  322.          * Populate the new cluster with unused dentries.
  323.          * We don't create the '.' and '..' entries, since they are
  324.          * optional and HelenOS VFS does not need them.
  325.          */
  326.         for (i = 0; i < bs->spc; i++) {
  327.             b = _fat_block_get(bs, dev_handle, mcl, i,
  328.                 BLOCK_FLAGS_NOREAD);
  329.             /* mark all dentries as never-used */
  330.             memset(b->data, 0, bps);
  331.             b->dirty = false;
  332.             block_put(b);
  333.         }
  334.         nodep->type = FAT_DIRECTORY;
  335.         nodep->firstc = mcl;
  336.         nodep->size = bps * bs->spc;
  337.     } else {
  338.         nodep->type = FAT_FILE;
  339.         nodep->firstc = FAT_CLST_RES0;
  340.         nodep->size = 0;
  341.     }
  342.     nodep->lnkcnt = 0;  /* not linked anywhere */
  343.     nodep->refcnt = 1;
  344.     nodep->dirty = true;
  345.  
  346.     nodep->idx = idxp;
  347.     idxp->nodep = nodep;
  348.  
  349.     futex_up(&idxp->lock);
  350.     return nodep;
  351. }
  352.  
  353. int fat_destroy_node(void *node)
  354. {
  355.     fat_node_t *nodep = (fat_node_t *)node;
  356.     fat_bs_t *bs;
  357.  
  358.     /*
  359.      * The node is not reachable from the file system. This means that the
  360.      * link count should be zero and that the index structure cannot be
  361.      * found in the position hash. Obviously, we don't need to lock the node
  362.      * nor its index structure.
  363.      */
  364.     assert(nodep->lnkcnt == 0);
  365.  
  366.     /*
  367.      * The node may not have any children.
  368.      */
  369.     assert(fat_has_children(node) == false);
  370.  
  371.     bs = block_bb_get(nodep->idx->dev_handle);
  372.     if (nodep->firstc != FAT_CLST_RES0) {
  373.         assert(nodep->size);
  374.         /* Free all clusters allocated to the node. */
  375.         fat_free_clusters(bs, nodep->idx->dev_handle, nodep->firstc);
  376.     }
  377.  
  378.     fat_idx_destroy(nodep->idx);
  379.     free(nodep);
  380.     return EOK;
  381. }
  382.  
  383. int fat_link(void *prnt, void *chld, const char *name)
  384. {
  385.     fat_node_t *parentp = (fat_node_t *)prnt;
  386.     fat_node_t *childp = (fat_node_t *)chld;
  387.     fat_dentry_t *d;
  388.     fat_bs_t *bs;
  389.     block_t *b;
  390.     int i, j;
  391.     uint16_t bps;
  392.     unsigned dps;
  393.     unsigned blocks;
  394.  
  395.     futex_down(&childp->lock);
  396.     if (childp->lnkcnt == 1) {
  397.         /*
  398.          * On FAT, we don't support multiple hard links.
  399.          */
  400.         futex_up(&childp->lock);
  401.         return EMLINK;
  402.     }
  403.     assert(childp->lnkcnt == 0);
  404.     futex_up(&childp->lock);
  405.  
  406.     if (!fat_dentry_name_verify(name)) {
  407.         /*
  408.          * Attempt to create unsupported name.
  409.          */
  410.         return ENOTSUP;
  411.     }
  412.  
  413.     /*
  414.      * Get us an unused parent node's dentry or grow the parent and allocate
  415.      * a new one.
  416.      */
  417.    
  418.     futex_down(&parentp->idx->lock);
  419.     bs = block_bb_get(parentp->idx->dev_handle);
  420.     bps = uint16_t_le2host(bs->bps);
  421.     dps = bps / sizeof(fat_dentry_t);
  422.  
  423.     blocks = parentp->size / bps;
  424.  
  425.     for (i = 0; i < blocks; i++) {
  426.         b = fat_block_get(bs, parentp, i, BLOCK_FLAGS_NONE);
  427.         for (j = 0; j < dps; j++) {
  428.             d = ((fat_dentry_t *)b->data) + j;
  429.             switch (fat_classify_dentry(d)) {
  430.             case FAT_DENTRY_SKIP:
  431.             case FAT_DENTRY_VALID:
  432.                 /* skipping used and meta entries */
  433.                 continue;
  434.             case FAT_DENTRY_FREE:
  435.             case FAT_DENTRY_LAST:
  436.                 /* found an empty slot */
  437.                 goto hit;
  438.             }
  439.         }
  440.         block_put(b);
  441.     }
  442.    
