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// Copyright (C) 2022 Luke Shumaker <lukeshu@lukeshu.com>
//
// SPDX-License-Identifier: GPL-2.0-or-later
package btrfsinspect
import (
"context"
"io"
"git.lukeshu.com/btrfs-progs-ng/lib/btrfs/btrfsitem"
"git.lukeshu.com/btrfs-progs-ng/lib/btrfs/btrfsvol"
"git.lukeshu.com/btrfs-progs-ng/lib/diskio"
)
// ShortSum //////////////////////////////////////////////////////////
type ShortSum string
// SumRun ////////////////////////////////////////////////////////////
type SumRun[Addr btrfsvol.IntAddr[Addr]] struct {
// How big a ShortSum is in this Run.
ChecksumSize int
// Base address where this run starts.
Addr Addr
// All of the ShortSums in this run, concatenated together.
//
// This is a 'string' rather than a 'ShortSum' to make it hard
// to accidentally use it as a single sum.
Sums string
}
func (run SumRun[Addr]) NumSums() int {
return len(run.Sums) / run.ChecksumSize
}
func (run SumRun[Addr]) Size() btrfsvol.AddrDelta {
return btrfsvol.AddrDelta(run.NumSums()) * btrfsitem.CSumBlockSize
}
// Get implements diskio.Sequence[int, ShortSum]
func (run SumRun[Addr]) Get(sumIdx int64) (ShortSum, error) {
if sumIdx < 0 || int(sumIdx) >= run.NumSums() {
return "", io.EOF
}
off := int(sumIdx) * run.ChecksumSize
return ShortSum(run.Sums[off : off+run.ChecksumSize]), nil
}
func (run SumRun[Addr]) SumForAddr(addr Addr) (ShortSum, bool) {
if addr < run.Addr || addr >= run.Addr.Add(run.Size()) {
return "", false
}
off := int((addr-run.Addr)/btrfsitem.CSumBlockSize) * run.ChecksumSize
return ShortSum(run.Sums[off : off+run.ChecksumSize]), true
}
func (run SumRun[Addr]) Walk(ctx context.Context, fn func(Addr, ShortSum) error) error {
for addr, off := run.Addr, 0; off < len(run.Sums); addr, off = addr+btrfsitem.CSumBlockSize, off+run.ChecksumSize {
if err := ctx.Err(); err != nil {
return err
}
if err := fn(addr, ShortSum(run.Sums[off:off+run.ChecksumSize])); err != nil {
return err
}
}
return nil
}
// SumRunWithGaps ////////////////////////////////////////////////////
type SumRunWithGaps[Addr btrfsvol.IntAddr[Addr]] struct {
Addr Addr
Size btrfsvol.AddrDelta
Runs []SumRun[Addr]
}
func (sg SumRunWithGaps[Addr]) NumSums() int {
return int(sg.Size / btrfsitem.CSumBlockSize)
}
func (sg SumRunWithGaps[Addr]) PctFull() float64 {
total := sg.NumSums()
var full int
for _, run := range sg.Runs {
full += run.NumSums()
}
return float64(full) / float64(total)
}
func (sg SumRunWithGaps[Addr]) SumForAddr(addr Addr) (ShortSum, error) {
if addr < sg.Addr || addr >= sg.Addr.Add(sg.Size) {
return "", io.EOF
}
for _, run := range sg.Runs {
if run.Addr > addr {
return "", diskio.ErrWildcard
}
if run.Addr.Add(run.Size()) <= addr {
continue
}
off := int((addr-run.Addr)/btrfsitem.CSumBlockSize) * run.ChecksumSize
return ShortSum(run.Sums[off : off+run.ChecksumSize]), nil
}
return "", diskio.ErrWildcard
}
// Get implements diskio.Sequence[int, ShortSum]
func (sg SumRunWithGaps[Addr]) Get(sumIdx int64) (ShortSum, error) {
addr := sg.Addr.Add(btrfsvol.AddrDelta(sumIdx) * btrfsitem.CSumBlockSize)
return sg.SumForAddr(addr)
}
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