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bee/vendor/github.com/derekparker/delve/proc/variables.go

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2017-03-19 22:45:54 +00:00
package proc
import (
"bytes"
"encoding/binary"
"errors"
"fmt"
"go/constant"
"go/parser"
"go/token"
"reflect"
"strings"
"unsafe"
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"github.com/derekparker/delve/dwarf/op"
"github.com/derekparker/delve/dwarf/reader"
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"golang.org/x/debug/dwarf"
)
const (
maxErrCount = 3 // Max number of read errors to accept while evaluating slices, arrays and structs
maxArrayStridePrefetch = 1024 // Maximum size of array stride for which we will prefetch the array contents
chanRecv = "chan receive"
chanSend = "chan send"
hashTophashEmpty = 0 // used by map reading code, indicates an empty bucket
hashMinTopHash = 4 // used by map reading code, indicates minimum value of tophash that isn't empty or evacuated
)
// Variable represents a variable. It contains the address, name,
// type and other information parsed from both the Dwarf information
// and the memory of the debugged process.
// If OnlyAddr is true, the variables value has not been loaded.
type Variable struct {
Addr uintptr
OnlyAddr bool
Name string
DwarfType dwarf.Type
RealType dwarf.Type
Kind reflect.Kind
mem memoryReadWriter
dbp *Process
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Value constant.Value
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Len int64
Cap int64
// Base address of arrays, Base address of the backing array for slices (0 for nil slices)
// Base address of the backing byte array for strings
// address of the struct backing chan and map variables
// address of the function entry point for function variables (0 for nil function pointers)
Base uintptr
stride int64
fieldType dwarf.Type
// number of elements to skip when loading a map
mapSkip int
Children []Variable
loaded bool
Unreadable error
}
type LoadConfig struct {
// FollowPointers requests pointers to be automatically dereferenced.
FollowPointers bool
// MaxVariableRecurse is how far to recurse when evaluating nested types.
MaxVariableRecurse int
// MaxStringLen is the maximum number of bytes read from a string
MaxStringLen int
// MaxArrayValues is the maximum number of elements read from an array, a slice or a map.
MaxArrayValues int
// MaxStructFields is the maximum number of fields read from a struct, -1 will read all fields.
MaxStructFields int
}
var loadSingleValue = LoadConfig{false, 0, 64, 0, 0}
var loadFullValue = LoadConfig{true, 1, 64, 64, -1}
// M represents a runtime M (OS thread) structure.
type M struct {
procid int // Thread ID or port.
spinning uint8 // Busy looping.
blocked uint8 // Waiting on futex / semaphore.
curg uintptr // Current G running on this thread.
}
// G status, from: src/runtime/runtime2.go
const (
Gidle uint64 = iota // 0
Grunnable // 1 runnable and on a run queue
Grunning // 2
Gsyscall // 3
Gwaiting // 4
GmoribundUnused // 5 currently unused, but hardcoded in gdb scripts
Gdead // 6
Genqueue // 7 Only the Gscanenqueue is used.
Gcopystack // 8 in this state when newstack is moving the stack
)
// G represents a runtime G (goroutine) structure (at least the
// fields that Delve is interested in).
type G struct {
ID int // Goroutine ID
PC uint64 // PC of goroutine when it was parked.
SP uint64 // SP of goroutine when it was parked.
GoPC uint64 // PC of 'go' statement that created this goroutine.
WaitReason string // Reason for goroutine being parked.
Status uint64
// Information on goroutine location
CurrentLoc Location
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// PC of entry to top-most deferred function.
DeferPC uint64
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// Thread that this goroutine is currently allocated to
thread *Thread
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dbp *Process
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}
// EvalScope is the scope for variable evaluation. Contains the thread,
// current location (PC), and canonical frame address.
type EvalScope struct {
Thread *Thread
PC uint64
CFA int64
}
// IsNilErr is returned when a variable is nil.
type IsNilErr struct {
name string
}
func (err *IsNilErr) Error() string {
return fmt.Sprintf("%s is nil", err.name)
}
func (scope *EvalScope) newVariable(name string, addr uintptr, dwarfType dwarf.Type) *Variable {
return newVariable(name, addr, dwarfType, scope.Thread.dbp, scope.Thread)
