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3504 | jermar | 1 | /* |
2 | * Copyright (c) 2008 Jakub Jermar |
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3 | * All rights reserved. |
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4 | * |
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5 | * Redistribution and use in source and binary forms, with or without |
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6 | * modification, are permitted provided that the following conditions |
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7 | * are met: |
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8 | * |
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9 | * - Redistributions of source code must retain the above copyright |
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10 | * notice, this list of conditions and the following disclaimer. |
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11 | * - Redistributions in binary form must reproduce the above copyright |
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12 | * notice, this list of conditions and the following disclaimer in the |
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13 | * documentation and/or other materials provided with the distribution. |
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14 | * - The name of the author may not be used to endorse or promote products |
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15 | * derived from this software without specific prior written permission. |
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16 | * |
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17 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR |
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18 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
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19 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. |
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20 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, |
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21 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
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22 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
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23 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
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24 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
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25 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF |
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26 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
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27 | */ |
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28 | |||
29 | /** @addtogroup fs |
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30 | * @{ |
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31 | */ |
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32 | |||
33 | /** |
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34 | * @file fat_fat.c |
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3517 | jermar | 35 | * @brief Functions that manipulate the File Allocation Tables. |
3504 | jermar | 36 | */ |
37 | |||
3506 | jermar | 38 | #include "fat_fat.h" |
39 | #include "fat_dentry.h" |
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40 | #include "fat.h" |
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41 | #include "../../vfs/vfs.h" |
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42 | #include <libfs.h> |
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3521 | jermar | 43 | #include <libblock.h> |
3506 | jermar | 44 | #include <errno.h> |
45 | #include <byteorder.h> |
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46 | #include <align.h> |
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47 | #include <assert.h> |
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4581 | mejdrech | 48 | #include <fibril_sync.h> |
49 | #include <mem.h> |
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3504 | jermar | 50 | |
3517 | jermar | 51 | /** |
4581 | mejdrech | 52 | * The fat_alloc_lock mutex protects all copies of the File Allocation Table |
3517 | jermar | 53 | * during allocation of clusters. The lock does not have to be held durring |
54 | * deallocation of clusters. |
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55 | */ |
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4581 | mejdrech | 56 | static FIBRIL_MUTEX_INITIALIZE(fat_alloc_lock); |
3517 | jermar | 57 | |
3550 | jermar | 58 | /** Walk the cluster chain. |
3518 | jermar | 59 | * |
3550 | jermar | 60 | * @param bs Buffer holding the boot sector for the file. |
61 | * @param dev_handle Device handle of the device with the file. |
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62 | * @param firstc First cluster to start the walk with. |
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3571 | jermar | 63 | * @param lastc If non-NULL, output argument hodling the last cluster number visited. |
3550 | jermar | 64 | * @param max_clusters Maximum number of clusters to visit. |
3518 | jermar | 65 | * |
3550 | jermar | 66 | * @return Number of clusters seen during the walk. |
3518 | jermar | 67 | */ |
3550 | jermar | 68 | uint16_t |
