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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_fat.c
  35.  * @brief   Functions that manipulate the file allocation tables.
  36.  */
  37.  
  38. #include "fat_fat.h"
  39. #include "fat_dentry.h"
  40. #include "fat.h"
  41. #include "../../vfs/vfs.h"
  42. #include <libfs.h>
  43. #include <errno.h>
  44. #include <byteorder.h>
  45. #include <align.h>
  46. #include <assert.h>
  47.  
  48. block_t *
  49. _fat_block_get(dev_handle_t dev_handle, fat_cluster_t firstc, off_t offset)
  50. {
  51.     block_t *bb;
  52.     block_t *b;
  53.     unsigned bps;
  54.     unsigned spc;
  55.     unsigned rscnt;     /* block address of the first FAT */
  56.     unsigned fatcnt;
  57.     unsigned rde;
  58.     unsigned rds;       /* root directory size */
  59.     unsigned sf;
  60.     unsigned ssa;       /* size of the system area */
  61.     unsigned clusters;
  62.     fat_cluster_t clst = firstc;
  63.     unsigned i;
  64.  
  65.     bb = block_get(dev_handle, BS_BLOCK, BS_SIZE);
  66.     bps = uint16_t_le2host(FAT_BS(bb)->bps);
  67.     spc = FAT_BS(bb)->spc;
  68.     rscnt = uint16_t_le2host(FAT_BS(bb)->rscnt);
  69.     fatcnt = FAT_BS(bb)->fatcnt;
  70.     rde = uint16_t_le2host(FAT_BS(bb)->root_ent_max);
  71.     sf = uint16_t_le2host(FAT_BS(bb)->sec_per_fat);
  72.     block_put(bb);
  73.  
  74.     rds = (sizeof(fat_dentry_t) * rde) / bps;
  75.     rds += ((sizeof(fat_dentry_t) * rde) % bps != 0);
  76.     ssa = rscnt + fatcnt * sf + rds;
  77.  
  78.     if (firstc == FAT_CLST_ROOT) {
  79.         /* root directory special case */
  80.         assert(offset < rds);
  81.         b = block_get(dev_handle, rscnt + fatcnt * sf + offset, bps);
  82.         return b;
  83.     }
  84.  
  85.     clusters = offset / spc;
  86.     for (i = 0; i < clusters; i++) {
  87.         unsigned fsec;  /* sector offset relative to FAT1 */
  88.         unsigned fidx;  /* FAT1 entry index */
  89.  
  90.         assert(clst >= FAT_CLST_FIRST && clst < FAT_CLST_BAD);
  91.         fsec = (clst * sizeof(fat_cluster_t)) / bps;
  92.         fidx = clst % (bps / sizeof(fat_cluster_t));
  93.         /* read FAT1 */
  94.         b = block_get(dev_handle, rscnt + fsec, bps);
  95.         clst = uint16_t_le2host(((fat_cluster_t *)b->data)[fidx]);
  96.         assert(clst != FAT_CLST_BAD);
  97.         assert(clst < FAT_CLST_LAST1);
  98.         block_put(b);
  99.     }
  100.  
  101.     b = block_get(dev_handle, ssa + (clst - FAT_CLST_FIRST) * spc +
  102.         offset % spc, bps);
  103.  
  104.     return b;
  105. }
  106.  
  107. /** Return number of blocks allocated to a file.
  108.  *
  109.  * @param dev_handle    Device handle of the device with the file.
  110.  * @param firstc    First cluster of the file.
  111.  *
  112.  * @return      Number of blocks allocated to the file.
  113.  */
  114. uint16_t
  115. _fat_blcks_get(dev_handle_t dev_handle, fat_cluster_t firstc)
  116. {
  117.     block_t *bb;
  118.     block_t *b;
  119.     unsigned bps;
  120.     unsigned spc;
  121.     unsigned rscnt;     /* block address of the first FAT */
  122.     unsigned clusters = 0;
  123.     fat_cluster_t clst = firstc;
  124.  