  443.     /*
  444.      * We need to grow the parent in order to create a new unused dentry.
  445.      */
  446.     futex_up(&parentp->idx->lock);
  447.     return ENOTSUP; /* XXX */
  448.  
  449. hit:
  450.     /*
  451.      * At this point we only establish the link between the parent and the
  452.      * child.  The dentry, except of the name and the extension, will remain
  453.      * uninitialized until the the corresponding node is synced. Thus the
  454.      * valid dentry data is kept in the child node structure.
  455.      */
  456.     memset(d, 0, sizeof(fat_dentry_t));
  457.     fat_dentry_name_set(d, name);
  458.     b->dirty = true;        /* need to sync block */
  459.     block_put(b);
  460.     futex_up(&parentp->idx->lock);
  461.  
  462.     futex_down(&childp->idx->lock);
  463.     childp->idx->pfc = parentp->firstc;
  464.     childp->idx->pdi = i * dps + j;
  465.     futex_up(&childp->idx->lock);
  466.  
  467.     futex_down(&childp->lock);
  468.     childp->lnkcnt = 1;
  469.     childp->dirty = true;       /* need to sync node */
  470.     futex_up(&childp->lock);
  471.  
  472.     /*
  473.      * Hash in the index structure into the position hash.
  474.      */
  475.     fat_idx_hashin(childp->idx);
  476.  
  477.     return EOK;
  478. }
  479.  
  480. int fat_unlink(void *prnt, void *chld)
  481. {
  482.     fat_node_t *parentp = (fat_node_t *)prnt;
  483.     fat_node_t *childp = (fat_node_t *)chld;
  484.     fat_bs_t *bs;
  485.     fat_dentry_t *d;
  486.     uint16_t bps;
  487.     block_t *b;
  488.  
  489.     futex_down(&parentp->lock);
  490.     futex_down(&childp->lock);
  491.     assert(childp->lnkcnt == 1);
  492.     futex_down(&childp->idx->lock);
  493.     bs = block_bb_get(childp->idx->dev_handle);
  494.     bps = uint16_t_le2host(bs->bps);
  495.  
  496.     b = _fat_block_get(bs, childp->idx->dev_handle, childp->idx->pfc,
  497.         (childp->idx->pdi * sizeof(fat_dentry_t)) / bps,
  498.         BLOCK_FLAGS_NONE);
  499.     d = (fat_dentry_t *)b->data +
  500.         (childp->idx->pdi % (bps / sizeof(fat_dentry_t)));
  501.     /* mark the dentry as not-currently-used */
  502.     d->name[0] = FAT_DENTRY_ERASED;
  503.     b->dirty = true;        /* need to sync block */
  504.     block_put(b);
  505.  
  506.     /* remove the index structure from the position hash */
  507.     fat_idx_hashout(childp->idx);
  508.     /* clear position information */
  509.     childp->idx->pfc = FAT_CLST_RES0;
  510.     childp->idx->pdi = 0;
  511.     futex_up(&childp->idx->lock);
  512.     childp->lnkcnt = 0;
  513.     childp->dirty = true;
  514.     futex_up(&childp->lock);
  515.     futex_up(&parentp->lock);
  516.  
  517.     return EOK;
  518. }
  519.  
  520. void *fat_match(void *prnt, const char *component)
  521. {
  522.     fat_bs_t *bs;
  523.     fat_node_t *parentp = (fat_node_t *)prnt;
  524.     char name[FAT_NAME_LEN + 1 + FAT_EXT_LEN + 1];
  525.     unsigned i, j;
  526.     unsigned bps;       /* bytes per sector */
  527.     unsigned dps;       /* dentries per sector */
  528.     unsigned blocks;
  529.     fat_dentry_t *d;
  530.     block_t *b;
  531.  
