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// Copyright 2019 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 imports
import (
"bytes"
"context"
"encoding/json"
"fmt"
"io/ioutil"
"os"
"path"
"path/filepath"
"regexp"
"sort"
"strconv"
"strings"
"golang.org/x/mod/module"
"golang.org/x/tools/internal/gocommand"
"golang.org/x/tools/internal/gopathwalk"
)
// ModuleResolver implements resolver for modules using the go command as little
// as feasible.
type ModuleResolver struct {
env *ProcessEnv
moduleCacheDir string
dummyVendorMod *gocommand.ModuleJSON // If vendoring is enabled, the pseudo-module that represents the /vendor directory.
roots []gopathwalk.Root
scanSema chan struct{} // scanSema prevents concurrent scans and guards scannedRoots.
scannedRoots map[gopathwalk.Root]bool
initialized bool
main *gocommand.ModuleJSON
modsByModPath []*gocommand.ModuleJSON // All modules, ordered by # of path components in module Path...
modsByDir []*gocommand.ModuleJSON // ...or Dir.
// moduleCacheCache stores information about the module cache.
moduleCacheCache *dirInfoCache
otherCache *dirInfoCache
}
func newModuleResolver(e *ProcessEnv) *ModuleResolver {
r := &ModuleResolver{
env: e,
scanSema: make(chan struct{}, 1),
}
r.scanSema <- struct{}{}
return r
}
func (r *ModuleResolver) init() error {
if r.initialized {
return nil
}
goenv, err := r.env.goEnv()
if err != nil {
return err
}
inv := gocommand.Invocation{
BuildFlags: r.env.BuildFlags,
ModFlag: r.env.ModFlag,
ModFile: r.env.ModFile,
Env: r.env.env(),
Logf: r.env.Logf,
WorkingDir: r.env.WorkingDir,
}
mainMod, vendorEnabled, err := gocommand.VendorEnabled(context.TODO(), inv, r.env.GocmdRunner)
if err != nil {
return err
}
if mainMod != nil && vendorEnabled {
// Vendor mode is on, so all the non-Main modules are irrelevant,
// and we need to search /vendor for everything.
r.main = mainMod
r.dummyVendorMod = &gocommand.ModuleJSON{
Path: "",
Dir: filepath.Join(mainMod.Dir, "vendor"),
}
r.modsByModPath = []*gocommand.ModuleJSON{mainMod, r.dummyVendorMod}
r.modsByDir = []*gocommand.ModuleJSON{mainMod, r.dummyVendorMod}
} else {
// Vendor mode is off, so run go list -m ... to find everything.
err := r.initAllMods()
// We expect an error when running outside of a module with
// GO111MODULE=on. Other errors are fatal.
if err != nil {
if errMsg := err.Error(); !strings.Contains(errMsg, "working directory is not part of a module") && !strings.Contains(errMsg, "go.mod file not found") {
return err
}
}
}
if gmc := r.env.Env["GOMODCACHE"]; gmc != "" {
r.moduleCacheDir = gmc
} else {
gopaths := filepath.SplitList(goenv["GOPATH"])
if len(gopaths) == 0 {
return fmt.Errorf("empty GOPATH")
}
r.moduleCacheDir = filepath.Join(gopaths[0], "/pkg/mod")
}
sort.Slice(r.modsByModPath, func(i, j int) bool {
count := func(x int) int {
return strings.Count(r.modsByModPath[x].Path, "/")
}
return count(j) < count(i) // descending order
})
sort.Slice(r.modsByDir, func(i, j int) bool {
count := func(x int) int {
return strings.Count(r.modsByDir[x].Dir, "/")
}
return count(j) < count(i) // descending order
})
r.roots = []gopathwalk.Root{
{filepath.Join(goenv["GOROOT"], "/src"), gopathwalk.RootGOROOT},
}
if r.main != nil {
r.roots = append(r.roots, gopathwalk.Root{r.main.Dir, gopathwalk.RootCurrentModule})
}
if vendorEnabled {
r.roots = append(r.roots, gopathwalk.Root{r.dummyVendorMod.Dir, gopathwalk.RootOther})
} else {
addDep := func(mod *gocommand.ModuleJSON) {
if mod.Replace == nil {
// This is redundant with the cache, but we'll skip it cheaply enough.
