SVR4 /bin/sh BUG Summary

[john.urban]

In article <1991May29.162012.25888 at digibd.com> rick at digibd.com (Rick Richardson) writes:
>I recently posted the enclosed script which demonstrates a
>bug in SVR4's Bourne shell.  With the help of the net,
>it appears that the bug is not restricted to just one
>architecture.  Failure has been reported on:
>

I thought I had replied to you before, but perhaps I forgot or it got lost.

This BUG does NOT exist on:
AT&T UNIX System V/386 Release 4.0 Version 2.1.  Both KSH and SH work fine
on the example.

Sincerely,

John Ben Urban
>
>#
>#	Demonstrates bug in SVR4 /bin/sh
>#	Works OK with /bin/sh on SVR3 and XENIX
>#	Works OK with /bin/ksh on SVR4
>#
>#	Should output the first line of /etc/passwd four times
>#	Only does it three times on SVR4 and then hangs
>#
>#	Seems to be related to changing fd0 in a function
>#
>read_by_func() {
>	exec 3<&0 0<$1
>	read x
>	echo $x
>	exec 0<&3 3<&-
>}
>
>exec 3<&0 0</etc/passwd
>read x
>echo $x
>exec 0<&3 3<&-
>
>exec 3<&0 0</etc/passwd
>read x
>echo $x
>exec 0<&3 3<&-
>
>read_by_func /etc/passwd
>
># Gets stuck here with /bin/sh...
>read_by_func /etc/passwd