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- // Copyright 2018 Google Inc. All Rights Reserved.
- //
- // Licensed under the Apache License, Version 2.0 (the "License");
- // you may not use this file except in compliance with the License.
- // You may obtain a copy of the License at
- //
- // http://www.apache.org/licenses/LICENSE-2.0
- //
- // Unless required by applicable law or agreed to in writing, software
- // distributed under the License is distributed on an "AS IS" BASIS,
- // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- // See the License for the specific language governing permissions and
- // limitations under the License.
-
- // +build linux
-
- 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
- }
- }
- }
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