r.roots = append(r.roots, gopathwalk.Root{mod.Dir, gopathwalk.RootModuleCache})
} else {
r.roots = append(r.roots, gopathwalk.Root{mod.Dir, gopathwalk.RootOther})
}
}
// Walk dependent modules before scanning the full mod cache, direct deps first.
for _, mod := range r.modsByModPath {
if !mod.Indirect && !mod.Main {
addDep(mod)
}
}
for _, mod := range r.modsByModPath {
if mod.Indirect && !mod.Main {
addDep(mod)
}
}
r.roots = append(r.roots, gopathwalk.Root{r.moduleCacheDir, gopathwalk.RootModuleCache})
}
r.scannedRoots = map[gopathwalk.Root]bool{}
if r.moduleCacheCache == nil {
r.moduleCacheCache = &dirInfoCache{
dirs: map[string]*directoryPackageInfo{},
listeners: map[*int]cacheListener{},
}
}
if r.otherCache == nil {
r.otherCache = &dirInfoCache{
dirs: map[string]*directoryPackageInfo{},
listeners: map[*int]cacheListener{},
}
}
r.initialized = true
return nil
}
func (r *ModuleResolver) initAllMods() error {
stdout, err := r.env.invokeGo(context.TODO(), "list", "-m", "-e", "-json", "...")
if err != nil {
return err
}
for dec := json.NewDecoder(stdout); dec.More(); {
mod := &gocommand.ModuleJSON{}
if err := dec.Decode(mod); err != nil {
return err
}
if mod.Dir == "" {
if r.env.Logf != nil {
r.env.Logf("module %v has not been downloaded and will be ignored", mod.Path)
}
// Can't do anything with a module that's not downloaded.
continue
}
// golang/go#36193: the go command doesn't always clean paths.
mod.Dir = filepath.Clean(mod.Dir)
r.modsByModPath = append(r.modsByModPath, mod)
r.modsByDir = append(r.modsByDir, mod)
if mod.Main {
r.main = mod
}
}
return nil
}
func (r *ModuleResolver) ClearForNewScan() {
<-r.scanSema
r.scannedRoots = map[gopathwalk.Root]bool{}
r.otherCache = &dirInfoCache{
dirs: map[string]*directoryPackageInfo{},
listeners: map[*int]cacheListener{},
}
r.scanSema <- struct{}{}
}
func (r *ModuleResolver) ClearForNewMod() {
<-r.scanSema
*r = ModuleResolver{
env: r.env,
moduleCacheCache: r.moduleCacheCache,
otherCache: r.otherCache,
scanSema: r.scanSema,
}
r.init()
r.scanSema <- struct{}{}
}
// findPackage returns the module and directory that contains the package at
// the given import path, or returns nil, "" if no module is in scope.
func (r *ModuleResolver) findPackage(importPath string) (*gocommand.ModuleJSON, string) {
// This can't find packages in the stdlib, but that's harmless for all
// the existing code paths.
for _, m := range r.modsByModPath {
if !strings.HasPrefix(importPath, m.Path) {
continue
}
pathInModule := importPath[len(m.Path):]
pkgDir := filepath.Join(m.Dir, pathInModule)
if r.dirIsNestedModule(pkgDir, m) {
continue
}
if info, ok := r.cacheLoad(pkgDir); ok {
if loaded, err := info.reachedStatus(nameLoaded); loaded {
if err != nil {
continue // No package in this dir.
}
return m, pkgDir
}
if scanned, err := info.reachedStatus(directoryScanned); scanned && err != nil {
continue // Dir is unreadable, etc.
}
// This is slightly wrong: a directory doesn't have to have an
// importable package to count as a package for package-to-module
// resolution. package main or _test files should count but
// don't.
