[Libguestfs] [hivex PATCH] Re-allocating unused blocks before assigning new blocks

[Shreyas Khare]

Hi Richard

I've added a new patch. See some in-line comments. That said, I made a 
couple of more changes to my patch, re-using the free_blocks for doing 
all allocations (i.e. not using h->endblocks at all).


On 2018-07-25 07:32 AM, Richard W.M. Jones wrote:
> On Mon, Jul 23, 2018 at 02:38:18PM -0400, Shreyas Khare wrote:
>> Hello Richard
>>
>> As discussed in the IRC channel, when merging a moderately large reg
>> file (~35MB) to a hiv file (~118 MB); hivex generates a huge hiv
>> file (~580 MB). These changes address that by creating a list of
>> unallocated blocks and reassigning unused blocks. I used https://github.com/msuhanov/regf/blob/master/Windows%20registry%20file%20format%20specification.md
>> as a reference for the structure of the hiv file (in addition to the
>> source code itself)
>>
>> Attaching the patch file.
> Just as a general comment, for the patch to go upstream at all it will
> need to be reformatted so it fits with the existing code style.
>
> [...]
Will do.
>>   /* Allocate a single block, first allocating an hbin (page) at the end
>>    * of the current file if necessary.  NB. To keep the implementation
>>    * simple and more likely to be correct, we do not reuse existing free
> This comment is left in place, but it's now obviously wrong.
Fixed.
> I'm a bit confused why we need a separate free list.  Can't we just
> use the existing bitmap?
I tried to use the existing bitmap, but wasn't successful initially with 
the 20 byte hbin headers on every page.
>
> Rich.
>


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