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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.     return ENOTSUP; /* not supported at the moment */
  483. }
  484.  
  485. void *fat_match(void *prnt, const char *component)
  486. {
  487.     fat_bs_t *bs;
  488.     fat_node_t *parentp = (fat_node_t *)prnt;
  489.     char name[FAT_NAME_LEN + 1 + FAT_EXT_LEN + 1];
  490.     unsigned i, j;
  491.     unsigned bps;       /* bytes per sector */
  492.     unsigned dps;       /* dentries per sector */
  493.     unsigned blocks;
  494.     fat_dentry_t *d;
  495.     block_t *b;
  496.  
  497.     futex_down(&parentp->idx->lock);
  498.     bs = block_bb_get(parentp->idx->dev_handle);
  499.     bps = uint16_t_le2host(bs->bps);
  500.     dps = bps / sizeof(fat_dentry_t);
  501.     blocks = parentp->size / bps;
  502.     for (i = 0; i < blocks; i++) {
  503.         b = fat_block_get(bs, parentp, i, BLOCK_FLAGS_NONE);
  504.         for (j = 0; j < dps; j++) {
  505.             d = ((fat_dentry_t *)b->data) + j;
  506.             switch (fat_classify_dentry(d)) {
  507.             case FAT_DENTRY_SKIP:
  508.             case FAT_DENTRY_FREE:
  509.                 continue;
  510.             case FAT_DENTRY_LAST:
  511.                 block_put(b);
  512.                 futex_up(&parentp->idx->lock);
  513.                 return NULL;
  514.             default:
  515.             case FAT_DENTRY_VALID:
  516.                 fat_dentry_name_get(d, name);
  517.                 break;
  518.             }
  519.             if (stricmp(name, component) == 0) {
  520.                 /* hit */
  521.                 void *node;
  522.                 /*
  523.                  * Assume tree hierarchy for locking.  We
  524.                  * already have the parent and now we are going
  525.                  * to lock the child.  Never lock in the oposite
  526.                  * order.
  527.                  */
  528.                 fat_idx_t *idx = fat_idx_get_by_pos(
  529.                     parentp->idx->dev_handle, parentp->firstc,
  530.                     i * dps + j);
  531.                 futex_up(&parentp->idx->lock);
  532.                 if (!idx) {
  533.                     /*
  534.                      * Can happen if memory is low or if we
  535.                      * run out of 32-bit indices.
  536.                      */
  537.                     block_put(b);
  538.                     return NULL;
  539.                 }
  540.                 node = fat_node_get_core(idx);
  541.                 futex_up(&idx->lock);
  542.                 block_put(b);
  543.                 return node;
  544.             }
  545.         }
  546.         block_put(b);
  547.     }
  548.  
  549.     futex_up(&parentp->idx->lock);
  550.     return NULL;
  551. }
  552.  
  553. fs_index_t fat_index_get(void *node)
  554. {
  555.     fat_node_t *fnodep = (fat_node_t *)node;
  556.     if (!fnodep)
  557.         return 0;
  558.     return fnodep->idx->index;
  559. }
  560.  
  561. size_t fat_size_get(void *node)
  562. {
  563.     return ((fat_node_t *)node)->size;
  564. }
  565.  
  566. unsigned fat_lnkcnt_get(void *node)
  567. {
  568.     return ((fat_node_t *)node)->lnkcnt;
  569. }
  570.  
  571. bool fat_has_children(void *node)
  572. {
  573.     fat_bs_t *bs;
  574.     fat_node_t *nodep = (fat_node_t *)node;
  575.     unsigned bps;
  576.     unsigned dps;
  577.     unsigned blocks;
  578.     block_t *b;
  579.     unsigned i, j;
  580.  
  581.     if (nodep->type != FAT_DIRECTORY)
  582.         return false;
  583.    
  584.     futex_down(&nodep->idx->lock);
  585.     bs = block_bb_get(nodep->idx->dev_handle);
  586.     bps = uint16_t_le2host(bs->bps);
  587.     dps = bps / sizeof(fat_dentry_t);
  588.  
  589.     blocks = nodep->size / bps;
  590.  
  591.     for (i = 0; i < blocks; i++) {
  592.         fat_dentry_t *d;
  593.    