// TODO(heschi): fix this.
if _, err := r.cachePackageName(info); err == nil {
return m, pkgDir
}
}
// Not cached. Read the filesystem.
pkgFiles, err := ioutil.ReadDir(pkgDir)
if err != nil {
continue
}
// A module only contains a package if it has buildable go
// files in that directory. If not, it could be provided by an
// outer module. See #29736.
for _, fi := range pkgFiles {
if ok, _ := r.env.matchFile(pkgDir, fi.Name()); ok {
return m, pkgDir
}
}
}
return nil, ""
}
func (r *ModuleResolver) cacheLoad(dir string) (directoryPackageInfo, bool) {
if info, ok := r.moduleCacheCache.Load(dir); ok {
return info, ok
}
return r.otherCache.Load(dir)
}
func (r *ModuleResolver) cacheStore(info directoryPackageInfo) {
if info.rootType == gopathwalk.RootModuleCache {
r.moduleCacheCache.Store(info.dir, info)
} else {
r.otherCache.Store(info.dir, info)
}
}
func (r *ModuleResolver) cacheKeys() []string {
return append(r.moduleCacheCache.Keys(), r.otherCache.Keys()...)
}
// cachePackageName caches the package name for a dir already in the cache.
func (r *ModuleResolver) cachePackageName(info directoryPackageInfo) (string, error) {
if info.rootType == gopathwalk.RootModuleCache {
return r.moduleCacheCache.CachePackageName(info)
}
return r.otherCache.CachePackageName(info)
}
func (r *ModuleResolver) cacheExports(ctx context.Context, env *ProcessEnv, info directoryPackageInfo) (string, []string, error) {
if info.rootType == gopathwalk.RootModuleCache {
return r.moduleCacheCache.CacheExports(ctx, env, info)
}
return r.otherCache.CacheExports(ctx, env, info)
}
// findModuleByDir returns the module that contains dir, or nil if no such
// module is in scope.
func (r *ModuleResolver) findModuleByDir(dir string) *gocommand.ModuleJSON {
// This is quite tricky and may not be correct. dir could be:
// - a package in the main module.
// - a replace target underneath the main module's directory.
// - a nested module in the above.
// - a replace target somewhere totally random.
// - a nested module in the above.
// - in the mod cache.
// - in /vendor/ in -mod=vendor mode.
// - nested module? Dunno.
// Rumor has it that replace targets cannot contain other replace targets.
for _, m := range r.modsByDir {
if !strings.HasPrefix(dir, m.Dir) {
continue
}
if r.dirIsNestedModule(dir, m) {
continue
}
return m
}
return nil
}
// dirIsNestedModule reports if dir is contained in a nested module underneath
// mod, not actually in mod.
func (r *ModuleResolver) dirIsNestedModule(dir string, mod *gocommand.ModuleJSON) bool {
if !strings.HasPrefix(dir, mod.Dir) {
return false
}
if r.dirInModuleCache(dir) {
// Nested modules in the module cache are pruned,
// so it cannot be a nested module.
return false
}
if mod != nil && mod == r.dummyVendorMod {
// The /vendor pseudomodule is flattened and doesn't actually count.
return false
}
modDir, _ := r.modInfo(dir)
if modDir == "" {
return false
}
return modDir != mod.Dir
}
func (r *ModuleResolver) modInfo(dir string) (modDir string, modName string) {
readModName := func(modFile string) string {
modBytes, err := ioutil.ReadFile(modFile)
if err != nil {
return ""
}
return modulePath(modBytes)
}
if r.dirInModuleCache(dir) {
if matches := modCacheRegexp.FindStringSubmatch(dir); len(matches) == 3 {
index := strings.Index(dir, matches[1]+"@"+matches[2])
modDir := filepath.Join(dir[:index], matches[1]+"@"+matches[2])
return modDir, readModName(filepath.Join(modDir, "go.mod"))
}
}
for {
if info, ok := r.cacheLoad(dir); ok {
return info.moduleDir, info.moduleName
}
f := filepath.Join(dir, "go.mod")
info, err := os.Stat(f)
if err == nil && !info.IsDir() {
return dir, readModName(f)
}
d := filepath.Dir(dir)
if len(d) >= len(dir) {
return "", "" // reached top of file system, no go.mod
}
dir = d
}
}
func (r *ModuleResolver) dirInModuleCache(dir string) bool {
if r.moduleCacheDir == "" {
return false
}
return strings.HasPrefix(dir, r.moduleCacheDir)
}
func (r *ModuleResolver) loadPackageNames(importPaths []string, srcDir string) (map[string]string, error) {
if err := r.init(); err != nil {
return nil, err
}
names := map[string]string{}
for _, path := range importPaths {
_, packageDir := r.findPackage(path)
if packageDir == "" {
continue
}
name, err := packageDirToName(packageDir)
if err != nil {
continue
}
names[path] = name
}
return names, nil
}
func (r *ModuleResolver) scan(ctx context.Context, callback *scanCallback) error {
if err := r.init(); err != nil {
return err
}
processDir := func(info directoryPackageInfo) {
// Skip this directory if we were not able to get the package information successfully.
