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// Copyright 2018 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 checker defines the implementation of the checker commands.
// The same code drives the multi-analysis driver, the single-analysis
// driver that is conventionally provided for convenience along with
// each analysis package, and the test driver.
package checker
import (
"bytes"
"encoding/gob"
"flag"
"fmt"
"go/token"
"go/types"
"log"
"os"
"reflect"
"runtime"
"runtime/pprof"
"runtime/trace"
"sort"
"strings"
"sync"
"time"
"golang.org/x/tools/go/analysis"
"golang.org/x/tools/go/analysis/internal/analysisflags"
"golang.org/x/tools/go/packages"
)
var (
// Debug is a set of single-letter flags:
//
// f show [f]acts as they are created
// p disable [p]arallel execution of analyzers
// s do additional [s]anity checks on fact types and serialization
// t show [t]iming info (NB: use 'p' flag to avoid GC/scheduler noise)
// v show [v]erbose logging
//
Debug = ""
// Log files for optional performance tracing.
CPUProfile, MemProfile, Trace string
)
// RegisterFlags registers command-line flags used by the analysis driver.
func RegisterFlags() {
// When adding flags here, remember to update
// the list of suppressed flags in analysisflags.
flag.StringVar(&Debug, "debug", Debug, `debug flags, any subset of "fpstv"`)
flag.StringVar(&CPUProfile, "cpuprofile", "", "write CPU profile to this file")
flag.StringVar(&MemProfile, "memprofile", "", "write memory profile to this file")
flag.StringVar(&Trace, "trace", "", "write trace log to this file")
}
// Run loads the packages specified by args using go/packages,
// then applies the specified analyzers to them.
// Analysis flags must already have been set.
// It provides most of the logic for the main functions of both the
// singlechecker and the multi-analysis commands.
// It returns the appropriate exit code.
func Run(args []string, analyzers []*analysis.Analyzer) (exitcode int) {
if CPUProfile != "" {
f, err := os.Create(CPUProfile)
if err != nil {
log.Fatal(err)
}
if err := pprof.StartCPUProfile(f); err != nil {
log.Fatal(err)
}
// NB: profile won't be written in case of error.
defer pprof.StopCPUProfile()
}
if Trace != "" {
f, err := os.Create(Trace)
if err != nil {
log.Fatal(err)
}
if err := trace.Start(f); err != nil {
log.Fatal(err)
}
// NB: trace log won't be written in case of error.
defer func() {
trace.Stop()
log.Printf("To view the trace, run:\n$ go tool trace view %s", Trace)
}()
}
if MemProfile != "" {
f, err := os.Create(MemProfile)
if err != nil {
log.Fatal(err)
}
// NB: memprofile won't be written in case of error.
defer func() {
runtime.GC() // get up-to-date statistics
if err := pprof.WriteHeapProfile(f); err != nil {
log.Fatalf("Writing memory profile: %v", err)
}
f.Close()
}()
}
// Load the packages.
if dbg('v') {
log.SetPrefix("")
log.SetFlags(log.Lmicroseconds) // display timing
log.Printf("load %s", args)
}
// Optimization: if the selected analyzers don't produce/consume
// facts, we need source only for the initial packages.
allSyntax := needFacts(analyzers)
initial, err := load(args, allSyntax)
if err != nil {
log.Print(err)
return 1 // load errors
}
// Print the results.
roots := analyze(initial, analyzers)
return printDiagnostics(roots)
}
// load loads the initial packages.
func load(patterns []string, allSyntax bool) ([]*packages.Package, error) {
mode := packages.LoadSyntax
if allSyntax {
mode = packages.LoadAllSyntax
}
conf := packages.Config{
Mode: mode,
Tests: true,
}
initial, err := packages.Load(&conf, patterns...)
if err == nil {
if n := packages.PrintErrors(initial); n > 1 {
err = fmt.Errorf("%d errors during loading", n)
} else if n == 1 {
err = fmt.Errorf("error during loading")
} else if len(initial) == 0 {
err = fmt.Errorf("%s matched no packages", strings.Join(patterns, " "))
}
}
return initial, err
}
// TestAnalyzer applies an analysis to a set of packages (and their
// dependencies if necessary) and returns the results.
//
// Facts about pkg are returned in a map keyed by object; package facts
// have a nil key.
