fix incorrect parentage issue

@xen-orchestra/backups/disks/RemoteDisk.mjs

@@ -89,6 +89,7 @@ export class RemoteDisk extends RandomAccessDisk {
   }
 
   /**
+   * Abstract
    * Gets the indexes of all blocks in the VHD.
    * @returns {Array<number>}
    */
@@ -96,6 +97,15 @@ export class RemoteDisk extends RandomAccessDisk {
     throw new Error(`getBlockIndexes must be implemented`)
   }
 
+  /**
+   * Abstract
+   * Returns the parent non inizialized instance
+   * @returns {RemoteDisk}
+   */
+  instantiateParent() {
+    throw new Error(`instantiateParent must be implemented`)
+  }
+
   /**
    * Abstract
    * Writes a full block.

@xen-orchestra/backups/disks/RemoteDisk.test.mjs

@@ -202,17 +202,25 @@ describe('tests RemoteVhdDiskChain', { concurrency: 1 }, () => {
   test('RemoteVhdDiskChain should read block', async () => {
     // Create parent and child VHDs
     const chainParent = await generateVhd(`${basePath}/parent.vhd`, { blocks: [0] })
-    await generateVhd(`${basePath}/child.vhd`, {
+    const chainChild = await generateVhd(`${basePath}/child.vhd`, {
       header: {
         parentUnicodeName: 'parent.vhd',
         parentUuid: chainParent.footer.uuid,
       },
       blocks: [1],
     })
+    await generateVhd(`${basePath}/child_2.vhd`, {
+      header: {
+        parentUnicodeName: 'child.vhd',
+        parentUuid: chainChild.footer.uuid,
+      },
+      blocks: [1],
+    })
 
     const parent = new RemoteVhdDisk({ handler, path: `${basePath}/parent.vhd` })
     const child = new RemoteVhdDisk({ handler, path: `${basePath}/child.vhd` })
-    const diskChain = new RemoteVhdDiskChain({ disks: [parent, child] })
+    const child_2 = new RemoteVhdDisk({ handler, path: `${basePath}/child_2.vhd` })
+    const diskChain = new RemoteVhdDiskChain({ disks: [parent, child, child_2] })
 
     await diskChain.init({ force: false })
 
@@ -362,18 +370,18 @@ describe('tests MergeVhdChain', { concurrency: 1 }, () => {
 
     // Create ancestor and children VHDs
     await generateVhd(`${basePath}/ancestor.vhd`, { blocks: [0, 1] })
-    const chainParent = await generateVhd(`${basePath}/child_1.vhd`, { blocks: [2] })
-    await generateVhd(`${basePath}/child_2.vhd`, {
+    const chainChild1 = await generateVhd(`${basePath}/child_1.vhd`, { blocks: [2] })
+    const chainChild2 = await generateVhd(`${basePath}/child_2.vhd`, {
       header: {
         parentUnicodeName: 'child_1.vhd',
-        parentUuid: chainParent.footer.uuid,
+        parentUuid: chainChild1.footer.uuid,
       },
       blocks: [3],
     })
     await generateVhd(`${basePath}/child_3.vhd`, {
       header: {
-        parentUnicodeName: 'child_1.vhd',
-        parentUuid: chainParent.footer.uuid,
+        parentUnicodeName: 'child_2.vhd',
+        parentUuid: chainChild2.footer.uuid,
       },
       blocks: [4],
     })