69 | fat_cluster_walk(fat_bs_t *bs, dev_handle_t dev_handle, fat_cluster_t firstc, |
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3571 | jermar | 70 | fat_cluster_t *lastc, uint16_t max_clusters) |
3506 | jermar | 71 | { |
72 | block_t *b; |
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73 | unsigned bps; |
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74 | unsigned rscnt; /* block address of the first FAT */ |
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3550 | jermar | 75 | uint16_t clusters = 0; |
3506 | jermar | 76 | fat_cluster_t clst = firstc; |
77 | |||
3516 | jermar | 78 | bps = uint16_t_le2host(bs->bps); |
79 | rscnt = uint16_t_le2host(bs->rscnt); |
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3506 | jermar | 80 | |
3550 | jermar | 81 | if (firstc == FAT_CLST_RES0) { |
82 | /* No space allocated to the file. */ |
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3571 | jermar | 83 | if (lastc) |
84 | *lastc = firstc; |
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3550 | jermar | 85 | return 0; |
3506 | jermar | 86 | } |
87 | |||
3550 | jermar | 88 | while (clst < FAT_CLST_LAST1 && clusters < max_clusters) { |
3571 | jermar | 89 | bn_t fsec; /* sector offset relative to FAT1 */ |
3506 | jermar | 90 | unsigned fidx; /* FAT1 entry index */ |
91 | |||
3550 | jermar | 92 | assert(clst >= FAT_CLST_FIRST); |
3571 | jermar | 93 | if (lastc) |
94 | *lastc = clst; /* remember the last cluster number */ |
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3506 | jermar | 95 | fsec = (clst * sizeof(fat_cluster_t)) / bps; |
96 | fidx = clst % (bps / sizeof(fat_cluster_t)); |
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97 | /* read FAT1 */ |
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3595 | jermar | 98 | b = block_get(dev_handle, rscnt + fsec, BLOCK_FLAGS_NONE); |
3506 | jermar | 99 | clst = uint16_t_le2host(((fat_cluster_t *)b->data)[fidx]); |
100 | assert(clst != FAT_CLST_BAD); |
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101 | block_put(b); |
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3550 | jermar | 102 | clusters++; |
3506 | jermar | 103 | } |
104 | |||
3571 | jermar | 105 | if (lastc && clst < FAT_CLST_LAST1) |
106 | *lastc = clst; |
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3506 | jermar | 107 | |
3550 | jermar | 108 | return clusters; |
3506 | jermar | 109 | } |
110 | |||
3550 | jermar | 111 | /** Read block from file located on a FAT file system. |
3506 | jermar | 112 | * |
3550 | jermar | 113 | * @param bs Buffer holding the boot sector of the file system. |
114 | * @param dev_handle Device handle of the file system. |
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115 | * @param firstc First cluster used by the file. Can be zero if the file |
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116 | * is empty. |
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3571 | jermar | 117 | * @param bn Block number. |
3595 | jermar | 118 | * @param flags Flags passed to libblock. |
3506 | jermar | 119 | * |
3550 | jermar | 120 | * @return Block structure holding the requested block. |
3506 | jermar | 121 | */ |
3550 | jermar | 122 | block_t * |
123 | _fat_block_get(fat_bs_t *bs, dev_handle_t dev_handle, fat_cluster_t firstc, |
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3595 | jermar | 124 | bn_t bn, int flags) |
3506 | jermar | 125 | { |
126 | block_t *b; |
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127 | unsigned bps; |
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128 | unsigned rscnt; /* block address of the first FAT */ |
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3550 | jermar | 129 | unsigned rde; |
130 | unsigned rds; /* root directory size */ |
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131 | unsigned sf; |
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132 | unsigned ssa; /* size of the system area */ |
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133 | unsigned clusters, max_clusters; |
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3572 | jermar | 134 | fat_cluster_t lastc; |
3506 | jermar | 135 | |
3516 | jermar | 136 | bps = uint16_t_le2host(bs->bps); |
137 | rscnt = uint16_t_le2host(bs->rscnt); |
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3550 | jermar | 138 | rde = uint16_t_le2host(bs->root_ent_max); |
139 | sf = uint16_t_le2host(bs->sec_per_fat); |
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3506 | jermar | 140 | |
3550 | jermar | 141 | rds = (sizeof(fat_dentry_t) * rde) / bps; |
142 | rds += ((sizeof(fat_dentry_t) * rde) % bps != 0); |
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143 | ssa = rscnt + bs->fatcnt * sf + rds; |
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144 | |||
145 | if (firstc == FAT_CLST_ROOT) { |
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146 | /* root directory special case */ |
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3571 | jermar | 147 | assert(bn < rds); |
3595 | jermar | 148 | b = block_get(dev_handle, rscnt + bs->fatcnt * sf + bn, flags); |
3550 | jermar | 149 | return b; |
3506 | jermar | 150 | } |
151 | |||
3571 | jermar | 152 | max_clusters = bn / bs->spc; |
153 | clusters = fat_cluster_walk(bs, dev_handle, firstc, &lastc, |
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3550 | jermar | 154 | max_clusters); |
