Bug in /bin/sh. Shell function redefinition in child.

Thread View: comp.bugs.sys5

2 messages

[T] Back to Threads [V] Tree View [G] Group Articles

2 total messages Started by erskine Thu, 03 Dec 1987 20:16

#650

Author: erskine
Date: Thu, 03 Dec 1987 20:16

74 lines
2600 bytes

][b

---------- Files required to reproduce the problem:

$ cat init.dom
echo hello
. ./init.std
echo goodbye
exit 0

$ cat init.std
std_perms()
{
cat << --EOF--
--EOF--
}

$ cat newdom
. ./init.std
./init.dom

---------- To reproduce the problem:

Create the previous files in one directory, make them executable, and
from the Bourne Shell (/bin/sh) type 

$ ./newdom

---------- I think the output should be:

$ ./newdom
hello
goodbye
$

---------- but on my system I get:

$
hello
./init.dom: shell memory fault$

---------- Commentary:

    	I'm running SCO Xenix System V version 2.2.1, and have found the
    bug demonstrated by the accompanying files.  By moving these files to
    subdirectories, and making corresponding changes in the scripts, /bin/sh
    goes into a tight CPU loop, disregarding signals.

	The problem is that shell functions, unlike variables, get passed on
    to child shell scripts. The redefinition of the shell function seems to
    cause a big problem for sh if the function makes use of the << operator.
    (But only if the function was inherited).  Should the function definition
    actually be inherited by child scripts? If yes, should shell variables also?
    To check to see, add the command 'set' as the first line in init.dom.
    If the functions are inherited, the definition of std_perms will be printed
    along with the environment.

	I phoned SCO who agreed that it is a bug, but who suggested that it
    might be appropriate to forbid this usage (redefinition of a shell
    function).  I certainly haven't used many interpreters that didn't allow
    redefinition of functions.

	Most importantly, WHAT DOES YOUR /bin/sh DO?  Please post to the net,
    especially if yours doesn't inherit shell functions. If you don't HAVE
    shell functions at all, LUCKY YOU, you don't have the bug! :-)

						Neil

||!][b
---------
Neil S. Erskine		MT&T - (902) 453-4915 x340
AP Computers 		USENET { garfield, watmath, ihnp4!utzoo!utai,
3845 Dutch Village Rd.		 uunet } !dalcs!force10!erskine
Halifax, N.S. B3L-4H9

Re: Bug in /bin/sh. Shell function redefinition in child.

#655

Author: Jim Davis
Date: Tue, 15 Dec 1987 04:38

54 lines
1854 bytes

Neil Erskine <erskine@force10.UUCP> writes:
ne>	---------- I think the output should be:
ne>	$ ./newdom
ne>	hello
ne>	goodbye
ne>	$
ne>	---------- but on my system I get:
ne>	$
ne>	hello
ne>	./init.dom: shell memory fault$

    This is also a problem on HP-UX (a.k.a. HPUX) 5.5.
The symptom is only slightly different.  I get the following output:
-------------------------------------------------------------
$ ./newdom
hello
./init.std: Memory fault in shell: cleaning up.
$ 
=============================================================
My files look like this shar describes.
# This is a shell archive.  Remove anything before this line,
# then unpack it by saving it in a file and typing "sh file".
#
# Wrapped by davis at hpljwd3 on Mon Dec 14 19:53:28 1987
#
# This archive contains:
#       init.dom        init.std        newdom
echo x - init.dom
cat >init.dom <<'@EOF'
echo hello
. ./init.std
echo goodbye
exit 0
@EOF
chmod 755 init.dom
echo x - init.std
cat >init.std <<'@EOF'
std_perms()
{
cat << --EOF--
--EOF--
}
@EOF
chmod 755 init.std
echo x - newdom
cat >newdom <<'@EOF'
. ./init.std
./init.dom
@EOF
chmod 755 newdom
exit 0
=============================================================
(I speak here in *no official capacity*, only as someone who tried it.)
Jim Davis	davis@hplabs.hp.com

Thread Navigation

This is a paginated view of messages in the thread with full content displayed inline.

Messages are displayed in chronological order, with the original post highlighted in green.

Use pagination controls to navigate through all messages in large threads.

Back to All Threads