//
// This entry point is used only by analysistest.
func TestAnalyzer(a *analysis.Analyzer, pkgs []*packages.Package) []*TestAnalyzerResult {
var results []*TestAnalyzerResult
for _, act := range analyze(pkgs, []*analysis.Analyzer{a}) {
facts := make(map[types.Object][]analysis.Fact)
for key, fact := range act.objectFacts {
if key.obj.Pkg() == act.pass.Pkg {
facts[key.obj] = append(facts[key.obj], fact)
}
}
for key, fact := range act.packageFacts {
if key.pkg == act.pass.Pkg {
facts[nil] = append(facts[nil], fact)
}
}
results = append(results, &TestAnalyzerResult{act.pass, act.diagnostics, facts, act.result, act.err})
}
return results
}
type TestAnalyzerResult struct {
Pass *analysis.Pass
Diagnostics []analysis.Diagnostic
Facts map[types.Object][]analysis.Fact
Result interface{}
Err error
}
func analyze(pkgs []*packages.Package, analyzers []*analysis.Analyzer) []*action {
// Construct the action graph.
if dbg('v') {
log.Printf("building graph of analysis passes")
}
// Each graph node (action) is one unit of analysis.
// Edges express package-to-package (vertical) dependencies,
// and analysis-to-analysis (horizontal) dependencies.
type key struct {
*analysis.Analyzer
*packages.Package
}
actions := make(map[key]*action)
var mkAction func(a *analysis.Analyzer, pkg *packages.Package) *action
mkAction = func(a *analysis.Analyzer, pkg *packages.Package) *action {
k := key{a, pkg}
act, ok := actions[k]
if !ok {
act = &action{a: a, pkg: pkg}
// Add a dependency on each required analyzers.
for _, req := range a.Requires {
act.deps = append(act.deps, mkAction(req, pkg))
}
// An analysis that consumes/produces facts
// must run on the package's dependencies too.
if len(a.FactTypes) > 0 {
paths := make([]string, 0, len(pkg.Imports))
for path := range pkg.Imports {
paths = append(paths, path)
}
sort.Strings(paths) // for determinism
for _, path := range paths {
dep := mkAction(a, pkg.Imports[path])
act.deps = append(act.deps, dep)
}
}
actions[k] = act
}
return act
}
// Build nodes for initial packages.
var roots []*action
for _, a := range analyzers {
for _, pkg := range pkgs {
root := mkAction(a, pkg)
root.isroot = true
roots = append(roots, root)
}
}
// Execute the graph in parallel.
execAll(roots)
return roots
}
// printDiagnostics prints the diagnostics for the root packages in either
// plain text or JSON format. JSON format also includes errors for any
// dependencies.
//
// It returns the exitcode: in plain mode, 0 for success, 1 for analysis
// errors, and 3 for diagnostics. We avoid 2 since the flag package uses
// it. JSON mode always succeeds at printing errors and diagnostics in a
// structured form to stdout.
func printDiagnostics(roots []*action) (exitcode int) {
// Print the output.
//
// Print diagnostics only for root packages,
// but errors for all packages.
printed := make(map[*action]bool)
var print func(*action)
var visitAll func(actions []*action)
visitAll = func(actions []*action) {
for _, act := range actions {
if !printed[act] {
printed[act] = true
visitAll(act.deps)
print(act)
}
}
}
if analysisflags.JSON {
// JSON output
tree := make(analysisflags.JSONTree)
print = func(act *action) {
var diags []analysis.Diagnostic
if act.isroot {
diags = act.diagnostics
}
tree.Add(act.pkg.Fset, act.pkg.ID, act.a.Name, diags, act.err)
}
visitAll(roots)
tree.Print()
} else {
// plain text output
// De-duplicate diagnostics by position (not token.Pos) to
// avoid double-reporting in source files that belong to
// multiple packages, such as foo and foo.test.
type key struct {
pos token.Position
end token.Position
*analysis.Analyzer
message string
}
seen := make(map[key]bool)
print = func(act *action) {
if act.err != nil {
fmt.Fprintf(os.Stderr, "%s: %v\n", act.a.Name, act.err)
exitcode = 1 // analysis failed, at least partially
return
}
if act.isroot {
for _, diag := range act.diagnostics {
// We don't display a.Name/f.Category
// as most users don't care.
