Exploring and Dynamically Patching Django/Python Using GDB (opens in new tab)

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81 pointsebroder13y ago11 comments

11 comments

Couldn't you do almost the exact same thing using pdb, without all the C API / register stuff?

Maybe I misunderstood the post, but it sounds like you're just stopping right before the request returns, reloading the module, generating a new response, and allowing execution to continue.

Why is GDB required for any of this?

ebroderOP13y ago

You're right! You could do all of this with pdb, but only if you have enough foresight to run the app under pdb to begin with (which I definitely never do).

Using GDB, you don't have to change the app or remember to run it in a particular way.

mickeyp13y ago

You could install a custom signal, like SIGUSR1, and have it trigger pdb when that signal is sent to your process.

1 more reply

robbles13y ago

Right, I see the use in this now. How difficult would it be to wrap this up in a reusable script that you could run directly, instead of having to manually work through the debugger prompt?

2 more replies

lucian190013y ago

Then perhaps it would be easier to use gdb just for bootstrapping pdb into the app?

pc13y ago

I've always missed this feature from Seaside/Smalltalk. (Not to mention having a proper language-level debugger at your disposal.)

agumonkey13y ago

nice use of cpython knowledge. very black magic, but very usefull in time.

j / k navigate · click thread line to collapse

11 comments

robbles13y ago

Couldn't you do almost the exact same thing using pdb, without all the C API / register stuff?

Maybe I misunderstood the post, but it sounds like you're just stopping right before the request returns, reloading the module, generating a new response, and allowing execution to continue.

Why is GDB required for any of this?

ebroderOP13y ago

You're right! You could do all of this with pdb, but only if you have enough foresight to run the app under pdb to begin with (which I definitely never do).

Using GDB, you don't have to change the app or remember to run it in a particular way.

mickeyp13y ago

You could install a custom signal, like SIGUSR1, and have it trigger pdb when that signal is sent to your process.

1 more reply

robbles13y ago

Right, I see the use in this now. How difficult would it be to wrap this up in a reusable script that you could run directly, instead of having to manually work through the debugger prompt?

2 more replies

lucian190013y ago

Then perhaps it would be easier to use gdb just for bootstrapping pdb into the app?

pc13y ago

I've always missed this feature from Seaside/Smalltalk. (Not to mention having a proper language-level debugger at your disposal.)

agumonkey13y ago

nice use of cpython knowledge. very black magic, but very usefull in time.

j / k navigate · click thread line to collapse