Re: [Gnu-arch-users] PANIC: Top-of-file arch tag crosses 1k boundary

[James Blackwell]

In lists.arch.users, you wrote:
>
>     > From: "Robert Anderson" <address@hidden>
>
>     > Shouldn't the algorithm look for the tag at the "bottom" location
>     > _first_?  And only if no tag is found, to search the top?
>
Tom Lord wrote:
> Unfortunate backwards compatability issue there.   No, it needs to
> search the top first.   The recently added error check is a good thing
> -- it should even be mirrored to check truncation of tags at the
> bottom..... but it appears to have been slightly botched in the
> current instance.

I don't agree. At the bottom of the file, the problem is entirely
different. A tag won't be seen at all (thus evidencing itself as 
no tag) , and that will clue the user in that their tag is too early.

I think that the truncation-at-the-top is a serious booboo because it
sets the user up for unpredictable results (Why does tla tell me that
"arch-tag: My Tag 1" and "arch-tag: My tag 2" are the same tag, not
realizing tla sees them as "arch-tag: My" and "arch-tag: My".

The problem gets even worse if the user adds/removes characters from the
head of the file, which causes the tag to *change*.

The edge case that we have here is that the user has a really short
file. He thought the tag was at the bottom of the file, but tla
interprets it as the top of the file.

Bob, what byte range is your arch-tag at? 


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