  594.         b = fat_block_get(bs, nodep, i, BLOCK_FLAGS_NONE);
  595.         for (j = 0; j < dps; j++) {
  596.             d = ((fat_dentry_t *)b->data) + j;
  597.             switch (fat_classify_dentry(d)) {
  598.             case FAT_DENTRY_SKIP:
  599.             case FAT_DENTRY_FREE:
  600.                 continue;
  601.             case FAT_DENTRY_LAST:
  602.                 block_put(b);
  603.                 futex_up(&nodep->idx->lock);
  604.                 return false;
  605.             default:
  606.             case FAT_DENTRY_VALID:
  607.                 block_put(b);
  608.                 futex_up(&nodep->idx->lock);
  609.                 return true;
  610.             }
  611.             block_put(b);
  612.             futex_up(&nodep->idx->lock);
  613.             return true;
  614.         }
  615.         block_put(b);
  616.     }
  617.  
  618.     futex_up(&nodep->idx->lock);
  619.     return false;
  620. }
  621.  
  622. void *fat_root_get(dev_handle_t dev_handle)
  623. {
  624.     return fat_node_get(dev_handle, 0);
  625. }
  626.  
  627. char fat_plb_get_char(unsigned pos)
  628. {
  629.     return fat_reg.plb_ro[pos % PLB_SIZE];
  630. }
  631.  
  632. bool fat_is_directory(void *node)
  633. {
  634.     return ((fat_node_t *)node)->type == FAT_DIRECTORY;
  635. }
  636.  
  637. bool fat_is_file(void *node)
  638. {
  639.     return ((fat_node_t *)node)->type == FAT_FILE;
  640. }
  641.  
  642. /** libfs operations */
  643. libfs_ops_t fat_libfs_ops = {
  644.     .match = fat_match,
  645.     .node_get = fat_node_get,
  646.     .node_put = fat_node_put,
  647.     .create = fat_create_node,
  648.     .destroy = fat_destroy_node,
  649.     .link = fat_link,
  650.     .unlink = fat_unlink,
  651.     .index_get = fat_index_get,
  652.     .size_get = fat_size_get,
  653.     .lnkcnt_get = fat_lnkcnt_get,
  654.     .has_children = fat_has_children,
  655.     .root_get = fat_root_get,
  656.     .plb_get_char = fat_plb_get_char,
  657.     .is_directory = fat_is_directory,
  658.     .is_file = fat_is_file
  659. };
  660.  
  661. /*
  662.  * VFS operations.
  663.  */
  664.  
  665. void fat_mounted(ipc_callid_t rid, ipc_call_t *request)
  666. {
  667.     dev_handle_t dev_handle = (dev_handle_t) IPC_GET_ARG1(*request);
  668.     fat_bs_t *bs;
  669.     uint16_t bps;
  670.     uint16_t rde;
  671.     int rc;
  672.  
  673.     /* initialize libblock */
  674.     rc = block_init(dev_handle, BS_SIZE);
  675.     if (rc != EOK) {
  676.         ipc_answer_0(rid, rc);
  677.         return;
  678.     }
  679.  
  680.     /* prepare the boot block */
  681.     rc = block_bb_read(dev_handle, BS_BLOCK * BS_SIZE, BS_SIZE);
  682.     if (rc != EOK) {
  683.         block_fini(dev_handle);
  684.         ipc_answer_0(rid, rc);
  685.         return;
  686.     }
  687.  
  688.     /* get the buffer with the boot sector */
  689.     bs = block_bb_get(dev_handle);
  690.    
  691.     /* Read the number of root directory entries. */
  692.     bps = uint16_t_le2host(bs->bps);
  693.     rde = uint16_t_le2host(bs->root_ent_max);
  694.  
  695.     if (bps != BS_SIZE) {
  696.         block_fini(dev_handle);
  697.         ipc_answer_0(rid, ENOTSUP);
  698.         return;
  699.     }
  700.  
  701.     /* Initialize the block cache */
  702.     rc = block_cache_init(dev_handle, bps, 0 /* XXX */);
  703.     if (rc != EOK) {
  704.         block_fini(dev_handle);
  705.         ipc_answer_0(rid, rc);
  706.         return;
  707.     }
  708.  
  709.     rc = fat_idx_init_by_dev_handle(dev_handle);
  710.     if (rc != EOK) {
  711.         block_fini(dev_handle);
  712.         ipc_answer_0(rid, rc);
  713.         return;
  714.     }
  715.  
  716.     /* Initialize the root node. */
  717.     fat_node_t *rootp = (fat_node_t *)malloc(sizeof(fat_node_t));
  718.     if (!rootp) {
  719.         block_fini(dev_handle);
  720.         fat_idx_fini_by_dev_handle(dev_handle);
  721.         ipc_answer_0(rid, ENOMEM);
  722.         return;
  723.     }
  724.     fat_node_initialize(rootp);
  725.  
