Change Mtime field to INT64 to adapt to new GRUB changes

[liushuyu]

This pull request changes the Mtime field to INT64 to adapt to the new GRUB changes

• GRUB upstream commit 81f1962393f4403e2b6b127f23524a962a236afb changed mtime to grub_int64_t

[MarsDoge]

Excellent！LGTM.

[pbatard]

Thanks!

I'll apply it when I get a chance, but since there was an EfiFs release recently, it'll probably be some time before you get another release that integrates this, unless you can point to a real-life issue that's going to happen before 2038.

[xry111]

unless you can point to a real-life issue that's going to happen before 2038.

AFAIK the issue is already happening: we observed the ls command in EFI shell outputting all dates as 1970-01-01 and applying this PR can fix the issue.

If I read the code correctly the change to EFI_GRUB_FILE will only make a real difference after 2038, but the change to GRUB_DIRHOOK_INFO is already making a difference now: the offset of the Mtime field will be changed from 4 to 8 with this PR. Thus my guess is without this PR we are reading Mtime from an incorrect offset (i.e. the grub code is putting mtime at offset 8 but we'd read it at offset 4).