// 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
}
// 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
}
}
}