[Lldb-commits] [PATCH] Move argument globbing to Target::Launch from Platform::LaunchProcess.

[Zachary Turner]

On Thu Feb 19 2015 at 4:42:54 PM Enrico Granata <egranata at apple.com> wrote:

> On Feb 19, 2015, at 4:33 PM, Zachary Turner <zturner at google.com> wrote:
>
> Is this not something we could solve by writing a function in Host that
> behaves the way we'd like it to behave on all platforms?
>
>
> I don’t think LLDB should be in the business of trying to pretend to be a
> shell. The magic of argdumper is that it gets launched via a shell, so the
> shell does all the magic expansion for us, and we just dump our list of
> arguments
> If you wanted to emulate that, you’d essentially be rewriting the bash
> command-line, nuances, corner cases, caveats and everything
> There is a program already that does all that, it’s called a shell
>
> Also, I am not sure there is a universal all-platforms notion of globbing.
> IIRC, on Windows, environment is referenced as %ENVVAR%, not $ENVVAR. You’d
> want to preserve those platform-specific conventions.
>
Are we actually planning to allow the use of environment variables in these
glob expressions?  Or is it just *. syntax?  Because if environment
variables are allowed, then there's no way to even write a platform
independent glob expression.  The reason I didn't bring this up earlier is
because Windows actually can glob with *. so the examples i had seen so far
would have worked.  If we want to say that you get arbitrary shell
expansion, then that's going to make tests very hard to write portably, and
I'm not crazy about the idea of seeing even more platform specific tests
going in.

So instead, why not just agree on a very simple subset of what the shell
does -- in particular allow the use of the character set [*.?] and just
write the glob function ourselves?


>
>   I mean it might be an ugly function, but the idea of passing stuff to an
> external program is kinda meh.
>
>
> Why?
>
Because I'm not convinced we actually need that level of flexibility.


>
>   FWIW launching a process is not a lightweight operation on windows like
> it is on other platforms, and there's actually noticeable overhead.  So it
> would be great if we could remove dependencies on external programs.
>
>
> PlatformWindows could very well decide that it does not support globbing
> if this is such a big deal.
>
It does though, just with a different set of rules.  So now any test that
goes in to test this has to have tests for each platform's shell syntax.
We should be trying to find abstractions to bring all the platforms
together IMO, not increasing the separation.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/lldb-commits/attachments/20150220/b728a86c/attachment.html>