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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 "../../vfs/vfs.h"
  40. #include <libfs.h>
  41. #include <ipc/ipc.h>
  42. #include <ipc/services.h>
  43. #include <ipc/devmap.h>
  44. #include <async.h>
  45. #include <errno.h>
  46. #include <string.h>
  47. #include <byteorder.h>
  48. #include <libadt/hash_table.h>
  49. #include <libadt/list.h>
  50. #include <assert.h>
  51. #include <futex.h>
  52. #include <sys/mman.h>
  53. #include <align.h>
  54.  
  55. #define BS_BLOCK        0
  56. #define BS_SIZE         512
  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. #define FAT_NAME_LEN        8
  65. #define FAT_EXT_LEN     3
  66.  
  67. #define FAT_PAD         ' '
  68.  
  69. #define FAT_DENTRY_UNUSED   0x00
  70. #define FAT_DENTRY_E5_ESC   0x05
  71. #define FAT_DENTRY_DOT      0x2e
  72. #define FAT_DENTRY_ERASED   0xe5
  73.  
  74. #define min(a, b)       ((a) < (b) ? (a) : (b))
  75.  
  76. static void dentry_name_canonify(fat_dentry_t *d, char *buf)
  77. {
  78.     int i;
  79.  
  80.     for (i = 0; i < FAT_NAME_LEN; i++) {
  81.         if (d->name[i] == FAT_PAD)
  82.             break;
  83.         if (d->name[i] == FAT_DENTRY_E5_ESC)
  84.             *buf++ = 0xe5;
  85.         else
  86.             *buf++ = d->name[i];
  87.     }
  88.     if (d->ext[0] != FAT_PAD)
  89.         *buf++ = '.';
  90.     for (i = 0; i < FAT_EXT_LEN; i++) {
  91.         if (d->ext[i] == FAT_PAD) {
  92.             *buf = '\0';
  93.             return;
  94.         }
  95.         if (d->ext[i] == FAT_DENTRY_E5_ESC)
  96.             *buf++ = 0xe5;
  97.         else
  98.             *buf++ = d->ext[i];
  99.     }
  100.     *buf = '\0';
  101. }
  102.  
  103. static int dev_phone = -1;      /* FIXME */
  104. static void *dev_buffer = NULL;     /* FIXME */
  105.  
  106. /* TODO move somewhere else */
  107. typedef struct {
  108.     void *data;
  109.     size_t size;
  110.     bool dirty;
  111. } block_t;
  112.  
  113. static block_t *block_get(dev_handle_t dev_handle, off_t offset, size_t bs)
  114. {
  115.     /* FIXME */
  116.     block_t *b;
  117.     off_t bufpos = 0;
  118.     size_t buflen = 0;
  119.     off_t pos = offset * bs;
  120.  
  121.     assert(dev_phone != -1);
  122.     assert(dev_buffer);
  123.  
  124.     b = malloc(sizeof(block_t));
  125.     if (!b)
  126.         return NULL;
  127.    
  128.     b->data = malloc(bs);
  129.     if (!b->data) {
  130.         free(b);
  131.         return NULL;
  132.     }
  133.     b->size = bs;
  134.  
  135.     if (!libfs_blockread(dev_phone, dev_buffer, &bufpos, &buflen, &pos,
  136.         b->data, bs, bs)) {
  137.         free(b->data);
  138.         free(b);
  139.         return NULL;
  140.     }
  141.  
  142.     return b;
  143. }
  144.  
  145. static void block_put(block_t *block)
  146. {
  147.     /* FIXME */
  148.     free(block->data);
  149.     free(block);
  150. }
  151.  
  152. #define FAT_BS(b)       ((fat_bs_t *)((b)->data))
  153.  
  154. #define FAT_CLST_RES0   0x0000
  155. #define FAT_CLST_RES1   0x0001
  156. #define FAT_CLST_FIRST  0x0002
  157. #define FAT_CLST_BAD    0xfff7
  158. #define FAT_CLST_LAST1  0xfff8
  159. #define FAT_CLST_LAST8  0xffff
  160.  
  161. /* internally used to mark root directory's parent */
  162. #define FAT_CLST_ROOTPAR    FAT_CLST_RES0
  163. /* internally used to mark root directory */
  164. #define FAT_CLST_ROOT       FAT_CLST_RES1
  165.  
  166. #define fat_block_get(np, off) \
  167.     _fat_block_get((np)->idx->dev_handle, (np)->firstc, (off))
  168.  
  169. static block_t *
  170. _fat_block_get(dev_handle_t dev_handle, fat_cluster_t firstc, off_t offset)
  171. {
  172.     block_t *bb;
  173.     block_t *b;
  174.     unsigned bps;
  175.     unsigned spc;
  176.     unsigned rscnt;     /* block address of the first FAT */
  177.     unsigned fatcnt;
  178.     unsigned rde;
  179.     unsigned rds;       /* root directory size */
  180.     unsigned sf;
  181.     unsigned ssa;       /* size of the system area */
  182.     unsigned clusters;
  183.     fat_cluster_t clst = firstc;
  184.     unsigned i;
  185.  