  726.     fat_idx_t *ridxp = fat_idx_get_by_pos(dev_handle, FAT_CLST_ROOTPAR, 0);
  727.     if (!ridxp) {
  728.         block_fini(dev_handle);
  729.         free(rootp);
  730.         fat_idx_fini_by_dev_handle(dev_handle);
  731.         ipc_answer_0(rid, ENOMEM);
  732.         return;
  733.     }
  734.     assert(ridxp->index == 0);
  735.     /* ridxp->lock held */
  736.  
  737.     rootp->type = FAT_DIRECTORY;
  738.     rootp->firstc = FAT_CLST_ROOT;
  739.     rootp->refcnt = 1;
  740.     rootp->lnkcnt = 0;  /* FS root is not linked */
  741.     rootp->size = rde * sizeof(fat_dentry_t);
  742.     rootp->idx = ridxp;
  743.     ridxp->nodep = rootp;
  744.    
  745.     futex_up(&ridxp->lock);
  746.  
  747.     ipc_answer_3(rid, EOK, ridxp->index, rootp->size, rootp->lnkcnt);
  748. }
  749.  
  750. void fat_mount(ipc_callid_t rid, ipc_call_t *request)
  751. {
  752.     ipc_answer_0(rid, ENOTSUP);
  753. }
  754.  
  755. void fat_lookup(ipc_callid_t rid, ipc_call_t *request)
  756. {
  757.     libfs_lookup(&fat_libfs_ops, fat_reg.fs_handle, rid, request);
  758. }
  759.  
  760. void fat_read(ipc_callid_t rid, ipc_call_t *request)
  761. {
  762.     dev_handle_t dev_handle = (dev_handle_t)IPC_GET_ARG1(*request);
  763.     fs_index_t index = (fs_index_t)IPC_GET_ARG2(*request);
  764.     off_t pos = (off_t)IPC_GET_ARG3(*request);
  765.     fat_node_t *nodep = (fat_node_t *)fat_node_get(dev_handle, index);
  766.     fat_bs_t *bs;
  767.     uint16_t bps;
  768.     size_t bytes;
  769.     block_t *b;
  770.  
  771.     if (!nodep) {
  772.         ipc_answer_0(rid, ENOENT);
  773.         return;
  774.     }
  775.  
  776.     ipc_callid_t callid;
  777.     size_t len;
  778.     if (!ipc_data_read_receive(&callid, &len)) {
  779.         fat_node_put(nodep);
  780.         ipc_answer_0(callid, EINVAL);
  781.         ipc_answer_0(rid, EINVAL);
  782.         return;
  783.     }
  784.  
  785.     bs = block_bb_get(dev_handle);
  786.     bps = uint16_t_le2host(bs->bps);
  787.  
  788.     if (nodep->type == FAT_FILE) {
  789.         /*
  790.          * Our strategy for regular file reads is to read one block at
  791.          * most and make use of the possibility to return less data than
  792.          * requested. This keeps the code very simple.
  793.          */
  794.         if (pos >= nodep->size) {
  795.             /* reading beyond the EOF */
  796.             bytes = 0;
  797.             (void) ipc_data_read_finalize(callid, NULL, 0);
  798.         } else {
  799.             bytes = min(len, bps - pos % bps);
  800.             bytes = min(bytes, nodep->size - pos);
  801.             b = fat_block_get(bs, nodep, pos / bps,
  802.                 BLOCK_FLAGS_NONE);
  803.             (void) ipc_data_read_finalize(callid, b->data + pos % bps,
  804.                 bytes);
  805.             block_put(b);
  806.         }
  807.     } else {
  808.         unsigned bnum;
  809.         off_t spos = pos;
  810.         char name[FAT_NAME_LEN + 1 + FAT_EXT_LEN + 1];
  811.         fat_dentry_t *d;
  812.  
  813.         assert(nodep->type == FAT_DIRECTORY);
  814.         assert(nodep->size % bps == 0);
  815.         assert(bps % sizeof(fat_dentry_t) == 0);
  816.  
  817.         /*
  818.          * Our strategy for readdir() is to use the position pointer as
  819.          * an index into the array of all dentries. On entry, it points
  820.          * to the first unread dentry. If we skip any dentries, we bump
  821.          * the position pointer accordingly.
  822.          */
  823.         bnum = (pos * sizeof(fat_dentry_t)) / bps;
  824.         while (bnum < nodep->size / bps) {
  825.             off_t o;
  826.  
