blob: 10939ddfb8479dafcbd0e48cff9ecb1d68332eb6 [file] [log] [blame]
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package main
import (
"fmt"
"go/token"
"golang.org/x/tools/cmd/guru/serial"
"golang.org/x/tools/go/callgraph"
"golang.org/x/tools/go/callgraph/static"
"golang.org/x/tools/go/loader"
"golang.org/x/tools/go/ssa"
"golang.org/x/tools/go/ssa/ssautil"
)
// The callstack function 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(q *Query) error {
fset := token.NewFileSet()
lconf := loader.Config{Fset: fset, Build: q.Build}
if err := setPTAScope(&lconf, q.Scope); err != nil {
return err
}
// Load/parse/type-check the program.
lprog, err := loadWithSoftErrors(&lconf)
if err != nil {
return err
}
qpos, err := parseQueryPos(lprog, q.Pos, false)
if err != nil {
return err
}
prog := ssautil.CreateProgram(lprog, 0)
ptaConfig, err := setupPTA(prog, lprog, q.PTALog, q.Reflection)
if err != nil {
return err
}
pkg := prog.Package(qpos.info.Pkg)
if pkg == nil {
return fmt.Errorf("no SSA package")
}
if !ssa.HasEnclosingFunction(pkg, qpos.path) {
return fmt.Errorf("this position is not inside a function")
}
// Defer SSA construction till after errors are reported.
prog.Build()
target := ssa.EnclosingFunction(pkg, qpos.path)
if target == nil {
return fmt.Errorf("no SSA function built for this location (dead code?)")
}
var callpath []*callgraph.Edge
isEnd := func(n *callgraph.Node) bool { return n.Func == target }
// First, build a callgraph containing only static call edges,
// and search for an arbitrary path from a root to the target function.
// This is quick, and the user wants a static path if one exists.
cg := static.CallGraph(prog)
cg.DeleteSyntheticNodes()
for _, ep := range entryPoints(ptaConfig.Mains) {
callpath = callgraph.PathSearch(cg.CreateNode(ep), isEnd)
if callpath != nil {
break
}
}
// No fully static path found.
// Run the pointer analysis and build a complete call graph.
if callpath == nil {
ptaConfig.BuildCallGraph = true
cg := ptrAnalysis(ptaConfig).CallGraph
cg.DeleteSyntheticNodes()
callpath = callgraph.PathSearch(cg.Root, isEnd)
if callpath != nil {
callpath = callpath[1:] // remove synthetic edge from <root>
}
}
q.Output(fset, &callstackResult{
qpos: qpos,
target: target,
callpath: callpath,
})
return nil
}
type callstackResult struct {
qpos *queryPos
target *ssa.Function
callpath []*callgraph.Edge
}
func (r *callstackResult) PrintPlain(printf printfFunc) {
if r.callpath != nil {
printf(r.qpos, "Found a call path from root to %s", r.target)
printf(r.target, "%s", r.target)
for i := len(r.callpath) - 1; i >= 0; i-- {
edge := r.callpath[i]
printf(edge, "%s from %s", edge.Description(), edge.Caller.Func)
}
} else {
printf(r.target, "%s is unreachable in this analysis scope", r.target)
}
}
func (r *callstackResult) JSON(fset *token.FileSet) []byte {
var callers []serial.Caller
for i := len(r.callpath) - 1; i >= 0; i-- { // (innermost first)
edge := r.callpath[i]
callers = append(callers, serial.Caller{
Pos: fset.Position(edge.Pos()).String(),
Caller: edge.Caller.Func.String(),
Desc: edge.Description(),
})
}
return toJSON(&serial.CallStack{
Pos: fset.Position(r.target.Pos()).String(),
Target: r.target.String(),
Callers: callers,
})
}