Fix context failed to execute because breakpoint.location is None

[RafaelLeeImg]

Fix context failed to execute because breakpoint.location is None when watchpoint is set

Description

Fix error of

[ Legend: Modified register | Code | Heap | Stack | String ]
[!] Command 'context' failed to execute properly, reason: argument of type 'NoneType' is not iterable

when breakpoints are set and breakpoint.location is not available.

How Has This Been Tested?

Architecture	Yes/No	Comments
x86-32	✖️
x86-64	Yes
ARM	✖️
AARCH64	✖️
MIPS	✖️
POWERPC	✖️
SPARC	✖️
RISC-V	✖️
make test	Yes

Checklist

• My PR was done against the dev branch, not master.
• My code follows the code style of this project.
• My change includes a change to the documentation, if required.
• My change adds tests as appropriate.
• I have read and agree to the CONTRIBUTING document.

[theguy147]

Thank you for the PR.

Usually it would be helpful if you could also provide a scenario in which this error occurs for you so other people can reproduce the issue and understand the problem better.

I looked into it some more: gdb.breakpoints() returns a list of breakpoint objects that are documented here. According to the docs location can actually be None if the breakpoint is a watchpoint (i guess your error occurred after you set a watchpoint?)

This identical issue can be found at 4 locations in GEF (not just 1): L5544, L5575, L8024 and this L8249. So it would be good if all of them could be patched.

P.S.
As to why your tests fail locally: If you have the possibility to investigate this further and/or send us the output of your make test (in a new issue here on GH) this would be helpful as well.

[hugsy]

Better now, all good for me

[RafaelLeeImg]

The condition I have is setting watchpoints in my debugging session.
Tests failed yesterday is because I have write ~/.gef.rc.
I removed the file ~/.gef.rc and installed all the dependencies, all tests passed on my local amd64 computer. About the identical lines in L5544, L5575, these requires IDA which I don't have, I cannot verify them.
I checked L8024, with the config contex.layout "code". It's already fixed with the commit 852f9f6.
Now, all tests in make test are passed.

[hugsy]

Yeah I wouldn't worry too much for you as long as tests pass on our CI.

Waiting for @theguy147 final review and we can merge.

Thanks @RafaelLeeImg