Ignoring SIGSEGV (was: no subject line)

[Greg 'groggy' Lehey]

On Tuesday, 29 July 2003 at  9:16:29 +0000, cool46 cool46 wrote:
> how can ignore SEGV signal on Freebsd?

You can't.

> I am not mean setting SEGV's handler to SIG_IGN,this way can prevent
> program to exit,but can't restore environment to continue this
> program,so the program will hang and can't exit for ever.

Of course.  What do you expect to happen?  A SIGSEGV is an indication
that the instruction being executed can't complete.  Ignoring a
signal means going back and continuing with that instruction.  You'll
get the SIGSEGV again.

> I see a way in Linux,you can see
> http://kaizo.us/mirrors/phrack/phrack58/p58-0x03 ,

This page returns an error message: Not a typewriter (ENOTTY).

> but this is depend on OS because it is closed to OS' underlying
> layer and it is not works on Freebsd.Could you give me a
> example?thanks.

There are two things you can do with a SIGSEGV:

1.  Stop it from happening.  This is preferable.
2.  Add a signal handler which performs some alternative function.
    For example, you might print out some information about the state
    of the program before terminating.

Greg
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