posn := act.pkg.Fset.Position(diag.Pos)
end := act.pkg.Fset.Position(diag.End)
k := key{posn, end, act.a, diag.Message}
if seen[k] {
continue // duplicate
}
seen[k] = true
analysisflags.PrintPlain(act.pkg.Fset, diag)
}
}
}
visitAll(roots)
if exitcode == 0 && len(seen) > 0 {
exitcode = 3 // successfuly produced diagnostics
}
}
// Print timing info.
if dbg('t') {
if !dbg('p') {
log.Println("Warning: times are mostly GC/scheduler noise; use -debug=tp to disable parallelism")
}
var all []*action
var total time.Duration
for act := range printed {
all = append(all, act)
total += act.duration
}
sort.Slice(all, func(i, j int) bool {
return all[i].duration > all[j].duration
})
// Print actions accounting for 90% of the total.
var sum time.Duration
for _, act := range all {
fmt.Fprintf(os.Stderr, "%s\t%s\n", act.duration, act)
sum += act.duration
if sum >= total*9/10 {
break
}
}
}
return exitcode
}
// needFacts reports whether any analysis required by the specified set
// needs facts. If so, we must load the entire program from source.
func needFacts(analyzers []*analysis.Analyzer) bool {
seen := make(map[*analysis.Analyzer]bool)
var q []*analysis.Analyzer // for BFS
q = append(q, analyzers...)
for len(q) > 0 {
a := q[0]
q = q[1:]
if !seen[a] {
seen[a] = true
if len(a.FactTypes) > 0 {
return true
}
q = append(q, a.Requires...)
}
}
return false
}
// An action represents one unit of analysis work: the application of
// one analysis to one package. Actions form a DAG, both within a
// package (as different analyzers are applied, either in sequence or
// parallel), and across packages (as dependencies are analyzed).
type action struct {
once sync.Once
a *analysis.Analyzer
pkg *packages.Package
pass *analysis.Pass
isroot bool
deps []*action
objectFacts map[objectFactKey]analysis.Fact
packageFacts map[packageFactKey]analysis.Fact
inputs map[*analysis.Analyzer]interface{}
result interface{}
diagnostics []analysis.Diagnostic
err error
duration time.Duration
}
type objectFactKey struct {
obj types.Object
typ reflect.Type
}
type packageFactKey struct {
pkg *types.Package
typ reflect.Type
}
func (act *action) String() string {
return fmt.Sprintf("%s@%s", act.a, act.pkg)
}
func execAll(actions []*action) {
sequential := dbg('p')
var wg sync.WaitGroup
for _, act := range actions {
wg.Add(1)
work := func(act *action) {
act.exec()
wg.Done()
}
if sequential {
work(act)
} else {
go work(act)
}
}
wg.Wait()
}
func (act *action) exec() { act.once.Do(act.execOnce) }
func (act *action) execOnce() {
// Analyze dependencies.
execAll(act.deps)
// TODO(adonovan): uncomment this during profiling.
// It won't build pre-go1.11 but conditional compilation
// using build tags isn't warranted.
//
// ctx, task := trace.NewTask(context.Background(), "exec")
// trace.Log(ctx, "pass", act.String())
// defer task.End()
// Record time spent in this node but not its dependencies.
// In parallel mode, due to GC/scheduler contention, the
// time is 5x higher than in sequential mode, even with a
// semaphore limiting the number of threads here.
// So use -debug=tp.
if dbg('t') {
t0 := time.Now()
defer func() { act.duration = time.Since(t0) }()
}
// Report an error if any dependency failed.
var failed []string
for _, dep := range act.deps {
if dep.err != nil {
failed = append(failed, dep.String())
}
}
if failed != nil {
sort.Strings(failed)
act.err = fmt.Errorf("failed prerequisites: %s", strings.Join(failed, ", "))
return
}
// Plumb the output values of the dependencies
// into the inputs of this action. Also facts.
inputs := make(map[*analysis.Analyzer]interface{})
act.objectFacts = make(map[objectFactKey]analysis.Fact)
act.packageFacts = make(map[packageFactKey]analysis.Fact)
for _, dep := range act.deps {
if dep.pkg == act.pkg {
// Same package, different analysis (horizontal edge):
// in-memory outputs of prerequisite analyzers
// become inputs to this analysis pass.
