[erlang-patches] Limit maximum line length in interactive shells

Stefan Zegenhagen <>
Tue May 7 16:22:10 CEST 2013

Dear all,

it seems as if I sent around the wrong version of the patch. Please find
the correct version attached to this e-mail.

Kind regards,

> one of our testers found out that he could reliably reboot our
> erlang-based device by just sending tons of 'A' characters to an
> interactive shell.
> It appears that the I/O server of the interactive shell (in group.erl)
> is always reading a full line before doing any end-of-input processing,
> so that by sending bytes without a newline in between, it slowly eats up
> all available memory.
> The patch attached to this e-mail fixes that by introducing a new
> io:setopt() option in group.erl named 'max_length' that is used to check
> whether the current line length exceeds this maximum whenever the line
> is edited. If an overlong line is detected, max_length bytes are
> returned immediately (without the actual stop condition being fulfilled,
> though, allowing I/O clients to detect this situation).
> max_length is allowed to be an integer() > 0 or 'unlimited'. The default
> is 'unlimited' to have the old behaviour by default.
> Kind regards,
> _______________________________________________
> erlang-patches mailing list
> http://erlang.org/mailman/listinfo/erlang-patches

Dr. Stefan Zegenhagen

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