  186.     bb = block_get(dev_handle, BS_BLOCK, BS_SIZE);
  187.     bps = uint16_t_le2host(FAT_BS(bb)->bps);
  188.     spc = FAT_BS(bb)->spc;
  189.     rscnt = uint16_t_le2host(FAT_BS(bb)->rscnt);
  190.     fatcnt = FAT_BS(bb)->fatcnt;
  191.     rde = uint16_t_le2host(FAT_BS(bb)->root_ent_max);
  192.     sf = uint16_t_le2host(FAT_BS(bb)->sec_per_fat);
  193.     block_put(bb);
  194.  
  195.     rds = (sizeof(fat_dentry_t) * rde) / bps;
  196.     rds += ((sizeof(fat_dentry_t) * rde) % bps != 0);
  197.     ssa = rscnt + fatcnt * sf + rds;
  198.  
  199.     if (firstc == FAT_CLST_ROOT) {
  200.         /* root directory special case */
  201.         assert(offset < rds);
  202.         b = block_get(dev_handle, rscnt + fatcnt * sf + offset, bps);
  203.         return b;
  204.     }
  205.  
  206.     clusters = offset / spc;
  207.     for (i = 0; i < clusters; i++) {
  208.         unsigned fsec;  /* sector offset relative to FAT1 */
  209.         unsigned fidx;  /* FAT1 entry index */
  210.  
  211.         assert(clst >= FAT_CLST_FIRST && clst < FAT_CLST_BAD);
  212.         fsec = (clst * sizeof(fat_cluster_t)) / bps;
  213.         fidx = clst % (bps / sizeof(fat_cluster_t));
  214.         /* read FAT1 */
  215.         b = block_get(dev_handle, rscnt + fsec, bps);
  216.         clst = uint16_t_le2host(((fat_cluster_t *)b->data)[fidx]);
  217.         assert(clst != FAT_CLST_BAD);
  218.         assert(clst < FAT_CLST_LAST1);
  219.         block_put(b);
  220.     }
  221.  
  222.     b = block_get(dev_handle, ssa + (clst - FAT_CLST_FIRST) * spc +
  223.         offset % spc, bps);
  224.  
  225.     return b;
  226. }
  227.  
  228. /** Return number of blocks allocated to a file.
  229.  *
  230.  * @param dev_handle    Device handle of the device with the file.
  231.  * @param firstc    First cluster of the file.
  232.  *
  233.  * @return      Number of blocks allocated to the file.
  234.  */
  235. static uint16_t
  236. _fat_blcks_get(dev_handle_t dev_handle, fat_cluster_t firstc)
  237. {
  238.     block_t *bb;
  239.     block_t *b;
  240.     unsigned bps;
  241.     unsigned spc;
  242.     unsigned rscnt;     /* block address of the first FAT */
  243.     unsigned clusters = 0;
  244.     fat_cluster_t clst = firstc;
  245.  
  246.     bb = block_get(dev_handle, BS_BLOCK, BS_SIZE);
  247.     bps = uint16_t_le2host(FAT_BS(bb)->bps);
  248.     spc = FAT_BS(bb)->spc;
  249.     rscnt = uint16_t_le2host(FAT_BS(bb)->rscnt);
  250.     block_put(bb);
  251.  
  252.     if (firstc == FAT_CLST_RES0) {
  253.         /* No space allocated to the file. */
  254.         return 0;
  255.     }
  256.  
  257.     while (clst < FAT_CLST_LAST1) {
  258.         unsigned fsec;  /* sector offset relative to FAT1 */
  259.         unsigned fidx;  /* FAT1 entry index */
  260.  
  261.         assert(clst >= FAT_CLST_FIRST);
  262.         fsec = (clst * sizeof(fat_cluster_t)) / bps;
  263.         fidx = clst % (bps / sizeof(fat_cluster_t));
  264.         /* read FAT1 */
  265.         b = block_get(dev_handle, rscnt + fsec, bps);
  266.         clst = uint16_t_le2host(((fat_cluster_t *)b->data)[fidx]);
  267.         assert(clst != FAT_CLST_BAD);
  268.         block_put(b);
  269.         clusters++;
  270.     }
  271.  
  272.     return clusters * spc;
  273. }
  274.  
  275. static void fat_node_initialize(fat_node_t *node)
  276. {
  277.     futex_initialize(&node->lock, 1);
  278.     node->idx = NULL;
  279.     node->type = 0;
  280.     link_initialize(&node->ffn_link);
  281.     node->size = 0;
  282.     node->lnkcnt = 0;
  283.     node->refcnt = 0;
  284.     node->dirty = false;
  285. }
  286.  
