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From: "Bart Schaefer" <schaefer@candle.brasslantern.com>
Message-Id: <960719125325.ZM320@candle.brasslantern.com>
Date: Fri, 19 Jul 1996 12:53:25 -0700
In-Reply-To: "Bart Schaefer" <schaefer>
        "Re: Another patch to compctl-examples CVS compctl, and a bug?" (Jul 14,  7:32pm)
References: <199607150102.DAA03226@turan.elte.hu> 
	<960714193241.ZM1933@candle.brasslantern.com>
Reply-To: schaefer@nbn.com
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To: schaefer@nbn.com, Zoltan Hidvegi <hzoli@cs.elte.hu>
Subject: Re: Another patch to compctl-examples CVS compctl, and a bug?
Cc: zsh-workers@math.gatech.edu
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On Jul 14,  7:32pm, Bart Schaefer wrote:
>
> On Jul 15,  3:02am, Zoltan Hidvegi wrote:
> } 
> }  	"${pref}${^${${(f@)$({<${pref}CVS/Entries} 2>/dev/null)}#/}%%/*}"
> 
> Here's the behavior I see in a directory that has no CVS subdirectory:
> 
> If I replace my `for ... echo' loop with your ${^...} solution above,
> then *every* time I hit TAB I get a newline on the terminal, and I
> never see any completions.  (Your solution works normally in a dir
> that *does* have a CVS subdir.)

I think I finally tracked this down, crashing my Linux 1.3.15 kernel
three times in the process.  (Use GDB to put a breakpoint on a system
call such as write(), and then watch what happens when the process
forks and the child uses the system call.)

When you write this form of READNULLCMD:

	$( { <nonexistentfile } 2>/dev/null )

Zsh forks to execute the { ... } part so that it can redirect stderr.
READNULLCMD in the child process then discovers that nonexistentfile
doesn't exist, and calls zerr() to output the "no such file" message.

This is all fine most of the time, but when the above is used in a
completion, zleactive==1 and so zerr() calls trashzle().  The child
thus messes up the parent's terminal.

However, I don't know where to put a `zleactive = 0;' to prevent this.
Does it go in getoutput()?  That would solve this particular case, but
there might be others.  Does it go in entersubsh()?  Or is entersubsh()
sometimes called when we haven't really forked?

Insights appreciated.