inputs[dep.a] = dep.result
} else if dep.a == act.a { // (always true)
// Same analysis, different package (vertical edge):
// serialized facts produced by prerequisite analysis
// become available to this analysis pass.
inheritFacts(act, dep)
}
}
// Run the analysis.
pass := &analysis.Pass{
Analyzer: act.a,
Fset: act.pkg.Fset,
Files: act.pkg.Syntax,
OtherFiles: act.pkg.OtherFiles,
Pkg: act.pkg.Types,
TypesInfo: act.pkg.TypesInfo,
TypesSizes: act.pkg.TypesSizes,
ResultOf: inputs,
Report: func(d analysis.Diagnostic) { act.diagnostics = append(act.diagnostics, d) },
ImportObjectFact: act.importObjectFact,
ExportObjectFact: act.exportObjectFact,
ImportPackageFact: act.importPackageFact,
ExportPackageFact: act.exportPackageFact,
AllObjectFacts: act.allObjectFacts,
AllPackageFacts: act.allPackageFacts,
}
act.pass = pass
var err error
if act.pkg.IllTyped && !pass.Analyzer.RunDespiteErrors {
err = fmt.Errorf("analysis skipped due to errors in package")
} else {
act.result, err = pass.Analyzer.Run(pass)
if err == nil {
if got, want := reflect.TypeOf(act.result), pass.Analyzer.ResultType; got != want {
err = fmt.Errorf(
"internal error: on package %s, analyzer %s returned a result of type %v, but declared ResultType %v",
pass.Pkg.Path(), pass.Analyzer, got, want)
}
}
}
act.err = err
// disallow calls after Run
pass.ExportObjectFact = nil
pass.ExportPackageFact = nil
}
// inheritFacts populates act.facts with
// those it obtains from its dependency, dep.
func inheritFacts(act, dep *action) {
serialize := dbg('s')
for key, fact := range dep.objectFacts {
// Filter out facts related to objects
// that are irrelevant downstream
// (equivalently: not in the compiler export data).
if !exportedFrom(key.obj, dep.pkg.Types) {
if false {
log.Printf("%v: discarding %T fact from %s for %s: %s", act, fact, dep, key.obj, fact)
}
continue
}
// Optionally serialize/deserialize fact
// to verify that it works across address spaces.
if serialize {
encodedFact, err := codeFact(fact)
if err != nil {
log.Panicf("internal error: encoding of %T fact failed in %v", fact, act)
}
fact = encodedFact
}
if false {
log.Printf("%v: inherited %T fact for %s: %s", act, fact, key.obj, fact)
}
act.objectFacts[key] = fact
}
for key, fact := range dep.packageFacts {
// TODO: filter out facts that belong to
// packages not mentioned in the export data
// to prevent side channels.
// Optionally serialize/deserialize fact
// to verify that it works across address spaces
// and is deterministic.
if serialize {
encodedFact, err := codeFact(fact)
if err != nil {
log.Panicf("internal error: encoding of %T fact failed in %v", fact, act)
}
fact = encodedFact
}
if false {
log.Printf("%v: inherited %T fact for %s: %s", act, fact, key.pkg.Path(), fact)
}
act.packageFacts[key] = fact
}
}
// codeFact encodes then decodes a fact,
// just to exercise that logic.
func codeFact(fact analysis.Fact) (analysis.Fact, error) {
// We encode facts one at a time.
// A real modular driver would emit all facts
// into one encoder to improve gob efficiency.
var buf bytes.Buffer
if err := gob.NewEncoder(&buf).Encode(fact); err != nil {
return nil, err
}
// Encode it twice and assert that we get the same bits.
// This helps detect nondeterministic Gob encoding (e.g. of maps).
var buf2 bytes.Buffer
if err := gob.NewEncoder(&buf2).Encode(fact); err != nil {
return nil, err
}
if !bytes.Equal(buf.Bytes(), buf2.Bytes()) {
return nil, fmt.Errorf("encoding of %T fact is nondeterministic", fact)
}
new := reflect.New(reflect.TypeOf(fact).Elem()).Interface().(analysis.Fact)
if err := gob.NewDecoder(&buf).Decode(new); err != nil {
return nil, err
}
return new, nil
}
// exportedFrom reports whether obj may be visible to a package that imports pkg.
// This includes not just the exported members of pkg, but also unexported
// constants, types, fields, and methods, perhaps belonging to oether packages,
// that find there way into the API.