}
func (t *Thread) newVariable(name string, addr uintptr, dwarfType dwarf.Type) *Variable {
return newVariable(name, addr, dwarfType, t.dbp, t)
}
func (v *Variable) newVariable(name string, addr uintptr, dwarfType dwarf.Type) *Variable {
return newVariable(name, addr, dwarfType, v.dbp, v.mem)
}
func newVariable(name string, addr uintptr, dwarfType dwarf.Type, dbp *Process, mem memoryReadWriter) *Variable {
v := &Variable{
Name: name,
Addr: addr,
DwarfType: dwarfType,
mem: mem,
dbp: dbp,
}
v.RealType = resolveTypedef(v.DwarfType)
switch t := v.RealType.(type) {
case *dwarf.PtrType:
v.Kind = reflect.Ptr
if _, isvoid := t.Type.(*dwarf.VoidType); isvoid {
v.Kind = reflect.UnsafePointer
}
case *dwarf.ChanType:
v.Kind = reflect.Chan
case *dwarf.MapType:
v.Kind = reflect.Map
case *dwarf.StringType:
v.Kind = reflect.String
v.stride = 1
v.fieldType = &dwarf.UintType{BasicType: dwarf.BasicType{CommonType: dwarf.CommonType{ByteSize: 1, Name: "byte"}, BitSize: 8, BitOffset: 0}}
if v.Addr != 0 {
v.Base, v.Len, v.Unreadable = readStringInfo(v.mem, v.dbp.arch, v.Addr)
}
case *dwarf.SliceType:
v.Kind = reflect.Slice
if v.Addr != 0 {
v.loadSliceInfo(t)
}
case *dwarf.InterfaceType:
v.Kind = reflect.Interface
case *dwarf.StructType:
v.Kind = reflect.Struct
case *dwarf.ArrayType:
v.Kind = reflect.Array
v.Base = v.Addr
v.Len = t.Count
v.Cap = -1
v.fieldType = t.Type
v.stride = 0
if t.Count > 0 {
v.stride = t.ByteSize / t.Count
}
case *dwarf.ComplexType:
switch t.ByteSize {
case 8:
v.Kind = reflect.Complex64
case 16:
v.Kind = reflect.Complex128
}
case *dwarf.IntType:
v.Kind = reflect.Int
case *dwarf.UintType:
v.Kind = reflect.Uint
case *dwarf.FloatType:
switch t.ByteSize {
case 4:
v.Kind = reflect.Float32
case 8:
v.Kind = reflect.Float64
}
case *dwarf.BoolType:
v.Kind = reflect.Bool
case *dwarf.FuncType:
v.Kind = reflect.Func
case *dwarf.VoidType:
v.Kind = reflect.Invalid
case *dwarf.UnspecifiedType:
v.Kind = reflect.Invalid
default:
v.Unreadable = fmt.Errorf("Unknown type: %T", t)
}
return v
}
func resolveTypedef(typ dwarf.Type) dwarf.Type {
for {
if tt, ok := typ.(*dwarf.TypedefType); ok {
typ = tt.Type
} else {
return typ
}
}
}
func newConstant(val constant.Value, mem memoryReadWriter) *Variable {
v := &Variable{Value: val, mem: mem, loaded: true}
switch val.Kind() {
case constant.Int:
v.Kind = reflect.Int
case constant.Float:
v.Kind = reflect.Float64
case constant.Bool:
v.Kind = reflect.Bool
case constant.Complex:
v.Kind = reflect.Complex128
case constant.String:
v.Kind = reflect.String
v.Len = int64(len(constant.StringVal(val)))
}
return v
}
var nilVariable = &Variable{
Name: "nil",
Addr: 0,
Base: 0,
Kind: reflect.Ptr,
Children: []Variable{{Addr: 0, OnlyAddr: true}},
}
func (v *Variable) clone() *Variable {
r := *v
return &r
}
// TypeString returns the string representation
// of the type of this variable.
func (v *Variable) TypeString() string {
if v == nilVariable {
return "nil"
}
if v.DwarfType != nil {
return v.DwarfType.Common().Name
}
return v.Kind.String()
}
func (v *Variable) toField(field *dwarf.StructField) (*Variable, error) {
if v.Unreadable != nil {
return v.clone(), nil
}
if v.Addr == 0 {
return nil, &IsNilErr{v.Name}
}
name := ""
if v.Name != "" {
parts := strings.Split(field.Name, ".")
if len(parts) > 1 {
name = fmt.Sprintf("%s.%s", v.Name, parts[1])
} else {
name = fmt.Sprintf("%s.%s", v.Name, field.Name)
}
}
return v.newVariable(name, uintptr(int64(v.Addr)+field.ByteOffset), field.Type), nil
}
// DwarfReader returns the DwarfReader containing the
// Dwarf information for the target process.
func (scope *EvalScope) DwarfReader() *reader.Reader {
return scope.Thread.dbp.DwarfReader()
}
// Type returns the Dwarf type entry at `offset`.
func (scope *EvalScope) Type(offset dwarf.Offset) (dwarf.Type, error) {
return scope.Thread.dbp.dwarf.Type(offset)
}
// PtrSize returns the size of a pointer.
func (scope *EvalScope) PtrSize() int {
return scope.Thread.dbp.arch.PtrSize()
}
// ChanRecvBlocked returns whether the goroutine is blocked on
// a channel read operation.
func (g *G) ChanRecvBlocked() bool {
return (g.thread == nil) && (g.WaitReason == chanRecv)
}
// chanRecvReturnAddr returns the address of the return from a channel read.
func (g *G) chanRecvReturnAddr(dbp *Process) (uint64, error) {
locs, err := g.Stacktrace(4)
if err != nil {
return 0, err
}
topLoc := locs[len(locs)-1]
return topLoc.Current.PC, nil
}
// NoGError returned when a G could not be found
// for a specific thread.