  287. static uint16_t fat_bps_get(dev_handle_t dev_handle)
  288. {
  289.     block_t *bb;
  290.     uint16_t bps;
  291.    
  292.     bb = block_get(dev_handle, BS_BLOCK, BS_SIZE);
  293.     assert(bb != NULL);
  294.     bps = uint16_t_le2host(FAT_BS(bb)->bps);
  295.     block_put(bb);
  296.  
  297.     return bps;
  298. }
  299.  
  300. typedef enum {
  301.     FAT_DENTRY_SKIP,
  302.     FAT_DENTRY_LAST,
  303.     FAT_DENTRY_VALID
  304. } fat_dentry_clsf_t;
  305.  
  306. static fat_dentry_clsf_t fat_classify_dentry(fat_dentry_t *d)
  307. {
  308.     if (d->attr & FAT_ATTR_VOLLABEL) {
  309.         /* volume label entry */
  310.         return FAT_DENTRY_SKIP;
  311.     }
  312.     if (d->name[0] == FAT_DENTRY_ERASED) {
  313.         /* not-currently-used entry */
  314.         return FAT_DENTRY_SKIP;
  315.     }
  316.     if (d->name[0] == FAT_DENTRY_UNUSED) {
  317.         /* never used entry */
  318.         return FAT_DENTRY_LAST;
  319.     }
  320.     if (d->name[0] == FAT_DENTRY_DOT) {
  321.         /*
  322.          * Most likely '.' or '..'.
  323.          * It cannot occur in a regular file name.
  324.          */
  325.         return FAT_DENTRY_SKIP;
  326.     }
  327.     return FAT_DENTRY_VALID;
  328. }
  329.  
  330. static void fat_node_sync(fat_node_t *node)
  331. {
  332.     /* TODO */
  333. }
  334.  
  335. /** Internal version of fat_node_get().
  336.  *
  337.  * @param idxp      Locked index structure.
  338.  */
  339. static void *fat_node_get_core(fat_idx_t *idxp)
  340. {
  341.     block_t *b;
  342.     fat_dentry_t *d;
  343.     fat_node_t *nodep = NULL;
  344.     unsigned bps;
  345.     unsigned dps;
  346.  
  347.     if (idxp->nodep) {
  348.         /*
  349.          * We are lucky.
  350.          * The node is already instantiated in memory.
  351.          */
  352.         futex_down(&idxp->nodep->lock);
  353.         if (!idxp->nodep->refcnt++)
  354.             list_remove(&idxp->nodep->ffn_link);
  355.         futex_up(&idxp->nodep->lock);
  356.         return idxp->nodep;
  357.     }
  358.  
  359.     /*
  360.      * We must instantiate the node from the file system.
  361.      */
  362.    
  363.     assert(idxp->pfc);
  364.  
  365.     futex_down(&ffn_futex);
  366.     if (!list_empty(&ffn_head)) {
  367.         /* Try to use a cached free node structure. */
  368.         fat_idx_t *idxp_tmp;
  369.         nodep = list_get_instance(ffn_head.next, fat_node_t, ffn_link);
  370.         if (futex_trydown(&nodep->lock) == ESYNCH_WOULD_BLOCK)
  371.             goto skip_cache;
  372.         idxp_tmp = nodep->idx;
  373.         if (futex_trydown(&idxp_tmp->lock) == ESYNCH_WOULD_BLOCK) {
  374.             futex_up(&nodep->lock);
  375.             goto skip_cache;
  376.         }
  377.         list_remove(&nodep->ffn_link);
  378.         futex_up(&ffn_futex);
  379.         if (nodep->dirty)
  380.             fat_node_sync(nodep);
  381.         idxp_tmp->nodep = NULL;
  382.         futex_up(&nodep->lock);
  383.         futex_up(&idxp_tmp->lock);
  384.     } else {
  385. skip_cache:
  386.         /* Try to allocate a new node structure. */
  387.         futex_up(&ffn_futex);
  388.         nodep = (fat_node_t *)malloc(sizeof(fat_node_t));
  389.         if (!nodep)
  390.             return NULL;
  391.     }
  392.     fat_node_initialize(nodep);
  393.  
  394.     bps = fat_bps_get(idxp->dev_handle);
  395.     dps = bps / sizeof(fat_dentry_t);
  396.  
  397.     /* Read the block that contains the dentry of interest. */
  398.     b = _fat_block_get(idxp->dev_handle, idxp->pfc,
  399.         (idxp->pdi * sizeof(fat_dentry_t)) / bps);
  400.     assert(b);
  401.  
  402.     d = ((fat_dentry_t *)b->data) + (idxp->pdi % dps);
  403.     if (d->attr & FAT_ATTR_SUBDIR) {
  404.         /*
  405.          * The only directory which does not have this bit set is the
  406.          * root directory itself. The root directory node is handled
  407.          * and initialized elsewhere.