@xen-orchestra/backups/disks/RemoteVhdDisk.mjs

@@ -16,6 +16,7 @@ import { DISK_TYPES } from 'vhd-lib/_constants.js'
 import { isVhdAlias, resolveVhdAlias } from 'vhd-lib/aliases.js'
 // import { set as setBitmap } from 'vhd-lib/_bitmap.js'
 import { stringify } from 'uuid'
+import { dirname, join } from 'node:path'
 
 export class RemoteVhdDisk extends RemoteDisk {
   /**
@@ -70,18 +71,19 @@ export class RemoteVhdDisk extends RemoteDisk {
    * @param {boolean} [options.force=false]
    * @returns {Promise<void>}
    */
-
   async init(options = {}) {
     if (this.#vhd === undefined) {
       try {
-        if ((await this.isDirectory()) && !isVhdAlias(this.#path)) {
-          throw Object.assign(new Error("Can't init vhd directory without using alias"), { code: 'NOT_SUPPORTED' })
-        }
-
         const { value, dispose } = await openVhd(this.#handler, await resolveVhdAlias(this.#handler, this.#path), {
           checkSecondFooter: !options.force,
         })
         this.#vhd = value
+
+        if ((await this.isDirectory()) && !isVhdAlias(this.#path)) {
+          this.#vhd = undefined
+          throw Object.assign(new Error("Can't init vhd directory without using alias"), { code: 'NOT_SUPPORTED' })
+        }
+
         this.#dispose = dispose
         await this.#vhd.readBlockAllocationTable()
         this.#isDifferencing = value.footer.diskType === DISK_TYPES.DIFFERENCING
@@ -204,6 +206,26 @@ export class RemoteVhdDisk extends RemoteDisk {
     return indexes
   }
 
+  /**
+   * Returns the parent non inizialized instance
+   * @returns {RemoteDisk}
+   */
+  instantiateParent() {
+    if (this.#vhd === undefined) {
+      throw new Error(`can't call instantiateParent of a RemoteVhdDisk before init`)
+    }
+
+    const parentPath = this.#vhd.header.parentUnicodeName
+    const fullParentPath = join(dirname(this.#path), parentPath)
+
+    if (!parentPath) {
+      throw new Error(`disk ${this.#path} doesn't have parents`)
+    }
+
+    const parent = new RemoteVhdDisk({ handler: this.#handler, path: fullParentPath })
+    return parent
+  }
+
   /**
    * Writes a full block into this VHD.
    * @param {DiskBlock} diskBlock
@@ -428,15 +450,10 @@ export class RemoteVhdDisk extends RemoteDisk {
    * @returns {Promise<boolean>}
    */
   async isDirectory() {
-    if (this.#vhd !== undefined) {
-      return this.#vhd instanceof VhdDirectory
-    } else {
-      try {
-        await this.#handler.readFile(await resolveVhdAlias(this.#handler, this.#path))
-        return false
-      } catch (err) {
-        return true
-      }
+    if (this.#vhd === undefined) {
+      throw new Error(`can't call isDirectory of a RemoteVhdDisk before init`)
     }
+
+    return this.#vhd instanceof VhdDirectory
   }
 }

@xen-orchestra/backups/disks/RemoteVhdDiskChain.mjs

@@ -56,9 +56,7 @@ export class RemoteVhdDiskChain extends RemoteDisk {
       await Promise.all(this.#disks.map(disk => disk.init(options)))
       let parentUuid = ''
       for (const [index, disk] of this.#disks.entries()) {
-        if (index === 0) {
-          parentUuid = disk.getUuid()
-        } else {
+        if (index !== 0) {
           if (!disk.isDifferencing()) {
             throw Object.assign(new Error("Can't init vhd directory with non differencing child disks"), {
               code: 'NOT_SUPPORTED',
@@ -70,6 +68,8 @@ export class RemoteVhdDiskChain extends RemoteDisk {
             })
           }
         }
+
+        parentUuid = disk.getUuid()
       }
     } catch (error) {
       await this.close()
@@ -178,6 +178,14 @@ export class RemoteVhdDiskChain extends RemoteDisk {
     return [...indexes]
   }
 
+  /**
+   * Returns the parent non inizialized instance
+   * @returns {RemoteDisk}
+   */
+  instantiateParent() {
+    return this.#disks[0].instantiateParent()
+  }
+
   /**
    * Writes a full block into this VHD.
    * @param {DiskBlock} diskBlock