| // Copyright 2014 The Go Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style |
| // license that can be found in the LICENSE file. |
| |
| package server |
| |
| import ( |
| "fmt" |
| "os" |
| "runtime" |
| "syscall" |
| "time" |
| ) |
| |
| // ptraceRun runs all the closures from fc on a dedicated OS thread. Errors |
| // are returned on ec. Both channels must be unbuffered, to ensure that the |
| // resultant error is sent back to the same goroutine that sent the closure. |
| func ptraceRun(fc chan func() error, ec chan error) { |
| if cap(fc) != 0 || cap(ec) != 0 { |
| panic("ptraceRun was given buffered channels") |
| } |
| runtime.LockOSThread() |
| for f := range fc { |
| ec <- f() |
| } |
| } |
| |
| func (s *Server) startProcess(name string, argv []string, attr *os.ProcAttr) (proc *os.Process, err error) { |
| s.fc <- func() error { |
| var err1 error |
| proc, err1 = os.StartProcess(name, argv, attr) |
| return err1 |
| } |
| err = <-s.ec |
| return |
| } |
| |
| func (s *Server) ptraceCont(pid int, signal int) (err error) { |
| s.fc <- func() error { |
| return syscall.PtraceCont(pid, signal) |
| } |
| return <-s.ec |
| } |
| |
| func (s *Server) ptraceGetRegs(pid int, regsout *syscall.PtraceRegs) (err error) { |
| s.fc <- func() error { |
| return syscall.PtraceGetRegs(pid, regsout) |
| } |
| return <-s.ec |
| } |
| |
| func (s *Server) ptracePeek(pid int, addr uintptr, out []byte) (err error) { |
| s.fc <- func() error { |
| n, err := syscall.PtracePeekText(pid, addr, out) |
| if err != nil { |
| return err |
| } |
| if n != len(out) { |
| return fmt.Errorf("ptracePeek: peeked %d bytes, want %d", n, len(out)) |
| } |
| return nil |
| } |
| return <-s.ec |
| } |
| |
| func (s *Server) ptracePoke(pid int, addr uintptr, data []byte) (err error) { |
| s.fc <- func() error { |
| n, err := syscall.PtracePokeText(pid, addr, data) |
| if err != nil { |
| return err |
| } |
| if n != len(data) { |
| return fmt.Errorf("ptracePoke: poked %d bytes, want %d", n, len(data)) |
| } |
| return nil |
| } |
| return <-s.ec |
| } |
| |
| func (s *Server) ptraceSetOptions(pid int, options int) (err error) { |
| s.fc <- func() error { |
| return syscall.PtraceSetOptions(pid, options) |
| } |
| return <-s.ec |
| } |
| |
| func (s *Server) ptraceSetRegs(pid int, regs *syscall.PtraceRegs) (err error) { |
| s.fc <- func() error { |
| return syscall.PtraceSetRegs(pid, regs) |
| } |
| return <-s.ec |
| } |
| |
| func (s *Server) ptraceSingleStep(pid int) (err error) { |
| s.fc <- func() error { |
| return syscall.PtraceSingleStep(pid) |
| } |
| return <-s.ec |
| } |
| |
| type breakpointsChangedError struct { |
| call call |
| } |
| |
| func (*breakpointsChangedError) Error() string { |
| return "breakpoints changed" |
| } |
| |
| func (s *Server) wait(pid int, allowBreakpointsChange bool) (wpid int, status syscall.WaitStatus, err error) { |
| // We poll syscall.Wait4 with WNOHANG, sleeping in between, as a poor man's |
| // waitpid-with-timeout. This allows adding and removing breakpoints |
| // concurrently with waiting to hit an existing breakpoint. |
| f := func() error { |
| var err1 error |
| wpid, err1 = syscall.Wait4(pid, &status, syscall.WALL|syscall.WNOHANG, nil) |
| return err1 |
| } |
| |
| const ( |
| minSleep = 1 * time.Microsecond |
| maxSleep = 100 * time.Millisecond |
| ) |
| for sleep := minSleep; ; { |
| s.fc <- f |
| err = <-s.ec |
| |
| // wpid == 0 means that wait found nothing (and returned due to WNOHANG). |
| if wpid != 0 { |
| return |
| } |
| |
| if allowBreakpointsChange { |
| select { |
| case c := <-s.breakpointc: |
| return 0, 0, &breakpointsChangedError{c} |
| default: |
| } |
| } |
| |
| time.Sleep(sleep) |
| if sleep < maxSleep { |
| sleep *= 10 |
| } |
| } |
| } |