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From: Arseny Maslennikov <ar@cs.msu.ru>
To: zsh-workers@zsh.org
Subject: 'while do done' hangs interactive zsh
Date: Sun, 16 May 2021 12:16:24 +0300	[thread overview]
Message-ID: <YKDi6GYtnBt1ZYTU@cello> (raw)

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Hi everyone!

When zsh tries to execute "while do; done", it enters a busy loop:

% dash -c 'while do; done'
dash: 1: Syntax error: "do" unexpected
% bash -c 'while do; done'
bash: -c: line 1: syntax error near unexpected token `do'
bash: -c: line 1: `while do; done'
% zsh -c 'while do; done' 	# never finishes/prompts by itself
^C
zsh -c 'while do; done'  27,73s user 0,00s system 99% cpu 27,732 total 4k maxrss

Even more, if the user enters "while do; done" in an interactive zsh
instance, the busy loop is not interruptible by ^C, ^\ or ^Z; the shell
has to be killed via some external means.

To be fair, I have discovered the bug with the semicolon omitted ("while do done").

Could we do something about this?

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             reply	other threads:[~2021-05-16  9:16 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-16  9:16 Arseny Maslennikov [this message]
2021-05-16 14:28 ` Bart Schaefer
2021-05-16 15:46   ` Bart Schaefer
2021-05-16 16:15     ` Mikael Magnusson
2021-05-16 16:22       ` Lawrence Velázquez
2021-05-16 17:47       ` Bart Schaefer
2021-05-16 18:23         ` Martijn Dekker
2021-05-16 19:59           ` Bart Schaefer
2021-05-16 20:34             ` Peter Stephenson
2021-05-16 21:19               ` [PATCH] volatile declarations (was Re: 'while do done' hangs interactive zsh) Bart Schaefer
2021-05-16 23:40                 ` Martijn Dekker
2021-05-16 16:43 ` 'while do done' hangs interactive zsh Stephane Chazelas
2021-05-16 18:02   ` Bart Schaefer
2021-05-16 18:25     ` Martijn Dekker

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