[U-Boot] [PATCH V2] hush: fix some quoted variable expansion issues

[Stephen Warren]

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.

>     diff --git a/common/hush.c b/common/hush.c
>     index 3f3a79c..66ece41 100644
>     --- a/common/hush.c
>     +++ b/common/hush.c
>     @@ -221,6 +221,7 @@ struct child_prog {
>             pid_t pid;                                      /* 0 if
>     exited */
>      #endif
>             char **argv;                            /* program name and
>     arguments */
>     +       int *argv_nonnull;
> 
> 
> This could do with a comment.

I did wonder if I should name this "quoted". I'd originally shied away
from this to prevent changing the terminology, but since hush.c has
diverged so much, perhaps that wouldn't be an issue...