/** Allocate clusters in FAT. * * This function will attempt to allocate the requested number of clusters in * the FAT. The FAT will be altered so that the allocated * clusters form an independent chain (i.e. a chain which does not belong to any * file yet). * * @param bs Buffer holding the boot sector of the file system. * @param service_id Service ID of the file system. * @param nclsts Number of clusters to allocate. * @param mcl Output parameter where the first cluster in the chain * will be returned. * @param lcl Output parameter where the last cluster in the chain * will be returned. * * @return EOK on success, a negative error code otherwise. */ int exfat_alloc_clusters(exfat_bs_t *bs, service_id_t service_id, unsigned nclsts, exfat_cluster_t *mcl, exfat_cluster_t *lcl) { exfat_cluster_t *lifo; /* stack for storing free cluster numbers */ unsigned found = 0; /* top of the free cluster number stack */ exfat_cluster_t clst; int rc = EOK; lifo = (exfat_cluster_t *) malloc(nclsts * sizeof(exfat_cluster_t)); if (!lifo) return ENOMEM; fibril_mutex_lock(&exfat_alloc_lock); for (clst = EXFAT_CLST_FIRST; clst < DATA_CNT(bs) + 2 && found < nclsts; clst++) { /* Need to rewrite because of multiple exfat_bitmap_get calls */ if (exfat_bitmap_is_free(bs, service_id, clst) == EOK) { /* * The cluster is free. Put it into our stack * of found clusters and mark it as non-free. */ lifo[found] = clst; rc = exfat_set_cluster(bs, service_id, clst, (found == 0) ? EXFAT_CLST_EOF : lifo[found - 1]); if (rc != EOK) goto exit_error; found++; rc = exfat_bitmap_set_cluster(bs, service_id, clst); if (rc != EOK) goto exit_error; } } if (rc == EOK && found == nclsts) { *mcl = lifo[found - 1]; *lcl = lifo[0]; free(lifo); fibril_mutex_unlock(&exfat_alloc_lock); return EOK; } rc = ENOSPC; exit_error: /* If something wrong - free the clusters */ while (found--) { (void) exfat_bitmap_clear_cluster(bs, service_id, lifo[found]); (void) exfat_set_cluster(bs, service_id, lifo[found], 0); } free(lifo); fibril_mutex_unlock(&exfat_alloc_lock); return rc; }
int exfat_bitmap_alloc_clusters(exfat_bs_t *bs, service_id_t service_id, exfat_cluster_t *firstc, exfat_cluster_t count) { exfat_cluster_t startc, endc; startc = EXFAT_CLST_FIRST; while (startc < DATA_CNT(bs) + 2) { endc = startc; while (exfat_bitmap_is_free(bs, service_id, endc) == EOK) { if ((endc - startc) + 1 == count) { *firstc = startc; return exfat_bitmap_set_clusters(bs, service_id, startc, count); } else endc++; } startc = endc+1; } return ENOSPC; }
int exfat_bitmap_append_clusters(exfat_bs_t *bs, exfat_node_t *nodep, exfat_cluster_t count) { if (nodep->firstc == 0) { return exfat_bitmap_alloc_clusters(bs, nodep->idx->service_id, &nodep->firstc, count); } else { exfat_cluster_t lastc, clst; lastc = nodep->firstc + ROUND_UP(nodep->size, BPC(bs)) / BPC(bs) - 1; clst = lastc + 1; while (exfat_bitmap_is_free(bs, nodep->idx->service_id, clst) == EOK) { if (clst - lastc == count){ return exfat_bitmap_set_clusters(bs, nodep->idx->service_id, lastc + 1, count); } else clst++; } return ENOSPC; } }