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proctl.go
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proctl.go
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// Package proctl provides functions for attaching to and manipulating
// a process during the debug session.
package proctl
import (
"debug/dwarf"
"debug/gosym"
"fmt"
"os"
"os/exec"
"path/filepath"
"strconv"
"strings"
"syscall"
sys "golang.org/x/sys/unix"
"github.com/derekparker/delve/dwarf/frame"
"github.com/derekparker/delve/dwarf/reader"
)
// Struct representing a debugged process. Holds onto pid, register values,
// process struct and process state.
type DebuggedProcess struct {
Pid int
Process *os.Process
Dwarf *dwarf.Data
GoSymTable *gosym.Table
FrameEntries frame.FrameDescriptionEntries
HWBreakPoints [4]*BreakPoint
BreakPoints map[uint64]*BreakPoint
Threads map[int]*ThreadContext
CurrentThread *ThreadContext
os *OSProcessDetails
breakpointIDCounter int
running bool
halt bool
}
// A ManualStopError happens when the user triggers a
// manual stop via SIGERM.
type ManualStopError struct{}
func (mse ManualStopError) Error() string {
return "Manual stop requested"
}
// Attach to an existing process with the given PID.
func Attach(pid int) (*DebuggedProcess, error) {
dbp, err := newDebugProcess(pid, true)
if err != nil {
return nil, err
}
return dbp, nil
}
// Create and begin debugging a new process. First entry in
// `cmd` is the program to run, and then rest are the arguments
// to be supplied to that process.
func Launch(cmd []string) (*DebuggedProcess, error) {
proc := exec.Command(cmd[0])
proc.Args = cmd
proc.Stdout = os.Stdout
proc.Stderr = os.Stderr
proc.SysProcAttr = &syscall.SysProcAttr{Ptrace: true}
if err := proc.Start(); err != nil {
return nil, err
}
_, _, err := wait(proc.Process.Pid, 0)
if err != nil {
return nil, fmt.Errorf("waiting for target execve failed: %s", err)
}
return newDebugProcess(proc.Process.Pid, false)
}
// Returns whether or not Delve thinks the debugged
// process is currently executing.
func (dbp *DebuggedProcess) Running() bool {
return dbp.running
}
// Find a location by string (file+line, function, breakpoint id, addr)
func (dbp *DebuggedProcess) FindLocation(str string) (uint64, error) {
// File + Line
if strings.ContainsRune(str, ':') {
fl := strings.Split(str, ":")
fileName, err := filepath.Abs(fl[0])
if err != nil {
return 0, err
}
line, err := strconv.Atoi(fl[1])
if err != nil {
return 0, err
}
pc, _, err := dbp.GoSymTable.LineToPC(fileName, line)
if err != nil {
return 0, err
}
return pc, nil
} else {
// Try to lookup by function name
fn := dbp.GoSymTable.LookupFunc(str)
if fn != nil {
return fn.Entry, nil
}
// Attempt to parse as number for breakpoint id or raw address
id, err := strconv.ParseUint(str, 0, 64)
if err != nil {
return 0, fmt.Errorf("unable to find location for %s", str)
}
// Use as breakpoint id
for _, bp := range dbp.HWBreakPoints {
if bp == nil {
continue
}
if uint64(bp.ID) == id {
return bp.Addr, nil
}
}
for _, bp := range dbp.BreakPoints {
if uint64(bp.ID) == id {
return bp.Addr, nil
}
}
// Last resort, use as raw address
return id, nil
}
}
// Sends out a request that the debugged process halt
// execution. Sends SIGSTOP to all threads.
func (dbp *DebuggedProcess) RequestManualStop() {
dbp.halt = true
for _, th := range dbp.Threads {
th.Halt()
}
dbp.running = false
}
// Sets a breakpoint at addr, and stores it in the process wide
// break point table. Setting a break point must be thread specific due to
// ptrace actions needing the thread to be in a signal-delivery-stop.
//
// Depending on hardware support, Delve will choose to either
// set a hardware or software breakpoint. Essentially, if the
// hardware supports it, and there are free debug registers, Delve
// will set a hardware breakpoint. Otherwise we fall back to software
// breakpoints, which are a bit more work for us.
func (dbp *DebuggedProcess) Break(addr uint64) (*BreakPoint, error) {
return dbp.setBreakpoint(dbp.CurrentThread.Id, addr)
}
// Sets a breakpoint by location string (function, file+line, address)
func (dbp *DebuggedProcess) BreakByLocation(loc string) (*BreakPoint, error) {
addr, err := dbp.FindLocation(loc)
if err != nil {
return nil, err
}
return dbp.Break(addr)
}
// Clears a breakpoint in the current thread.