type NoGError struct {
tid int
}
func (ng NoGError) Error() string {
return fmt.Sprintf("no G executing on thread %d", ng.tid)
}
func (gvar *Variable) parseG() (*G, error) {
mem := gvar.mem
dbp := gvar.dbp
gaddr := uint64(gvar.Addr)
_, deref := gvar.RealType.(*dwarf.PtrType)
if deref {
gaddrbytes, err := mem.readMemory(uintptr(gaddr), dbp.arch.PtrSize())
if err != nil {
return nil, fmt.Errorf("error derefing *G %s", err)
}
gaddr = binary.LittleEndian.Uint64(gaddrbytes)
}
if gaddr == 0 {
id := 0
if thread, ok := mem.(*Thread); ok {
id = thread.ID
}
return nil, NoGError{tid: id}
}
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gvar.loadValue(loadFullValue)
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if gvar.Unreadable != nil {
return nil, gvar.Unreadable
}
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schedVar := gvar.toFieldNamed("sched")
pc, _ := constant.Int64Val(schedVar.toFieldNamed("pc").Value)
sp, _ := constant.Int64Val(schedVar.toFieldNamed("sp").Value)
id, _ := constant.Int64Val(gvar.toFieldNamed("goid").Value)
gopc, _ := constant.Int64Val(gvar.toFieldNamed("gopc").Value)
waitReason := constant.StringVal(gvar.toFieldNamed("waitreason").Value)
d := gvar.toFieldNamed("_defer")
deferPC := int64(0)
fnvar := d.toFieldNamed("fn")
if fnvar != nil {
fnvalvar := fnvar.toFieldNamed("fn")
deferPC, _ = constant.Int64Val(fnvalvar.Value)
}
status, _ := constant.Int64Val(gvar.toFieldNamed("atomicstatus").Value)
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f, l, fn := gvar.dbp.goSymTable.PCToLine(uint64(pc))
g := &G{
ID: int(id),
GoPC: uint64(gopc),
PC: uint64(pc),
SP: uint64(sp),
WaitReason: waitReason,
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DeferPC: uint64(deferPC),
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Status: uint64(status),
CurrentLoc: Location{PC: uint64(pc), File: f, Line: l, Fn: fn},
dbp: gvar.dbp,
}
return g, nil
}
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func (v *Variable) toFieldNamed(name string) *Variable {
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v, err := v.structMember(name)
if err != nil {
return nil
}
v.loadValue(loadFullValue)
if v.Unreadable != nil {
return nil
}
return v
}
// From $GOROOT/src/runtime/traceback.go:597
// isExportedRuntime reports whether name is an exported runtime function.
// It is only for runtime functions, so ASCII A-Z is fine.
func isExportedRuntime(name string) bool {
const n = len("runtime.")
return len(name) > n && name[:n] == "runtime." && 'A' <= name[n] && name[n] <= 'Z'
}
// UserCurrent returns the location the users code is at,
// or was at before entering a runtime function.
func (g *G) UserCurrent() Location {
it, err := g.stackIterator()
if err != nil {
return g.CurrentLoc
}
for it.Next() {
frame := it.Frame()
if frame.Call.Fn != nil {
name := frame.Call.Fn.Name
if (strings.Index(name, ".") >= 0) && (!strings.HasPrefix(name, "runtime.") || isExportedRuntime(name)) {
return frame.Call
}
}
}
return g.CurrentLoc
}
// Go returns the location of the 'go' statement
// that spawned this goroutine.
func (g *G) Go() Location {
f, l, fn := g.dbp.goSymTable.PCToLine(g.GoPC)
return Location{PC: g.GoPC, File: f, Line: l, Fn: fn}
}
// EvalVariable returns the value of the given expression (backwards compatibility).
func (scope *EvalScope) EvalVariable(name string, cfg LoadConfig) (*Variable, error) {
return scope.EvalExpression(name, cfg)
}
// SetVariable sets the value of the named variable
func (scope *EvalScope) SetVariable(name, value string) error {
t, err := parser.ParseExpr(name)
if err != nil {
return err
}
xv, err := scope.evalAST(t)
if err != nil {
return err
}
if xv.Addr == 0 {
return fmt.Errorf("Can not assign to \"%s\"", name)
}
if xv.Unreadable != nil {
return fmt.Errorf("Expression \"%s\" is unreadable: %v", name, xv.Unreadable)
}
t, err = parser.ParseExpr(value)
if err != nil {
return err
}
yv, err := scope.evalAST(t)
if err != nil {
return err
}
yv.loadValue(loadSingleValue)
if err := yv.isType(xv.RealType, xv.Kind); err != nil {
return err
}
if yv.Unreadable != nil {
return fmt.Errorf("Expression \"%s\" is unreadable: %v", value, yv.Unreadable)
}
return xv.setValue(yv)
}
func (scope *EvalScope) extractVariableFromEntry(entry *dwarf.Entry, cfg LoadConfig) (*Variable, error) {
rdr := scope.DwarfReader()
v, err := scope.extractVarInfoFromEntry(entry, rdr)
if err != nil {
return nil, err
}
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v.loadValue(cfg)
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return v, nil
}
func (scope *EvalScope) extractVarInfo(varName string) (*Variable, error) {
reader := scope.DwarfReader()
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_, err := reader.SeekToFunction(scope.PC)
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if err != nil {
return nil, err
}
for entry, err := reader.NextScopeVariable(); entry != nil; entry, err = reader.NextScopeVariable() {
if err != nil {
return nil, err
}
n, ok := entry.Val(dwarf.AttrName).(string)
if !ok {
continue
}
if n == varName {
return scope.extractVarInfoFromEntry(entry, reader)
}
}
return nil, fmt.Errorf("could not find symbol value for %s", varName)
}
// LocalVariables returns all local variables from the current function scope.
func (scope *EvalScope) LocalVariables(cfg LoadConfig) ([]*Variable, error) {
return scope.variablesByTag(dwarf.TagVariable, cfg)
}
// FunctionArguments returns the name, value, and type of all current function arguments.
func (scope *EvalScope) FunctionArguments(cfg LoadConfig) ([]*Variable, error) {
return scope.variablesByTag(dwarf.TagFormalParameter, cfg)
}
// PackageVariables returns the name, value, and type of all package variables in the application.
func (scope *EvalScope) PackageVariables(cfg LoadConfig) ([]*Variable, error) {
var vars []*Variable
reader := scope.DwarfReader()
var utypoff dwarf.Offset
utypentry, err := reader.SeekToTypeNamed("<unspecified>")
if err == nil {
utypoff = utypentry.Offset
}
for entry, err := reader.NextPackageVariable(); entry != nil; entry, err = reader.NextPackageVariable() {
if err != nil {
return nil, err
}
if typoff, ok := entry.Val(dwarf.AttrType).(dwarf.Offset); !ok || typoff == utypoff {
continue
}
// Ignore errors trying to extract values
val, err := scope.extractVariableFromEntry(entry, cfg)
if err != nil {
continue
}
vars = append(vars, val)
}
return vars, nil
}
// EvalPackageVariable will evaluate the package level variable
// specified by 'name'.