  827.             b = fat_block_get(bs, nodep, bnum, BLOCK_FLAGS_NONE);
  828.             for (o = pos % (bps / sizeof(fat_dentry_t));
  829.                 o < bps / sizeof(fat_dentry_t);
  830.                 o++, pos++) {
  831.                 d = ((fat_dentry_t *)b->data) + o;
  832.                 switch (fat_classify_dentry(d)) {
  833.                 case FAT_DENTRY_SKIP:
  834.                 case FAT_DENTRY_FREE:
  835.                     continue;
  836.                 case FAT_DENTRY_LAST:
  837.                     block_put(b);
  838.                     goto miss;
  839.                 default:
  840.                 case FAT_DENTRY_VALID:
  841.                     fat_dentry_name_get(d, name);
  842.                     block_put(b);
  843.                     goto hit;
  844.                 }
  845.             }
  846.             block_put(b);
  847.             bnum++;
  848.         }
  849. miss:
  850.         fat_node_put(nodep);
  851.         ipc_answer_0(callid, ENOENT);
  852.         ipc_answer_1(rid, ENOENT, 0);
  853.         return;
  854. hit:
  855.         (void) ipc_data_read_finalize(callid, name, strlen(name) + 1);
  856.         bytes = (pos - spos) + 1;
  857.     }
  858.  
  859.     fat_node_put(nodep);
  860.     ipc_answer_1(rid, EOK, (ipcarg_t)bytes);
  861. }
  862.  
  863. void fat_write(ipc_callid_t rid, ipc_call_t *request)
  864. {
  865.     dev_handle_t dev_handle = (dev_handle_t)IPC_GET_ARG1(*request);
  866.     fs_index_t index = (fs_index_t)IPC_GET_ARG2(*request);
  867.     off_t pos = (off_t)IPC_GET_ARG3(*request);
  868.     fat_node_t *nodep = (fat_node_t *)fat_node_get(dev_handle, index);
  869.     fat_bs_t *bs;
  870.     size_t bytes;
  871.     block_t *b;
  872.     uint16_t bps;
  873.     unsigned spc;
  874.     unsigned bpc;       /* bytes per cluster */
  875.     off_t boundary;
  876.     int flags = BLOCK_FLAGS_NONE;
  877.    
  878.     if (!nodep) {
  879.         ipc_answer_0(rid, ENOENT);
  880.         return;
  881.     }
  882.    
  883.     ipc_callid_t callid;
  884.     size_t len;
  885.     if (!ipc_data_write_receive(&callid, &len)) {
  886.         fat_node_put(nodep);
  887.         ipc_answer_0(callid, EINVAL);
  888.         ipc_answer_0(rid, EINVAL);
  889.         return;
  890.     }
  891.  
  892.     bs = block_bb_get(dev_handle);
  893.     bps = uint16_t_le2host(bs->bps);
  894.     spc = bs->spc;
  895.     bpc = bps * spc;
  896.  
  897.     /*
  898.      * In all scenarios, we will attempt to write out only one block worth
  899.      * of data at maximum. There might be some more efficient approaches,
  900.      * but this one greatly simplifies fat_write(). Note that we can afford
  901.      * to do this because the client must be ready to handle the return
  902.      * value signalizing a smaller number of bytes written.
  903.      */
  904.     bytes = min(len, bps - pos % bps);
  905.     if (bytes == bps)
  906.         flags |= BLOCK_FLAGS_NOREAD;
  907.    
  908.     boundary = ROUND_UP(nodep->size, bpc);
  909.     if (pos < boundary) {
  910.         /*
  911.          * This is the easier case - we are either overwriting already
  912.          * existing contents or writing behind the EOF, but still within
  913.          * the limits of the last cluster. The node size may grow to the
  914.          * next block size boundary.
  915.          */
  916.         fat_fill_gap(bs, nodep, FAT_CLST_RES0, pos);
  917.         b = fat_block_get(bs, nodep, pos / bps, flags);
  918.         (void) ipc_data_write_finalize(callid, b->data + pos % bps,
  919.             bytes);
  920.         b->dirty = true;        /* need to sync block */
  921.         block_put(b);
  922.         if (pos + bytes > nodep->size) {
  923.             nodep->size = pos + bytes;
  924.             nodep->dirty = true;    /* need to sync node */
  925.         }
  926.         ipc_answer_2(rid, EOK, bytes, nodep->size);
  927.         fat_node_put(nodep);
  928.         return;
  929.     } else {
  930.         /*
  931.          * This is the more difficult case. We must allocate new
  932.          * clusters for the node and zero them out.
  933.          */
  934.         int status;
  935.         unsigned nclsts;
  936.         fat_cluster_t mcl, lcl;
  937.  
