Interrupting target execution on Linux using GDB/MI
James Milne
jamesm@filmlight.ltd.uk
Wed Apr 1 16:37:00 GMT 2009
Hi,
I'm writing a debugger for an interpreted language, and I'm using GDB
as the underlying mechanism for instrumenting the interpreter process.
I have my debugger application process which fork()/execs() gdb and
uses the GDB/MI interface to communicate with it.
I then instruct GDB to load my target executable, set a breakpoint on
main(), specify the arguments I want to pass to the executable using "-
exec-arguments", and then start the executable using "-exec-run". The
executable is the interpreter for the language I'm working with.
Once my breakpoint is hit, I can set further breakpoints within the
interpreter which I use to trace its execution. I can then resume
execution of the target by sending "-exec-continue".
This is all fine, and works correctly. The problem occurs when I want
to interrupt the execution of the target process.
I trap the PID of the inferior process by analysing the stream records
returned from GDB, specifically looking for the first "[New Thread
<blah> (LWP <pid>)]" style response.
On OS X 10.5.6 using Apple's gdb (GNU gdb 6.3.50-20050815 (Apple
version gdb-962)), I have to interrupt the target process by sending a
SIGINT signal directly to the inferior process. This works correctly
and causes GDB to interrupt the execution of the inferior.
However, if I send SIGINT to the inferior using GDB 6.3 or 6.8 on
Linux (CentOS 4.3), GDB returns the following:
&"Quit\n"
^error,msg="Quit"
If I send SIGINT to the gdb process itself, it ignores it.
What is the correct procedure when using GDB/MI to interrupt the
execution of the inferior process?
Regards
James Milne
FilmLight Ltd.
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