[Bug: Busybox 1.22.1] false return 0 instead of 1 with '--help' switch.

[Joshua Judson Rosen]

On 2014-09-02 14:22, Harald Becker wrote:
> Hi Joshua !
>
>> It's also interesting that busybox "false --help" behaves completely
>> differently
>> depending on whether it's invoked from within a busybox shell or not:
>
> This is wrong!

Hi Harald--

It might be wrong, but it's nonetheless true and not a mistake on my part. ;)


> You called different versions, not Busybox false.
>
>>      * invoking "false" as an ash builtin bypasses the "--help" check,
>>        does not print the usage message, and exits with EXIT_FAILURE
>>        per false_main().
>
> Here you probably used a shell function, which overrides the applet in Busybox.
>
> Look in your profile or sourced scripts, anywhere there I expect a definition
> like: "false() { return 1; }"

Sorry, I meant falsecmd(), not false_main().

Look in ash.c, where you'll see these definitions:

	static int FAST_FUNC
	falsecmd(int argc UNUSED_PARAM, char **argv UNUSED_PARAM)
	{
		return 1;
	}
[...]
	/* Keep these in proper order since it is searched via bsearch() */
	static const struct builtincmd builtintab[] = {
[...]
		{ BUILTIN_REGULAR       "false"   , falsecmd   },
[...]
	}

> This case is not concerned with the question which Busybox false shall return.
> The maintainer of your profile script is inquestion, for what your shell
> function does.

I'm saying I was surprised that there are two different implementations of
"busybox false", and that their behaviors disagree with each other.

If you want to verify this experimentally, look at this:

	jrosen at bz:~/src/busybox$ ./busybox false --help; echo $?
	BusyBox v1.23.0.git (2014-09-02 13:43:43 EDT) multi-call binary.
	
	Usage: false
	
	Return an exit code of FALSE (1)
	
	0
	jrosen at bz:~/src/busybox$ ln -svfn busybox false
	`false' -> `busybox'
	jrosen at bz:~/src/busybox$ ./false --help; echo $?
	BusyBox v1.23.0.git (2014-09-02 13:43:43 EDT) multi-call binary.
	
	Usage: false
	
	Return an exit code of FALSE (1)
	
	0
	jrosen at bz:~/src/busybox$ ./busybox sh -c './false --help; echo $?'
	BusyBox v1.23.0.git (2014-09-02 13:43:43 EDT) multi-call binary.
	
	Usage: false
	
	Return an exit code of FALSE (1)
	
	0
	jrosen at bz:~/src/busybox$ ./busybox sh -c 'type false; false --help; echo $?'
	false is a shell builtin
	1
	jrosen at bz:~/src/busybox$


Please, don't take my word for it--or Bastian's. Try it yourself.

>>      * invoking "false" directly as "/bin/false" or "busybox false"
>>        bypasses false_main(), prints the usage message, and exits
>>        with 0 per run_applet_no_and_exit().
>
> This is due to common handling of --help in Busybox. The common code displays
> the usage message and exits.

Yes. That's what I said. ;)

If you want to approach this via code inspection, the "false --help returns 0" 
change
was efd0698f74caab0a0c8a51228b923ee142e8e278 in git, and that change affects only
the `false binary', not the "false command" in busybox ash.

Did you look at my patch? It brings the two "false" commands into alignment with
each other--as well as into alignment with both POSIX and GNU coreutils "false".

-- 
"'tis an ill wind that blows no minds."