Add limit flag for heap commands which overrides heap-dereference-limit

[k4lizen]

Useful especially when one wants to see more (or less) chunks printed for one run of the command.

As mentioned here: https://github.com/pwndbg/pwndbg/issues/2376#issuecomment-2296825757

[disconnect3d]

EDIT: Eh, obviously "limit flags" are not there, but some limits are passed via heap-dereference-limit. Sorry for my confusion below.

I believe such limit flags are already there:

dc@dc:~/pwndbg$ rg heap_chain_limit
pwndbg/gdblib/heap/__init__.py
51:heap_chain_limit = add_heap_param(

pwndbg/gdblib/heap/ptmalloc.py
776:                limit=pwndbg.gdblib.heap.heap_chain_limit,
1260:                limit=pwndbg.gdblib.heap.heap_chain_limit,
1367:        chain_size = int(pwndbg.gdblib.heap.heap_chain_limit)

pwndbg/commands/heap.py
30:from pwndbg.gdblib.heap import heap_chain_limit
105:                chain_fd[0], limit=heap_chain_limit, offset=offset, safe_linking=safe_lnk

Hmm, the format_bin function does pwndbg.chain.format(..., limit=heap_chain_limit, ...) -- does heap_chain_limit refer to a parameter here, or its copy? I wonder if one does set heap-dereference-limit 100 will this value be properly resolved here?

Update: Yes. I confirmed that this value is resolved properly and an updated value is used.

So the limitation of dereferencing is used properly when displaying various bins and linked lists.

[disconnect3d]

Now, yeah, the bins (and maybe some other?) command does not have a --limit flag.

Alternatively to adding such flag, we could extend the help string to inform about heap-dereference-limit parameter.

[disconnect3d]

@k4lizen is this still valid and needed? maybe we implemented it somehow? shall we close it?

[k4lizen]

Hm, where did the original issue go? It had some relevant info :(

It is valid and unimplemented though probably not too important a feature