  532.     futex_down(&parentp->idx->lock);
  533.     bs = block_bb_get(parentp->idx->dev_handle);
  534.     bps = uint16_t_le2host(bs->bps);
  535.     dps = bps / sizeof(fat_dentry_t);
  536.     blocks = parentp->size / bps;
  537.     for (i = 0; i < blocks; i++) {
  538.         b = fat_block_get(bs, parentp, i, BLOCK_FLAGS_NONE);
  539.         for (j = 0; j < dps; j++) {
  540.             d = ((fat_dentry_t *)b->data) + j;
  541.             switch (fat_classify_dentry(d)) {
  542.             case FAT_DENTRY_SKIP:
  543.             case FAT_DENTRY_FREE:
  544.                 continue;
  545.             case FAT_DENTRY_LAST:
  546.                 block_put(b);
  547.                 futex_up(&parentp->idx->lock);
  548.                 return NULL;
  549.             default:
  550.             case FAT_DENTRY_VALID:
  551.                 fat_dentry_name_get(d, name);
  552.                 break;
  553.             }
  554.             if (fat_dentry_namecmp(name, component) == 0) {
  555.                 /* hit */
  556.                 void *node;
  557.                 /*
  558.                  * Assume tree hierarchy for locking.  We
  559.                  * already have the parent and now we are going
  560.                  * to lock the child.  Never lock in the oposite
  561.                  * order.
  562.                  */
  563.                 fat_idx_t *idx = fat_idx_get_by_pos(
  564.                     parentp->idx->dev_handle, parentp->firstc,
  565.                     i * dps + j);
  566.                 futex_up(&parentp->idx->lock);
  567.                 if (!idx) {
  568.                     /*
  569.                      * Can happen if memory is low or if we
  570.                      * run out of 32-bit indices.
  571.                      */
  572.                     block_put(b);
  573.                     return NULL;
  574.                 }
  575.                 node = fat_node_get_core(idx);
  576.                 futex_up(&idx->lock);
  577.                 block_put(b);
  578.                 return node;
  579.             }
  580.         }
  581.         block_put(b);
  582.     }
  583.  
  584.     futex_up(&parentp->idx->lock);
  585.     return NULL;
  586. }
  587.  
  588. fs_index_t fat_index_get(void *node)
  589. {
  590.     fat_node_t *fnodep = (fat_node_t *)node;
  591.     if (!fnodep)
  592.         return 0;
  593.     return fnodep->idx->index;
  594. }
  595.  
  596. size_t fat_size_get(void *node)
  597. {
  598.     return ((fat_node_t *)node)->size;
  599. }
  600.  
  601. unsigned fat_lnkcnt_get(void *node)
  602. {
  603.     return ((fat_node_t *)node)->lnkcnt;
  604. }
  605.  
  606. bool fat_has_children(void *node)
  607. {
  608.     fat_bs_t *bs;
  609.     fat_node_t *nodep = (fat_node_t *)node;
  610.     unsigned bps;
  611.     unsigned dps;
  612.     unsigned blocks;
  613.     block_t *b;
  614.     unsigned i, j;
  615.  
  616.     if (nodep->type != FAT_DIRECTORY)
  617.         return false;
  618.    
  619.     futex_down(&nodep->idx->lock);
  620.     bs = block_bb_get(nodep->idx->dev_handle);
  621.     bps = uint16_t_le2host(bs->bps);
  622.     dps = bps / sizeof(fat_dentry_t);
  623.  
  624.     blocks = nodep->size / bps;
  625.  
  626.     for (i = 0; i < blocks; i++) {
  627.         fat_dentry_t *d;
  628.    
  629.         b = fat_block_get(bs, nodep, i, BLOCK_FLAGS_NONE);
  630.         for (j = 0; j < dps; j++) {
  631.             d = ((fat_dentry_t *)b->data) + j;
  632.             switch (fat_classify_dentry(d)) {
  633.             case FAT_DENTRY_SKIP:
  634.             case FAT_DENTRY_FREE:
  635.                 continue;
  636.             case FAT_DENTRY_LAST:
  637.                 block_put(b);
  638.                 futex_up(&nodep->idx->lock);
  639.                 return false;
  640.             default:
  641.             case FAT_DENTRY_VALID:
  642.                 block_put(b);
  643.                 futex_up(&nodep->idx->lock);
  644.                 return true;
  645.             }
  646.             block_put(b);
  647.             futex_up(&nodep->idx->lock);
  648.             return true;
  649.         }
  650.         block_put(b);
  651.     }
  652.  
  653.     futex_up(&nodep->idx->lock);
  654.     return false;
  655. }
  656.  
  657. void *fat_root_get(dev_handle_t dev_handle)
  658. {
  659.     return fat_node_get(dev_handle, 0);
  660. }
  661.  