  408.          */
  409.         nodep->type = FAT_DIRECTORY;
  410.         /*
  411.          * Unfortunately, the 'size' field of the FAT dentry is not
  412.          * defined for the directory entry type. We must determine the
  413.          * size of the directory by walking the FAT.
  414.          */
  415.         nodep->size = bps * _fat_blcks_get(idxp->dev_handle,
  416.             uint16_t_le2host(d->firstc));
  417.     } else {
  418.         nodep->type = FAT_FILE;
  419.         nodep->size = uint32_t_le2host(d->size);
  420.     }
  421.     nodep->firstc = uint16_t_le2host(d->firstc);
  422.     nodep->lnkcnt = 1;
  423.     nodep->refcnt = 1;
  424.  
  425.     block_put(b);
  426.  
  427.     /* Link the idx structure with the node structure. */
  428.     nodep->idx = idxp;
  429.     idxp->nodep = nodep;
  430.  
  431.     return nodep;
  432. }
  433.  
  434. /** Instantiate a FAT in-core node. */
  435. static void *fat_node_get(dev_handle_t dev_handle, fs_index_t index)
  436. {
  437.     void *node;
  438.     fat_idx_t *idxp;
  439.  
  440.     idxp = fat_idx_get_by_index(dev_handle, index);
  441.     if (!idxp)
  442.         return NULL;
  443.     /* idxp->lock held */
  444.     node = fat_node_get_core(idxp);
  445.     futex_up(&idxp->lock);
  446.     return node;
  447. }
  448.  
  449. static void fat_node_put(void *node)
  450. {
  451.     fat_node_t *nodep = (fat_node_t *)node;
  452.  
  453.     futex_down(&nodep->lock);
  454.     if (!--nodep->refcnt) {
  455.         futex_down(&ffn_futex);
  456.         list_append(&nodep->ffn_link, &ffn_head);
  457.         futex_up(&ffn_futex);
  458.     }
  459.     futex_up(&nodep->lock);
  460. }
  461.  
  462. static void *fat_create(int flags)
  463. {
  464.     return NULL;    /* not supported at the moment */
  465. }
  466.  
  467. static int fat_destroy(void *node)
  468. {
  469.     return ENOTSUP; /* not supported at the moment */
  470. }
  471.  
  472. static bool fat_link(void *prnt, void *chld, const char *name)
  473. {
  474.     return false;   /* not supported at the moment */
  475. }
  476.  
  477. static int fat_unlink(void *prnt, void *chld)
  478. {
  479.     return ENOTSUP; /* not supported at the moment */
  480. }
  481.  
  482. static void *fat_match(void *prnt, const char *component)
  483. {
  484.     fat_node_t *parentp = (fat_node_t *)prnt;
  485.     char name[FAT_NAME_LEN + 1 + FAT_EXT_LEN + 1];
  486.     unsigned i, j;
  487.     unsigned bps;       /* bytes per sector */
  488.     unsigned dps;       /* dentries per sector */
  489.     unsigned blocks;
  490.     fat_dentry_t *d;
  491.     block_t *b;
  492.  
  493.     futex_down(&parentp->idx->lock);
  494.     bps = fat_bps_get(parentp->idx->dev_handle);
  495.     dps = bps / sizeof(fat_dentry_t);
  496.     blocks = parentp->size / bps + (parentp->size % bps != 0);
  497.     for (i = 0; i < blocks; i++) {
  498.         unsigned dentries;
  499.        
  500.         b = fat_block_get(parentp, i);
  501.         dentries = (i == blocks - 1) ?
  502.             parentp->size % sizeof(fat_dentry_t) :
  503.             dps;
  504.         for (j = 0; j < dentries; j++) {
  505.             d = ((fat_dentry_t *)b->data) + j;
  506.             switch (fat_classify_dentry(d)) {
  507.             case FAT_DENTRY_SKIP:
  508.                 continue;
  509.             case FAT_DENTRY_LAST:
  510.                 block_put(b);
  511.                 futex_up(&parentp->idx->lock);
  512.                 return NULL;
  513.             default:
  514.             case FAT_DENTRY_VALID:
  515.                 dentry_name_canonify(d, name);
  516.                 break;
  517.             }
  518.             if (stricmp(name, component) == 0) {
  519.                 /* hit */
  520.                 void *node;
  521.                 /*
  522.                  * Assume tree hierarchy for locking.  We
  523.                  * already have the parent and now we are going
  524.                  * to lock the child.  Never lock in the oposite
  525.                  * order.
  526.                  */
  527.                 fat_idx_t *idx = fat_idx_get_by_pos(
  528.                     parentp->idx->dev_handle, parentp->firstc,
  529.                     i * dps + j);
  530.                 futex_up(&parentp->idx->lock);
  531.                 if (!idx) {
  532.                     /*
  533.                      * Can happen if memory is low or if we
  534.                      * run out of 32-bit indices.
