// Callstack displays an arbitrary path from a root of the callgraph
// to the function at the current position.
//
// The information may be misleading in a context-insensitive
// analysis. e.g. the call path X->Y->Z might be infeasible if Y never
// calls Z when it is called from X. TODO(adonovan): think about UI.
//
// TODO(adonovan): permit user to specify a starting point other than
// the analysis root.
//
func callstack(o *Oracle, qpos *QueryPos) (queryResult, error) {
pkg := o.prog.Package(qpos.info.Pkg)
if pkg == nil {
return nil, fmt.Errorf("no SSA package")
}
if !ssa.HasEnclosingFunction(pkg, qpos.path) {
return nil, fmt.Errorf("this position is not inside a function")
}
buildSSA(o)
target := ssa.EnclosingFunction(pkg, qpos.path)
if target == nil {
return nil, fmt.Errorf("no SSA function built for this location (dead code?)")
}
// Run the pointer analysis and build the complete call graph.
o.config.BuildCallGraph = true
callgraph := ptrAnalysis(o).CallGraph
// Search for an arbitrary path from a root to the target function.
isEnd := func(n call.GraphNode) bool { return n.Func() == target }
callpath := call.PathSearch(callgraph.Root(), isEnd)
if callpath != nil {
callpath = callpath[1:] // remove synthetic edge from <root>
}
return &callstackResult{
qpos: qpos,
target: target,
callpath: callpath,
}, nil
}
// Callers reports the possible callers of the function
// immediately enclosing the specified source location.
//
// TODO(adonovan): if a caller is a wrapper, show the caller's caller.
//
func callers(o *Oracle, qpos *QueryPos) (queryResult, error) {
pkg := o.prog.Package(qpos.info.Pkg)
if pkg == nil {
return nil, fmt.Errorf("no SSA package")
}
if !ssa.HasEnclosingFunction(pkg, qpos.path) {
return nil, fmt.Errorf("this position is not inside a function")
}
buildSSA(o)
target := ssa.EnclosingFunction(pkg, qpos.path)
if target == nil {
return nil, fmt.Errorf("no SSA function built for this location (dead code?)")
}
// Run the pointer analysis, recording each
// call found to originate from target.
o.config.BuildCallGraph = true
callgraph := ptrAnalysis(o).CallGraph
var edges []call.Edge
call.GraphVisitEdges(callgraph, func(edge call.Edge) error {
if edge.Callee.Func() == target {
edges = append(edges, edge)
}
return nil
})
// TODO(adonovan): sort + dedup calls to ensure test determinism.
return &callersResult{
target: target,
callgraph: callgraph,
edges: edges,
}, nil
}
// Callees reports the possible callees of the function call site
// identified by the specified source location.
//
// TODO(adonovan): if a callee is a wrapper, show the callee's callee.
//
func callees(o *Oracle, qpos *QueryPos) (queryResult, error) {
pkg := o.prog.Package(qpos.info.Pkg)
if pkg == nil {
return nil, fmt.Errorf("no SSA package")
}
// Determine the enclosing call for the specified position.
var e *ast.CallExpr
for _, n := range qpos.path {
if e, _ = n.(*ast.CallExpr); e != nil {
break
}
}
if e == nil {
return nil, fmt.Errorf("there is no function call here")
}
// TODO(adonovan): issue an error if the call is "too far
// away" from the current selection, as this most likely is
// not what the user intended.
// Reject type conversions.
if qpos.info.IsType(e.Fun) {
return nil, fmt.Errorf("this is a type conversion, not a function call")
}
// Reject calls to built-ins.
if id, ok := unparen(e.Fun).(*ast.Ident); ok {
if b, ok := qpos.info.ObjectOf(id).(*types.Builtin); ok {
return nil, fmt.Errorf("this is a call to the built-in '%s' operator", b.Name())
}
}
buildSSA(o)
// Ascertain calling function and call site.
callerFn := ssa.EnclosingFunction(pkg, qpos.path)
if callerFn == nil {
return nil, fmt.Errorf("no SSA function built for this location (dead code?)")
