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Copy pathcontext_done.go
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240 lines (232 loc) · 7.23 KB
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Copy pathcontext_done.go
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240 lines (232 loc) · 7.23 KB
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package contracttrace
import (
"go/types"
"strings"
"golang.org/x/tools/go/ssa"
)
func contextAdapterName(method *types.Func) string {
if method == nil {
return ""
}
name := method.Name()
for _, suffix := range []string{"$bound", "$thunk"} {
name = strings.TrimSuffix(name, suffix)
}
return name
}
// contextMethod identifies the standard context interface method by its
// declared object. A same-named method on a concrete context is not enough.
func contextMethod(method *types.Func, name string) bool {
if method == nil || method.Pkg() == nil || method.Pkg().Path() != "context" || method.Name() != name {
return false
}
object, ok := method.Origin().Type().(*types.Signature)
if !ok || object.Recv() == nil {
return false
}
named, ok := method.Pkg().Scope().Lookup("Context").Type().Underlying().(*types.Interface)
if !ok {
return false
}
named.Complete()
for i := 0; i < named.NumMethods(); i++ {
candidate := named.Method(i)
if candidate.Name() == name && candidate.Origin() == method.Origin() {
return true
}
}
return false
}
func contextSelectedMethod(receiverType types.Type, name string) *types.Func {
if receiverType == nil || (name != "Done" && name != "Err") {
return nil
}
selection := types.NewMethodSet(receiverType).Lookup(nil, name)
if selection == nil {
return nil
}
method, ok := selection.Obj().(*types.Func)
if !ok || !contextMethod(method, name) {
return nil
}
return method
}
// contextCallReceiver returns the actual receiver flow for a standard
// context method call, including generated method expressions and bound
// method values. The method projection helper follows only the SSA adapter's
// declared selector path and never falls back to its outer wrapper value.
func (a *flowAnalysis) contextCallReceiver(common *ssa.CallCommon, name string) (flowValue, bool, bool) {
if common == nil {
return emptyFlow(), false, false
}
if common.IsInvoke() {
method := common.Method
if !contextMethod(method, name) {
method = contextSelectedMethod(common.Value.Type(), name)
}
if method == nil || !contextMethod(method, name) {
return emptyFlow(), false, false
}
receiver := a.get(common.Value)
projected, _, status := a.projectMethodExpressionReceiver(receiver, common.Value.Type(), method)
if status == methodReceiverProjectionUnsupported {
projected = unresolvedProjectedReceiver()
}
return projected, true, status == methodReceiverProjectionUnsupported
}
targets := a.targets(common)
result := emptyFlow()
matched, uncertain := false, false
calleeFlow := a.get(common.Value)
uncertain = calleeFlow.functionUnknown || calleeFlow.functionNil || calleeFlow.boundReceiverUnknown
for _, target := range sortedFunctions(targets) {
functionObject, ok := target.Object().(*types.Func)
if !ok || contextAdapterName(functionObject) != name {
uncertain = true
continue
}
declaredMethod := functionObject
declared, ok := declaredMethod.Type().(*types.Signature)
if !ok || declared.Recv() == nil || target.Signature == nil {
uncertain = true
continue
}
callable := target.Signature
if len(common.Args) > callable.Params().Len() {
uncertain = true
continue
}
// A method expression carries the receiver as its first explicit
// argument. A bound method wrapper instead recovers its captured receiver.
if callable.Params().Len() > declared.Params().Len() {
if len(common.Args) == 0 {
uncertain = true
continue
}
receiver := a.get(common.Args[0])
method := contextSelectedMethod(common.Args[0].Type(), name)
if method == nil {
continue
}
matched = true
projected, _, status := a.projectMethodExpressionReceiver(receiver, common.Args[0].Type(), method)
if status == methodReceiverProjectionUnsupported {
projected = unresolvedProjectedReceiver()
uncertain = true
}
a.merge(&result, projected)
continue
}
bound := a.get(common.Value)
receiver, exists := bound.boundReceivers[target]
if !exists {
continue
}
matched = true
for address := range receiver.addresses {
result.addresses[address] = true
}
uncertain = uncertain || receiver.unknown || bound.boundReceiverUnknown || bound.interfaceUnknown || bound.sqlUnknown || bound.functionUnknown || bound.functionNil
}
if !matched {
return emptyFlow(), false, false
}
result.interfaceUnknown = result.interfaceUnknown || uncertain || len(result.addresses) == 0
return result, true, result.interfaceUnknown
}
func (a *flowAnalysis) modelDone(call *ssa.Call, ix *index) {
common := call.Common()
receiver, matched, uncertain := a.contextCallReceiver(common, "Done")
if !matched {
return
}
if a.special == nil {
a.special = map[*ssa.Call][]flowValue{}
}
result := emptyFlow()
result.interfaceUnknown = uncertain || receiver.interfaceUnknown || receiver.boundReceiverUnknown || receiver.sqlUnknown
visited := map[string]bool{}
queue := []string{}
for _, key := range sortedKeys(receiver.addresses) {
if strings.HasPrefix(key, "context:") {
queue = append(queue, key)
} else {
result.interfaceUnknown = true
}
}
resolved := false
for head := 0; head < len(queue); head++ {
key := queue[head]
if visited[key] {
continue
}
visited[key] = true
site, known := a.contextKeys[key]
if !known {
result.interfaceUnknown = true
continue
}
resolved = true
if site.unknown {
result.interfaceUnknown = true
}
if site.needsCancel {
channel := resourceID("channel", "context_done", key)
value := emptyFlow()
value.addresses[channel] = true
a.merge(&result, value)
if a.doneChannels == nil {
a.doneChannels = map[string]string{}
}
a.doneChannels[channel] = key
if ix.funcs[channel] == nil {
ix.funcs[channel] = &function{node: Node{ID: channel, Name: "Done signal for " + site.name, Kind: "channel", Evidence: ix.evidence(site.position)}}
}
}
hasNilDone := false
hasWithValue := false
for _, constructor := range site.names {
hasNilDone = hasNilDone || constructor == "Background" || constructor == "TODO" || constructor == "WithoutCancel"
hasWithValue = hasWithValue || constructor == "WithValue"
}
if hasNilDone {
value := emptyFlow()
value.effects["nil_done:"+key] = true
a.merge(&result, value)
if site.needsCancel || hasWithValue {
result.interfaceUnknown = true
}
}
if hasWithValue {
parents := site.parents["WithValue"]
parentFlow := emptyFlow()
for _, parent := range sortedSSAValues(parents) {
a.merge(&parentFlow, a.get(parent))
}
if site.parentUnknown || site.unknown || parentFlow.interfaceUnknown || parentFlow.sqlUnknown || parentFlow.boundReceiverUnknown || len(parentFlow.addresses) == 0 {
result.interfaceUnknown = true
}
for _, parent := range sortedKeys(parentFlow.addresses) {
if strings.HasPrefix(parent, "context:") {
queue = append(queue, parent)
} else {
result.interfaceUnknown = true
}
}
if site.needsCancel || hasNilDone {
result.interfaceUnknown = true
}
}
}
if !resolved {
result.interfaceUnknown = true
}
a.special[call] = []flowValue{result}
}
func (a *flowAnalysis) doneRelationships(ix *index) {
for _, channel := range sortedKeys(a.doneChannels) {
key := a.doneChannels[channel]
site := a.contextKeys[key]
ix.edge(key, channel, "context_done_signal", "possible", site.position)
}
}