sigaction() function

[Andrew Haley]

ranjith kumar wrote:

>        I have one question about sigaction() function.
> Suppose in a program  sigaction() is called to change the action taken
> by the process on receipt of a SIGTRAP signal.
>  Let us say sigaction function is:
>                 void sig_sigaction(int, siginfo_t *, void *);
> When the program hits a trap at  address=the contents of register
> REGPC(program counter),
>  let us say the registers are REGPC,REG1,.........
> 
> So when that trap is hit, KERNEL will modify the REGPC to point to
> starting address of 'sig_sigaction' function.
> But what about other registers and stack?? KERNEL may modify other
> registers and may write some thing on stack??

That's right.  All the registers are saved in the siginfo_t struct
on the stack, and are restored when your sigaction() function
returns.  But all this is a bit off-topic.

> Please ignore me if this question is not related to this group.

Why on earth did you cross-post to all these groups?  This is
never going to be right.

Andrew.