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|
package rule
import (
"go/ast"
"github.com/mgechev/revive/lint"
)
// UnconditionalRecursionRule lints given else constructs.
type UnconditionalRecursionRule struct{}
// Apply applies the rule to given file.
func (r *UnconditionalRecursionRule) Apply(file *lint.File, _ lint.Arguments) []lint.Failure {
var failures []lint.Failure
onFailure := func(failure lint.Failure) {
failures = append(failures, failure)
}
w := lintUnconditionalRecursionRule{onFailure: onFailure}
ast.Walk(w, file.AST)
return failures
}
// Name returns the rule name.
func (r *UnconditionalRecursionRule) Name() string {
return "unconditional-recursion"
}
type funcDesc struct {
reciverID *ast.Ident
id *ast.Ident
}
func (fd *funcDesc) equal(other *funcDesc) bool {
receiversAreEqual := (fd.reciverID == nil && other.reciverID == nil) || fd.reciverID != nil && other.reciverID != nil && fd.reciverID.Name == other.reciverID.Name
idsAreEqual := (fd.id == nil && other.id == nil) || fd.id.Name == other.id.Name
return receiversAreEqual && idsAreEqual
}
type funcStatus struct {
funcDesc *funcDesc
seenConditionalExit bool
}
type lintUnconditionalRecursionRule struct {
onFailure func(lint.Failure)
currentFunc *funcStatus
}
// Visit will traverse the file AST.
// The rule is based in the following algorithm: inside each function body we search for calls to the function itself.
// We do not search inside conditional control structures (if, for, switch, ...) because any recursive call inside them is conditioned
// We do search inside conditional control structures are statements that will take the control out of the function (return, exit, panic)
// If we find conditional control exits, it means the function is NOT unconditionally-recursive
// If we find a recursive call before finding any conditional exit, a failure is generated
// In resume: if we found a recursive call control-dependant from the entry point of the function then we raise a failure.
func (w lintUnconditionalRecursionRule) Visit(node ast.Node) ast.Visitor {
switch n := node.(type) {
case *ast.FuncDecl:
var rec *ast.Ident
switch {
case n.Recv == nil || n.Recv.NumFields() < 1 || len(n.Recv.List[0].Names) < 1:
rec = nil
default:
rec = n.Recv.List[0].Names[0]
}
w.currentFunc = &funcStatus{&funcDesc{rec, n.Name}, false}
case *ast.CallExpr:
var funcID *ast.Ident
var selector *ast.Ident
switch c := n.Fun.(type) {
case *ast.Ident:
selector = nil
funcID = c
case *ast.SelectorExpr:
var ok bool
selector, ok = c.X.(*ast.Ident)
if !ok { // a.b....Foo()
return nil
}
funcID = c.Sel
default:
return w
}
if w.currentFunc != nil && // not in a func body
!w.currentFunc.seenConditionalExit && // there is a conditional exit in the function
w.currentFunc.funcDesc.equal(&funcDesc{selector, funcID}) {
w.onFailure(lint.Failure{
Category: "logic",
Confidence: 1,
Node: n,
Failure: "unconditional recursive call",
})
}
case *ast.IfStmt:
w.updateFuncStatus(n.Body)
w.updateFuncStatus(n.Else)
return nil
case *ast.SelectStmt:
w.updateFuncStatus(n.Body)
return nil
case *ast.RangeStmt:
w.updateFuncStatus(n.Body)
return nil
case *ast.TypeSwitchStmt:
w.updateFuncStatus(n.Body)
return nil
case *ast.SwitchStmt:
w.updateFuncStatus(n.Body)
return nil
case *ast.GoStmt:
for _, a := range n.Call.Args {
ast.Walk(w, a) // check if arguments have a recursive call
}
return nil // recursive async call is not an issue
case *ast.ForStmt:
if n.Cond != nil {
return nil
}
// unconditional loop
return w
}
return w
}
func (w *lintUnconditionalRecursionRule) updateFuncStatus(node ast.Node) {
if node == nil || w.currentFunc == nil || w.currentFunc.seenConditionalExit {
return
}
w.currentFunc.seenConditionalExit = w.hasControlExit(node)
}
var exitFunctions = map[string]map[string]bool{
"os": map[string]bool{"Exit": true},
"syscall": map[string]bool{"Exit": true},
"log": map[string]bool{
"Fatal": true,
"Fatalf": true,
"Fatalln": true,
"Panic": true,
"Panicf": true,
"Panicln": true,
},
}
func (w *lintUnconditionalRecursionRule) hasControlExit(node ast.Node) bool {
// isExit returns true if the given node makes control exit the function
isExit := func(node ast.Node) bool {
switch n := node.(type) {
case *ast.ReturnStmt:
return true
case *ast.CallExpr:
if isIdent(n.Fun, "panic") {
return true
}
se, ok := n.Fun.(*ast.SelectorExpr)
if !ok {
return false
}
id, ok := se.X.(*ast.Ident)
if !ok {
return false
}
fn := se.Sel.Name
pkg := id.Name
if exitFunctions[pkg] != nil && exitFunctions[pkg][fn] { // it's a call to an exit function
return true
}
}
return false
}
return len(pick(node, isExit, nil)) != 0
}
|
