| 54,127 → 54,118 |
|---|
| */ |
| static futex_t fat_alloc_lock = FUTEX_INITIALIZER; |
| |
| /** Read block from file located on a FAT file system. |
| /** Walk the cluster chain. |
| * |
| * @param bs Buffer holding the boot sector of the file system. |
| * @param dev_handle Device handle of the file system. |
| * @param firstc First cluster used by the file. Can be zero if the file |
| * is empty. |
| * @param offset Offset in blocks. |
| * @param bs Buffer holding the boot sector for the file. |
| * @param dev_handle Device handle of the device with the file. |
| * @param firstc First cluster to start the walk with. |
| * @param penult If non-NULL, output argument hodling the |
| * the penultimate cluster visited. |
| * @param ult If non-NULL, output argument holding the |
| * ultimate cluster visited. |
| * @param max_clusters Maximum number of clusters to visit. |
| * |
| * @return Block structure holding the requested block. |
| * @return Number of clusters seen during the walk. |
| */ |
| block_t * |
| _fat_block_get(fat_bs_t *bs, dev_handle_t dev_handle, fat_cluster_t firstc, |
| off_t offset) |
| uint16_t |
| fat_cluster_walk(fat_bs_t *bs, dev_handle_t dev_handle, fat_cluster_t firstc, |
| fat_cluster_t *penult, fat_cluster_t *ult, uint16_t max_clusters) |
| { |
| 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; |
| uint16_t clusters = 0; |
| fat_cluster_t clst = firstc; |
| unsigned i; |
| |
| bps = uint16_t_le2host(bs->bps); |
| spc = bs->spc; |
| rscnt = uint16_t_le2host(bs->rscnt); |
| fatcnt = bs->fatcnt; |
| rde = uint16_t_le2host(bs->root_ent_max); |
| sf = uint16_t_le2host(bs->sec_per_fat); |
| |
| 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; |
| if (firstc == FAT_CLST_RES0) { |
| /* No space allocated to the file. */ |
| if (ult) |
| *ult = firstc; |
| return 0; |
| } |
| |
| clusters = offset / spc; |
| for (i = 0; i < clusters; i++) { |
| /* At this point, the meaning of penult is not well-defined. */ |
| if (penult) |
| *penult = FAT_CLST_RES0; |
| |
| while (clst < FAT_CLST_LAST1 && clusters < max_clusters) { |
| unsigned fsec; /* sector offset relative to FAT1 */ |
| unsigned fidx; /* FAT1 entry index */ |
| |
| assert(clst >= FAT_CLST_FIRST && clst < FAT_CLST_BAD); |
| assert(clst >= FAT_CLST_FIRST); |
| if (penult) |
| *penult = clst; /* remember the penultimate cluster */ |
| fsec = (clst * sizeof(fat_cluster_t)) / bps; |
| fidx = clst % (bps / sizeof(fat_cluster_t)); |
| /* read FAT1 */ |
| b = block_get(dev_handle, rscnt + fsec, bps); |
| b = block_get(dev_handle, rscnt + fsec); |
| clst = uint16_t_le2host(((fat_cluster_t *)b->data)[fidx]); |
| assert(clst != FAT_CLST_BAD); |
| assert(clst < FAT_CLST_LAST1); |
| block_put(b); |
| clusters++; |
| } |
| |
| b = block_get(dev_handle, ssa + (clst - FAT_CLST_FIRST) * spc + |
| offset % spc, bps); |
| if (ult) |
| *ult = clst; |
| |
| return b; |
| return clusters; |
| } |
| |
| /** Return number of blocks allocated to a file. |
| /** Read block from file located on a FAT file system. |
| * |
| * @param bs Buffer holding the boot sector for the file. |
| * @param dev_handle Device handle of the device with the file. |
| * @param firstc First cluster of the file. |
| * @param lastc If non-NULL, output argument holding the |
| * last cluster. |
| * @param bs Buffer holding the boot sector of the file system. |
| * @param dev_handle Device handle of the file system. |
