Re: Crazy idea: generate a pseudo-random value for tramp-end-of-output

[Francis Litterio]

address@hidden (Kai Großjohann) writes:

> The second reason for not incorporating the change is that people
> might see strange behavior which cannot be reproduced.  I don't like
> bugs that go away if you look at them.  Therefore I wanted to have a
> fixed prompt so that people who complain about a misbehavior can at
> least reproduce the problem when I ask them.

I hadn't thought of that.  My change makes TRAMP non-deterministic in
some small way.  This is often not desirable in software.

> But I can see that the issue is different for
> tramp-handle-shell-command, where the string "/////" might indeed
> occur.
>
> Your (and Daniel's) suggestion could easily be extended to deal with
> the first problem I'm mentioning above, by including "///" in the
> prompt.  But I don't know how to deal with the second issue.
>
> Ideas?

Well, the output of a user-supplied shell command could contain just
about any byte sequence (even binary data).  This was what motivated me
to use the MD5 hash of some unpredictable data.  It's a bit pattern
known only to TRAMP, and it's _astronomically_ unlikely to occur in the
output of remote commands.  I'm more likely to be killed by a meteor
within the next 10 seconds than to experience an accidental collision
between tramp-end-of-output and remote command output.

[Pause for 10 seconds.]

See. :-)  I'm only half kidding.  A hash function like MD5 is
"cryptographically secure" because it exhibits the feature that if you
change just one bit in the input data, then, on average, half of the
bits in the hash change.  This is what makes collisions so unlikely.
--
Francis Litterio
address@hidden
http://world.std.com/~franl/
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