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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 <async.h>
  43. #include <errno.h>
  44. #include <string.h>
  45. #include <byteorder.h>
  46.  
  47. #define FAT_NAME_LEN        8
  48. #define FAT_EXT_LEN     3
  49.  
  50. #define FAT_PAD         ' '
  51.  
  52. #define FAT_DENTRY_UNUSED   0x00
  53. #define FAT_DENTRY_E5_ESC   0x05
  54. #define FAT_DENTRY_DOT      0x2e
  55. #define FAT_DENTRY_ERASED   0xe5
  56.  
  57. static void dentry_name_canonify(fat_dentry_t *d, char *buf)
  58. {
  59.     int i;
  60.  
  61.     for (i = 0; i < FAT_NAME_LEN; i++) {
  62.         if (d->name[i] == FAT_PAD) {
  63.             buf++;
  64.             break;
  65.         }
  66.         if (d->name[i] == FAT_DENTRY_E5_ESC)
  67.             *buf++ = 0xe5;
  68.         else
  69.             *buf++ = d->name[i];
  70.     }
  71.     if (d->ext[0] != FAT_PAD)
  72.         *buf++ = '.';
  73.     for (i = 0; i < FAT_EXT_LEN; i++) {
  74.         if (d->ext[i] == FAT_PAD) {
  75.             *buf = '\0';
  76.             return;
  77.         }
  78.         if (d->ext[i] == FAT_DENTRY_E5_ESC)
  79.             *buf++ = 0xe5;
  80.         else
  81.             *buf++ = d->ext[i];
  82.     }
  83. }
  84.  
  85. /* TODO and also move somewhere else */
  86. typedef struct {
  87.     void *data;
  88. } block_t;
  89.  
  90. static block_t *block_get(dev_handle_t dev_handle, off_t offset)
  91. {
  92.     return NULL;    /* TODO */
  93. }
  94.  
  95. static block_t *fat_block_get(fat_node_t *node, off_t offset) {
  96.     return NULL;    /* TODO */
  97. }
  98.  
  99. static void block_put(block_t *block)
  100. {
  101.     /* TODO */
  102. }
  103.  
  104. static void *fat_node_get(dev_handle_t dev_handle, fs_index_t index)
  105. {
  106.     return NULL;    /* TODO */
  107. }
  108.  
  109. #define BS_BLOCK    0
  110.  
  111. static void *fat_match(void *prnt, const char *component)
  112. {
  113.     fat_node_t *parentp = (fat_node_t *)prnt;
  114.     char name[FAT_NAME_LEN + 1 + FAT_EXT_LEN + 1];
  115.     unsigned i, j;
  116.     unsigned dps;       /* dentries per sector */
  117.     unsigned blocks;
  118.     fat_dentry_t *d;
  119.     block_t *bb;
  120.     block_t *b;
  121.     fat_bs_t *bs;
  122.  
  123.     bb = block_get(parentp->dev_handle, BS_BLOCK);
  124.     if (!bb)
  125.         return NULL;
  126.     bs = (fat_bs_t *)bb->data;
  127.     dps = bs->bps / sizeof(fat_dentry_t);
  128.     blocks = parentp->size / bs->bps + (parentp->size % bs->bps != 0);
  129.     block_put(bb);
  130.     for (i = 0; i < blocks; i++) {
  131.         unsigned dentries;
  132.        
  133.         b = fat_block_get(parentp, i);
  134.         if (!b)
  135.             return NULL;
  136.  
  137.         dentries = (i == blocks - 1) ?
  138.             parentp->size % sizeof(fat_dentry_t) :
  139.             dps;
  140.         for (j = 0; j < dentries; j++) {
  141.             d = ((fat_dentry_t *)b->data) + j;
  142.             if (d->attr & FAT_ATTR_VOLLABEL) {
  143.                 /* volume label entry */
  144.                 continue;
  145.             }
  146.             if (d->name[0] == FAT_DENTRY_ERASED) {
  147.                 /* not-currently-used entry */
  148.                 continue;
  149.             }
  150.             if (d->name[0] == FAT_DENTRY_UNUSED) {
  151.                 /* never used entry */
  152.                 block_put(b);
  153.                 return NULL;
  154.             }
  155.             if (d->name[0] == FAT_DENTRY_DOT) {
  156.                 /*
  157.                  * Most likely '.' or '..'.
  158.                  * It cannot occur in a regular file name.
  159.                  */
  160.                 continue;
  161.             }
  162.        
  163.             dentry_name_canonify(d, name);
  164.             if (strcmp(name, component) == 0) {
  165.                 /* hit */
  166.                 void *node = fat_node_get(parentp->dev_handle,
  167.                     (fs_index_t)uint16_t_le2host(d->firstc));
  168.                 block_put(b);
  169.                 return node;
  170.             }
  171.         }
  172.         block_put(b);
  173.     }
  174.  
  175.     return NULL;
  176. }
  177.  
  178. /** libfs operations */
  179. libfs_ops_t fat_libfs_ops = {
  180.     .match = fat_match,
  181.     .node_get = fat_node_get,
  182.     .create = NULL,
  183.     .destroy = NULL,
  184.     .link = NULL,
  185.     .unlink = NULL,
  186.     .index_get = NULL,
  187.     .size_get = NULL,
  188.     .lnkcnt_get = NULL,
  189.     .has_children = NULL,
  190.     .root_get = NULL,
  191.     .plb_get_char = NULL,
  192.     .is_directory = NULL,
  193.     .is_file = NULL
  194. };
  195.  
  196. void fat_lookup(ipc_callid_t rid, ipc_call_t *request)
  197. {
  198.     libfs_lookup(&fat_libfs_ops, fat_reg.fs_handle, rid, request);
  199. }
  200.  
  201. /**
  202.  * @}
  203.  */
  204.