  125.     bb = block_get(dev_handle, BS_BLOCK, BS_SIZE);
  126.     bps = uint16_t_le2host(FAT_BS(bb)->bps);
  127.     spc = FAT_BS(bb)->spc;
  128.     rscnt = uint16_t_le2host(FAT_BS(bb)->rscnt);
  129.     block_put(bb);
  130.  
  131.     if (firstc == FAT_CLST_RES0) {
  132.         /* No space allocated to the file. */
  133.         return 0;
  134.     }
  135.  
  136.     while (clst < FAT_CLST_LAST1) {
  137.         unsigned fsec;  /* sector offset relative to FAT1 */
  138.         unsigned fidx;  /* FAT1 entry index */
  139.  
  140.         assert(clst >= FAT_CLST_FIRST);
  141.         fsec = (clst * sizeof(fat_cluster_t)) / bps;
  142.         fidx = clst % (bps / sizeof(fat_cluster_t));
  143.         /* read FAT1 */
  144.         b = block_get(dev_handle, rscnt + fsec, bps);
  145.         clst = uint16_t_le2host(((fat_cluster_t *)b->data)[fidx]);
  146.         assert(clst != FAT_CLST_BAD);
  147.         block_put(b);
  148.         clusters++;
  149.     }
  150.  
  151.     return clusters * spc;
  152. }
  153.  
  154. uint16_t fat_bps_get(dev_handle_t dev_handle)
  155. {
  156.     block_t *bb;
  157.     uint16_t bps;
  158.    
  159.     bb = block_get(dev_handle, BS_BLOCK, BS_SIZE);
  160.     assert(bb != NULL);
  161.     bps = uint16_t_le2host(FAT_BS(bb)->bps);
  162.     block_put(bb);
  163.  
  164.     return bps;
  165. }
  166.  
  167. /** Fill the gap between EOF and a new file position.
  168.  *
  169.  * @param nodep     FAT node with the gap.
  170.  * @param mcl       First cluster in an independent cluster chain that will
  171.  *          be later appended to the end of the node's own cluster
  172.  *          chain. If pos is still in the last allocated cluster,
  173.  *          this argument is ignored.
  174.  * @param pos       Position in the last node block.
  175.  */
  176. void fat_fill_gap(fat_node_t *nodep, fat_cluster_t mcl, off_t pos)
  177. {
  178.     uint16_t bps;
  179.     unsigned spc;
  180.     block_t *bb, *b;
  181.     off_t o, boundary;
  182.  
  183.     bb = block_get(nodep->idx->dev_handle, BS_BLOCK, BS_SIZE);
  184.     bps = uint16_t_le2host(FAT_BS(bb)->bps);
  185.     spc = FAT_BS(bb)->spc;
  186.     block_put(bb);
  187.    
  188.     boundary = ROUND_UP(nodep->size, bps * spc);
  189.  
  190.     /* zero out already allocated space */
  191.     for (o = nodep->size - 1; o < pos && o < boundary;
  192.         o = ALIGN_DOWN(o + bps, bps)) {
  193.         b = fat_block_get(nodep, o / bps);
  194.         memset(b->data + o % bps, 0, bps - o % bps);
  195.         b->dirty = true;        /* need to sync node */
  196.         block_put(b);
  197.     }
  198.    
  199.     if (o >= pos)
  200.         return;
  201.    
  202.     /* zero out the initial part of the new cluster chain */
  203.     for (o = boundary; o < pos; o += bps) {
  204.         b = _fat_block_get(nodep->idx->dev_handle, mcl,
  205.             (o - boundary) / bps);
  206.         memset(b->data, 0, min(bps, pos - o));
  207.         b->dirty = true;        /* need to sync node */
  208.         block_put(b);
  209.     }
  210. }
  211.  
  212. void
  213. fat_mark_cluster(dev_handle_t dev_handle, unsigned fatno, fat_cluster_t clst,
  214.     fat_cluster_t value)
  215. {
  216.     /* TODO */
  217. }
  218.  
