Golang PtraceRegs.PC方法代码示例

// doTrap handles SIGTRAP debug events with a cause of 0.  These can
// be caused either by an installed breakpoint, a breakpoint in the
// program text, or by single stepping.
//
// TODO(austin) I think we also get this on an execve syscall.
func (ev *debugEvent) doTrap() (threadState, os.Error) {
	t := ev.t

	if t.state == singleStepping {
		return stopped, nil
	}

	// Hit a breakpoint.  Linux leaves the program counter after
	// the breakpoint.  If this is an installed breakpoint, we
	// need to back the PC up to the breakpoint PC.
	var regs syscall.PtraceRegs
	err := t.ptraceGetRegs(&regs)
	if err != nil {
		return stopped, err
	}

	b, ok := t.proc.breakpoints[uintptr(regs.PC())-uintptr(len(bpinst386))]
	if !ok {
		// We must have hit a breakpoint that was actually in
		// the program.  Leave the IP where it is so we don't
		// re-execute the breakpoint instruction.  Expose the
		// fact that we stopped with a SIGTRAP.
		return stoppedSignal, nil
	}

	t.breakpoint = b
	t.logTrace("at breakpoint %v, backing up PC from %#x", b, regs.PC())

	regs.SetPC(uint64(b.pc))
	err = t.ptraceSetRegs(&regs)
	if err != nil {
		return stopped, err
	}
	return stoppedBreakpoint, nil
}

func (t *thread) logTrace(format string, args ...interface{}) {
	if !trace {
		return
	}
	logLock.Lock()
	defer logLock.Unlock()
	fmt.Fprintf(os.Stderr, "Thread %d", t.tid)
	if traceIP {
		var regs syscall.PtraceRegs
		err := t.ptraceGetRegs(&regs)
		if err == nil {
			fmt.Fprintf(os.Stderr, "@%x", regs.PC())
		}
	}
	fmt.Fprint(os.Stderr, ": ")
	fmt.Fprintf(os.Stderr, format, args...)
	fmt.Fprint(os.Stderr, "\n")
}

func (p *process) Continue() os.Error {
	// Single step any threads that are stopped at breakpoints so
	// we can reinstall breakpoints.
	var ready chan os.Error
	count := 0

	err := p.do(func() os.Error {
		// We make the ready channel big enough to hold all
		// ready message so we don't jam up the monitor if we
		// stop listening (e.g., if there's an error).
		ready = make(chan os.Error, len(p.threads))

		for _, t := range p.threads {
			if !t.state.isStopped() {
				continue
			}

			// We use the breakpoint map directly here
			// instead of checking the stop cause because
			// it could have been stopped at a breakpoint
			// for some other reason, or the breakpoint
			// could have been added since it was stopped.
			var regs syscall.PtraceRegs
			err := t.ptraceGetRegs(&regs)
			if err != nil {
				return err
			}
			if b, ok := p.breakpoints[uintptr(regs.PC())]; ok {
				t.logTrace("stepping over breakpoint %v", b)
				if err := t.stepAsync(ready); err != nil {
					return err
				}
				count++
			}
		}
		return nil
	})
	if err != nil {
		p.stopMonitor(err)
		return err
	}

	// Wait for single stepping threads
	for count > 0 {
		err = <-ready
		if err != nil {
			p.stopMonitor(err)
			return err
		}
		count--
	}

	// Continue all threads
	err = p.do(func() os.Error {
		if err := p.installBreakpoints(); err != nil {
			return err
		}

		for _, t := range p.threads {
			var err os.Error
			switch {
			case !t.state.isStopped():
				continue

			case t.state == stoppedSignal && t.signal != syscall.SIGSTOP && t.signal != syscall.SIGTRAP:
				t.logTrace("continuing with signal %d", t.signal)
				err = t.ptraceContWithSignal(t.signal)

			default:
				t.logTrace("continuing")
				err = t.ptraceCont()
			}
			if err != nil {
				return err
			}
			if t.state == stoppedExiting {
				t.setState(exiting)
			} else {
				t.setState(running)
			}
		}
		return nil
	})
	if err != nil {
		// TODO(austin) Do we need to stop the monitor with
		// this error atomically with the do-routine above?
		p.stopMonitor(err)
		return err
	}

	return nil
}