  662. char fat_plb_get_char(unsigned pos)
  663. {
  664.     return fat_reg.plb_ro[pos % PLB_SIZE];
  665. }
  666.  
  667. bool fat_is_directory(void *node)
  668. {
  669.     return ((fat_node_t *)node)->type == FAT_DIRECTORY;
  670. }
  671.  
  672. bool fat_is_file(void *node)
  673. {
  674.     return ((fat_node_t *)node)->type == FAT_FILE;
  675. }
  676.  
  677. /** libfs operations */
  678. libfs_ops_t fat_libfs_ops = {
  679.     .match = fat_match,
  680.     .node_get = fat_node_get,
  681.     .node_put = fat_node_put,
  682.     .create = fat_create_node,
  683.     .destroy = fat_destroy_node,
  684.     .link = fat_link,
  685.     .unlink = fat_unlink,
  686.     .index_get = fat_index_get,
  687.     .size_get = fat_size_get,
  688.     .lnkcnt_get = fat_lnkcnt_get,
  689.     .has_children = fat_has_children,
  690.     .root_get = fat_root_get,
  691.     .plb_get_char = fat_plb_get_char,
  692.     .is_directory = fat_is_directory,
  693.     .is_file = fat_is_file
  694. };
  695.  
  696. /*
  697.  * VFS operations.
  698.  */
  699.  
  700. void fat_mounted(ipc_callid_t rid, ipc_call_t *request)
  701. {
  702.     dev_handle_t dev_handle = (dev_handle_t) IPC_GET_ARG1(*request);
  703.     fat_bs_t *bs;
  704.     uint16_t bps;
  705.     uint16_t rde;
  706.     int rc;
  707.  
  708.     /* initialize libblock */
  709.     rc = block_init(dev_handle, BS_SIZE);
  710.     if (rc != EOK) {
  711.         ipc_answer_0(rid, rc);
  712.         return;
  713.     }
  714.  
  715.     /* prepare the boot block */
  716.     rc = block_bb_read(dev_handle, BS_BLOCK * BS_SIZE, BS_SIZE);
  717.     if (rc != EOK) {
  718.         block_fini(dev_handle);
  719.         ipc_answer_0(rid, rc);
  720.         return;
  721.     }
  722.  
  723.     /* get the buffer with the boot sector */
  724.     bs = block_bb_get(dev_handle);
  725.    
  726.     /* Read the number of root directory entries. */
  727.     bps = uint16_t_le2host(bs->bps);
  728.     rde = uint16_t_le2host(bs->root_ent_max);
  729.  
  730.     if (bps != BS_SIZE) {
  731.         block_fini(dev_handle);
  732.         ipc_answer_0(rid, ENOTSUP);
  733.         return;
  734.     }
  735.  
  736.     /* Initialize the block cache */
  737.     rc = block_cache_init(dev_handle, bps, 0 /* XXX */);
  738.     if (rc != EOK) {
  739.         block_fini(dev_handle);
  740.         ipc_answer_0(rid, rc);
  741.         return;
  742.     }
  743.  
  744.     rc = fat_idx_init_by_dev_handle(dev_handle);
  745.     if (rc != EOK) {
  746.         block_fini(dev_handle);
  747.         ipc_answer_0(rid, rc);
  748.         return;
  749.     }
  750.  
  751.     /* Initialize the root node. */
  752.     fat_node_t *rootp = (fat_node_t *)malloc(sizeof(fat_node_t));
  753.     if (!rootp) {
  754.         block_fini(dev_handle);
  755.         fat_idx_fini_by_dev_handle(dev_handle);
  756.         ipc_answer_0(rid, ENOMEM);
  757.         return;
  758.     }
  759.     fat_node_initialize(rootp);
  760.  
  761.     fat_idx_t *ridxp = fat_idx_get_by_pos(dev_handle, FAT_CLST_ROOTPAR, 0);
  762.     if (!ridxp) {
  763.         block_fini(dev_handle);
  764.         free(rootp);
  765.         fat_idx_fini_by_dev_handle(dev_handle);
  766.         ipc_answer_0(rid, ENOMEM);
  767.         return;
  768.     }
  769.     assert(ridxp->index == 0);
  770.     /* ridxp->lock held */
  771.  
  772.     rootp->type = FAT_DIRECTORY;
  773.     rootp->firstc = FAT_CLST_ROOT;
  774.     rootp->refcnt = 1;
  775.     rootp->lnkcnt = 0;  /* FS root is not linked */
  776.     rootp->size = rde * sizeof(fat_dentry_t);
  777.     rootp->idx = ridxp;
  778.     ridxp->nodep = rootp;
  779.    
