| 35,7 → 35,265 |
|---|
| * @brief Functions that manipulate the file allocation tables. |
| */ |
| |
| #include "fat_fat.h" |
| #include "fat_dentry.h" |
| #include "fat.h" |
| #include "../../vfs/vfs.h" |
| #include <libfs.h> |
| #include <errno.h> |
| #include <byteorder.h> |
| #include <align.h> |
| #include <assert.h> |
| |
| block_t * |
| _fat_block_get(dev_handle_t dev_handle, fat_cluster_t firstc, off_t offset) |
| { |
| block_t *bb; |
| block_t *b; |
| unsigned bps; |
| unsigned spc; |
| unsigned rscnt; /* block address of the first FAT */ |
| unsigned fatcnt; |
| unsigned rde; |
| unsigned rds; /* root directory size */ |
| unsigned sf; |
| unsigned ssa; /* size of the system area */ |
| unsigned clusters; |
| fat_cluster_t clst = firstc; |
| unsigned i; |
| |
| bb = block_get(dev_handle, BS_BLOCK, BS_SIZE); |
| bps = uint16_t_le2host(FAT_BS(bb)->bps); |
| spc = FAT_BS(bb)->spc; |
| rscnt = uint16_t_le2host(FAT_BS(bb)->rscnt); |
| fatcnt = FAT_BS(bb)->fatcnt; |
| rde = uint16_t_le2host(FAT_BS(bb)->root_ent_max); |
| sf = uint16_t_le2host(FAT_BS(bb)->sec_per_fat); |
| block_put(bb); |
| |
| rds = (sizeof(fat_dentry_t) * rde) / bps; |
| rds += ((sizeof(fat_dentry_t) * rde) % bps != 0); |
| ssa = rscnt + fatcnt * sf + rds; |
| |
| if (firstc == FAT_CLST_ROOT) { |
| /* root directory special case */ |
| assert(offset < rds); |
| b = block_get(dev_handle, rscnt + fatcnt * sf + offset, bps); |
| return b; |
| } |
| |
| clusters = offset / spc; |
| for (i = 0; i < clusters; i++) { |
| unsigned fsec; /* sector offset relative to FAT1 */ |
| unsigned fidx; /* FAT1 entry index */ |
| |
| assert(clst >= FAT_CLST_FIRST && clst < FAT_CLST_BAD); |
| fsec = (clst * sizeof(fat_cluster_t)) / bps; |
| fidx = clst % (bps / sizeof(fat_cluster_t)); |
| /* read FAT1 */ |
| b = block_get(dev_handle, rscnt + fsec, bps); |
| clst = uint16_t_le2host(((fat_cluster_t *)b->data)[fidx]); |
| assert(clst != FAT_CLST_BAD); |
| assert(clst < FAT_CLST_LAST1); |
| block_put(b); |
| } |
| |
| b = block_get(dev_handle, ssa + (clst - FAT_CLST_FIRST) * spc + |
| offset % spc, bps); |
| |
| return b; |
| } |
| |
| /** Return number of blocks allocated to a file. |
| * |
| * @param dev_handle Device handle of the device with the file. |
| * @param firstc First cluster of the file. |
| * |
| * @return Number of blocks allocated to the file. |
| */ |
| uint16_t |
| _fat_blcks_get(dev_handle_t dev_handle, fat_cluster_t firstc) |
| { |
| block_t *bb; |
| block_t *b; |
| unsigned bps; |
| unsigned spc; |
| unsigned rscnt; /* block address of the first FAT */ |
| unsigned clusters = 0; |
| fat_cluster_t clst = firstc; |
| |
| bb = block_get(dev_handle, BS_BLOCK, BS_SIZE); |
| bps = uint16_t_le2host(FAT_BS(bb)->bps); |
| spc = FAT_BS(bb)->spc; |
| rscnt = uint16_t_le2host(FAT_BS(bb)->rscnt); |
| block_put(bb); |
| |
| if (firstc == FAT_CLST_RES0) { |
| /* No space allocated to the file. */ |
| return 0; |
| } |
| |
| while (clst < FAT_CLST_LAST1) { |
| unsigned fsec; /* sector offset relative to FAT1 */ |
| unsigned fidx; /* FAT1 entry index */ |
| |
| assert(clst >= FAT_CLST_FIRST); |
| fsec = (clst * sizeof(fat_cluster_t)) / bps; |
| fidx = clst % (bps / sizeof(fat_cluster_t)); |
| /* read FAT1 */ |
| b = block_get(dev_handle, rscnt + fsec, bps); |
| clst = uint16_t_le2host(((fat_cluster_t *)b->data)[fidx]); |
| assert(clst != FAT_CLST_BAD); |
| block_put(b); |
| clusters++; |
| } |
| |
| return clusters * spc; |
| } |
| |
| uint16_t fat_bps_get(dev_handle_t dev_handle) |
| { |
| block_t *bb; |
| uint16_t bps; |
| |
| bb = block_get(dev_handle, BS_BLOCK, BS_SIZE); |
| assert(bb != NULL); |
| bps = uint16_t_le2host(FAT_BS(bb)->bps); |
