[U-Boot] [PATCH V2] hush: fix some quoted variable expansion issues
Tom Rini
trini at ti.com
Mon Mar 3 09:28:20 EST 2014
On Sat, Mar 01, 2014 at 09:26:26PM -0700, Stephen Warren wrote:
> On 03/01/2014 05:10 PM, Simon Glass wrote:
> > Hi Stephen,
> >
> > On 27 February 2014 22:00, Stephen Warren <swarren at wwwdotorg.org
> > <mailto:swarren at wwwdotorg.org>> wrote:
> >
> > The following shell command fails:
> >
> > if test -z "$x"; then echo "zero"; else echo "non-zero"; fi
> >
> > (assuming $x does not exist, it prints "non-zero" rather than "zero").
> >
> > ... since "$x" expands to nothing, and the argument is completely
> > dropped, causing too few to be passed to -z, causing cmd_test() to
> > error out early.
> >
> > This is because when variable expansions are processed by make_string(),
> > the expanded results are concatenated back into a new string. However,
> > no quoting is applied when doing so, so any empty variables simply don't
> > generate any parameter when the combined string is parsed again.
> >
> > Fix this by explicitly replacing quoting any argument that was
> > originally
> > quoted when re-generating a string from the already-parsed argument
> > list.
> >
> > This also fixes loss of whitespace in commands such as:
> >
> > setenv space " "
> > setenv var " 1${space}${space} 2 "
> > echo ">>${var}<<"
> >
> >
> > Is there an upstream still for hush, or are we so far away that it
> > doesn't matter? If there is, was this bug fixed there?
>
> Well, the comments at the head of the file say it came from Busybox, but
> it's obviously diverged massively since it was imported:
>
> $ wc -l busybox/shell/hush.c u-boot/common/hush.c
> 9156 busybox/shell/hush.c
> 3682 u-boot/common/hush.c
> $ diff -u busybox/shell/hush.c u-boot/common/hush.c|wc -l
> 12264
>
> Also, the function this patch touches doesn't seem to exist under that
> name any more. From a quick look at the source, I couldn't tell what the
> equivalent is.
>
> Perhaps replaying patches to that file in Busybox since the fork might
> be more useful.
>
> A quick Google search for "hush" or "hush shell" doesn't seem to yield
> any other alternative upstreams.
For reference the patch is at http://patchwork.ozlabs.org/patch/325023/
Since U-Boot and Barebox are the only users of this particular hush
fork, and from G+ they also have this problem, maybe we can use this as
a starting point of a little more friendly coordination between the
projects?
--
Tom
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