func (dbp *Process) EvalPackageVariable(name string, cfg LoadConfig) (*Variable, error) {
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scope := &EvalScope{Thread: dbp.CurrentThread, PC: 0, CFA: 0}
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v, err := scope.packageVarAddr(name)
if err != nil {
return nil, err
}
v.loadValue(cfg)
return v, nil
}
func (scope *EvalScope) packageVarAddr(name string) (*Variable, error) {
reader := scope.DwarfReader()
for entry, err := reader.NextPackageVariable(); entry != nil; entry, err = reader.NextPackageVariable() {
if err != nil {
return nil, err
}
n, ok := entry.Val(dwarf.AttrName).(string)
if !ok {
continue
}
if n == name {
return scope.extractVarInfoFromEntry(entry, reader)
}
}
return nil, fmt.Errorf("could not find symbol value for %s", name)
}
func (v *Variable) structMember(memberName string) (*Variable, error) {
if v.Unreadable != nil {
return v.clone(), nil
}
structVar := v.maybeDereference()
structVar.Name = v.Name
if structVar.Unreadable != nil {
return structVar, nil
}
switch t := structVar.RealType.(type) {
case *dwarf.StructType:
for _, field := range t.Field {
if field.Name != memberName {
continue
}
return structVar.toField(field)
}
// Check for embedded field only if field was
// not a regular struct member
for _, field := range t.Field {
isEmbeddedStructMember :=
(field.Type.Common().Name == field.Name) ||
(len(field.Name) > 1 &&
field.Name[0] == '*' &&
field.Type.Common().Name[1:] == field.Name[1:])
if !isEmbeddedStructMember {
continue
}
// Check for embedded field referenced by type name
parts := strings.Split(field.Name, ".")
if len(parts) > 1 && parts[1] == memberName {
embeddedVar, err := structVar.toField(field)
if err != nil {
return nil, err
}
return embeddedVar, nil
}
// Recursively check for promoted fields on the embedded field
embeddedVar, err := structVar.toField(field)
if err != nil {
return nil, err
}
embeddedVar.Name = structVar.Name
embeddedField, err := embeddedVar.structMember(memberName)
if embeddedField != nil {
return embeddedField, nil
}
}
return nil, fmt.Errorf("%s has no member %s", v.Name, memberName)
default:
if v.Name == "" {
return nil, fmt.Errorf("type %s is not a struct", structVar.TypeString())
}
return nil, fmt.Errorf("%s (type %s) is not a struct", v.Name, structVar.TypeString())
}
}
// Extracts the name and type of a variable from a dwarf entry
// then executes the instructions given in the DW_AT_location attribute to grab the variable's address
func (scope *EvalScope) extractVarInfoFromEntry(entry *dwarf.Entry, rdr *reader.Reader) (*Variable, error) {
if entry == nil {
return nil, fmt.Errorf("invalid entry")
}
if entry.Tag != dwarf.TagFormalParameter && entry.Tag != dwarf.TagVariable {
return nil, fmt.Errorf("invalid entry tag, only supports FormalParameter and Variable, got %s", entry.Tag.String())
}
n, ok := entry.Val(dwarf.AttrName).(string)
if !ok {
return nil, fmt.Errorf("type assertion failed")
}
offset, ok := entry.Val(dwarf.AttrType).(dwarf.Offset)
if !ok {
return nil, fmt.Errorf("type assertion failed")
}
t, err := scope.Type(offset)
if err != nil {
return nil, err
}
instructions, ok := entry.Val(dwarf.AttrLocation).([]byte)
if !ok {
return nil, fmt.Errorf("type assertion failed")
}
addr, err := op.ExecuteStackProgram(scope.CFA, instructions)
if err != nil {
return nil, err
}
return scope.newVariable(n, uintptr(addr), t), nil
}
// If v is a pointer a new variable is returned containing the value pointed by v.
func (v *Variable) maybeDereference() *Variable {
if v.Unreadable != nil {
return v
}
switch t := v.RealType.(type) {
case *dwarf.PtrType:
ptrval, err := readUintRaw(v.mem, uintptr(v.Addr), t.ByteSize)
r := v.newVariable("", uintptr(ptrval), t.Type)
if err != nil {
r.Unreadable = err
}
return r
default:
return v
}
}
// Extracts the value of the variable at the given address.
func (v *Variable) loadValue(cfg LoadConfig) {
v.loadValueInternal(0, cfg)
}
func (v *Variable) loadValueInternal(recurseLevel int, cfg LoadConfig) {
if v.Unreadable != nil || v.loaded || (v.Addr == 0 && v.Base == 0) {
return
}
v.loaded = true
switch v.Kind {
case reflect.Ptr, reflect.UnsafePointer:
v.Len = 1
v.Children = []Variable{*v.maybeDereference()}
if cfg.FollowPointers {
// Don't increase the recursion level when dereferencing pointers
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v.Children[0].loadValueInternal(recurseLevel, cfg)
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} else {
v.Children[0].OnlyAddr = true
}
case reflect.Chan:
sv := v.clone()
sv.RealType = resolveTypedef(&(sv.RealType.(*dwarf.ChanType).TypedefType))
sv = sv.maybeDereference()
sv.loadValueInternal(0, loadFullValue)
v.Children = sv.Children
v.Len = sv.Len
v.Base = sv.Addr
case reflect.Map:
if recurseLevel <= cfg.MaxVariableRecurse {
v.loadMap(recurseLevel, cfg)
}
case reflect.String:
var val string
val, v.Unreadable = readStringValue(v.mem, v.Base, v.Len, cfg)
v.Value = constant.MakeString(val)
case reflect.Slice, reflect.Array:
v.loadArrayValues(recurseLevel, cfg)
case reflect.Struct:
v.mem = cacheMemory(v.mem, v.Addr, int(v.RealType.Size()))
t := v.RealType.(*dwarf.StructType)
v.Len = int64(len(t.Field))
// Recursively call extractValue to grab
// the value of all the members of the struct.
