Re: [RFC] efivars write(2) races

From: Lingzhu Xiang
Date: Sun Jan 27 2013 - 21:38:22 EST


On 01/25/2013 09:18 PM, Matt Fleming wrote:
4. EFI_VARIABLE_APPEND_WRITE with EFI_OUT_OF_RESOURCES truncates size but you
can still read its content.

I'm not sure what you mean by this. Could you please explain?

Oops, this one is incorrect. I was testing EFI_VARIABLE_APPEND_WRITE
using this:

printf "\x47\x00\x00\x00\x00" >test-1-$guid

So it truncates the file before writing, but efivarfs figures out the right
size afterwards. The size remains zero if the write fails.

I should be using this for appending:

printf "\x47\x00\x00\x00\x00" >>test-1-$guid
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