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Message-ID: <41117E4A.1040502@gnu.org>
Date: Thu, 05 Aug 2004 00:24:00 -0000
From: Andrew Cagney <cagney@gnu.org>
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To: Qing Zhang <qzhang@cs.utah.edu>
Cc: gdb@sources.redhat.com
Subject: Re: pausing gdb
References: <Pine.GSO.4.50L0.0408041707180.7882-100000@faith.cs.utah.edu>
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> Hi,
> 
> Can anyone tell me how ctrl-c is handled in gdb?  More importantly how
> is gdb able to continue from a sigint.
> 
> your help is much appreciated.

I'm assuming this is UNIX.  Check the man pages for ptrace, and wait. 
The sequence, assuming that GDB's attached to the process (aka inferior):

- GDB's blocked on wait() ; inferior process running
- user enters CNTRL-C
- kernel, instead of delivering cntrl-c to inferior process, unblocks 
GDB returning a ``SIGINT'' indication for that wait() call
- GDB interacts with user
- user enters "continue"
- gdb does ptrace (continue)
- kernel resumes inferior process (signal is never delivered)

Andrew