// pointsto runs the pointer analysis on the selected expression,
// and reports its points-to set (for a pointer-like expression)
// or its dynamic types (for an interface, reflect.Value, or
// reflect.Type expression) and their points-to sets.
//
// All printed sets are sorted to ensure determinism.
//
func pointsto(o *Oracle, qpos *QueryPos) (queryResult, error) {
path, action := findInterestingNode(qpos.info, qpos.path)
if action != actionExpr {
return nil, fmt.Errorf("pointer analysis wants an expression; got %s",
astutil.NodeDescription(qpos.path[0]))
}
var expr ast.Expr
var obj types.Object
switch n := path[0].(type) {
case *ast.ValueSpec:
// ambiguous ValueSpec containing multiple names
return nil, fmt.Errorf("multiple value specification")
case *ast.Ident:
obj = qpos.info.ObjectOf(n)
expr = n
case ast.Expr:
expr = n
default:
// TODO(adonovan): is this reachable?
return nil, fmt.Errorf("unexpected AST for expr: %T", n)
}
// Reject non-pointerlike types (includes all constants).
typ := qpos.info.TypeOf(expr)
if !pointer.CanPoint(typ) {
return nil, fmt.Errorf("pointer analysis wants an expression of reference type; got %s", typ)
}
// Determine the ssa.Value for the expression.
var value ssa.Value
var isAddr bool
var err error
if obj != nil {
// def/ref of func/var object
value, isAddr, err = ssaValueForIdent(o.prog, qpos.info, obj, path)
} else {
value, isAddr, err = ssaValueForExpr(o.prog, qpos.info, path)
}
if err != nil {
return nil, err // e.g. trivially dead code
}
// Run the pointer analysis.
ptrs, err := runPTA(o, value, isAddr)
if err != nil {
return nil, err // e.g. analytically unreachable
}
return &pointstoResult{
qpos: qpos,
typ: typ,
ptrs: ptrs,
}, nil
}
func describeValue(o *Oracle, qpos *QueryPos, path []ast.Node) (*describeValueResult, error) {
var expr ast.Expr
var obj types.Object
switch n := path[0].(type) {
case *ast.ValueSpec:
// ambiguous ValueSpec containing multiple names
return nil, fmt.Errorf("multiple value specification")
case *ast.Ident:
obj = qpos.info.ObjectOf(n)
expr = n
case ast.Expr:
expr = n
default:
// Is this reachable?
return nil, fmt.Errorf("unexpected AST for expr: %T", n)
}
typ := qpos.info.TypeOf(expr)
constVal := qpos.info.ValueOf(expr)
// From this point on, we cannot fail with an error.
// Failure to run the pointer analysis will be reported later.
//
// Our disposition to pointer analysis may be one of the following:
// - ok: ssa.Value was const or func.
// - error: no ssa.Value for expr (e.g. trivially dead code)
// - ok: ssa.Value is non-pointerlike
// - error: no Pointer for ssa.Value (e.g. analytically unreachable)
// - ok: Pointer has empty points-to set
// - ok: Pointer has non-empty points-to set
// ptaErr is non-nil only in the "error:" cases.
var ptaErr error
var ptrs []pointerResult
// Only run pointer analysis on pointerlike expression types.
if pointer.CanPoint(typ) {
// Determine the ssa.Value for the expression.
var value ssa.Value
if obj != nil {
// def/ref of func/var/const object
value, ptaErr = ssaValueForIdent(o.prog, qpos.info, obj, path)
} else {
// any other expression
if qpos.info.ValueOf(path[0].(ast.Expr)) == nil { // non-constant?
value, ptaErr = ssaValueForExpr(o.prog, qpos.info, path)
}
}
if value != nil {
// TODO(adonovan): IsIdentical may be too strict;
// perhaps we need is-assignable or even
// has-same-underlying-representation?
indirect := types.IsIdentical(types.NewPointer(typ), value.Type())
ptrs, ptaErr = describePointer(o, value, indirect)
}
}
return &describeValueResult{
qpos: qpos,
expr: expr,
typ: typ,
constVal: constVal,
obj: obj,
ptaErr: ptaErr,
ptrs: ptrs,
}, nil
}
func doOneInput(input, filename string) bool {
impctx := &importer.Config{Build: &build.Default}
imp := importer.New(impctx)
// Parsing.
f, err := parser.ParseFile(imp.Fset, filename, input, 0)
if err != nil {
// TODO(adonovan): err is a scanner error list;
// display all errors not just first?
