On Tue, Aug 14, 2001 at 09:11:58PM -0700, brian o'shea wrote:
> On Tue, Aug 14, 2001 at 07:47:50PM -0700, Hans Zaunere wrote:
> > > [...]
> > > > 2) If a 10k binary is running, the signal is sent, and the program
> > > > is reloaded from disk, but is 100k (or 1k even) how does the
> > > > signal handling function get called, taking into account what
> > > > Stevens says. Steven states that the sigmask remains for calls
> > > > across exec, so wouldn't the wrong address to the handler function
> > > > be used?
> > >
> > > No, the signal mask is not the address of the handler function. It
> > > is the bit mask which determines which signals are blocked.
> > >
> >
> > Sorry, I think I miss spoke myself. If a signal handler is setup in
> > the running process, and exec is called, replacing the same program,
> > but this time, the program is much smaller or bigger, will the signal
> > handler function be in the right place? The same program is exec'd,
> > but since it's a different size, won't the signal handler function
> > pointer, point to the wrong place?
>
> If a program calls exec on the file that is the current text file (i.e.
> argv[0]), then the text segment of the process will be the same size as
> it was before the call to exec, because it will be identical. The only
> reason why the process' size might (and probably will) be different is
> because of any dynamically allocated memory, and because of and stack
> growth from function calls and local variable allocation. Neither of
> these effect the address of any of the functions in the program
> (including the signal handlers).
This is not necessarily true; a program might exec() a file by the same
name, but with different contents - e.g. restarting a recompiled server.
G'luck,
Peter
--
I've heard that this sentence is a rumor.
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