if recurseLevel <= cfg.MaxVariableRecurse {
v.Children = make([]Variable, 0, len(t.Field))
for i, field := range t.Field {
if cfg.MaxStructFields >= 0 && len(v.Children) >= cfg.MaxStructFields {
break
}
f, _ := v.toField(field)
v.Children = append(v.Children, *f)
v.Children[i].Name = field.Name
v.Children[i].loadValueInternal(recurseLevel+1, cfg)
}
}
case reflect.Interface:
v.loadInterface(recurseLevel, true, cfg)
case reflect.Complex64, reflect.Complex128:
v.readComplex(v.RealType.(*dwarf.ComplexType).ByteSize)
case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
var val int64
val, v.Unreadable = readIntRaw(v.mem, v.Addr, v.RealType.(*dwarf.IntType).ByteSize)
v.Value = constant.MakeInt64(val)
case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
var val uint64
val, v.Unreadable = readUintRaw(v.mem, v.Addr, v.RealType.(*dwarf.UintType).ByteSize)
v.Value = constant.MakeUint64(val)
case reflect.Bool:
val, err := v.mem.readMemory(v.Addr, 1)
v.Unreadable = err
if err == nil {
v.Value = constant.MakeBool(val[0] != 0)
}
case reflect.Float32, reflect.Float64:
var val float64
val, v.Unreadable = v.readFloatRaw(v.RealType.(*dwarf.FloatType).ByteSize)
v.Value = constant.MakeFloat64(val)
case reflect.Func:
v.readFunctionPtr()
default:
v.Unreadable = fmt.Errorf("unknown or unsupported kind: \"%s\"", v.Kind.String())
}
}
func (v *Variable) setValue(y *Variable) error {
var err error
switch v.Kind {
case reflect.Float32, reflect.Float64:
f, _ := constant.Float64Val(y.Value)
err = v.writeFloatRaw(f, v.RealType.Size())
case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
n, _ := constant.Int64Val(y.Value)
err = v.writeUint(uint64(n), v.RealType.Size())
case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
n, _ := constant.Uint64Val(y.Value)
err = v.writeUint(n, v.RealType.Size())
case reflect.Bool:
err = v.writeBool(constant.BoolVal(y.Value))
case reflect.Complex64, reflect.Complex128:
real, _ := constant.Float64Val(constant.Real(y.Value))
imag, _ := constant.Float64Val(constant.Imag(y.Value))
err = v.writeComplex(real, imag, v.RealType.Size())
default:
if t, isptr := v.RealType.(*dwarf.PtrType); isptr {
err = v.writeUint(uint64(y.Children[0].Addr), int64(t.ByteSize))
} else {
return fmt.Errorf("can not set variables of type %s (not implemented)", v.Kind.String())
}
}
return err
}
func readStringInfo(mem memoryReadWriter, arch Arch, addr uintptr) (uintptr, int64, error) {
// string data structure is always two ptrs in size. Addr, followed by len
// http://research.swtch.com/godata
mem = cacheMemory(mem, addr, arch.PtrSize()*2)
// read len
val, err := mem.readMemory(addr+uintptr(arch.PtrSize()), arch.PtrSize())
if err != nil {
return 0, 0, fmt.Errorf("could not read string len %s", err)
}
strlen := int64(binary.LittleEndian.Uint64(val))
if strlen < 0 {
return 0, 0, fmt.Errorf("invalid length: %d", strlen)
}
// read addr
val, err = mem.readMemory(addr, arch.PtrSize())
if err != nil {
return 0, 0, fmt.Errorf("could not read string pointer %s", err)
}
addr = uintptr(binary.LittleEndian.Uint64(val))
if addr == 0 {
return 0, 0, nil
}
return addr, strlen, nil
}
func readStringValue(mem memoryReadWriter, addr uintptr, strlen int64, cfg LoadConfig) (string, error) {
count := strlen
if count > int64(cfg.MaxStringLen) {
count = int64(cfg.MaxStringLen)
}
val, err := mem.readMemory(addr, int(count))
if err != nil {
return "", fmt.Errorf("could not read string at %#v due to %s", addr, err)
}
retstr := *(*string)(unsafe.Pointer(&val))
return retstr, nil
}
func (v *Variable) loadSliceInfo(t *dwarf.SliceType) {
v.mem = cacheMemory(v.mem, v.Addr, int(t.Size()))
var err error
for _, f := range t.Field {
switch f.Name {
case "array":
var base uint64
base, err = readUintRaw(v.mem, uintptr(int64(v.Addr)+f.ByteOffset), f.Type.Size())
if err == nil {
v.Base = uintptr(base)
// Dereference array type to get value type
ptrType, ok := f.Type.(*dwarf.PtrType)
if !ok {
v.Unreadable = fmt.Errorf("Invalid type %s in slice array", f.Type)
return
}
v.fieldType = ptrType.Type
}
case "len":
lstrAddr, _ := v.toField(f)
lstrAddr.loadValue(loadSingleValue)
err = lstrAddr.Unreadable
if err == nil {
v.Len, _ = constant.Int64Val(lstrAddr.Value)
}
case "cap":
cstrAddr, _ := v.toField(f)
cstrAddr.loadValue(loadSingleValue)
err = cstrAddr.Unreadable
if err == nil {
v.Cap, _ = constant.Int64Val(cstrAddr.Value)
}
}
if err != nil {
v.Unreadable = err
return
}
}
v.stride = v.fieldType.Size()
if t, ok := v.fieldType.(*dwarf.PtrType); ok {
v.stride = t.ByteSize
}
return
}
func (v *Variable) loadArrayValues(recurseLevel int, cfg LoadConfig) {
if v.Unreadable != nil {
return
}
if v.Len < 0 {
v.Unreadable = errors.New("Negative array length")
return
}
count := v.Len
// Cap number of elements
if count > int64(cfg.MaxArrayValues) {