  535.                      */
  536.                     block_put(b);
  537.                     return NULL;
  538.                 }
  539.                 node = fat_node_get_core(idx);
  540.                 futex_up(&idx->lock);
  541.                 block_put(b);
  542.                 return node;
  543.             }
  544.         }
  545.         block_put(b);
  546.     }
  547.     futex_up(&parentp->idx->lock);
  548.     return NULL;
  549. }
  550.  
  551. static fs_index_t fat_index_get(void *node)
  552. {
  553.     fat_node_t *fnodep = (fat_node_t *)node;
  554.     if (!fnodep)
  555.         return 0;
  556.     return fnodep->idx->index;
  557. }
  558.  
  559. static size_t fat_size_get(void *node)
  560. {
  561.     return ((fat_node_t *)node)->size;
  562. }
  563.  
  564. static unsigned fat_lnkcnt_get(void *node)
  565. {
  566.     return ((fat_node_t *)node)->lnkcnt;
  567. }
  568.  
  569. static bool fat_has_children(void *node)
  570. {
  571.     fat_node_t *nodep = (fat_node_t *)node;
  572.     unsigned bps;
  573.     unsigned dps;
  574.     unsigned blocks;
  575.     block_t *b;
  576.     unsigned i, j;
  577.  
  578.     if (nodep->type != FAT_DIRECTORY)
  579.         return false;
  580.  
  581.     futex_down(&nodep->idx->lock);
  582.     bps = fat_bps_get(nodep->idx->dev_handle);
  583.     dps = bps / sizeof(fat_dentry_t);
  584.  
  585.     blocks = nodep->size / bps + (nodep->size % bps != 0);
  586.  
  587.     for (i = 0; i < blocks; i++) {
  588.         unsigned dentries;
  589.         fat_dentry_t *d;
  590.    
  591.         b = fat_block_get(nodep, i);
  592.         dentries = (i == blocks - 1) ?
  593.             nodep->size % sizeof(fat_dentry_t) :
  594.             dps;
  595.         for (j = 0; j < dentries; j++) {
  596.             d = ((fat_dentry_t *)b->data) + j;
  597.             switch (fat_classify_dentry(d)) {
  598.             case FAT_DENTRY_SKIP:
  599.                 continue;
  600.             case FAT_DENTRY_LAST:
  601.                 block_put(b);
  602.                 futex_up(&nodep->idx->lock);
  603.                 return false;
  604.             default:
  605.             case FAT_DENTRY_VALID:
  606.                 block_put(b);
  607.                 futex_up(&nodep->idx->lock);
  608.                 return true;
  609.             }
  610.             block_put(b);
  611.             futex_up(&nodep->idx->lock);
  612.             return true;
  613.         }
  614.         block_put(b);
  615.     }
  616.  
  617.     futex_up(&nodep->idx->lock);
  618.     return false;
  619. }
  620.  
  621. static void *fat_root_get(dev_handle_t dev_handle)
  622. {
  623.     return fat_node_get(dev_handle, 0);
  624. }
  625.  
  626. static char fat_plb_get_char(unsigned pos)
  627. {
  628.     return fat_reg.plb_ro[pos % PLB_SIZE];
  629. }
  630.  
  631. static bool fat_is_directory(void *node)
  632. {
  633.     return ((fat_node_t *)node)->type == FAT_DIRECTORY;
  634. }
  635.  
  636. static bool fat_is_file(void *node)
  637. {
  638.     return ((fat_node_t *)node)->type == FAT_FILE;
  639. }
  640.  
  641. /** libfs operations */
  642. libfs_ops_t fat_libfs_ops = {
  643.     .match = fat_match,
  644.     .node_get = fat_node_get,
  645.     .node_put = fat_node_put,
  646.     .create = fat_create,
  647.     .destroy = fat_destroy,
  648.     .link = fat_link,
  649.     .unlink = fat_unlink,
  650.     .index_get = fat_index_get,
  651.     .size_get = fat_size_get,
  652.     .lnkcnt_get = fat_lnkcnt_get,
  653.     .has_children = fat_has_children,
  654.     .root_get = fat_root_get,
  655.     .plb_get_char = fat_plb_get_char,
  656.     .is_directory = fat_is_directory,
  657.     .is_file = fat_is_file
  658. };
  659.  
  660. void fat_mounted(ipc_callid_t rid, ipc_call_t *request)
  661. {
  662.     dev_handle_t dev_handle = (dev_handle_t) IPC_GET_ARG1(*request);
  663.     block_t *bb;
  664.     uint16_t bps;
  665.     uint16_t rde;
  666.     int rc;
  667.  
  668.     /*
  669.      * For now, we don't bother to remember dev_handle, dev_phone or
  670.      * dev_buffer in some data structure. We use global variables because we
  671.      * know there will be at most one mount on this file system.
  672.      * Of course, this is a huge TODO item.