155 | assert(clusters == max_clusters); |
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3506 | jermar | 156 | |
3550 | jermar | 157 | b = block_get(dev_handle, ssa + (lastc - FAT_CLST_FIRST) * bs->spc + |
3595 | jermar | 158 | bn % bs->spc, flags); |
3506 | jermar | 159 | |
3550 | jermar | 160 | return b; |
3506 | jermar | 161 | } |
162 | |||
163 | /** Fill the gap between EOF and a new file position. |
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164 | * |
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3516 | jermar | 165 | * @param bs Buffer holding the boot sector for nodep. |
3506 | jermar | 166 | * @param nodep FAT node with the gap. |
167 | * @param mcl First cluster in an independent cluster chain that will |
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168 | * be later appended to the end of the node's own cluster |
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169 | * chain. If pos is still in the last allocated cluster, |
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170 | * this argument is ignored. |
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171 | * @param pos Position in the last node block. |
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172 | */ |
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3516 | jermar | 173 | void fat_fill_gap(fat_bs_t *bs, fat_node_t *nodep, fat_cluster_t mcl, off_t pos) |
3506 | jermar | 174 | { |
175 | uint16_t bps; |
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176 | unsigned spc; |
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3516 | jermar | 177 | block_t *b; |
3506 | jermar | 178 | off_t o, boundary; |
179 | |||
3516 | jermar | 180 | bps = uint16_t_le2host(bs->bps); |
181 | spc = bs->spc; |
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3506 | jermar | 182 | |
183 | boundary = ROUND_UP(nodep->size, bps * spc); |
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184 | |||
185 | /* zero out already allocated space */ |
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3652 | jermar | 186 | for (o = nodep->size; o < pos && o < boundary; |
3506 | jermar | 187 | o = ALIGN_DOWN(o + bps, bps)) { |
3595 | jermar | 188 | int flags = (o % bps == 0) ? |
189 | BLOCK_FLAGS_NOREAD : BLOCK_FLAGS_NONE; |
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190 | b = fat_block_get(bs, nodep, o / bps, flags); |
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3506 | jermar | 191 | memset(b->data + o % bps, 0, bps - o % bps); |
192 | b->dirty = true; /* need to sync node */ |
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193 | block_put(b); |
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194 | } |
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195 | |||
196 | if (o >= pos) |
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197 | return; |
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198 | |||
199 | /* zero out the initial part of the new cluster chain */ |
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200 | for (o = boundary; o < pos; o += bps) { |
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3516 | jermar | 201 | b = _fat_block_get(bs, nodep->idx->dev_handle, mcl, |
3595 | jermar | 202 | (o - boundary) / bps, BLOCK_FLAGS_NOREAD); |
3506 | jermar | 203 | memset(b->data, 0, min(bps, pos - o)); |
204 | b->dirty = true; /* need to sync node */ |
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205 | block_put(b); |
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206 | } |
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207 | } |
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208 | |||
3572 | jermar | 209 | /** Get cluster from the first FAT. |
3518 | jermar | 210 | * |
211 | * @param bs Buffer holding the boot sector for the file system. |
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212 | * @param dev_handle Device handle for the file system. |
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3572 | jermar | 213 | * @param clst Cluster which to get. |
214 | * |
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215 | * @return Value found in the cluster. |
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216 | */ |
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217 | fat_cluster_t |
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218 | fat_get_cluster(fat_bs_t *bs, dev_handle_t dev_handle, fat_cluster_t clst) |
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219 | { |
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220 | block_t *b; |
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221 | uint16_t bps; |
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222 | uint16_t rscnt; |
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223 | fat_cluster_t *cp, value; |
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224 | |||
225 | bps = uint16_t_le2host(bs->bps); |
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226 | rscnt = uint16_t_le2host(bs->rscnt); |
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227 | |||
3595 | jermar | 228 | b = block_get(dev_handle, rscnt + (clst * sizeof(fat_cluster_t)) / bps, |
229 | BLOCK_FLAGS_NONE); |
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3572 | jermar | 230 | cp = (fat_cluster_t *)b->data + clst % (bps / sizeof(fat_cluster_t)); |
231 | value = uint16_t_le2host(*cp); |