count = int64(cfg.MaxArrayValues)
}
if v.stride < maxArrayStridePrefetch {
v.mem = cacheMemory(v.mem, v.Base, int(v.stride*count))
}
errcount := 0
for i := int64(0); i < count; i++ {
fieldvar := v.newVariable("", uintptr(int64(v.Base)+(i*v.stride)), v.fieldType)
fieldvar.loadValueInternal(recurseLevel+1, cfg)
if fieldvar.Unreadable != nil {
errcount++
}
v.Children = append(v.Children, *fieldvar)
if errcount > maxErrCount {
break
}
}
}
func (v *Variable) readComplex(size int64) {
var fs int64
switch size {
case 8:
fs = 4
case 16:
fs = 8
default:
v.Unreadable = fmt.Errorf("invalid size (%d) for complex type", size)
return
}
ftyp := &dwarf.FloatType{BasicType: dwarf.BasicType{CommonType: dwarf.CommonType{ByteSize: fs, Name: fmt.Sprintf("float%d", fs)}, BitSize: fs * 8, BitOffset: 0}}
realvar := v.newVariable("real", v.Addr, ftyp)
imagvar := v.newVariable("imaginary", v.Addr+uintptr(fs), ftyp)
realvar.loadValue(loadSingleValue)
imagvar.loadValue(loadSingleValue)
v.Value = constant.BinaryOp(realvar.Value, token.ADD, constant.MakeImag(imagvar.Value))
}
func (v *Variable) writeComplex(real, imag float64, size int64) error {
err := v.writeFloatRaw(real, int64(size/2))
if err != nil {
return err
}
imagaddr := *v
imagaddr.Addr += uintptr(size / 2)
return imagaddr.writeFloatRaw(imag, int64(size/2))
}
func readIntRaw(mem memoryReadWriter, addr uintptr, size int64) (int64, error) {
var n int64
val, err := mem.readMemory(addr, int(size))
if err != nil {
return 0, err
}
switch size {
case 1:
n = int64(int8(val[0]))
case 2:
n = int64(int16(binary.LittleEndian.Uint16(val)))
case 4:
n = int64(int32(binary.LittleEndian.Uint32(val)))
case 8:
n = int64(binary.LittleEndian.Uint64(val))
}
return n, nil
}
func (v *Variable) writeUint(value uint64, size int64) error {
val := make([]byte, size)
switch size {
case 1:
val[0] = byte(value)
case 2:
binary.LittleEndian.PutUint16(val, uint16(value))
case 4:
binary.LittleEndian.PutUint32(val, uint32(value))
case 8:
binary.LittleEndian.PutUint64(val, uint64(value))
}
_, err := v.mem.writeMemory(v.Addr, val)
return err
}
func readUintRaw(mem memoryReadWriter, addr uintptr, size int64) (uint64, error) {
var n uint64
val, err := mem.readMemory(addr, int(size))
if err != nil {
return 0, err
}
switch size {
case 1:
n = uint64(val[0])
case 2:
n = uint64(binary.LittleEndian.Uint16(val))
case 4:
n = uint64(binary.LittleEndian.Uint32(val))
case 8:
n = uint64(binary.LittleEndian.Uint64(val))
}
return n, nil
}
func (v *Variable) readFloatRaw(size int64) (float64, error) {
val, err := v.mem.readMemory(v.Addr, int(size))
if err != nil {
return 0.0, err
}
buf := bytes.NewBuffer(val)
switch size {
case 4:
n := float32(0)
binary.Read(buf, binary.LittleEndian, &n)
return float64(n), nil
case 8:
n := float64(0)
binary.Read(buf, binary.LittleEndian, &n)
return n, nil
}
return 0.0, fmt.Errorf("could not read float")
}
func (v *Variable) writeFloatRaw(f float64, size int64) error {
buf := bytes.NewBuffer(make([]byte, 0, size))
switch size {
case 4:
n := float32(f)
binary.Write(buf, binary.LittleEndian, n)
case 8:
n := float64(f)
binary.Write(buf, binary.LittleEndian, n)
}
_, err := v.mem.writeMemory(v.Addr, buf.Bytes())
return err
}
func (v *Variable) writeBool(value bool) error {
val := []byte{0}
val[0] = *(*byte)(unsafe.Pointer(&value))
_, err := v.mem.writeMemory(v.Addr, val)
return err
}
func (v *Variable) readFunctionPtr() {
val, err := v.mem.readMemory(v.Addr, v.dbp.arch.PtrSize())
if err != nil {
v.Unreadable = err
return
}
// dereference pointer to find function pc
fnaddr := uintptr(binary.LittleEndian.Uint64(val))
if fnaddr == 0 {
v.Base = 0
v.Value = constant.MakeString("")
return
}
val, err = v.mem.readMemory(fnaddr, v.dbp.arch.PtrSize())
if err != nil {
v.Unreadable = err
return
}
v.Base = uintptr(binary.LittleEndian.Uint64(val))
fn := v.dbp.goSymTable.PCToFunc(uint64(v.Base))
if fn == nil {
v.Unreadable = fmt.Errorf("could not find function for %#v", v.Base)
return
}
v.Value = constant.MakeString(fn.Name)
}
func (v *Variable) loadMap(recurseLevel int, cfg LoadConfig) {
it := v.mapIterator()
if it == nil {
return
}
for skip := 0; skip < v.mapSkip; skip++ {
if ok := it.next(); !ok {
v.Unreadable = fmt.Errorf("map index out of bounds")
return
}
}
count := 0
errcount := 0
for it.next() {
if count >= cfg.MaxArrayValues {
break
}
key := it.key()
val := it.value()
key.loadValueInternal(recurseLevel+1, cfg)
val.loadValueInternal(recurseLevel+1, cfg)
if key.Unreadable != nil || val.Unreadable != nil {
errcount++
}
v.Children = append(v.Children, *key)
v.Children = append(v.Children, *val)
count++
if errcount > maxErrCount {
break
}
}
}
type mapIterator struct {
v *Variable
numbuckets uint64
oldmask uint64
buckets *Variable
oldbuckets *Variable
b *Variable
bidx uint64
tophashes *Variable
keys *Variable
values *Variable
