[PATCH] [lld] MachO: calculating file offsets in final objects

[Tim Northover]

Hi,

I believe we were calculating file and vm offsets incorrectly in final
(non-relocatable) MachO files.

The most obvious failure was in vmaddr, where the constraint that
segments begin at a page was being ignored. lld itself detected this,
and failed to linke with an invalid format error.

However, even when this was addressed, the mechanisms for calculating
fileoffset and filesize turned out to be inadequate. For fileoffset,
the values weren't advancing at all between segments, with obviously
bad results. For filesize, we were taking a "best guess" based on the
segment's size. In reality I think this needs to be calculated based
on the sections in that segment: basically the last byte actually
filled with data (so ignore S_ZEROFILL), rounded up to page size.

The attached two patches should take care of these issues. Do they
look reasonable?

Cheers.

Tim.
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