// This is an overapproximation of the more accurate approach used by
// gc export data, which walks the type graph, but it's much simpler.
//
// TODO(adonovan): do more accurate filtering by walking the type graph.
func exportedFrom(obj types.Object, pkg *types.Package) bool {
switch obj := obj.(type) {
case *types.Func:
return obj.Exported() && obj.Pkg() == pkg ||
obj.Type().(*types.Signature).Recv() != nil
case *types.Var:
return obj.Exported() && obj.Pkg() == pkg ||
obj.IsField()
case *types.TypeName, *types.Const:
return true
}
return false // Nil, Builtin, Label, or PkgName
}
// importObjectFact implements Pass.ImportObjectFact.
// Given a non-nil pointer ptr of type *T, where *T satisfies Fact,
// importObjectFact copies the fact value to *ptr.
func (act *action) importObjectFact(obj types.Object, ptr analysis.Fact) bool {
if obj == nil {
panic("nil object")
}
key := objectFactKey{obj, factType(ptr)}
if v, ok := act.objectFacts[key]; ok {
reflect.ValueOf(ptr).Elem().Set(reflect.ValueOf(v).Elem())
return true
}
return false
}
// exportObjectFact implements Pass.ExportObjectFact.
func (act *action) exportObjectFact(obj types.Object, fact analysis.Fact) {
if act.pass.ExportObjectFact == nil {
log.Panicf("%s: Pass.ExportObjectFact(%s, %T) called after Run", act, obj, fact)
}
if obj.Pkg() != act.pkg.Types {
log.Panicf("internal error: in analysis %s of package %s: Fact.Set(%s, %T): can't set facts on objects belonging another package",
act.a, act.pkg, obj, fact)
}
key := objectFactKey{obj, factType(fact)}
act.objectFacts[key] = fact // clobber any existing entry
if dbg('f') {
objstr := types.ObjectString(obj, (*types.Package).Name)
fmt.Fprintf(os.Stderr, "%s: object %s has fact %s\n",
act.pkg.Fset.Position(obj.Pos()), objstr, fact)
}
}
// allObjectFacts implements Pass.AllObjectFacts.
func (act *action) allObjectFacts() []analysis.ObjectFact {
facts := make([]analysis.ObjectFact, 0, len(act.objectFacts))
for k := range act.objectFacts {
facts = append(facts, analysis.ObjectFact{k.obj, act.objectFacts[k]})
}
return facts
}
// importPackageFact implements Pass.ImportPackageFact.
// Given a non-nil pointer ptr of type *T, where *T satisfies Fact,
// fact copies the fact value to *ptr.
func (act *action) importPackageFact(pkg *types.Package, ptr analysis.Fact) bool {
if pkg == nil {
panic("nil package")
}
key := packageFactKey{pkg, factType(ptr)}
if v, ok := act.packageFacts[key]; ok {
reflect.ValueOf(ptr).Elem().Set(reflect.ValueOf(v).Elem())
return true
}
return false
}
// exportPackageFact implements Pass.ExportPackageFact.
func (act *action) exportPackageFact(fact analysis.Fact) {
if act.pass.ExportPackageFact == nil {
log.Panicf("%s: Pass.ExportPackageFact(%T) called after Run", act, fact)
}
key := packageFactKey{act.pass.Pkg, factType(fact)}
act.packageFacts[key] = fact // clobber any existing entry
if dbg('f') {
fmt.Fprintf(os.Stderr, "%s: package %s has fact %s\n",
act.pkg.Fset.Position(act.pass.Files[0].Pos()), act.pass.Pkg.Path(), fact)
}
}
func factType(fact analysis.Fact) reflect.Type {
t := reflect.TypeOf(fact)
if t.Kind() != reflect.Ptr {
log.Fatalf("invalid Fact type: got %T, want pointer", t)
}
return t
}
// allObjectFacts implements Pass.AllObjectFacts.
func (act *action) allPackageFacts() []analysis.PackageFact {
facts := make([]analysis.PackageFact, 0, len(act.packageFacts))
for k := range act.packageFacts {
facts = append(facts, analysis.PackageFact{k.pkg, act.packageFacts[k]})
}
return facts
}
func dbg(b byte) bool { return strings.IndexByte(Debug, b) >= 0 }