  780.     futex_up(&ridxp->lock);
  781.  
  782.     ipc_answer_3(rid, EOK, ridxp->index, rootp->size, rootp->lnkcnt);
  783. }
  784.  
  785. void fat_mount(ipc_callid_t rid, ipc_call_t *request)
  786. {
  787.     ipc_answer_0(rid, ENOTSUP);
  788. }
  789.  
  790. void fat_lookup(ipc_callid_t rid, ipc_call_t *request)
  791. {
  792.     libfs_lookup(&fat_libfs_ops, fat_reg.fs_handle, rid, request);
  793. }
  794.  
  795. void fat_read(ipc_callid_t rid, ipc_call_t *request)
  796. {
  797.     dev_handle_t dev_handle = (dev_handle_t)IPC_GET_ARG1(*request);
  798.     fs_index_t index = (fs_index_t)IPC_GET_ARG2(*request);
  799.     off_t pos = (off_t)IPC_GET_ARG3(*request);
  800.     fat_node_t *nodep = (fat_node_t *)fat_node_get(dev_handle, index);
  801.     fat_bs_t *bs;
  802.     uint16_t bps;
  803.     size_t bytes;
  804.     block_t *b;
  805.  
  806.     if (!nodep) {
  807.         ipc_answer_0(rid, ENOENT);
  808.         return;
  809.     }
  810.  
  811.     ipc_callid_t callid;
  812.     size_t len;
  813.     if (!ipc_data_read_receive(&callid, &len)) {
  814.         fat_node_put(nodep);
  815.         ipc_answer_0(callid, EINVAL);
  816.         ipc_answer_0(rid, EINVAL);
  817.         return;
  818.     }
  819.  
  820.     bs = block_bb_get(dev_handle);
  821.     bps = uint16_t_le2host(bs->bps);
  822.  
  823.     if (nodep->type == FAT_FILE) {
  824.         /*
  825.          * Our strategy for regular file reads is to read one block at
  826.          * most and make use of the possibility to return less data than
  827.          * requested. This keeps the code very simple.
  828.          */
  829.         if (pos >= nodep->size) {
  830.             /* reading beyond the EOF */
  831.             bytes = 0;
  832.             (void) ipc_data_read_finalize(callid, NULL, 0);
  833.         } else {
  834.             bytes = min(len, bps - pos % bps);
  835.             bytes = min(bytes, nodep->size - pos);
  836.             b = fat_block_get(bs, nodep, pos / bps,
  837.                 BLOCK_FLAGS_NONE);
  838.             (void) ipc_data_read_finalize(callid, b->data + pos % bps,
  839.                 bytes);
  840.             block_put(b);
  841.         }
  842.     } else {
  843.         unsigned bnum;
  844.         off_t spos = pos;
  845.         char name[FAT_NAME_LEN + 1 + FAT_EXT_LEN + 1];
  846.         fat_dentry_t *d;
  847.  
  848.         assert(nodep->type == FAT_DIRECTORY);
  849.         assert(nodep->size % bps == 0);
  850.         assert(bps % sizeof(fat_dentry_t) == 0);
  851.  
  852.         /*
  853.          * Our strategy for readdir() is to use the position pointer as
  854.          * an index into the array of all dentries. On entry, it points
  855.          * to the first unread dentry. If we skip any dentries, we bump
  856.          * the position pointer accordingly.
  857.          */
  858.         bnum = (pos * sizeof(fat_dentry_t)) / bps;
  859.         while (bnum < nodep->size / bps) {
  860.             off_t o;
  861.  
  862.             b = fat_block_get(bs, nodep, bnum, BLOCK_FLAGS_NONE);
  863.             for (o = pos % (bps / sizeof(fat_dentry_t));
  864.                 o < bps / sizeof(fat_dentry_t);
  865.                 o++, pos++) {
  866.                 d = ((fat_dentry_t *)b->data) + o;
  867.                 switch (fat_classify_dentry(d)) {
  868.                 case FAT_DENTRY_SKIP:
  869.                 case FAT_DENTRY_FREE:
  870.                     continue;
  871.                 case FAT_DENTRY_LAST:
  872.                     block_put(b);
  873.                     goto miss;
  874.                 default:
  875.                 case FAT_DENTRY_VALID:
  876.                     fat_dentry_name_get(d, name);
  877.                     block_put(b);
  878.                     goto hit;
  879.                 }
  880.             }
  881.             block_put(b);
  882.             bnum++;
  883.         }
  884. miss:
  885.         fat_node_put(nodep);
  886.         ipc_answer_0(callid, ENOENT);
  887.         ipc_answer_1(rid, ENOENT, 0);
  888.         return;
  889. hit:
  890.         (void) ipc_data_read_finalize(callid, name, strlen(name) + 1);
  891.         bytes = (pos - spos) + 1;
  892.     }
  893.  