| block_put(bb); |
| |
| return bps; |
| } |
| |
| /** Fill the gap between EOF and a new file position. |
| * |
| * @param nodep FAT node with the gap. |
| * @param mcl First cluster in an independent cluster chain that will |
| * be later appended to the end of the node's own cluster |
| * chain. If pos is still in the last allocated cluster, |
| * this argument is ignored. |
| * @param pos Position in the last node block. |
| */ |
| void fat_fill_gap(fat_node_t *nodep, fat_cluster_t mcl, off_t pos) |
| { |
| uint16_t bps; |
| unsigned spc; |
| block_t *bb, *b; |
| off_t o, boundary; |
| |
| bb = block_get(nodep->idx->dev_handle, BS_BLOCK, BS_SIZE); |
| bps = uint16_t_le2host(FAT_BS(bb)->bps); |
| spc = FAT_BS(bb)->spc; |
| block_put(bb); |
| |
| boundary = ROUND_UP(nodep->size, bps * spc); |
| |
| /* zero out already allocated space */ |
| for (o = nodep->size - 1; o < pos && o < boundary; |
| o = ALIGN_DOWN(o + bps, bps)) { |
| b = fat_block_get(nodep, o / bps); |
| memset(b->data + o % bps, 0, bps - o % bps); |
| b->dirty = true; /* need to sync node */ |
| block_put(b); |
| } |
| |
| if (o >= pos) |
| return; |
| |
| /* zero out the initial part of the new cluster chain */ |
| for (o = boundary; o < pos; o += bps) { |
| b = _fat_block_get(nodep->idx->dev_handle, mcl, |
| (o - boundary) / bps); |
| memset(b->data, 0, min(bps, pos - o)); |
| b->dirty = true; /* need to sync node */ |
| block_put(b); |
| } |
| } |
| |
| void |
| fat_mark_cluster(dev_handle_t dev_handle, unsigned fatno, fat_cluster_t clst, |
| fat_cluster_t value) |
| { |
| /* TODO */ |
| } |
| |
| void |
| fat_alloc_shadow_clusters(dev_handle_t dev_handle, fat_cluster_t *lifo, |
| unsigned nclsts) |
| { |
| /* TODO */ |
| } |
| |
| int |
| fat_alloc_clusters(dev_handle_t dev_handle, unsigned nclsts, fat_cluster_t *mcl, |
| fat_cluster_t *lcl) |
| { |
| uint16_t bps; |
| uint16_t rscnt; |
| uint16_t sf; |
| block_t *bb, *blk; |
| fat_cluster_t *lifo; /* stack for storing free cluster numbers */ |
| unsigned found = 0; /* top of the free cluster number stack */ |
| unsigned b, c, cl; |
| |
| lifo = (fat_cluster_t *) malloc(nclsts * sizeof(fat_cluster_t)); |
| if (lifo) |
| return ENOMEM; |
| |
| bb = block_get(dev_handle, BS_BLOCK, BS_SIZE); |
| bps = uint16_t_le2host(FAT_BS(bb)->bps); |
| rscnt = uint16_t_le2host(FAT_BS(bb)->rscnt); |
| sf = uint16_t_le2host(FAT_BS(bb)->sec_per_fat); |
| block_put(bb); |
| |
| /* |
| * Search FAT1 for unused clusters. |
| */ |
| for (b = 0, cl = 0; b < sf; blk++) { |
| blk = block_get(dev_handle, rscnt + b, bps); |
| for (c = 0; c < bps / sizeof(fat_cluster_t); c++, cl++) { |
| fat_cluster_t *clst = (fat_cluster_t *)blk->data + c; |
| if (*clst == FAT_CLST_RES0) { |
| /* |
| * The cluster is free. Put it into our stack |
| * of found clusters and mark it as non-free. |
| */ |
| lifo[found] = cl; |
| if (found == 0) |
| *clst = FAT_CLST_LAST1; |
| else |
| *clst = lifo[found - 1]; |
| blk->dirty = true; /* need to sync block */ |
| if (++found == nclsts) { |
| /* we are almost done */ |
| block_put(blk); |
| /* update the shadow copies of FAT */ |
| fat_alloc_shadow_clusters(dev_handle, |
| lifo, nclsts); |
| *mcl = lifo[found - 1]; |
| *lcl = lifo[0]; |
| free(lifo); |
| return EOK; |
| } |
| } |
| } |
| block_put(blk); |
| } |
| |
| /* |
| * We could not find enough clusters. Now we need to free the clusters |
| * we have allocated so far. |
| */ |
| while (found--) |
| fat_mark_cluster(dev_handle, FAT1, lifo[found], FAT_CLST_RES0); |
| |
| free(lifo); |
| return ENOSPC; |
| } |
| |
| void fat_append_clusters(fat_node_t *nodep, fat_cluster_t mcl) |
| { |
| } |
| |
| /** |
| * @} |
| */ |