}
// Find the call site.
site, err := findCallSite(callerFn, e.Lparen)
if err != nil {
return nil, err
}
funcs, err := findCallees(o, site)
if err != nil {
return nil, err
}
return &calleesResult{
site: site,
funcs: funcs,
}, nil
}
// ssaValueForExpr returns the ssa.Value of the non-ast.Ident
// expression whose path to the root of the AST is path. It may
// return a nil Value without an error to indicate the pointer
// analysis is not appropriate.
//
func ssaValueForExpr(prog *ssa.Program, qinfo *importer.PackageInfo, path []ast.Node) (ssa.Value, error) {
pkg := prog.Package(qinfo.Pkg)
pkg.SetDebugMode(true)
pkg.Build()
fn := ssa.EnclosingFunction(pkg, path)
if fn == nil {
return nil, fmt.Errorf("no SSA function built for this location (dead code?)")
}
if v := fn.ValueForExpr(path[0].(ast.Expr)); v != nil {
return v, nil
}
return nil, fmt.Errorf("can't locate SSA Value for expression in %s", fn)
}
// TODO(adonovan): move this test into ssa.
func TestEnclosingFunction(t *testing.T) {
tests := []struct {
input string // the input file
substr string // first occurrence of this string denotes interval
fn string // name of expected containing function
}{
// We use distinctive numbers as syntactic landmarks.
// Ordinary function:
{`package main
func f() { println(1003) }`,
"100", "main.f"},
// Methods:
{`package main
type T int
func (t T) f() { println(200) }`,
"200", "(main.T).f"},
// Function literal:
{`package main
func f() { println(func() { print(300) }) }`,
"300", "[email protected]"},
// Doubly nested
{`package main
func f() { println(func() { print(func() { print(350) })})}`,
"350", "[email protected]"},
// Implicit init for package-level var initializer.
{"package main; var a = 400", "400", "main.init"},
// No code for constants:
{"package main; const a = 500", "500", "(none)"},
// Explicit init()
{"package main; func init() { println(600) }", "600", "main.init$1"},
// Multiple explicit init functions:
{`package main
func init() { println("foo") }
func init() { println(800) }`,
"800", "main.init$2"},
// init() containing FuncLit.
{`package main
func init() { println(func(){print(900)}) }`,
"900", "[email protected]"},
}
for _, test := range tests {
imp := importer.New(new(importer.Config)) // (NB: no go/build.Config)
f, start, end := findInterval(t, imp.Fset, test.input, test.substr)
if f == nil {
continue
}
path, exact := importer.PathEnclosingInterval(f, start, end)
if !exact {
t.Errorf("EnclosingFunction(%q) not exact", test.substr)
continue
}
mainInfo := imp.CreatePackage("main", f)
prog := ssa.NewProgram(imp.Fset, 0)
if err := prog.CreatePackages(imp); err != nil {
t.Error(err)
continue
}
pkg := prog.Package(mainInfo.Pkg)
pkg.Build()
name := "(none)"
fn := ssa.EnclosingFunction(pkg, path)
if fn != nil {
name = fn.String()
}
if name != test.fn {
t.Errorf("EnclosingFunction(%q in %q) got %s, want %s",
test.substr, test.input, name, test.fn)
continue
}
// While we're here: test HasEnclosingFunction.
if has := ssa.HasEnclosingFunction(pkg, path); has != (fn != nil) {
t.Errorf("HasEnclosingFunction(%q in %q) got %v, want %v",
test.substr, test.input, has, fn != nil)
continue
}
}
}
// Ensure that, in debug mode, we can determine the ssa.Value
// corresponding to every ast.Expr.
func TestValueForExpr(t *testing.T) {
imp := importer.New(new(importer.Config)) // (uses GCImporter)
f, err := parser.ParseFile(imp.Fset, "testdata/valueforexpr.go", nil, parser.ParseComments)
if err != nil {
t.Error(err)
return
}
mainInfo := imp.CreatePackage("main", f)
prog := ssa.NewProgram(imp.Fset, 0)
if err := prog.CreatePackages(imp); err != nil {
t.Error(err)
return
}
mainPkg := prog.Package(mainInfo.Pkg)
mainPkg.SetDebugMode(true)
mainPkg.Build()
if false {
// debugging
for _, mem := range mainPkg.Members {
if fn, ok := mem.(*ssa.Function); ok {
fn.DumpTo(os.Stderr)
}
}
}
// Find the actual AST node for each canonical position.