  894.     fat_node_put(nodep);
  895.     ipc_answer_1(rid, EOK, (ipcarg_t)bytes);
  896. }
  897.  
  898. void fat_write(ipc_callid_t rid, ipc_call_t *request)
  899. {
  900.     dev_handle_t dev_handle = (dev_handle_t)IPC_GET_ARG1(*request);
  901.     fs_index_t index = (fs_index_t)IPC_GET_ARG2(*request);
  902.     off_t pos = (off_t)IPC_GET_ARG3(*request);
  903.     fat_node_t *nodep = (fat_node_t *)fat_node_get(dev_handle, index);
  904.     fat_bs_t *bs;
  905.     size_t bytes;
  906.     block_t *b;
  907.     uint16_t bps;
  908.     unsigned spc;
  909.     unsigned bpc;       /* bytes per cluster */
  910.     off_t boundary;
  911.     int flags = BLOCK_FLAGS_NONE;
  912.    
  913.     if (!nodep) {
  914.         ipc_answer_0(rid, ENOENT);
  915.         return;
  916.     }
  917.    
  918.     ipc_callid_t callid;
  919.     size_t len;
  920.     if (!ipc_data_write_receive(&callid, &len)) {
  921.         fat_node_put(nodep);
  922.         ipc_answer_0(callid, EINVAL);
  923.         ipc_answer_0(rid, EINVAL);
  924.         return;
  925.     }
  926.  
  927.     bs = block_bb_get(dev_handle);
  928.     bps = uint16_t_le2host(bs->bps);
  929.     spc = bs->spc;
  930.     bpc = bps * spc;
  931.  
  932.     /*
  933.      * In all scenarios, we will attempt to write out only one block worth
  934.      * of data at maximum. There might be some more efficient approaches,
  935.      * but this one greatly simplifies fat_write(). Note that we can afford
  936.      * to do this because the client must be ready to handle the return
  937.      * value signalizing a smaller number of bytes written.
  938.      */
  939.     bytes = min(len, bps - pos % bps);
  940.     if (bytes == bps)
  941.         flags |= BLOCK_FLAGS_NOREAD;
  942.    
  943.     boundary = ROUND_UP(nodep->size, bpc);
  944.     if (pos < boundary) {
  945.         /*
  946.          * This is the easier case - we are either overwriting already
  947.          * existing contents or writing behind the EOF, but still within
  948.          * the limits of the last cluster. The node size may grow to the
  949.          * next block size boundary.
  950.          */
  951.         fat_fill_gap(bs, nodep, FAT_CLST_RES0, pos);
  952.         b = fat_block_get(bs, nodep, pos / bps, flags);
  953.         (void) ipc_data_write_finalize(callid, b->data + pos % bps,
  954.             bytes);
  955.         b->dirty = true;        /* need to sync block */
  956.         block_put(b);
  957.         if (pos + bytes > nodep->size) {
  958.             nodep->size = pos + bytes;
  959.             nodep->dirty = true;    /* need to sync node */
  960.         }
  961.         ipc_answer_2(rid, EOK, bytes, nodep->size);
  962.         fat_node_put(nodep);
  963.         return;
  964.     } else {
  965.         /*
  966.          * This is the more difficult case. We must allocate new
  967.          * clusters for the node and zero them out.
  968.          */
  969.         int status;
  970.         unsigned nclsts;
  971.         fat_cluster_t mcl, lcl;
  972.  
