Re: [PATCH] Remove shell dependency in env.c

"H. Peter Anvin" [off-list ref] writes:

This patch adds an invocation of "env", so rsh.c works for C-shell users 
as well as Bourne shell users.

Hmph.  I think the original code is buggy already.  If the path
has a single quote in it, you would get into a problem.  If the
remote end first interprets what is given to it with C-shell,
then it probably would also barf if path had a '!' in it, too,
even though we quote the entire thing within a single-quote
pair.

Junio C Hamano wrote:

"H. Peter Anvin" [off-list ref] writes:

quoted

This patch adds an invocation of "env", so rsh.c works for C-shell users 
as well as Bourne shell users.

Hmph.  I think the original code is buggy already.  If the path
has a single quote in it, you would get into a problem.  If the
remote end first interprets what is given to it with C-shell,
then it probably would also barf if path had a '!' in it, too,
even though we quote the entire thing within a single-quote
pair.

True.  The better method is to \-escape any questionable characters, 
instead of trying to use quotes.  I'll try to write that up.

	-hpa

Okay, I'm trying to put together some rules that should work across shells.

For byte values:

0		Hopeless - not representable in C strings
1-31,127	Prefix with ^V if (and only if!) entered at a prompt,
		as opposed to passed in the ssh command field
32-126		\-escape all characters except -+_@=:.,/ and
  		ASCII alphanumerics
128-		Don't escape (would have to be done differently
  		depending on locale, and shouldn't be needed)

Anyone know of a system for which that breaks horribly?  The 1-31,127 
stuff is iffy, but I just don't know of anything that's more reliable. 
Unfortunately \010-style quoting doesn't work in any of the common shells.

	-hpa

On Thu, 15 Sep 2005, H. Peter Anvin wrote:

Okay, I'm trying to put together some rules that should work across shells.

Does anybody really still use tcsh? It's a broken mess.

Junio's "sq_quote()" works wonderfully on any valid shells. The fact that 
tcsh expands ! even inside single quotes is just pure braindamage.

You could expand "sq_quote" to handle '!' and '\' characters the exact
same way it handles the single tick (end single-tick quoting, do \! or \\
and start single-tick quoting again) and that might be good enough for
tcsh.

IOW, the string "a\b'c!d" would become 'a'\\'b'\''c'\!'d' after 
surrounding sq_quote with single-ticks.

Insane?

		Linus

Linus Torvalds wrote:

Does anybody really still use tcsh? It's a broken mess.

Yes.

Junio's "sq_quote()" works wonderfully on any valid shells. The fact that 
tcsh expands ! even inside single quotes is just pure braindamage.

You could expand "sq_quote" to handle '!' and '\' characters the exact
same way it handles the single tick (end single-tick quoting, do \! or \\
and start single-tick quoting again) and that might be good enough for
tcsh.

It seems easier to just \-escape any special characters.

	-hpa

This patch does proper quoting, and uses "env" to be compatible with 
tcsh.  As a side benefit, I believe the code is a lot cleaner to read.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>