call_function for non-kernel programs

[septatrix]

I would like to call functions for/from normal userspace progs. The only available thing I found, however, was drgn.helpers.experimental.kmodify.call_function which seems to be reserved for usage when prog is the kernel. Is there an alternative for debugging normal programs?

PS: This is primarily for functions in coredumps, not in running programs. My current use-case is exploring binary files for which I am using the "Custom Programs" snipped but it might also be useful for paused, non-custom programs

[osandov]

drgn doesn't have a way to do this for userspace at the moment, unfortunately. Adding this for live programs is feasible but needs a bunch of preparation work (see #320; I'll add this request there, too).

Doing this for core dumps would be an extra step on top of that. You need a running process to actually execute the function, so we'd have to do some extra craziness like run the binary with a breakpoint at main, or fabricate a process with its memory initialized from the core dump.

In short, I love the idea but am currently prioritizing kernel support.

[septatrix]

In short, I love the idea but am currently prioritizing kernel support.

Completely understandable, thanks for the great tool by the way. I am currently doing a kernel programming course at university where we develop our own simple filesystem and it is really helpful! I am actually using it to traverse the block device and output a DOT file to graphviz for debugging/visualization

[osandov]

I am actually using it to traverse the block device and output a DOT file to graphviz for debugging/visualization

That sounds really cool!