fix(xo-vmdk-to-vhd/grabTables): read each entry independently (#5255)

Reading all entries at once cause problems on some VMDKs (those generated by VirtualBox) because they appear to be distributed throughout the VMDK thus making the buffer not fit in memory.

See https://xcp-ng.org/forum/topic/3374/cannot-import-ova-from-virtualbox/14?_=1599689219209

CHANGELOG.unreleased.md

@@ -16,6 +16,8 @@
 
 > Users must be able to say: “I had this issue, happy to know it's fixed”
 
+- [Import VMDK] Fix `No position specified for vmdisk1` error (PR [#5255](https://github.com/vatesfr/xen-orchestra/pull/5255))
+
 ### Packages to release
 
 > Packages will be released in the order they are here, therefore, they should
@@ -33,4 +35,5 @@
 >
 > In case of conflict, the highest (lowest in previous list) `$version` wins.
 
+- xo-vmdk-to-vhd patch
 - xo-web minor

packages/xo-vmdk-to-vhd/src/vmdk-read-table.js

@@ -50,28 +50,14 @@ async function grabTables(
   fileAccessor
 ) {
   const cachedGrainTables = []
-  let grainTableAddresMin = Infinity
-  let grainTableAddressMax = -Infinity
   for (let i = 0; i < grainDirectoryEntries; i++) {
     const grainTableAddr = grainDir[i] * SECTOR_SIZE
     if (grainTableAddr !== 0) {
-      grainTableAddresMin = Math.min(grainTableAddresMin, grainTableAddr)
-      grainTableAddressMax = Math.max(
-        grainTableAddressMax,
-        grainTableAddr + grainTablePhysicalSize
-      )
-    }
-  }
-  const grainTableBuffer = await fileAccessor(
-    grainTableAddresMin,
-    grainTableAddressMax
-  )
-  for (let i = 0; i < grainDirectoryEntries; i++) {
-    const grainTableAddr = grainDir[i] * SECTOR_SIZE
-    if (grainTableAddr !== 0) {
-      const addr = grainTableAddr - grainTableAddresMin
       cachedGrainTables[i] = new Uint32Array(
-        grainTableBuffer.slice(addr, addr + grainTablePhysicalSize)
+        await fileAccessor(
+          grainTableAddr,
+          grainTableAddr + grainTablePhysicalSize
+        )
       )
     }
   }