func (dbp *DebuggedProcess) Clear(addr uint64) (*BreakPoint, error) {
return dbp.clearBreakpoint(dbp.CurrentThread.Id, addr)
}
// Clears a breakpoint by location (function, file+line, address, breakpoint id)
func (dbp *DebuggedProcess) ClearByLocation(loc string) (*BreakPoint, error) {
addr, err := dbp.FindLocation(loc)
if err != nil {
return nil, err
}
return dbp.Clear(addr)
}
// Returns the status of the current main thread context.
func (dbp *DebuggedProcess) Status() *sys.WaitStatus {
return dbp.CurrentThread.Status
}
// Loop through all threads, printing their information
// to the console.
func (dbp *DebuggedProcess) PrintThreadInfo() error {
for _, th := range dbp.Threads {
if err := th.PrintInfo(); err != nil {
return err
}
}
return nil
}
// Step over function calls.
func (dbp *DebuggedProcess) Next() error {
var runnable []*ThreadContext
fn := func() error {
for _, th := range dbp.Threads {
// Continue any blocked M so that the
// scheduler can continue to do its'
// job correctly.
if th.blocked() {
err := th.Continue()
if err != nil {
return err
}
continue
}
runnable = append(runnable, th)
}
for _, th := range runnable {
err := th.Next()
if err != nil && err != sys.ESRCH {
return err
}
}
return dbp.Halt()
}
return dbp.run(fn)
}
// Resume process.
func (dbp *DebuggedProcess) Continue() error {
for _, thread := range dbp.Threads {
err := thread.Continue()
if err != nil {
return err
}
}
fn := func() error {
wpid, _, err := trapWait(dbp, -1)
if err != nil {
return err
}
thread, ok := dbp.Threads[wpid]
if !ok {
return fmt.Errorf("could not find thread for %d", wpid)
}
if wpid != dbp.CurrentThread.Id {
fmt.Printf("thread context changed from %d to %d\n", dbp.CurrentThread.Id, thread.Id)
dbp.CurrentThread = thread
}
pc, err := thread.CurrentPC()
if err != nil {
return err
}
// Check to see if we hit a runtime.breakpoint
fn := dbp.GoSymTable.PCToFunc(pc)
if fn != nil && fn.Name == "runtime.breakpoint" {
// step twice to get back to user code
for i := 0; i < 2; i++ {
err = thread.Step()
if err != nil {
return err
}
}
dbp.Halt()
return nil
}
// Check for hardware breakpoint
for _, bp := range dbp.HWBreakPoints {
if bp != nil && bp.Addr == pc {
if !bp.temp {
return dbp.Halt()
}
return nil
}
}
// Check to see if we have hit a software breakpoint.
if bp, ok := dbp.BreakPoints[pc-1]; ok {
if !bp.temp {
return dbp.Halt()
}
return nil
}
return fmt.Errorf("unrecognized breakpoint %#v", pc)
}
return dbp.run(fn)
}
// Steps through process.
func (dbp *DebuggedProcess) Step() (err error) {
fn := func() error {
for _, th := range dbp.Threads {
if th.blocked() {
continue
}
err := th.Step()
if err != nil {
return err
}
}
return nil
}
return dbp.run(fn)
}
// Obtains register values from what Delve considers to be the current
// thread of the traced process.
func (dbp *DebuggedProcess) Registers() (Registers, error) {
return dbp.CurrentThread.Registers()
}
func (dbp *DebuggedProcess) CurrentPC() (uint64, error) {
return dbp.CurrentThread.CurrentPC()
}
// Returns the value of the named symbol.
func (dbp *DebuggedProcess) EvalSymbol(name string) (*Variable, error) {
return dbp.CurrentThread.EvalSymbol(name)
}
// Returns a reader for the dwarf data
func (dbp *DebuggedProcess) DwarfReader() *reader.Reader {
return reader.New(dbp.Dwarf)
}
// Returns a new DebuggedProcess struct.
func newDebugProcess(pid int, attach bool) (*DebuggedProcess, error) {
dbp := DebuggedProcess{
Pid: pid,
Threads: make(map[int]*ThreadContext),
BreakPoints: make(map[uint64]*BreakPoint),
os: new(OSProcessDetails),
}
if attach {
err := sys.PtraceAttach(pid)
if err != nil {
return nil, err
}
_, _, err = wait(pid, 0)
if err != nil {
return nil, err
}
}
proc, err := os.FindProcess(pid)
if err != nil {
return nil, err
}
dbp.Process = proc
err = dbp.LoadInformation()
if err != nil {
return nil, err
}
if err := dbp.updateThreadList(); err != nil {
return nil, err
}
return &dbp, nil
}
func (dbp *DebuggedProcess) run(fn func() error) error {
dbp.running = true
dbp.halt = false
defer func() { dbp.running = false }()
if err := fn(); err != nil {
if _, ok := err.(ManualStopError); !ok {
return err
}
}
return nil
}
type ProcessExitedError struct {
pid int
}
func (pe ProcessExitedError) Error() string {
return fmt.Sprintf("process %d has exited", pe.pid)
}