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https://github.com/cloud-hypervisor/cloud-hypervisor.git
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63db385c3c
Move L1 and L2 table entry helpers, division utilities and related constants from mod.rs into a dedicated util.rs submodule. Both mod.rs and metadata.rs import from util. No functional changes. Signed-off-by: Anatol Belski <anbelski@linux.microsoft.com>
80 lines
3.1 KiB
Rust
80 lines
3.1 KiB
Rust
// Copyright 2018 The Chromium OS Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE-BSD-3-Clause file.
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//
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// Copyright 2026 The Cloud Hypervisor Authors. All rights reserved.
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//
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// SPDX-License-Identifier: Apache-2.0 AND BSD-3-Clause
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//! Pure helper functions and constants for QCOW2 L1/L2 table entry
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//! manipulation and integer arithmetic. Shared across the `qcow` submodules.
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/// Nesting depth limit for disk formats that can open other disk files.
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pub(crate) const MAX_NESTING_DEPTH: u32 = 10;
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// bits 0-8 and 56-63 are reserved.
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pub(super) const L1_TABLE_OFFSET_MASK: u64 = 0x00ff_ffff_ffff_fe00;
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pub(super) const L2_TABLE_OFFSET_MASK: u64 = 0x00ff_ffff_ffff_fe00;
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// Flags
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pub(super) const ZERO_FLAG: u64 = 1 << 0;
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pub(super) const COMPRESSED_FLAG: u64 = 1 << 62;
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pub(super) const COMPRESSED_SECTOR_SIZE: u64 = 512;
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pub(super) const CLUSTER_USED_FLAG: u64 = 1 << 63;
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/// Check if L2 entry is empty (unallocated).
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pub(super) fn l2_entry_is_empty(l2_entry: u64) -> bool {
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l2_entry == 0
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}
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/// Check bit 0 - only valid for standard clusters.
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pub(super) fn l2_entry_is_zero(l2_entry: u64) -> bool {
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l2_entry & ZERO_FLAG != 0
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}
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/// Check if L2 entry refers to a compressed cluster.
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pub(super) fn l2_entry_is_compressed(l2_entry: u64) -> bool {
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l2_entry & COMPRESSED_FLAG != 0
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}
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/// Get file offset and size of compressed cluster data.
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pub(super) fn l2_entry_compressed_cluster_layout(l2_entry: u64, cluster_bits: u32) -> (u64, usize) {
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let compressed_size_shift = 62 - (cluster_bits - 8);
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let compressed_size_mask = (1 << (cluster_bits - 8)) - 1;
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let compressed_cluster_addr = l2_entry & ((1 << compressed_size_shift) - 1);
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let nsectors = (l2_entry >> compressed_size_shift & compressed_size_mask) + 1;
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let compressed_cluster_size = ((nsectors * COMPRESSED_SECTOR_SIZE)
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- (compressed_cluster_addr & (COMPRESSED_SECTOR_SIZE - 1)))
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as usize;
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(compressed_cluster_addr, compressed_cluster_size)
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}
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/// Get file offset of standard (non-compressed) cluster.
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pub(super) fn l2_entry_std_cluster_addr(l2_entry: u64) -> u64 {
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l2_entry & L2_TABLE_OFFSET_MASK
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}
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/// Make L2 entry for standard (non-compressed) cluster.
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pub(super) fn l2_entry_make_std(cluster_addr: u64) -> u64 {
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(cluster_addr & L2_TABLE_OFFSET_MASK) | CLUSTER_USED_FLAG
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}
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/// Make L2 entry for preallocated zero cluster.
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pub(super) fn l2_entry_make_zero(cluster_addr: u64) -> u64 {
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(cluster_addr & L2_TABLE_OFFSET_MASK) | CLUSTER_USED_FLAG | ZERO_FLAG
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}
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/// Make L1 entry with optional flags.
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pub(super) fn l1_entry_make(cluster_addr: u64, refcount_is_one: bool) -> u64 {
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(cluster_addr & L1_TABLE_OFFSET_MASK) | (refcount_is_one as u64 * CLUSTER_USED_FLAG)
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}
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/// Ceiling of the division of `dividend`/`divisor`.
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pub(super) fn div_round_up_u32(dividend: u32, divisor: u32) -> u32 {
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dividend / divisor + u32::from(!dividend.is_multiple_of(divisor))
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}
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/// Ceiling of the division of `dividend`/`divisor`.
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pub(super) fn div_round_up_u64(dividend: u64, divisor: u64) -> u64 {
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dividend / divisor + u64::from(!dividend.is_multiple_of(divisor))
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}
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