[RFC PATCH v2] Allow applets to be implemented as scripts

[Michael Conrad]

On 11/7/2018 9:18 AM, Kang-Che Sung wrote:
> On Wed, Nov 7, 2018 at 9:54 PM Tito wrote:
>> this embedded scripts patch looks like "featuritis" at its best to me.
>> It is adding complexity for solving what problem exactly:
>> avoiding to copy the scripts manually to the new system or to
>> the new firmware image?
> I see one advantage of embedding scripts into busybox binary:
> compression. The script could remain compressed in a firmware or
> read-only image, saving space, and is useful for users who build
> busybox only to run a specific script (installation, embedded
> system startup, or something else non-trivial).
> I think it's okay for that use case.

IMHO squashfs is a better option all around.  The main use case I 
imagine is that you want a recovery shell to live alongside a regular 
system image, and have the embedded scripts only available when running 
busybox sh, and save some integration work of mounting the rest of the 
recovery file tree at the appropriate places.  For example, if your 
/etc/profile is only valid for bash, then if you want to run busybox ash 
on that system it would help to have /etc/profile load magically from 
within busybox.

The main downside I see is that it violates the Principle of Least 
Astonishment.

>> One side effect I fear will derive from this patch is that
>> users which would be capable of sending patches for bugs
>> they find in bb will resort to simply scrap the applet and add
>> an embedded script as it is faster.
> I disagree. Embedded script always has an overhead of starting a shell
> interpreter, although I acknowledge the size advantage the script can
> provide, as long as many coreutils are present in that environment.
> The script won't worth embedding if you don't intend to build a shell or
> coreutils in busybox.

It sounds like not just the overhead of the interpreter, but also the 
overhead of decompressing them on each execution.

But, there are lots of standard unix tools which are seldom-used and 
don't have much performance requirement, and if they can be implemented 
as a shell script half the size of the comparable machine code, then 
that makes sense.

-Mike

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.busybox.net/pipermail/busybox/attachments/20181109/bd451982/attachment.html>