Re: ptrace problems

["Pramode C.E" <iclabs@xxxxxxxx>]

On Mon, 28 Feb 2000, Shourya Sarcar wrote:

> 
> Programmerz,
> This is a little pair of programs I wrote. The father tries to behave
> like a debugger and get the register values of the child. But I keep on
> getting incorrect results. Rather no results at all.
> Help, someone. Anyone .

hello,
Your code worked with two modifications which I am giving below.

> 	err=ptrace(PTRACE_ATTACH,child_pid,0,0);
> 	if (err<0) 
> 		fatal_error("Invalid Ptrace in PTRACE_ATTACH");
> 	else
> 		printf("Successful ptrace ATTACH\n");
> 		 

	sleep(1);	/* Wait for some time. I have not dug up
			   the source to find out why this works.
			   But it works! If you find the reason,
 			   please inform me. I am curious. */
	
> 	/*Get the regs */
> 	err=ptrace(PT_GETREGS,child_pid,NULL,gpregs);
> 	printf ("Err = %d\n",err);
> 	if (err<0) fatal_error("Invalid Ptrace in GETREGS");
> 	printf("EAX : 0x%lx\n",gpregs[EAX]);
> 	printf("CS  : 0x%lx\n",gpregs[CS]);
> 	printf("EIP : 0x%lx\n",gpregs[EIP]);


	Modification in execed process.
> 		
> 	for (i=0;i<1000000000L;i+=5);
> 	printf("Program new stopped\n");

	for(;;);	/* just to make extra sure no premature death
 		           occurs */
> 	
> 	return 0;
> }
						regards,
						pramode.