if scanned, err := info.reachedStatus(directoryScanned); !scanned || err != nil {
return
}
pkg, err := r.canonicalize(info)
if err != nil {
return
}
if !callback.dirFound(pkg) {
return
}
pkg.packageName, err = r.cachePackageName(info)
if err != nil {
return
}
if !callback.packageNameLoaded(pkg) {
return
}
_, exports, err := r.loadExports(ctx, pkg, false)
if err != nil {
return
}
callback.exportsLoaded(pkg, exports)
}
// Start processing everything in the cache, and listen for the new stuff
// we discover in the walk below.
stop1 := r.moduleCacheCache.ScanAndListen(ctx, processDir)
defer stop1()
stop2 := r.otherCache.ScanAndListen(ctx, processDir)
defer stop2()
// We assume cached directories are fully cached, including all their
// children, and have not changed. We can skip them.
skip := func(root gopathwalk.Root, dir string) bool {
info, ok := r.cacheLoad(dir)
if !ok {
return false
}
// This directory can be skipped as long as we have already scanned it.
// Packages with errors will continue to have errors, so there is no need
// to rescan them.
packageScanned, _ := info.reachedStatus(directoryScanned)
return packageScanned
}
// Add anything new to the cache, and process it if we're still listening.
add := func(root gopathwalk.Root, dir string) {
r.cacheStore(r.scanDirForPackage(root, dir))
}
// r.roots and the callback are not necessarily safe to use in the
// goroutine below. Process them eagerly.
roots := filterRoots(r.roots, callback.rootFound)
// We can't cancel walks, because we need them to finish to have a usable
// cache. Instead, run them in a separate goroutine and detach.
scanDone := make(chan struct{})
go func() {
select {
case <-ctx.Done():
return
case <-r.scanSema:
}
defer func() { r.scanSema <- struct{}{} }()
// We have the lock on r.scannedRoots, and no other scans can run.
for _, root := range roots {
if ctx.Err() != nil {
return
}
if r.scannedRoots[root] {
continue
}
gopathwalk.WalkSkip([]gopathwalk.Root{root}, add, skip, gopathwalk.Options{Logf: r.env.Logf, ModulesEnabled: true})
r.scannedRoots[root] = true
}
close(scanDone)
}()
select {
case <-ctx.Done():
case <-scanDone:
}
return nil
}
func (r *ModuleResolver) scoreImportPath(ctx context.Context, path string) float64 {
if _, ok := stdlib[path]; ok {
return MaxRelevance
}
mod, _ := r.findPackage(path)
return modRelevance(mod)
}
func modRelevance(mod *gocommand.ModuleJSON) float64 {
var relevance float64
switch {
case mod == nil: // out of scope
return MaxRelevance - 4
case mod.Indirect:
relevance = MaxRelevance - 3
case !mod.Main:
relevance = MaxRelevance - 2
default:
relevance = MaxRelevance - 1 // main module ties with stdlib
}
_, versionString, ok := module.SplitPathVersion(mod.Path)
if ok {
index := strings.Index(versionString, "v")
if index == -1 {
return relevance
}
if versionNumber, err := strconv.ParseFloat(versionString[index+1:], 64); err == nil {
relevance += versionNumber / 1000
}
}
return relevance
}
// canonicalize gets the result of canonicalizing the packages using the results
// of initializing the resolver from 'go list -m'.
func (r *ModuleResolver) canonicalize(info directoryPackageInfo) (*pkg, error) {
// Packages in GOROOT are already canonical, regardless of the std/cmd modules.
if info.rootType == gopathwalk.RootGOROOT {
return &pkg{
importPathShort: info.nonCanonicalImportPath,
dir: info.dir,
packageName: path.Base(info.nonCanonicalImportPath),
relevance: MaxRelevance,
}, nil
}
importPath := info.nonCanonicalImportPath
mod := r.findModuleByDir(info.dir)
// Check if the directory is underneath a module that's in scope.