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232 | block_put(b); |
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233 | |||
234 | return value; |
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235 | } |
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236 | |||
237 | /** Set cluster in one instance of FAT. |
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238 | * |
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239 | * @param bs Buffer holding the boot sector for the file system. |
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240 | * @param dev_handle Device handle for the file system. |
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3518 | jermar | 241 | * @param fatno Number of the FAT instance where to make the change. |
3572 | jermar | 242 | * @param clst Cluster which is to be set. |
243 | * @param value Value to set the cluster with. |
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3518 | jermar | 244 | */ |
3506 | jermar | 245 | void |
3572 | jermar | 246 | fat_set_cluster(fat_bs_t *bs, dev_handle_t dev_handle, unsigned fatno, |
3516 | jermar | 247 | fat_cluster_t clst, fat_cluster_t value) |
3506 | jermar | 248 | { |
3516 | jermar | 249 | block_t *b; |
3510 | jermar | 250 | uint16_t bps; |
251 | uint16_t rscnt; |
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252 | uint16_t sf; |
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253 | fat_cluster_t *cp; |
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254 | |||
3516 | jermar | 255 | bps = uint16_t_le2host(bs->bps); |
256 | rscnt = uint16_t_le2host(bs->rscnt); |
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257 | sf = uint16_t_le2host(bs->sec_per_fat); |
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3510 | jermar | 258 | |
3516 | jermar | 259 | assert(fatno < bs->fatcnt); |
260 | b = block_get(dev_handle, rscnt + sf * fatno + |
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3595 | jermar | 261 | (clst * sizeof(fat_cluster_t)) / bps, BLOCK_FLAGS_NONE); |
3516 | jermar | 262 | cp = (fat_cluster_t *)b->data + clst % (bps / sizeof(fat_cluster_t)); |
3510 | jermar | 263 | *cp = host2uint16_t_le(value); |
3516 | jermar | 264 | b->dirty = true; /* need to sync block */ |
265 | block_put(b); |
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3506 | jermar | 266 | } |
267 | |||
3518 | jermar | 268 | /** Replay the allocatoin of clusters in all shadow instances of FAT. |
269 | * |
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270 | * @param bs Buffer holding the boot sector of the file system. |
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271 | * @param dev_handle Device handle of the file system. |
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272 | * @param lifo Chain of allocated clusters. |
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273 | * @param nclsts Number of clusters in the lifo chain. |
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274 | */ |
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3516 | jermar | 275 | void fat_alloc_shadow_clusters(fat_bs_t *bs, dev_handle_t dev_handle, |
276 | fat_cluster_t *lifo, unsigned nclsts) |
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3506 | jermar | 277 | { |
3507 | jermar | 278 | uint8_t fatno; |
279 | unsigned c; |
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280 | |||
3516 | jermar | 281 | for (fatno = FAT1 + 1; fatno < bs->fatcnt; fatno++) { |
3507 | jermar | 282 | for (c = 0; c < nclsts; c++) { |
3572 | jermar | 283 | fat_set_cluster(bs, dev_handle, fatno, lifo[c], |
3507 | jermar | 284 | c == 0 ? FAT_CLST_LAST1 : lifo[c - 1]); |
285 | } |
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286 | } |
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3506 | jermar | 287 | } |
288 | |||
3632 | jermar | 289 | /** Allocate clusters in all copies of FAT. |
3518 | jermar | 290 | * |
291 | * This function will attempt to allocate the requested number of clusters in |
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3632 | jermar | 292 | * all instances of the FAT. The FAT will be altered so that the allocated |
3518 | jermar | 293 | * clusters form an independent chain (i.e. a chain which does not belong to any |
294 | * file yet). |
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295 | * |
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296 | * @param bs Buffer holding the boot sector of the file system. |
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297 | * @param dev_handle Device handle of the file system. |
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298 | * @param nclsts Number of clusters to allocate. |
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299 | * @param mcl Output parameter where the first cluster in the chain |
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300 | * will be returned. |
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301 | * @param lcl Output parameter where the last cluster in the chain |
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302 | * will be returned. |
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303 | * |
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304 | * @return EOK on success, a negative error code otherwise. |
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305 | */ |
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3506 | jermar | 306 | int |