  673.      */
  674.     dev_buffer = mmap(NULL, BS_SIZE, PROTO_READ | PROTO_WRITE,
  675.         MAP_ANONYMOUS | MAP_PRIVATE, 0, 0);
  676.    
  677.     if (!dev_buffer) {
  678.         ipc_answer_0(rid, ENOMEM);
  679.         return;
  680.     }
  681.  
  682.     dev_phone = ipc_connect_me_to(PHONE_NS, SERVICE_DEVMAP,
  683.         DEVMAP_CONNECT_TO_DEVICE, dev_handle);
  684.  
  685.     if (dev_phone < 0) {
  686.         munmap(dev_buffer, BS_SIZE);
  687.         ipc_answer_0(rid, dev_phone);
  688.         return;
  689.     }
  690.  
  691.     rc = ipc_share_out_start(dev_phone, dev_buffer,
  692.         AS_AREA_READ | AS_AREA_WRITE);
  693.     if (rc != EOK) {
  694.             munmap(dev_buffer, BS_SIZE);
  695.         ipc_answer_0(rid, rc);
  696.         return;
  697.     }
  698.  
  699.     /* Read the number of root directory entries. */
  700.     bb = block_get(dev_handle, BS_BLOCK, BS_SIZE);
  701.     bps = uint16_t_le2host(FAT_BS(bb)->bps);
  702.     rde = uint16_t_le2host(FAT_BS(bb)->root_ent_max);
  703.     block_put(bb);
  704.  
  705.     if (bps != BS_SIZE) {
  706.         munmap(dev_buffer, BS_SIZE);
  707.         ipc_answer_0(rid, ENOTSUP);
  708.         return;
  709.     }
  710.  
  711.     rc = fat_idx_init_by_dev_handle(dev_handle);
  712.     if (rc != EOK) {
  713.             munmap(dev_buffer, BS_SIZE);
  714.         ipc_answer_0(rid, rc);
  715.         return;
  716.     }
  717.  
  718.     /* Initialize the root node. */
  719.     fat_node_t *rootp = (fat_node_t *)malloc(sizeof(fat_node_t));
  720.     if (!rootp) {
  721.             munmap(dev_buffer, BS_SIZE);
  722.         fat_idx_fini_by_dev_handle(dev_handle);
  723.         ipc_answer_0(rid, ENOMEM);
  724.         return;
  725.     }
  726.     fat_node_initialize(rootp);
  727.  
  728.     fat_idx_t *ridxp = fat_idx_get_by_pos(dev_handle, FAT_CLST_ROOTPAR, 0);
  729.     if (!ridxp) {
  730.             munmap(dev_buffer, BS_SIZE);
  731.         free(rootp);
  732.         fat_idx_fini_by_dev_handle(dev_handle);
  733.         ipc_answer_0(rid, ENOMEM);
  734.         return;
  735.     }
  736.     assert(ridxp->index == 0);
  737.     /* ridxp->lock held */
  738.  
  739.     rootp->type = FAT_DIRECTORY;
  740.     rootp->firstc = FAT_CLST_ROOT;
  741.     rootp->refcnt = 1;
  742.     rootp->lnkcnt = 0;  /* FS root is not linked */
  743.     rootp->size = rde * sizeof(fat_dentry_t);
  744.     rootp->idx = ridxp;
  745.     ridxp->nodep = rootp;
  746.    
  747.     futex_up(&ridxp->lock);
  748.  
  749.     ipc_answer_3(rid, EOK, ridxp->index, rootp->size, rootp->lnkcnt);
  750. }
  751.  
  752. void fat_mount(ipc_callid_t rid, ipc_call_t *request)
  753. {
  754.     ipc_answer_0(rid, ENOTSUP);
  755. }
  756.  
  757. void fat_lookup(ipc_callid_t rid, ipc_call_t *request)
  758. {
  759.     libfs_lookup(&fat_libfs_ops, fat_reg.fs_handle, rid, request);
  760. }
  761.  
  762. void fat_read(ipc_callid_t rid, ipc_call_t *request)
  763. {
  764.     dev_handle_t dev_handle = (dev_handle_t)IPC_GET_ARG1(*request);
  765.     fs_index_t index = (fs_index_t)IPC_GET_ARG2(*request);
  766.     off_t pos = (off_t)IPC_GET_ARG3(*request);
  767.     fat_node_t *nodep = (fat_node_t *)fat_node_get(dev_handle, index);
  768.     uint16_t bps = fat_bps_get(dev_handle);
  769.     size_t bytes;
  770.     block_t *b;
  771.  
  772.     if (!nodep) {
  773.         ipc_answer_0(rid, ENOENT);
  774.         return;
  775.     }
  776.  
  777.     ipc_callid_t callid;
  778.     size_t len;
  779.     if (!ipc_data_read_receive(&callid, &len)) {
  780.         fat_node_put(nodep);
  781.         ipc_answer_0(callid, EINVAL);
  782.         ipc_answer_0(rid, EINVAL);
  783.         return;
  784.     }
  785.  