  938.         nclsts = (ROUND_UP(pos + bytes, bpc) - boundary) / bpc;
  939.         /* create an independent chain of nclsts clusters in all FATs */
  940.         status = fat_alloc_clusters(bs, dev_handle, nclsts, &mcl, &lcl);
  941.         if (status != EOK) {
  942.             /* could not allocate a chain of nclsts clusters */
  943.             fat_node_put(nodep);
  944.             ipc_answer_0(callid, status);
  945.             ipc_answer_0(rid, status);
  946.             return;
  947.         }
  948.         /* zero fill any gaps */
  949.         fat_fill_gap(bs, nodep, mcl, pos);
  950.         b = _fat_block_get(bs, dev_handle, lcl, (pos / bps) % spc,
  951.             flags);
  952.         (void) ipc_data_write_finalize(callid, b->data + pos % bps,
  953.             bytes);
  954.         b->dirty = true;        /* need to sync block */
  955.         block_put(b);
  956.         /*
  957.          * Append the cluster chain starting in mcl to the end of the
  958.          * node's cluster chain.
  959.          */
  960.         fat_append_clusters(bs, nodep, mcl);
  961.         nodep->size = pos + bytes;
  962.         nodep->dirty = true;        /* need to sync node */
  963.         ipc_answer_2(rid, EOK, bytes, nodep->size);
  964.         fat_node_put(nodep);
  965.         return;
  966.     }
  967. }
  968.  
  969. void fat_truncate(ipc_callid_t rid, ipc_call_t *request)
  970. {
  971.     dev_handle_t dev_handle = (dev_handle_t)IPC_GET_ARG1(*request);
  972.     fs_index_t index = (fs_index_t)IPC_GET_ARG2(*request);
  973.     size_t size = (off_t)IPC_GET_ARG3(*request);
  974.     fat_node_t *nodep = (fat_node_t *)fat_node_get(dev_handle, index);
  975.     fat_bs_t *bs;
  976.     uint16_t bps;
  977.     uint8_t spc;
  978.     unsigned bpc;   /* bytes per cluster */
  979.     int rc;
  980.  
  981.     if (!nodep) {
  982.         ipc_answer_0(rid, ENOENT);
  983.         return;
  984.     }
  985.  
  986.     bs = block_bb_get(dev_handle);
  987.     bps = uint16_t_le2host(bs->bps);
  988.     spc = bs->spc;
  989.     bpc = bps * spc;
  990.  
  991.     if (nodep->size == size) {
  992.         rc = EOK;
  993.     } else if (nodep->size < size) {
  994.         /*
  995.          * The standard says we have the freedom to grow the node.
  996.          * For now, we simply return an error.
  997.          */
  998.         rc = EINVAL;
  999.     } else if (ROUND_UP(nodep->size, bpc) == ROUND_UP(size, bpc)) {
  1000.         /*
  1001.          * The node will be shrunk, but no clusters will be deallocated.
  1002.          */
  1003.         nodep->size = size;
  1004.         nodep->dirty = true;        /* need to sync node */
  1005.         rc = EOK;  
  1006.     } else {
  1007.         /*
  1008.          * The node will be shrunk, clusters will be deallocated.
  1009.          */
  1010.         if (size == 0) {
  1011.             fat_chop_clusters(bs, nodep, FAT_CLST_RES0);
  1012.         } else {
  1013.             fat_cluster_t lastc;
  1014.             (void) fat_cluster_walk(bs, dev_handle, nodep->firstc,
  1015.                 &lastc, (size - 1) / bpc);
  1016.             fat_chop_clusters(bs, nodep, lastc);
  1017.         }
  1018.         nodep->size = size;
  1019.         nodep->dirty = true;        /* need to sync node */
  1020.         rc = EOK;  
  1021.     }
  1022.     fat_node_put(nodep);
  1023.     ipc_answer_0(rid, rc);
  1024.     return;
  1025. }
  1026.  
  1027. void fat_destroy(ipc_callid_t rid, ipc_call_t *request)
  1028. {
  1029.     dev_handle_t dev_handle = (dev_handle_t)IPC_GET_ARG1(*request);
  1030.     fs_index_t index = (fs_index_t)IPC_GET_ARG2(*request);
  1031.     int rc;
  1032.  
  1033.     fat_node_t *nodep = fat_node_get(dev_handle, index);
  1034.     if (!nodep) {
  1035.         ipc_answer_0(rid, ENOENT);
  1036.         return;
  1037.     }
  1038.  
  1039.     rc = fat_destroy_node(nodep);
  1040.     ipc_answer_0(rid, rc);
  1041. }
  1042.  
  1043. /**
  1044.  * @}
  1045.  */
  1046.