Re: ksh: bug with quoted parameter expansion
On Fri, Jan 26, 2018 at 11:31:40AM +0100, Klemens Nanni wrote:
> On Fri, Jan 26, 2018 at 09:41:45AM +0100, Klemens Nanni wrote:
> > On Wed, Jan 24, 2018 at 04:15:24PM +0100, m...@josuah.net wrote:
> > > I found a bug in ksh's parameter expansion on an edge case:
> > >
> > > true $(true "${USER#'"'}")
> > >
> > > /home/sh[4]: no closing quote
> > >
> > > The problem seems to occurs when all of these conditions are present:
> > >
> > > 1. On ${var#pattern} or ${var%pattern} parameter expansion
> > > 2. When the pattern contains a singly quoted double quote: '"'
> > > 3. While expansion occurs withing $(...), (but not `...`)
> > > 4. While the expansion is quoted: "${var#pattern}".
> > As anton@ pointed out, this is known behaviour. The following will work:
> >
> > true $(true "${USER#\"}")
> > true $(true "${USER#"\""}")
> >
> Forgot to mention: `` are not subject to this, the bug lives in $() alone.
>From the end of ksh(1)
BUGS
$(command) expressions are currently parsed by finding the closest
matching (unquoted) parenthesis. Thus constructs inside $(command) may
produce an error. For example, the parenthesis in ‘x);;’ is interpreted
as the closing parenthesis in ‘$(case x in x);; *);; esac)’.
Re: ksh: bug with quoted parameter expansion
On Fri, Jan 26, 2018 at 09:41:45AM +0100, Klemens Nanni wrote:
> On Wed, Jan 24, 2018 at 04:15:24PM +0100, m...@josuah.net wrote:
> > I found a bug in ksh's parameter expansion on an edge case:
> >
> > true $(true "${USER#'"'}")
> >
> > /home/sh[4]: no closing quote
> >
> > The problem seems to occurs when all of these conditions are present:
> >
> > 1. On ${var#pattern} or ${var%pattern} parameter expansion
> > 2. When the pattern contains a singly quoted double quote: '"'
> > 3. While expansion occurs withing $(...), (but not `...`)
> > 4. While the expansion is quoted: "${var#pattern}".
> As anton@ pointed out, this is known behaviour. The following will work:
>
> true $(true "${USER#\"}")
> true $(true "${USER#"\""}")
>
Forgot to mention: `` are not subject to this, the bug lives in $() alone.
Re: ksh: bug with quoted parameter expansion
On Wed, Jan 24, 2018 at 04:15:24PM +0100, m...@josuah.net wrote:
> I found a bug in ksh's parameter expansion on an edge case:
>
> true $(true "${USER#'"'}")
>
> /home/sh[4]: no closing quote
>
> The problem seems to occurs when all of these conditions are present:
>
> 1. On ${var#pattern} or ${var%pattern} parameter expansion
> 2. When the pattern contains a singly quoted double quote: '"'
> 3. While expansion occurs withing $(...), (but not `...`)
> 4. While the expansion is quoted: "${var#pattern}".
As anton@ pointed out, this is known behaviour. The following will work:
true $(true "${USER#\"}")
true $(true "${USER#"\""}")
Re: ksh: bug with quoted parameter expansion
On Wed, Jan 24, 2018 at 04:15:24PM +0100, m...@josuah.net wrote:
> I found a bug in ksh's parameter expansion on an edge case:
>
> true $(true "${USER#'"'}")
>
> /home/sh[4]: no closing quote
>
> The problem seems to occurs when all of these conditions are present:
>
> 1. On ${var#pattern} or ${var%pattern} parameter expansion
> 2. When the pattern contains a singly quoted double quote: '"'
> 3. While expansion occurs withing $(...), (but not `...`)
> 4. While the expansion is quoted: "${var#pattern}".
>
> true can be replaced by other commands or var=...
> if '"' gets replaced by \", the issue disappear
>
> The bin/ksh/lex.c seems to use a big switch+goto table with one label
> per grammar context. Maybe by jumping from context to context in a
> specific pattern like above is producing the issue.
>
> I did try to figure out where, but I lack time for now.
>
> I hope the problem does not come from my way to test it and that it
> have not been fixed.
>
> $ uname -a # also tested with /bin/ksh
> OpenBSD t470s 6.2 GENERIC.MP#134 amd64
>
> $ cvs co bin/ksh/; cd bin/ksh; make
> [...]
>
> $ ./ksh ~/sh
> /home/sh[4]: no closing quote
For the record, probably related to this:
$ pwd
/usr/src/bin/ksh
$ sed -n 474,479p lex.c
case SCSPAREN: /* $( .. ) */
/* todo: deal with $(...) quoting properly
* kludge to partly fake quoting inside $(..): doesn't
* really work because nested $(..) or ${..} inside
* double quotes aren't dealt with.
*/
ksh: bug with quoted parameter expansion
I found a bug in ksh's parameter expansion on an edge case:
true $(true "${USER#'"'}")
/home/sh[4]: no closing quote
The problem seems to occurs when all of these conditions are present:
1. On ${var#pattern} or ${var%pattern} parameter expansion
2. When the pattern contains a singly quoted double quote: '"'
3. While expansion occurs withing $(...), (but not `...`)
4. While the expansion is quoted: "${var#pattern}".
true can be replaced by other commands or var=...
if '"' gets replaced by \", the issue disappear
The bin/ksh/lex.c seems to use a big switch+goto table with one label
per grammar context. Maybe by jumping from context to context in a
specific pattern like above is producing the issue.
I did try to figure out where, but I lack time for now.
I hope the problem does not come from my way to test it and that it
have not been fixed.
$ uname -a # also tested with /bin/ksh
OpenBSD t470s 6.2 GENERIC.MP#134 amd64
$ cvs co bin/ksh/; cd bin/ksh; make
[...]
$ ./ksh ~/sh
/home/sh[4]: no closing quote