  786.     if (nodep->type == FAT_FILE) {
  787.         /*
  788.          * Our strategy for regular file reads is to read one block at
  789.          * most and make use of the possibility to return less data than
  790.          * requested. This keeps the code very simple.
  791.          */
  792.         bytes = min(len, bps - pos % bps);
  793.         b = fat_block_get(nodep, pos / bps);
  794.         (void) ipc_data_read_finalize(callid, b->data + pos % bps,
  795.             bytes);
  796.         block_put(b);
  797.     } else {
  798.         unsigned bnum;
  799.         off_t spos = pos;
  800.         char name[FAT_NAME_LEN + 1 + FAT_EXT_LEN + 1];
  801.         fat_dentry_t *d;
  802.  
  803.         assert(nodep->type == FAT_DIRECTORY);
  804.         assert(nodep->size % bps == 0);
  805.         assert(bps % sizeof(fat_dentry_t) == 0);
  806.  
  807.         /*
  808.          * Our strategy for readdir() is to use the position pointer as
  809.          * an index into the array of all dentries. On entry, it points
  810.          * to the first unread dentry. If we skip any dentries, we bump
  811.          * the position pointer accordingly.
  812.          */
  813.         bnum = (pos * sizeof(fat_dentry_t)) / bps;
  814.         while (bnum < nodep->size / bps) {
  815.             off_t o;
  816.  
  817.             b = fat_block_get(nodep, bnum);
  818.             for (o = pos % (bps / sizeof(fat_dentry_t));
  819.                 o < bps / sizeof(fat_dentry_t);
  820.                 o++, pos++) {
  821.                 d = ((fat_dentry_t *)b->data) + o;
  822.                 switch (fat_classify_dentry(d)) {
  823.                 case FAT_DENTRY_SKIP:
  824.                     continue;
  825.                 case FAT_DENTRY_LAST:
  826.                     block_put(b);
  827.                     goto miss;
  828.                 default:
  829.                 case FAT_DENTRY_VALID:
  830.                     dentry_name_canonify(d, name);
  831.                     block_put(b);
  832.                     goto hit;
  833.                 }
  834.             }
  835.             block_put(b);
  836.             bnum++;
  837.         }
  838. miss:
  839.         fat_node_put(nodep);
  840.         ipc_answer_0(callid, ENOENT);
  841.         ipc_answer_1(rid, ENOENT, 0);
  842.         return;
  843. hit:
  844.         (void) ipc_data_read_finalize(callid, name, strlen(name) + 1);
  845.         bytes = (pos - spos) + 1;
  846.     }
  847.  
  848.     fat_node_put(nodep);
  849.     ipc_answer_1(rid, EOK, (ipcarg_t)bytes);
  850. }
  851.  
  852. /** Fill the gap between EOF and a new file position.
  853.  *
  854.  * @param nodep     FAT node with the gap.
  855.  * @param mcl       First cluster in an independent cluster chain that will
  856.  *          be later appended to the end of the node's own cluster
  857.  *          chain. If pos is still in the last allocated cluster,
  858.  *          this argument is ignored.
  859.  * @param pos       Position in the last node block.
  860.  */
  861. static void
  862. fat_fill_gap(fat_node_t *nodep, fat_cluster_t mcl, off_t pos)
  863. {
  864.     uint16_t bps;
  865.     unsigned spc;
  866.     block_t *bb, *b;
  867.     off_t o, boundary;
  868.  
  869.     bb = block_get(nodep->idx->dev_handle, BS_BLOCK, BS_SIZE);
  870.     bps = uint16_t_le2host(FAT_BS(bb)->bps);
  871.     spc = FAT_BS(bb)->spc;
  872.     block_put(bb);
  873.    
  874.     boundary = ROUND_UP(nodep->size, bps * spc);
  875.  
  876.     /* zero out already allocated space */
  877.     for (o = nodep->size - 1; o < pos && o < boundary;
  878.         o = ALIGN_DOWN(o + bps, bps)) {
  879.         b = fat_block_get(nodep, o / bps);
  880.         memset(b->data + o % bps, 0, bps - o % bps);
  881.         b->dirty = true;        /* need to sync node */
  882.         block_put(b);
  883.     }
  884.    
  885.     if (o >= pos)
  886.         return;
  887.    
  888.     /* zero out the initial part of the new cluster chain */
  889.     for (o = boundary; o < pos; o += bps) {
  890.         b = _fat_block_get(nodep->idx->dev_handle, mcl,
  891.             (o - boundary) / bps);
  892.         memset(b->data, 0, min(bps, pos - o));
  893.         b->dirty = true;
  894.         block_put(b);
  895.     }
  896. }
  897.  
  898. static int
  899. fat_alloc_clusters(unsigned nclsts, fat_cluster_t *mcl, fat_cluster_t *lcl)
  900. {
  901.     return ENOTSUP; /* TODO */
  902. }
  903.  
