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proc: fix embedded field search (#2320)

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Both structMember and findMethod implemented a depth-first search in
embedded fields but the Go specification requires a breadth-first
search. They also allowed promotion of fields in the concrete type of
embedded interfaces even though this is not allowed by Go.
Furthermore they both lacked protection from infinite recursion
when a type embeds itself and the user requests a non-existent field.

Fixes #2316
This commit is contained in:
Alessandro Arzilli
2021-01-29 18:25:31 +01:00
committed by GitHub
parent dceffacb89
commit f19d5e5c13
5 changed files with 162 additions and 102 deletions
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40
_fixtures/testvariables2.go
View File

@ -106,6 +106,38 @@ type List struct {
Next *List
}
type T struct {
F string
}
type W1 struct {
T
}
func (*W1) M() {}
type I interface{ M() }
type W2 struct {
W1
T
}
type W3 struct {
I
T
}
type W4 struct {
I
}
type W5 struct {
*W5
}
var _ I = (*W2)(nil)
func main() {
i1 := 1
i2 := 2
@ -312,6 +344,12 @@ func main() {
ll := &List{0, &List{1, &List{2, &List{3, &List{4, nil}}}}}
unread := (*int)(unsafe.Pointer(uintptr(12345)))
w2 := &W2{W1{T{"T-inside-W1"}}, T{"T-inside-W2"}}
w3 := &W3{&W1{T{"T-inside-W1"}}, T{"T-inside-W3"}}
w4 := &W4{&W1{T{"T-inside-W1"}}}
w5 := &W5{nil}
w5.W5 = w5
var amb1 = 1
runtime.Breakpoint()
for amb1 := 0; amb1 < 10; amb1++ {
@ -319,5 +357,5 @@ func main() {
}
runtime.Breakpoint()
fmt.Println(i1, i2, i3, p1, amb1, s1, s3, a0, a1, p2, p3, s2, as1, str1, f1, fn1, fn2, nilslice, nilptr, ch1, chnil, m1, mnil, m2, m3, m4, upnil, up1, i4, i5, i6, err1, err2, errnil, iface1, iface2, ifacenil, arr1, parr, cpx1, const1, iface3, iface4, recursive1, recursive1.x, iface5, iface2fn1, iface2fn2, bencharr, benchparr, mapinf, mainMenu, b, b2, sd, anonstruct1, anonstruct2, anoniface1, anonfunc, mapanonstruct1, ifacearr, efacearr, ni8, ni16, ni32, ni64, pinf, ninf, nan, zsvmap, zsslice, zsvar, tm, errtypednil, emptyslice, emptymap, byteslice, runeslice, bytearray, runearray, longstr, nilstruct, as2, as2.NonPointerRecieverMethod, s4, iface2map, issue1578, ll, unread)
fmt.Println(i1, i2, i3, p1, amb1, s1, s3, a0, a1, p2, p3, s2, as1, str1, f1, fn1, fn2, nilslice, nilptr, ch1, chnil, m1, mnil, m2, m3, m4, upnil, up1, i4, i5, i6, err1, err2, errnil, iface1, iface2, ifacenil, arr1, parr, cpx1, const1, iface3, iface4, recursive1, recursive1.x, iface5, iface2fn1, iface2fn2, bencharr, benchparr, mapinf, mainMenu, b, b2, sd, anonstruct1, anonstruct2, anoniface1, anonfunc, mapanonstruct1, ifacearr, efacearr, ni8, ni16, ni32, ni64, pinf, ninf, nan, zsvmap, zsslice, zsvar, tm, errtypednil, emptyslice, emptymap, byteslice, runeslice, bytearray, runearray, longstr, nilstruct, as2, as2.NonPointerRecieverMethod, s4, iface2map, issue1578, ll, unread, w2, w3, w4, w5)
}

24
pkg/proc/eval.go
View File

@ -1963,6 +1963,17 @@ func (v *Variable) findMethod(mname string) (*Variable, error) {
return v.Children[0].findMethod(mname)
}
queue := []*Variable{v}
seen := map[string]struct{}{}
for len(queue) > 0 {
v := queue[0]
queue = append(queue[:0], queue[1:]...)
if _, isseen := seen[v.RealType.String()]; isseen {
continue
}
seen[v.RealType.String()] = struct{}{}
typ := v.DwarfType
ptyp, isptr := typ.(*godwarf.PtrType)
if isptr {
@ -1973,7 +1984,7 @@ func (v *Variable) findMethod(mname string) (*Variable, error) {
dot := strings.LastIndex(typePath, ".")
if dot < 0 {
// probably just a C type
return nil, nil
continue
}
pkg := typePath[:dot]
@ -2004,10 +2015,8 @@ func (v *Variable) findMethod(mname string) (*Variable, error) {
}
return r, nil
}
return v.tryFindMethodInEmbeddedFields(mname)
}
func (v *Variable) tryFindMethodInEmbeddedFields(mname string) (*Variable, error) {
// queue embedded fields for search
structVar := v.maybeDereference()
structVar.Name = v.Name
if structVar.Unreadable != nil {
@ -2017,19 +2026,16 @@ func (v *Variable) tryFindMethodInEmbeddedFields(mname string) (*Variable, error
case *godwarf.StructType:
for _, field := range t.Field {
if field.Embedded {
// Recursively check for promoted fields on the embedded field
embeddedVar, err := structVar.toField(field)
if err != nil {
return nil, err
}
if embeddedMethod, err := embeddedVar.findMethod(mname); err != nil {
return nil, err
} else if embeddedMethod != nil {
return embeddedMethod, nil
queue = append(queue, embeddedVar)
}
}
}
}
return nil, nil
}

