In a gdb python script, how do I set or modify the commands list for a breakpoint?
I can do this trivially by hand. For example to change the commands list for breakpoint 2, at the prompt I can enter:
(gdb) commands 2
Type commands for breakpoint(s) 2, one per line.
End with a line saying just "end".
>info reg rax
>set $rax=0x1234
>end
Yet, from a gdb python script I cannot seem to execute a multiline command.
gdb.execute("commands 2\ninfo reg rax\nset $rax=0x1234\nend\n")
Just gets me an output like
(gdb) source blah.py
>
and it is sitting there for more input. It won't move on until I type end and press enter. Then it just gives complaints making it clear it has not correctly parsed anything after the commands 2 of that string.
Trying to input each line separately doesn't help. For example the script:
gdb.execute("commands 2")
gdb.execute("info reg rax")
gdb.execute("set $rax=0x1234")
gdb.execute("end")
waits for more input from the user during the first execute, and so has similar problems. And while mostly wishful, the following doesn't work either:
gdb.execute(["commands 2","info reg rax","set $rax=0x1234","end"])
It is easy to programatically get the list of breakpoints with gdb.breakpoints(). And these objects have a property commands, which I can see any commands I set by hand or from a native gdb script. However if I try to modify this property, it fails. So once something is set by hand, or a gdb script, there appears to be no way for a python script to edit it. The API document is missing a lot of helpful information, but it does state https://sourceware.org/gdb/onlinedocs/gdb/Breakpoints-In-Python.html#Breakpoints-In-Python Variable: Breakpoint.commands ... This attribute is not writable.
And no, I don't consider it a useful answer to "never use gdb scripts" or "never enter commands by hand" and "instead always write a python gdb.Breakpoint subclass with Breakpoint.stop() set to do something special, and rewrite all existing scripts to use such features". I can only seem to find information for that workaround. But I'm not willing to give up current methods of interaction just due to a gdb quirk.
Since I can easily run commands to do what I want by hand, there must be a way to modify or set the breakpoint commands from a gdb python script. How do I do this?