if mod != nil {
// It is. If dir is the target of a replace directive,
// our guessed import path is wrong. Use the real one.
if mod.Dir == info.dir {
importPath = mod.Path
} else {
dirInMod := info.dir[len(mod.Dir)+len("/"):]
importPath = path.Join(mod.Path, filepath.ToSlash(dirInMod))
}
} else if !strings.HasPrefix(importPath, info.moduleName) {
// The module's name doesn't match the package's import path. It
// probably needs a replace directive we don't have.
return nil, fmt.Errorf("package in %q is not valid without a replace statement", info.dir)
}
res := &pkg{
importPathShort: importPath,
dir: info.dir,
relevance: modRelevance(mod),
}
// We may have discovered a package that has a different version
// in scope already. Canonicalize to that one if possible.
if _, canonicalDir := r.findPackage(importPath); canonicalDir != "" {
res.dir = canonicalDir
}
return res, nil
}
func (r *ModuleResolver) loadExports(ctx context.Context, pkg *pkg, includeTest bool) (string, []string, error) {
if err := r.init(); err != nil {
return "", nil, err
}
if info, ok := r.cacheLoad(pkg.dir); ok && !includeTest {
return r.cacheExports(ctx, r.env, info)
}
return loadExportsFromFiles(ctx, r.env, pkg.dir, includeTest)
}
func (r *ModuleResolver) scanDirForPackage(root gopathwalk.Root, dir string) directoryPackageInfo {
subdir := ""
if dir != root.Path {
subdir = dir[len(root.Path)+len("/"):]
}
importPath := filepath.ToSlash(subdir)
if strings.HasPrefix(importPath, "vendor/") {
// Only enter vendor directories if they're explicitly requested as a root.
return directoryPackageInfo{
status: directoryScanned,
err: fmt.Errorf("unwanted vendor directory"),
}
}
switch root.Type {
case gopathwalk.RootCurrentModule:
importPath = path.Join(r.main.Path, filepath.ToSlash(subdir))
case gopathwalk.RootModuleCache:
matches := modCacheRegexp.FindStringSubmatch(subdir)
if len(matches) == 0 {
return directoryPackageInfo{
status: directoryScanned,
err: fmt.Errorf("invalid module cache path: %v", subdir),
}
}
modPath, err := module.UnescapePath(filepath.ToSlash(matches[1]))
if err != nil {
if r.env.Logf != nil {
r.env.Logf("decoding module cache path %q: %v", subdir, err)
}
return directoryPackageInfo{
status: directoryScanned,
err: fmt.Errorf("decoding module cache path %q: %v", subdir, err),
}
}
importPath = path.Join(modPath, filepath.ToSlash(matches[3]))
}
modDir, modName := r.modInfo(dir)
result := directoryPackageInfo{
status: directoryScanned,
dir: dir,
rootType: root.Type,
nonCanonicalImportPath: importPath,
moduleDir: modDir,
moduleName: modName,
}
if root.Type == gopathwalk.RootGOROOT {
// stdlib packages are always in scope, despite the confusing go.mod
return result
}
return result
}
// modCacheRegexp splits a path in a module cache into module, module version, and package.
var modCacheRegexp = regexp.MustCompile(`(.*)@([^/\\]*)(.*)`)
var (
slashSlash = []byte("//")
moduleStr = []byte("module")
)
// modulePath returns the module path from the gomod file text.
// If it cannot find a module path, it returns an empty string.
// It is tolerant of unrelated problems in the go.mod file.
//
// Copied from cmd/go/internal/modfile.
func modulePath(mod []byte) string {
for len(mod) > 0 {
line := mod
mod = nil
if i := bytes.IndexByte(line, '\n'); i >= 0 {
line, mod = line[:i], line[i+1:]
}
if i := bytes.Index(line, slashSlash); i >= 0 {
line = line[:i]
}
line = bytes.TrimSpace(line)
if !bytes.HasPrefix(line, moduleStr) {
continue
}
line = line[len(moduleStr):]
n := len(line)
line = bytes.TrimSpace(line)
if len(line) == n || len(line) == 0 {
continue
}
if line[0] == '"' || line[0] == '`' {
p, err := strconv.Unquote(string(line))
if err != nil {
return "" // malformed quoted string or multiline module path
}
return p
}
return string(line)
}
return "" // missing module path
}