parenExprByPos := make(map[token.Pos]*ast.ParenExpr)
ast.Inspect(f, func(n ast.Node) bool {
if n != nil {
if e, ok := n.(*ast.ParenExpr); ok {
parenExprByPos[e.Pos()] = e
}
}
return true
})
// Find all annotations of form /*@kind*/.
for _, c := range f.Comments {
text := strings.TrimSpace(c.Text())
if text == "" || text[0] != '@' {
continue
}
text = text[1:]
pos := c.End() + 1
position := imp.Fset.Position(pos)
var e ast.Expr
if target := parenExprByPos[pos]; target == nil {
t.Errorf("%s: annotation doesn't precede ParenExpr: %q", position, text)
continue
} else {
e = target.X
}
path, _ := importer.PathEnclosingInterval(f, pos, pos)
if path == nil {
t.Errorf("%s: can't find AST path from root to comment: %s", position, text)
continue
}
fn := ssa.EnclosingFunction(mainPkg, path)
if fn == nil {
t.Errorf("%s: can't find enclosing function", position)
continue
}
v, gotAddr := fn.ValueForExpr(e) // (may be nil)
got := strings.TrimPrefix(fmt.Sprintf("%T", v), "*ssa.")
if want := text; got != want {
t.Errorf("%s: got value %q, want %q", position, got, want)
}
if v != nil {
T := v.Type()
if gotAddr {
T = T.Underlying().(*types.Pointer).Elem() // deref
}
if !types.IsIdentical(T, mainInfo.TypeOf(e)) {
t.Errorf("%s: got type %s, want %s", position, mainInfo.TypeOf(e), T)
}
}
}
}
// Callees reports the possible callees of the function call site
// identified by the specified source location.
//
// TODO(adonovan): if a callee is a wrapper, show the callee's callee.
//
func callees(o *Oracle, qpos *QueryPos) (queryResult, error) {
pkg := o.prog.Package(qpos.info.Pkg)
if pkg == nil {
return nil, fmt.Errorf("no SSA package")
}
// Determine the enclosing call for the specified position.
var e *ast.CallExpr
for _, n := range qpos.path {
if e, _ = n.(*ast.CallExpr); e != nil {
break
}
}
if e == nil {
return nil, fmt.Errorf("there is no function call here")
}
// TODO(adonovan): issue an error if the call is "too far
// away" from the current selection, as this most likely is
// not what the user intended.
// Reject type conversions.
if qpos.info.IsType(e.Fun) {
return nil, fmt.Errorf("this is a type conversion, not a function call")
}
// Reject calls to built-ins.
if id, ok := unparen(e.Fun).(*ast.Ident); ok {
if b, ok := qpos.info.ObjectOf(id).(*types.Builtin); ok {
return nil, fmt.Errorf("this is a call to the built-in '%s' operator", b.Name())
}
}
buildSSA(o)
// Ascertain calling function and call site.
callerFn := ssa.EnclosingFunction(pkg, qpos.path)
if callerFn == nil {
return nil, fmt.Errorf("no SSA function built for this location (dead code?)")
}
o.config.BuildCallGraph = true
callgraph := ptrAnalysis(o).CallGraph
// Find the call site and all edges from it.
var site ssa.CallInstruction
calleesMap := make(map[*ssa.Function]bool)
for _, n := range callgraph.Nodes() {
if n.Func() == callerFn {
if site == nil {
// First node for callerFn: identify the site.
for _, s := range n.Sites() {
if s.Pos() == e.Lparen {
site = s
break
}
}
if site == nil {
return nil, fmt.Errorf("this call site is unreachable in this analysis")
}
}
for _, edge := range n.Edges() {
if edge.Site == site {
calleesMap[edge.Callee.Func()] = true
}
}
}
}
if site == nil {
return nil, fmt.Errorf("this function is unreachable in this analysis")
}
// Discard context, de-duplicate and sort.
funcs := make([]*ssa.Function, 0, len(calleesMap))
for f := range calleesMap {
funcs = append(funcs, f)
}
sort.Sort(byFuncPos(funcs))
return &calleesResult{
site: site,
funcs: funcs,
}, nil
}