509070 - We need a tool to strip metadata from ABC/SWF

Status: RESOLVED WONTFIX

(Tamarin Graveyard :: Tools, enhancement, P3)

Description

[Steven Johnson]

The "native" metadata used by nativegen.py isn't needed at runtime and can (should) be stripped from the ABC/SWF data embedded in the runtime. We don't have a convenient tool to do this, but it would probably be straightforward to write one from abcdump.

Comment 1

[Lars T Hansen]

Tentatively targeting for Serrano because there's a real chance that some of the nativegen.py / exact GC changes will entail a greater use of 'native' metadata.

Comment 2

[Trevor Baker]

Moving to Brannan.

Comment 3

[William Maddox]

I don't have a lot of confidence that abcdump internalizes the ABC completely enough to enable reliable bit-for-bit reconstruction, at least I had to add exception table parsing to it at one point in order to see the effect of fuzzing.  Some simplification is possible, since the transformation is essentially just relocation, but a careful review of what is being parsed will be needed in addition to reconstructing the stripped binary output.

I suggest that a somewhat simpler and more easily verifiable approach would be to simply compile the builtins twice -- once producing the metadata for the benefit of nativegen.py, and again with metadata output suppressed for inclusion in the runtime.  This would require a compiler switch to suppress metadata output.

In any case, such a modified compiler would be needed to properly test a stripping tool, as the stripped output should be bit-for-bit identical to code that is otherwise generated by the same compiler from the same source, but with the metadata omitted.

Comment 4

[Steven Johnson]

(In reply to comment #3)
> I suggest that a somewhat simpler and more easily verifiable approach would
> be to simply compile the builtins twice

I like it.

Comment 5

[Dan Smith]

Do we have any data on the size added by the additional "native" metadata for the built-ins?

Comment 6

[Sylvestre Ledru [:Sylvestre]]

Tamarin is a dead project now. Mass WONTFIX.

Comment 7

[Sylvestre Ledru [:Sylvestre]]

Tamarin isn't maintained anymore. WONTFIX remaining bugs.