fmt.Println(err)
return false
}
// Create single-file main package and import its dependencies.
info := imp.CreatePackage("main", f)
// SSA creation + building.
prog := ssa.NewProgram(imp.Fset, ssa.SanityCheckFunctions)
if err := prog.CreatePackages(imp); err != nil {
fmt.Println(err)
return false
}
prog.BuildAll()
mainpkg := prog.Package(info.Pkg)
ptrmain := mainpkg // main package for the pointer analysis
if mainpkg.Func("main") == nil {
// No main function; assume it's a test.
ptrmain = prog.CreateTestMainPackage(mainpkg)
}
ok := true
lineMapping := make(map[string]string) // maps "file:line" to @line tag
// Parse expectations in this input.
var exps []*expectation
re := regexp.MustCompile("// *@([a-z]*) *(.*)$")
lines := strings.Split(input, "\n")
for linenum, line := range lines {
linenum++ // make it 1-based
if matches := re.FindAllStringSubmatch(line, -1); matches != nil {
match := matches[0]
kind, rest := match[1], match[2]
e := &expectation{kind: kind, filename: filename, linenum: linenum}
if kind == "line" {
if rest == "" {
ok = false
e.errorf("@%s expectation requires identifier", kind)
} else {
lineMapping[fmt.Sprintf("%s:%d", filename, linenum)] = rest
}
continue
}
if e.needsProbe() && !strings.Contains(line, "print(") {
ok = false
e.errorf("@%s expectation must follow call to print(x)", kind)
continue
}
switch kind {
case "pointsto":
e.args = split(rest, "|")
case "types":
for _, typstr := range split(rest, "|") {
var t types.Type = types.Typ[types.Invalid] // means "..."
if typstr != "..." {
texpr, err := parser.ParseExpr(typstr)
if err != nil {
ok = false
// Don't print err since its location is bad.
e.errorf("'%s' is not a valid type", typstr)
continue
}
mainFileScope := mainpkg.Object.Scope().Child(0)
t, _, err = types.EvalNode(imp.Fset, texpr, mainpkg.Object, mainFileScope)
if err != nil {
ok = false
// Don't print err since its location is bad.
e.errorf("'%s' is not a valid type: %s", typstr, err)
continue
}
}
e.types = append(e.types, t)
}
case "calls":
e.args = split(rest, "->")
// TODO(adonovan): eagerly reject the
// expectation if fn doesn't denote
// existing function, rather than fail
// the expectation after analysis.
if len(e.args) != 2 {
ok = false
e.errorf("@calls expectation wants 'caller -> callee' arguments")
continue
}
case "warning":
lit, err := strconv.Unquote(strings.TrimSpace(rest))
if err != nil {
ok = false
e.errorf("couldn't parse @warning operand: %s", err.Error())
continue
}
e.args = append(e.args, lit)
default:
ok = false
e.errorf("unknown expectation kind: %s", e)
continue
}
exps = append(exps, e)
}
}
var log bytes.Buffer
// Run the analysis.
config := &pointer.Config{
Reflection: true,
BuildCallGraph: true,
QueryPrintCalls: true,
Mains: []*ssa.Package{ptrmain},
Log: &log,
}
// Print the log is there was an error or a panic.
complete := false
defer func() {
if !complete || !ok {
log.WriteTo(os.Stderr)
}
}()
result := pointer.Analyze(config)
// Check the expectations.
for _, e := range exps {
var call *ssa.CallCommon
var ptr pointer.Pointer
var tProbe types.Type
if e.needsProbe() {
if call, ptr = findProbe(prog, result.PrintCalls, e); call == nil {
ok = false
e.errorf("unreachable print() statement has expectation %s", e)
continue
}
tProbe = call.Args[0].Type()
if !pointer.CanPoint(tProbe) {
ok = false
e.errorf("expectation on non-pointerlike operand: %s", tProbe)
continue
}
}
switch e.kind {
case "pointsto":
if !checkPointsToExpectation(e, ptr, lineMapping, prog) {
ok = false
}
case "types":
if !checkTypesExpectation(e, ptr, tProbe) {
ok = false
}
case "calls":
if !checkCallsExpectation(prog, e, result.CallGraph) {
ok = false
}
case "warning":
if !checkWarningExpectation(prog, e, result.Warnings) {
ok = false
}
}
}
complete = true
// ok = false // debugging: uncomment to always see log
return ok
}