  219. void fat_alloc_shadow_clusters(dev_handle_t dev_handle, fat_cluster_t *lifo,
  220.     unsigned nclsts)
  221. {
  222.     uint8_t fatcnt;
  223.     uint8_t fatno;
  224.     unsigned c;
  225.     block_t *bb;
  226.  
  227.     bb = block_get(dev_handle, BS_BLOCK, BS_SIZE);
  228.     fatcnt = FAT_BS(bb)->fatcnt;
  229.     block_put(bb);
  230.    
  231.     for (fatno = FAT1 + 1; fatno < fatcnt; fatno++) {
  232.         for (c = 0; c < nclsts; c++) {
  233.             fat_mark_cluster(dev_handle, fatno, lifo[c],
  234.                 c == 0 ? FAT_CLST_LAST1 : lifo[c - 1]);
  235.         }
  236.     }
  237. }
  238.  
  239. int
  240. fat_alloc_clusters(dev_handle_t dev_handle, unsigned nclsts, fat_cluster_t *mcl,
  241.     fat_cluster_t *lcl)
  242. {
  243.     uint16_t bps;
  244.     uint16_t rscnt;
  245.     uint16_t sf;
  246.     block_t *bb, *blk;
  247.     fat_cluster_t *lifo;    /* stack for storing free cluster numbers */
  248.     unsigned found = 0; /* top of the free cluster number stack */
  249.     unsigned b, c, cl;
  250.  
  251.     lifo = (fat_cluster_t *) malloc(nclsts * sizeof(fat_cluster_t));
  252.     if (lifo)
  253.         return ENOMEM;
  254.    
  255.     bb = block_get(dev_handle, BS_BLOCK, BS_SIZE);
  256.     bps = uint16_t_le2host(FAT_BS(bb)->bps);
  257.     rscnt = uint16_t_le2host(FAT_BS(bb)->rscnt);
  258.     sf = uint16_t_le2host(FAT_BS(bb)->sec_per_fat);
  259.     block_put(bb);
  260.    
  261.     /*
  262.      * Search FAT1 for unused clusters.
  263.      */
  264.     for (b = 0, cl = 0; b < sf; blk++) {
  265.         blk = block_get(dev_handle, rscnt + b, bps);
  266.         for (c = 0; c < bps / sizeof(fat_cluster_t); c++, cl++) {
  267.             fat_cluster_t *clst = (fat_cluster_t *)blk->data + c;
  268.             if (*clst == FAT_CLST_RES0) {
  269.                 /*
  270.                  * The cluster is free. Put it into our stack
  271.                  * of found clusters and mark it as non-free.
  272.                  */
  273.                 lifo[found] = cl;
  274.                 if (found == 0)
  275.                     *clst = FAT_CLST_LAST1;
  276.                 else
  277.                     *clst = lifo[found - 1];
  278.                 blk->dirty = true;  /* need to sync block */
  279.                 if (++found == nclsts) {
  280.                     /* we are almost done */
  281.                     block_put(blk);
  282.                     /* update the shadow copies of FAT */
  283.                     fat_alloc_shadow_clusters(dev_handle,
  284.                         lifo, nclsts);
  285.                     *mcl = lifo[found - 1];
  286.                     *lcl = lifo[0];
  287.                     free(lifo);
  288.                     return EOK;
  289.                 }
  290.             }
  291.         }
  292.         block_put(blk);
  293.     }
  294.  
  295.     /*
  296.      * We could not find enough clusters. Now we need to free the clusters
  297.      * we have allocated so far.
  298.      */
  299.     while (found--)
  300.         fat_mark_cluster(dev_handle, FAT1, lifo[found], FAT_CLST_RES0);
  301.    
  302.     free(lifo);
  303.     return ENOSPC;
  304. }
  305.  
  306. void fat_append_clusters(fat_node_t *nodep, fat_cluster_t mcl)
  307. {
  308. }
  309.  
  310. /**
  311.  * @}
  312.  */
  313.