overflow *Variable
idx int64
}
// Code derived from go/src/runtime/hashmap.go
func (v *Variable) mapIterator() *mapIterator {
sv := v.clone()
sv.RealType = resolveTypedef(&(sv.RealType.(*dwarf.MapType).TypedefType))
sv = sv.maybeDereference()
v.Base = sv.Addr
maptype, ok := sv.RealType.(*dwarf.StructType)
if !ok {
v.Unreadable = fmt.Errorf("wrong real type for map")
return nil
}
it := &mapIterator{v: v, bidx: 0, b: nil, idx: 0}
if sv.Addr == 0 {
it.numbuckets = 0
return it
}
v.mem = cacheMemory(v.mem, v.Base, int(v.RealType.Size()))
for _, f := range maptype.Field {
var err error
field, _ := sv.toField(f)
switch f.Name {
case "count":
v.Len, err = field.asInt()
case "B":
var b uint64
b, err = field.asUint()
it.numbuckets = 1 << b
it.oldmask = (1 << (b - 1)) - 1
case "buckets":
it.buckets = field.maybeDereference()
case "oldbuckets":
it.oldbuckets = field.maybeDereference()
}
if err != nil {
v.Unreadable = err
return nil
}
}
return it
}
func (it *mapIterator) nextBucket() bool {
if it.overflow != nil && it.overflow.Addr > 0 {
it.b = it.overflow
} else {
it.b = nil
for it.bidx < it.numbuckets {
it.b = it.buckets.clone()
it.b.Addr += uintptr(uint64(it.buckets.DwarfType.Size()) * it.bidx)
if it.oldbuckets.Addr <= 0 {
break
}
// if oldbuckets is not nil we are iterating through a map that is in
// the middle of a grow.
// if the bucket we are looking at hasn't been filled in we iterate
// instead through its corresponding "oldbucket" (i.e. the bucket the
// elements of this bucket are coming from) but only if this is the first
// of the two buckets being created from the same oldbucket (otherwise we
// would print some keys twice)
oldbidx := it.bidx & it.oldmask
oldb := it.oldbuckets.clone()
oldb.Addr += uintptr(uint64(it.oldbuckets.DwarfType.Size()) * oldbidx)
if mapEvacuated(oldb) {
break
}
if oldbidx == it.bidx {
it.b = oldb
break
}
// oldbucket origin for current bucket has not been evacuated but we have already
// iterated over it so we should just skip it
it.b = nil
it.bidx++
}
if it.b == nil {
return false
}
it.bidx++
}
if it.b.Addr <= 0 {
return false
}
it.b.mem = cacheMemory(it.b.mem, it.b.Addr, int(it.b.RealType.Size()))
it.tophashes = nil
it.keys = nil
it.values = nil
it.overflow = nil
for _, f := range it.b.DwarfType.(*dwarf.StructType).Field {
field, err := it.b.toField(f)
if err != nil {
it.v.Unreadable = err
return false
}
if field.Unreadable != nil {
it.v.Unreadable = field.Unreadable
return false
}
switch f.Name {
case "tophash":
it.tophashes = field
case "keys":
it.keys = field
case "values":
it.values = field
case "overflow":
it.overflow = field.maybeDereference()
}
}
// sanity checks
if it.tophashes == nil || it.keys == nil || it.values == nil {
it.v.Unreadable = fmt.Errorf("malformed map type")
return false
}
if it.tophashes.Kind != reflect.Array || it.keys.Kind != reflect.Array || it.values.Kind != reflect.Array {
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it.v.Unreadable = fmt.Errorf("malformed map type: keys, values or tophash of a bucket is not an array")
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return false
}
if it.tophashes.Len != it.keys.Len || it.tophashes.Len != it.values.Len {
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it.v.Unreadable = fmt.Errorf("malformed map type: inconsistent array length in bucket")
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return false
}
return true
}
func (it *mapIterator) next() bool {
for {
if it.b == nil || it.idx >= it.tophashes.Len {
r := it.nextBucket()
if !r {
return false
}
it.idx = 0
}
tophash, _ := it.tophashes.sliceAccess(int(it.idx))
h, err := tophash.asUint()
if err != nil {
it.v.Unreadable = fmt.Errorf("unreadable tophash: %v", err)
return false
}
it.idx++
if h != hashTophashEmpty {
return true
}
}
}
func (it *mapIterator) key() *Variable {
k, _ := it.keys.sliceAccess(int(it.idx - 1))
return k
}
func (it *mapIterator) value() *Variable {
v, _ := it.values.sliceAccess(int(it.idx - 1))
return v
}
func mapEvacuated(b *Variable) bool {
if b.Addr == 0 {
return true
}
for _, f := range b.DwarfType.(*dwarf.StructType).Field {
if f.Name != "tophash" {
continue
}
tophashes, _ := b.toField(f)
tophash0var, _ := tophashes.sliceAccess(0)
tophash0, err := tophash0var.asUint()
if err != nil {
return true
}
return tophash0 > hashTophashEmpty && tophash0 < hashMinTopHash
}
return true
}
func (v *Variable) loadInterface(recurseLevel int, loadData bool, cfg LoadConfig) {
var _type, typestring, data *Variable
var typ dwarf.Type
var err error
isnil := false
// An interface variable is implemented either by a runtime.iface
// struct or a runtime.eface struct. The difference being that empty
// interfaces (i.e. "interface {}") are represented by runtime.eface
// and non-empty interfaces by runtime.iface.
