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fix(vhd-merge/chainVhd): correctly compute header checksum (#419)

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Fixes vatesfr/xo-web#1656
This commit is contained in:
Julien Fontanet 2016-10-13 18:49:58 +02:00 committed by GitHub
parent 36fe49f3f5
commit 524355b59c
1 changed files with 34 additions and 8 deletions
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42
src/vhd-merge.js
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@ -1,4 +1,5 @@
import fu from '@nraynaud/struct-fu'
import isEqual from 'lodash/isEqual'
import {
noop,
@ -146,13 +147,15 @@ const unpackField = (field, buf) => {
// Returns the checksum of a raw struct.
// The raw struct (footer or header) is altered with the new sum.
function checksumStruct (rawStruct, checksumField) {
function checksumStruct (rawStruct, struct) {
const checksumField = struct.fields.checksum
let sum = 0
// Reset current sum.
packField(checksumField, 0, rawStruct)
for (let i = 0; i < VHD_FOOTER_SIZE; i++) {
for (let i = 0, n = struct.size; i < n; i++) {
sum = (sum + rawStruct[i]) & 0xFFFFFFFF
}
@ -255,7 +258,7 @@ class Vhd {
)
const sum = unpackField(fuFooter.fields.checksum, buf)
const sumToTest = checksumStruct(buf, fuFooter.fields.checksum)
const sumToTest = checksumStruct(buf, fuFooter)
// Checksum child & parent.
if (sumToTest !== sum) {
@ -499,7 +502,7 @@ class Vhd {
const offset = this.getEndOfData()
const rawFooter = fuFooter.pack(footer)
footer.checksum = checksumStruct(rawFooter, fuFooter.fields.checksum)
footer.checksum = checksumStruct(rawFooter, fuFooter)
debug(`Write footer at: ${offset} (checksum=${footer.checksum}). (data=${rawFooter.toString('hex')})`)
await this._write(rawFooter, 0)
@ -509,7 +512,7 @@ class Vhd {
async writeHeader () {
const { header } = this
const rawHeader = fuHeader.pack(header)
header.checksum = checksumStruct(rawHeader, fuHeader.fields.checksum)
header.checksum = checksumStruct(rawHeader, fuHeader)
const offset = VHD_FOOTER_SIZE
debug(`Write header at: ${offset} (checksum=${header.checksum}). (data=${rawHeader.toString('hex')})`)
await this._write(rawHeader, offset)
@ -520,6 +523,8 @@ class Vhd {
//
// Child must be a delta backup !
// Parent must be a full backup !
//
// TODO: update the identifier of the parent VHD.
export default async function vhdMerge (
parentHandler, parentPath,
childHandler, childPath
@ -583,13 +588,34 @@ export async function chainVhd (
parentVhd.readHeaderAndFooter(),
childVhd.readHeaderAndFooter()
])
const { header } = childVhd
const parentName = parentPath.split('/').pop()
const parentUuid = parentVhd.footer.uuid
if (childVhd.header.parentUuid !== parentUuid || childVhd.header.parentUnicodeName !== parentName) {
childVhd.header.parentUuid = parentUuid
childVhd.header.parentUnicodeName = parentName
if (
header.parentUnicodeName !== parentName ||
!isEqual(header.parentUuid, parentUuid)
) {
header.parentUuid = parentUuid
header.parentUnicodeName = parentName
await childVhd.writeHeader()
return true
}
// The checksum was broken between xo-server v5.2.4 and v5.2.5
//
// Replace by a correct checksum if necessary.
//
// TODO: remove when enough time as passed (6 months).
{
const rawHeader = fuHeader.pack(header)
const checksum = checksumStruct(rawHeader, fuHeader)
if (checksum !== header.checksum) {
childVhd._write(rawHeader, VHD_FOOTER_SIZE)
return true
}
}
return false
}