/** 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_clear_clusters(exfat_bs_t *bs, service_id_t service_id, exfat_cluster_t firstc, exfat_cluster_t count) { int rc; exfat_cluster_t clst; clst = firstc; while (clst < firstc + count) { rc = exfat_bitmap_clear_cluster(bs, service_id, clst); if (rc != EOK) return rc; clst++; } return EOK; }
/** Free clusters forming a cluster chain in FAT. * * @param bs Buffer hodling the boot sector of the file system. * @param service_id Service ID of the file system. * @param firstc First cluster in the chain which is to be freed. * * @return EOK on success or a negative return code. */ int exfat_free_clusters(exfat_bs_t *bs, service_id_t service_id, exfat_cluster_t firstc) { exfat_cluster_t nextc; int rc; /* Mark all clusters in the chain as free */ while (firstc != EXFAT_CLST_EOF) { assert(firstc >= EXFAT_CLST_FIRST && firstc < EXFAT_CLST_BAD); rc = exfat_get_cluster(bs, service_id, firstc, &nextc); if (rc != EOK) return rc; rc = exfat_set_cluster(bs, service_id, firstc, 0); if (rc != EOK) return rc; rc = exfat_bitmap_clear_cluster(bs, service_id, firstc); if (rc != EOK) return rc; firstc = nextc; } return EOK; }