  973.         nclsts = (ROUND_UP(pos + bytes, bpc) - boundary) / bpc;
  974.         /* create an independent chain of nclsts clusters in all FATs */
  975.         status = fat_alloc_clusters(bs, dev_handle, nclsts, &mcl, &lcl);
  976.         if (status != EOK) {
  977.             /* could not allocate a chain of nclsts clusters */
  978.             fat_node_put(nodep);
  979.             ipc_answer_0(callid, status);
  980.             ipc_answer_0(rid, status);
  981.             return;
  982.         }
  983.         /* zero fill any gaps */
  984.         fat_fill_gap(bs, nodep, mcl, pos);
  985.         b = _fat_block_get(bs, dev_handle, lcl, (pos / bps) % spc,
  986.             flags);
  987.         (void) ipc_data_write_finalize(callid, b->data + pos % bps,
  988.             bytes);
  989.         b->dirty = true;        /* need to sync block */
  990.         block_put(b);
  991.         /*
  992.          * Append the cluster chain starting in mcl to the end of the
  993.          * node's cluster chain.
  994.          */
  995.         fat_append_clusters(bs, nodep, mcl);
  996.         nodep->size = pos + bytes;
  997.         nodep->dirty = true;        /* need to sync node */
  998.         ipc_answer_2(rid, EOK, bytes, nodep->size);
  999.         fat_node_put(nodep);
  1000.         return;
  1001.     }
  1002. }
  1003.  
  1004. void fat_truncate(ipc_callid_t rid, ipc_call_t *request)
  1005. {
  1006.     dev_handle_t dev_handle = (dev_handle_t)IPC_GET_ARG1(*request);
  1007.     fs_index_t index = (fs_index_t)IPC_GET_ARG2(*request);
  1008.     size_t size = (off_t)IPC_GET_ARG3(*request);
  1009.     fat_node_t *nodep = (fat_node_t *)fat_node_get(dev_handle, index);
  1010.     fat_bs_t *bs;
  1011.     uint16_t bps;
  1012.     uint8_t spc;
  1013.     unsigned bpc;   /* bytes per cluster */
  1014.     int rc;
  1015.  
  1016.     if (!nodep) {
  1017.         ipc_answer_0(rid, ENOENT);
  1018.         return;
  1019.     }
  1020.  
  1021.     bs = block_bb_get(dev_handle);
  1022.     bps = uint16_t_le2host(bs->bps);
  1023.     spc = bs->spc;
  1024.     bpc = bps * spc;
  1025.  
  1026.     if (nodep->size == size) {
  1027.         rc = EOK;
  1028.     } else if (nodep->size < size) {
  1029.         /*
  1030.          * The standard says we have the freedom to grow the node.
  1031.          * For now, we simply return an error.
  1032.          */
  1033.         rc = EINVAL;
  1034.     } else if (ROUND_UP(nodep->size, bpc) == ROUND_UP(size, bpc)) {
  1035.         /*
  1036.          * The node will be shrunk, but no clusters will be deallocated.
  1037.          */
  1038.         nodep->size = size;
  1039.         nodep->dirty = true;        /* need to sync node */
  1040.         rc = EOK;  
  1041.     } else {
  1042.         /*
  1043.          * The node will be shrunk, clusters will be deallocated.
  1044.          */
  1045.         if (size == 0) {
  1046.             fat_chop_clusters(bs, nodep, FAT_CLST_RES0);
  1047.         } else {
  1048.             fat_cluster_t lastc;
  1049.             (void) fat_cluster_walk(bs, dev_handle, nodep->firstc,
  1050.                 &lastc, (size - 1) / bpc);
  1051.             fat_chop_clusters(bs, nodep, lastc);
  1052.         }
  1053.         nodep->size = size;
  1054.         nodep->dirty = true;        /* need to sync node */
  1055.         rc = EOK;  
  1056.     }
  1057.     fat_node_put(nodep);
  1058.     ipc_answer_0(rid, rc);
  1059.     return;
  1060. }
  1061.  
  1062. void fat_destroy(ipc_callid_t rid, ipc_call_t *request)
  1063. {
  1064.     dev_handle_t dev_handle = (dev_handle_t)IPC_GET_ARG1(*request);
  1065.     fs_index_t index = (fs_index_t)IPC_GET_ARG2(*request);
  1066.     int rc;
  1067.  
  1068.     fat_node_t *nodep = fat_node_get(dev_handle, index);
  1069.     if (!nodep) {
  1070.         ipc_answer_0(rid, ENOENT);
  1071.         return;
  1072.     }
  1073.  
  1074.     rc = fat_destroy_node(nodep);
  1075.     ipc_answer_0(rid, rc);
  1076. }
  1077.  
  1078. /**
  1079.  * @}
  1080.  */
  1081.