3516 | jermar | 307 | fat_alloc_clusters(fat_bs_t *bs, dev_handle_t dev_handle, unsigned nclsts, |
308 | fat_cluster_t *mcl, fat_cluster_t *lcl) |
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3506 | jermar | 309 | { |
310 | uint16_t bps; |
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311 | uint16_t rscnt; |
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312 | uint16_t sf; |
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3516 | jermar | 313 | block_t *blk; |
3506 | jermar | 314 | fat_cluster_t *lifo; /* stack for storing free cluster numbers */ |
315 | unsigned found = 0; /* top of the free cluster number stack */ |
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316 | unsigned b, c, cl; |
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317 | |||
318 | lifo = (fat_cluster_t *) malloc(nclsts * sizeof(fat_cluster_t)); |
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3632 | jermar | 319 | if (!lifo) |
3506 | jermar | 320 | return ENOMEM; |
321 | |||
3516 | jermar | 322 | bps = uint16_t_le2host(bs->bps); |
323 | rscnt = uint16_t_le2host(bs->rscnt); |
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324 | sf = uint16_t_le2host(bs->sec_per_fat); |
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3506 | jermar | 325 | |
326 | /* |
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327 | * Search FAT1 for unused clusters. |
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328 | */ |
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4581 | mejdrech | 329 | fibril_mutex_lock(&fat_alloc_lock); |
3632 | jermar | 330 | for (b = 0, cl = 0; b < sf; b++) { |
331 | blk = block_get(dev_handle, rscnt + b, BLOCK_FLAGS_NONE); |
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3506 | jermar | 332 | for (c = 0; c < bps / sizeof(fat_cluster_t); c++, cl++) { |
333 | fat_cluster_t *clst = (fat_cluster_t *)blk->data + c; |
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3512 | jermar | 334 | if (uint16_t_le2host(*clst) == FAT_CLST_RES0) { |
3506 | jermar | 335 | /* |
336 | * The cluster is free. Put it into our stack |
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337 | * of found clusters and mark it as non-free. |
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338 | */ |
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339 | lifo[found] = cl; |
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3512 | jermar | 340 | *clst = (found == 0) ? |
341 | host2uint16_t_le(FAT_CLST_LAST1) : |
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342 | host2uint16_t_le(lifo[found - 1]); |
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3506 | jermar | 343 | blk->dirty = true; /* need to sync block */ |
344 | if (++found == nclsts) { |
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345 | /* we are almost done */ |
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346 | block_put(blk); |
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347 | /* update the shadow copies of FAT */ |
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3516 | jermar | 348 | fat_alloc_shadow_clusters(bs, |
349 | dev_handle, lifo, nclsts); |
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3506 | jermar | 350 | *mcl = lifo[found - 1]; |
351 | *lcl = lifo[0]; |
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352 | free(lifo); |
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4581 | mejdrech | 353 | fibril_mutex_unlock(&fat_alloc_lock); |
3506 | jermar | 354 | return EOK; |
355 | } |
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356 | } |
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357 | } |
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358 | block_put(blk); |
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359 | } |
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4581 | mejdrech | 360 | fibril_mutex_unlock(&fat_alloc_lock); |
3506 | jermar | 361 | |
362 | /* |
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363 | * We could not find enough clusters. Now we need to free the clusters |
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364 | * we have allocated so far. |
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365 | */ |
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3516 | jermar | 366 | while (found--) { |
3572 | jermar | 367 | fat_set_cluster(bs, dev_handle, FAT1, lifo[found], |
3516 | jermar | 368 | FAT_CLST_RES0); |
369 | } |
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3506 | jermar | 370 | |
371 | free(lifo); |
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372 | return ENOSPC; |
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373 | } |
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374 | |||
3572 | jermar | 375 | /** Free clusters forming a cluster chain in all copies of FAT. |
376 | * |
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377 | * @param bs Buffer hodling the boot sector of the file system. |
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378 | * @param dev_handle Device handle of the file system. |
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379 | * @param firstc First cluster in the chain which is to be freed. |
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380 | */ |
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381 | void |