  904. static void
  905. fat_append_clusters(fat_node_t *nodep, fat_cluster_t mcl)
  906. {
  907. }
  908.  
  909. void fat_write(ipc_callid_t rid, ipc_call_t *request)
  910. {
  911.     dev_handle_t dev_handle = (dev_handle_t)IPC_GET_ARG1(*request);
  912.     fs_index_t index = (fs_index_t)IPC_GET_ARG2(*request);
  913.     off_t pos = (off_t)IPC_GET_ARG3(*request);
  914.     fat_node_t *nodep = (fat_node_t *)fat_node_get(dev_handle, index);
  915.     size_t bytes;
  916.     block_t *b, *bb;
  917.     uint16_t bps;
  918.     unsigned spc;
  919.     off_t boundary;
  920.    
  921.     if (!nodep) {
  922.         ipc_answer_0(rid, ENOENT);
  923.         return;
  924.     }
  925.    
  926.     /* XXX remove me when you are ready */
  927.     {
  928.         ipc_answer_0(rid, ENOTSUP);
  929.         fat_node_put(nodep);
  930.         return;
  931.     }
  932.  
  933.     ipc_callid_t callid;
  934.     size_t len;
  935.     if (!ipc_data_write_receive(&callid, &len)) {
  936.         fat_node_put(nodep);
  937.         ipc_answer_0(callid, EINVAL);
  938.         ipc_answer_0(rid, EINVAL);
  939.         return;
  940.     }
  941.  
  942.     /*
  943.      * In all scenarios, we will attempt to write out only one block worth
  944.      * of data at maximum. There might be some more efficient approaches,
  945.      * but this one greatly simplifies fat_write(). Note that we can afford
  946.      * to do this because the client must be ready to handle the return
  947.      * value signalizing a smaller number of bytes written.
  948.      */
  949.     bytes = min(len, bps - pos % bps);
  950.  
  951.     bb = block_get(dev_handle, BS_BLOCK, BS_SIZE);
  952.     bps = uint16_t_le2host(FAT_BS(bb)->bps);
  953.     spc = FAT_BS(bb)->spc;
  954.     block_put(bb);
  955.    
  956.     boundary = ROUND_UP(nodep->size, bps * spc);
  957.     if (pos < boundary) {
  958.         /*
  959.          * This is the easier case - we are either overwriting already
  960.          * existing contents or writing behind the EOF, but still within
  961.          * the limits of the last cluster. The node size may grow to the
  962.          * next block size boundary.
  963.          */
  964.         fat_fill_gap(nodep, FAT_CLST_RES0, pos);
  965.         b = fat_block_get(nodep, pos / bps);
  966.         (void) ipc_data_write_finalize(callid, b->data + pos % bps,
  967.             bytes);
  968.         b->dirty = true;        /* need to sync block */
  969.         block_put(b);
  970.         if (pos + bytes > nodep->size) {
  971.             nodep->size = pos + bytes;
  972.             nodep->dirty = true;    /* need to sync node */
  973.         }
  974.         fat_node_put(nodep);
  975.         ipc_answer_1(rid, EOK, bytes); 
  976.         return;
  977.     } else {
  978.         /*
  979.          * This is the more difficult case. We must allocate new
  980.          * clusters for the node and zero them out.
  981.          */
  982.         int status;
  983.         unsigned nclsts;
  984.         fat_cluster_t mcl, lcl;
  985.    
  986.         nclsts = (ROUND_UP(pos + bytes, bps * spc) - boundary) /
  987.             bps * spc;
  988.         /* create an independent chain of nclsts clusters in all FATs */
  989.         status = fat_alloc_clusters(nclsts, &mcl, &lcl);
  990.         if (status != EOK) {
  991.             /* could not allocate a chain of nclsts clusters */
  992.             fat_node_put(nodep);
  993.             ipc_answer_0(callid, status);
  994.             ipc_answer_0(rid, status);
  995.             return;
  996.         }
  997.         /* zero fill any gaps */
  998.         fat_fill_gap(nodep, mcl, pos);
  999.         b = _fat_block_get(dev_handle, lcl, (pos / bps) % spc);
  1000.         (void) ipc_data_write_finalize(callid, b->data + pos % bps,
  1001.             bytes);
  1002.         b->dirty = true;        /* need to sync block */
  1003.         block_put(b);
  1004.         /*
  1005.          * Append the cluster chain starting in mcl to the end of the
  1006.          * node's cluster chain.
  1007.          */
  1008.         fat_append_clusters(nodep, mcl);
  1009.         nodep->size = pos + bytes;
  1010.         nodep->dirty = true;        /* need to sync node */
  1011.         fat_node_put(nodep);
  1012.         ipc_answer_1(rid, EOK, bytes);
  1013.         return;
  1014.     }
  1015. }
  1016.  
  1017. /**
  1018.  * @}
  1019.  */
  1020.