| * @param firstc First cluster used by the file. Can be zero if the file |
| * is empty. |
| * @param offset Offset in blocks. |
| * |
| * @return Number of blocks allocated to the file. |
| * @return Block structure holding the requested block. |
| */ |
| uint16_t |
| _fat_blcks_get(fat_bs_t *bs, dev_handle_t dev_handle, fat_cluster_t firstc, |
| fat_cluster_t *lastc) |
| block_t * |
| _fat_block_get(fat_bs_t *bs, dev_handle_t dev_handle, fat_cluster_t firstc, |
| off_t offset) |
| { |
| block_t *b; |
| unsigned bps; |
| unsigned spc; |
| unsigned rscnt; /* block address of the first FAT */ |
| unsigned clusters = 0; |
| fat_cluster_t clst = firstc; |
| unsigned rde; |
| unsigned rds; /* root directory size */ |
| unsigned sf; |
| unsigned ssa; /* size of the system area */ |
| unsigned clusters, max_clusters; |
| fat_cluster_t lastc, clst = firstc; |
| |
| bps = uint16_t_le2host(bs->bps); |
| spc = bs->spc; |
| rscnt = uint16_t_le2host(bs->rscnt); |
| rde = uint16_t_le2host(bs->root_ent_max); |
| sf = uint16_t_le2host(bs->sec_per_fat); |
| |
| if (firstc == FAT_CLST_RES0) { |
| /* No space allocated to the file. */ |
| if (lastc) |
| *lastc = firstc; |
| return 0; |
| rds = (sizeof(fat_dentry_t) * rde) / bps; |
| rds += ((sizeof(fat_dentry_t) * rde) % bps != 0); |
| ssa = rscnt + bs->fatcnt * sf + rds; |
| |
| if (firstc == FAT_CLST_ROOT) { |
| /* root directory special case */ |
| assert(offset < rds); |
| b = block_get(dev_handle, rscnt + bs->fatcnt * sf + offset); |
| return b; |
| } |
| |
| while (clst < FAT_CLST_LAST1) { |
| unsigned fsec; /* sector offset relative to FAT1 */ |
| unsigned fidx; /* FAT1 entry index */ |
| max_clusters = offset / bs->spc; |
| clusters = fat_cluster_walk(bs, dev_handle, firstc, NULL, &lastc, |
| max_clusters); |
| assert(clusters == max_clusters); |
| |
| assert(clst >= FAT_CLST_FIRST); |
| if (lastc) |
| *lastc = clst; /* remember the last cluster */ |
| 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++; |
| } |
| b = block_get(dev_handle, ssa + (lastc - FAT_CLST_FIRST) * bs->spc + |
| offset % bs->spc); |
| |
| if (lastc) |
| *lastc = clst; |
| return clusters * spc; |
| return b; |
| } |
| |
| |
| /** Fill the gap between EOF and a new file position. |
| * |
| * @param bs Buffer holding the boot sector for nodep. |
| 243,7 → 234,7 |
|---|
| |
| assert(fatno < bs->fatcnt); |
| b = block_get(dev_handle, rscnt + sf * fatno + |
| (clst * sizeof(fat_cluster_t)) / bps, bps); |
| (clst * sizeof(fat_cluster_t)) / bps); |
| cp = (fat_cluster_t *)b->data + clst % (bps / sizeof(fat_cluster_t)); |
| *cp = host2uint16_t_le(value); |
| b->dirty = true; /* need to sync block */ |
| 313,7 → 304,7 |
|---|
| */ |
| futex_down(&fat_alloc_lock); |
| for (b = 0, cl = 0; b < sf; blk++) { |
| blk = block_get(dev_handle, rscnt + b, bps); |
| blk = block_get(dev_handle, rscnt + b); |
| for (c = 0; c < bps / sizeof(fat_cluster_t); c++, cl++) { |
| fat_cluster_t *clst = (fat_cluster_t *)blk->data + c; |
| if (uint16_t_le2host(*clst) == FAT_CLST_RES0) { |
| 369,7 → 360,9 |
|---|
| fat_cluster_t lcl; |
| uint8_t fatno; |
| |
| if (_fat_blcks_get(bs, dev_handle, nodep->firstc, &lcl) == 0) { |
| if (fat_cluster_walk(bs, nodep->idx->dev_handle, nodep->firstc, &lcl, |
| NULL, (uint16_t) -1) == 0) { |
| /* No clusters allocated to the node yet. */ |
| nodep->firstc = host2uint16_t_le(mcl); |
| nodep->dirty = true; /* need to sync node */ |
| return; |