48
pkg/proc/variables.go
View File

@ -1060,6 +1060,19 @@ func (v *Variable) structMember(memberName string) (*Variable, error) {
v = &v.Children[0]
}
}
queue := []*Variable{v}
seen := map[string]struct{}{} // prevent infinite loops
first := true
for len(queue) > 0 {
v := queue[0]
queue = append(queue[:0], queue[1:]...)
if _, isseen := seen[v.RealType.String()]; isseen {
continue
}
seen[v.RealType.String()] = struct{}{}
structVar := v.maybeDereference()
structVar.Name = v.Name
if structVar.Unreadable != nil {
@ -1069,14 +1082,9 @@ func (v *Variable) structMember(memberName string) (*Variable, error) {
switch t := structVar.RealType.(type) {
case *godwarf.StructType:
for _, field := range t.Field {
if field.Name != memberName {
continue
}
if field.Name == memberName {
return structVar.toField(field)
}
// Check for embedded field only if field was
// not a regular struct member
for _, field := range t.Field {
isEmbeddedStructMember :=
field.Embedded ||
(field.Type.Common().Name == field.Name) ||
@ -1086,34 +1094,28 @@ func (v *Variable) structMember(memberName string) (*Variable, error) {
if !isEmbeddedStructMember {
continue
}
embeddedVar, err := structVar.toField(field)
if err != nil {
return nil, err
}
// 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, _ := embeddedVar.structMember(memberName)
if embeddedField != nil {
return embeddedField, nil
queue = append(queue, embeddedVar)
}
}
return nil, fmt.Errorf("%s has no member %s", vname, memberName)
default:
if v.Name == "" {
return nil, fmt.Errorf("type %s is not a struct", structVar.TypeString())
}
if first {
return nil, fmt.Errorf("%s (type %s) is not a struct", vname, structVar.TypeString())
}
}
first = false
}
return nil, fmt.Errorf("%s has no member %s", vname, memberName)
}
func readVarEntry(entry *godwarf.Tree, image *Image) (name string, typ godwarf.Type, err error) {
name, ok := entry.Val(dwarf.AttrName).(string)

4
service/dap/server_test.go
View File

@ -1026,7 +1026,7 @@ func TestScopesAndVariablesRequests2(t *testing.T) {
execute: func() {
client.StackTraceRequest(1, 0, 20)
stack := client.ExpectStackTraceResponse(t)
expectStackFrames(t, stack, "main.main", 317, 1000, 3, 3)
expectStackFrames(t, stack, "main.main", -1, 1000, 3, 3)
client.ScopesRequest(1000)
scopes := client.ExpectScopesResponse(t)
@ -1039,7 +1039,7 @@ func TestScopesAndVariablesRequests2(t *testing.T) {
execute: func() {
client.StackTraceRequest(1, 0, 20)
stack := client.ExpectStackTraceResponse(t)
expectStackFrames(t, stack, "main.main", 322, 1000, 3, 3)
expectStackFrames(t, stack, "main.main", -1, 1000, 3, 3)
client.ScopesRequest(1000)
scopes := client.ExpectScopesResponse(t)

14
service/test/variables_test.go
View File

@ -504,6 +504,20 @@ func TestEmbeddedStruct(t *testing.T) {
{"b.C.s", true, "\"hello\"", "\"hello\"", "string", nil},
{"b.s", true, "\"hello\"", "\"hello\"", "string", nil},
{"b2", true, "main.B {A: main.A {val: 42}, C: *main.C nil, a: main.A {val: 47}, ptr: *main.A nil}", "main.B {A: (*main.A)(0x…", "main.B", nil},
// Issue 2316: field promotion is breadth first and embedded interfaces never get promoted
{"w2.W1.T.F", true, `"T-inside-W1"`, `"T-inside-W1"`, "string", nil},
{"w2.W1.F", true, `"T-inside-W1"`, `"T-inside-W1"`, "string", nil},
{"w2.T.F", true, `"T-inside-W2"`, `"T-inside-W2"`, "string", nil},
{"w2.F", true, `"T-inside-W2"`, `"T-inside-W2"`, "string", nil},
{"w3.I.T.F", false, `"T-inside-W1"`, `"T-inside-W1"`, "string", nil},
{"w3.I.F", false, `"T-inside-W1"`, `"T-inside-W1"`, "string", nil},
{"w3.T.F", true, `"T-inside-W3"`, `"T-inside-W3"`, "string", nil},
{"w3.F", true, `"T-inside-W3"`, `"T-inside-W3"`, "string", nil},
{"w4.I.T.F", false, `"T-inside-W1"`, `"T-inside-W1"`, "string", nil},
{"w4.I.F", false, `"T-inside-W1"`, `"T-inside-W1"`, "string", nil},
{"w4.F", false, ``, ``, "", errors.New("w4 has no member F")},
{"w5.F", false, ``, ``, "", errors.New("w5 has no member F")},
}
assertNoError(p.Continue(), t, "Continue()")