//
// For both runtime.ifaces and runtime.efaces the data is stored in v.data
//
// The concrete type however is stored in v.tab._type for non-empty
// interfaces and in v._type for empty interfaces.
//
// For nil empty interface variables _type will be nil, for nil
// non-empty interface variables tab will be nil
//
// In either case the _type field is a pointer to a runtime._type struct.
//
// Before go1.7 _type used to have a field named 'string' containing
// the name of the type. Since go1.7 the field has been replaced by a
// str field that contains an offset in the module data, the concrete
// type must be calculated using the str address along with the value
// of v.tab._type (v._type for empty interfaces).
//
// The following code works for both runtime.iface and runtime.eface
// and sets the go17 flag when the 'string' field can not be found
// but the str field was found
go17 := false
v.mem = cacheMemory(v.mem, v.Addr, int(v.RealType.Size()))
ityp := resolveTypedef(&v.RealType.(*dwarf.InterfaceType).TypedefType).(*dwarf.StructType)
for _, f := range ityp.Field {
switch f.Name {
case "tab": // for runtime.iface
tab, _ := v.toField(f)
tab = tab.maybeDereference()
isnil = tab.Addr == 0
if !isnil {
_type, err = tab.structMember("_type")
if err != nil {
v.Unreadable = fmt.Errorf("invalid interface type: %v", err)
return
}
typestring, err = _type.structMember("_string")
if err == nil {
typestring = typestring.maybeDereference()
} else {
go17 = true
}
}
case "_type": // for runtime.eface
_type, _ = v.toField(f)
_type = _type.maybeDereference()
isnil = _type.Addr == 0
if !isnil {
typestring, err = _type.structMember("_string")
if err == nil {
typestring = typestring.maybeDereference()
} else {
go17 = true
}
}
case "data":
data, _ = v.toField(f)
}
}
if isnil {
// interface to nil
data = data.maybeDereference()
v.Children = []Variable{*data}
if loadData {
v.Children[0].loadValueInternal(recurseLevel, cfg)
}
return
}
if data == nil {
v.Unreadable = fmt.Errorf("invalid interface type")
return
}
var kind int64
if go17 {
// No 'string' field use 'str' and 'runtime.firstmoduledata' to
// find out what the concrete type is
_type = _type.maybeDereference()
var typename string
typename, kind, err = nameOfRuntimeType(_type)
if err != nil {
v.Unreadable = fmt.Errorf("invalid interface type: %v", err)
return
}
typ, err = v.dbp.findType(typename)
if err != nil {
v.Unreadable = fmt.Errorf("interface type %q not found for %#x: %v", typename, data.Addr, err)
return
}
} else {
if typestring == nil || typestring.Addr == 0 || typestring.Kind != reflect.String {
v.Unreadable = fmt.Errorf("invalid interface type")
return
}
typestring.loadValue(LoadConfig{false, 0, 512, 0, 0})
if typestring.Unreadable != nil {
v.Unreadable = fmt.Errorf("invalid interface type: %v", typestring.Unreadable)
return
}
typename := constant.StringVal(typestring.Value)
t, err := parser.ParseExpr(typename)
if err != nil {
v.Unreadable = fmt.Errorf("invalid interface type, unparsable data type: %v", err)
return
}
typ, err = v.dbp.findTypeExpr(t)
if err != nil {
v.Unreadable = fmt.Errorf("interface type %q not found for %#x: %v", typename, data.Addr, err)
return
}
}
if kind&kindDirectIface == 0 {
realtyp := resolveTypedef(typ)
if _, isptr := realtyp.(*dwarf.PtrType); !isptr {
typ = v.dbp.pointerTo(typ)
}
}
data = data.newVariable("data", data.Addr, typ)
v.Children = []Variable{*data}
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if loadData {
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v.Children[0].loadValueInternal(recurseLevel, cfg)
} else {
v.Children[0].OnlyAddr = true
}
return
}
// Fetches all variables of a specific type in the current function scope
func (scope *EvalScope) variablesByTag(tag dwarf.Tag, cfg LoadConfig) ([]*Variable, error) {
reader := scope.DwarfReader()
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_, err := reader.SeekToFunction(scope.PC)
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if err != nil {
return nil, err
}
var vars []*Variable
for entry, err := reader.NextScopeVariable(); entry != nil; entry, err = reader.NextScopeVariable() {
if err != nil {
return nil, err
}
if entry.Tag == tag {
val, err := scope.extractVariableFromEntry(entry, cfg)
if err != nil {
// skip variables that we can't parse yet
continue
}
vars = append(vars, val)
}
}
return vars, nil
}