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382 | fat_free_clusters(fat_bs_t *bs, dev_handle_t dev_handle, fat_cluster_t firstc) |
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383 | { |
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384 | unsigned fatno; |
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385 | fat_cluster_t nextc; |
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386 | |||
387 | /* Mark all clusters in the chain as free in all copies of FAT. */ |
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388 | while (firstc < FAT_CLST_LAST1) { |
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3637 | jermar | 389 | assert(firstc >= FAT_CLST_FIRST && firstc < FAT_CLST_BAD); |
3572 | jermar | 390 | nextc = fat_get_cluster(bs, dev_handle, firstc); |
391 | for (fatno = FAT1; fatno < bs->fatcnt; fatno++) |
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392 | fat_set_cluster(bs, dev_handle, fatno, firstc, |
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393 | FAT_CLST_RES0); |
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394 | firstc = nextc; |
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395 | } |
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396 | } |
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397 | |||
3518 | jermar | 398 | /** Append a cluster chain to the last file cluster in all FATs. |
399 | * |
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3572 | jermar | 400 | * @param bs Buffer holding the boot sector of the file system. |
3518 | jermar | 401 | * @param nodep Node representing the file. |
402 | * @param mcl First cluster of the cluster chain to append. |
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403 | */ |
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3516 | jermar | 404 | void fat_append_clusters(fat_bs_t *bs, fat_node_t *nodep, fat_cluster_t mcl) |
3506 | jermar | 405 | { |
3516 | jermar | 406 | dev_handle_t dev_handle = nodep->idx->dev_handle; |
3513 | jermar | 407 | fat_cluster_t lcl; |
3516 | jermar | 408 | uint8_t fatno; |
3513 | jermar | 409 | |
3572 | jermar | 410 | if (fat_cluster_walk(bs, dev_handle, nodep->firstc, &lcl, |
3571 | jermar | 411 | (uint16_t) -1) == 0) { |
3550 | jermar | 412 | /* No clusters allocated to the node yet. */ |
3656 | jermar | 413 | nodep->firstc = mcl; |
3513 | jermar | 414 | nodep->dirty = true; /* need to sync node */ |
415 | return; |
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416 | } |
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417 | |||
3516 | jermar | 418 | for (fatno = FAT1; fatno < bs->fatcnt; fatno++) |
3572 | jermar | 419 | fat_set_cluster(bs, nodep->idx->dev_handle, fatno, lcl, mcl); |
3506 | jermar | 420 | } |
421 | |||
3572 | jermar | 422 | /** Chop off node clusters in all copies of FAT. |
423 | * |
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424 | * @param bs Buffer holding the boot sector of the file system. |
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425 | * @param nodep FAT node where the chopping will take place. |
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426 | * @param lastc Last cluster which will remain in the node. If this |
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427 | * argument is FAT_CLST_RES0, then all clusters will |
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3573 | jermar | 428 | * be chopped off. |
3572 | jermar | 429 | */ |
430 | void fat_chop_clusters(fat_bs_t *bs, fat_node_t *nodep, fat_cluster_t lastc) |
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431 | { |
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432 | dev_handle_t dev_handle = nodep->idx->dev_handle; |
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433 | if (lastc == FAT_CLST_RES0) { |
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434 | /* The node will have zero size and no clusters allocated. */ |
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435 | fat_free_clusters(bs, dev_handle, nodep->firstc); |
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436 | nodep->firstc = FAT_CLST_RES0; |
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437 | nodep->dirty = true; /* need to sync node */ |
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438 | } else { |
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439 | fat_cluster_t nextc; |
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440 | unsigned fatno; |
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441 | |||
442 | nextc = fat_get_cluster(bs, dev_handle, lastc); |
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443 | |||
444 | /* Terminate the cluster chain in all copies of FAT. */ |
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445 | for (fatno = FAT1; fatno < bs->fatcnt; fatno++) |
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446 | fat_set_cluster(bs, dev_handle, fatno, lastc, FAT_CLST_LAST1); |
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447 | |||
448 | /* Free all following clusters. */ |
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449 | fat_free_clusters(bs, dev_handle, nextc); |
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450 | } |
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451 | } |
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452 | |||
3504 | jermar | 453 | /** |
454 | * @} |
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455 | */ |