+// 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 gopathwalk is like filepath.Walk but specialized for finding Go
+// packages, particularly in $GOPATH and $GOROOT.
+package gopathwalk
+
+import (
+ "bufio"
+ "bytes"
+ "fmt"
+ "io/ioutil"
+ "log"
+ "os"
+ "path/filepath"
+ "strings"
+ "time"
+
+ "golang.org/x/tools/internal/fastwalk"
+)
+
+// Options controls the behavior of a Walk call.
+type Options struct {
+ // If Logf is non-nil, debug logging is enabled through this function.
+ Logf func(format string, args ...interface{})
+ // Search module caches. Also disables legacy goimports ignore rules.
+ ModulesEnabled bool
+}
+
+// RootType indicates the type of a Root.
+type RootType int
+
+const (
+ RootUnknown RootType = iota
+ RootGOROOT
+ RootGOPATH
+ RootCurrentModule
+ RootModuleCache
+ RootOther
+)
+
+// A Root is a starting point for a Walk.
+type Root struct {
+ Path string
+ Type RootType
+}
+
+// Walk walks Go source directories ($GOROOT, $GOPATH, etc) to find packages.
+// For each package found, add will be called (concurrently) with the absolute
+// paths of the containing source directory and the package directory.
+// add will be called concurrently.
+func Walk(roots []Root, add func(root Root, dir string), opts Options) {
+ WalkSkip(roots, add, func(Root, string) bool { return false }, opts)
+}
+
+// WalkSkip walks Go source directories ($GOROOT, $GOPATH, etc) to find packages.
+// For each package found, add will be called (concurrently) with the absolute
+// paths of the containing source directory and the package directory.
+// For each directory that will be scanned, skip will be called (concurrently)
+// with the absolute paths of the containing source directory and the directory.
+// If skip returns false on a directory it will be processed.
+// add will be called concurrently.
+// skip will be called concurrently.
+func WalkSkip(roots []Root, add func(root Root, dir string), skip func(root Root, dir string) bool, opts Options) {
+ for _, root := range roots {
+ walkDir(root, add, skip, opts)
+ }
+}
+
+// walkDir creates a walker and starts fastwalk with this walker.
+func walkDir(root Root, add func(Root, string), skip func(root Root, dir string) bool, opts Options) {
+ if _, err := os.Stat(root.Path); os.IsNotExist(err) {
+ if opts.Logf != nil {
+ opts.Logf("skipping nonexistent directory: %v", root.Path)
+ }
+ return
+ }
+ start := time.Now()
+ if opts.Logf != nil {
+ opts.Logf("gopathwalk: scanning %s", root.Path)
+ }
+ w := &walker{
+ root: root,
+ add: add,
+ skip: skip,
+ opts: opts,
+ }
+ w.init()
+ if err := fastwalk.Walk(root.Path, w.walk); err != nil {
+ log.Printf("gopathwalk: scanning directory %v: %v", root.Path, err)
+ }
+
+ if opts.Logf != nil {
+ opts.Logf("gopathwalk: scanned %s in %v", root.Path, time.Since(start))
+ }
+}
+
+// walker is the callback for fastwalk.Walk.
+type walker struct {
+ root Root // The source directory to scan.
+ add func(Root, string) // The callback that will be invoked for every possible Go package dir.
+ skip func(Root, string) bool // The callback that will be invoked for every dir. dir is skipped if it returns true.
+ opts Options // Options passed to Walk by the user.
+
+ ignoredDirs []os.FileInfo // The ignored directories, loaded from .goimportsignore files.
+}
+
+// init initializes the walker based on its Options
+func (w *walker) init() {
+ var ignoredPaths []string
+ if w.root.Type == RootModuleCache {
+ ignoredPaths = []string{"cache"}
+ }
+ if !w.opts.ModulesEnabled && w.root.Type == RootGOPATH {
+ ignoredPaths = w.getIgnoredDirs(w.root.Path)
+ ignoredPaths = append(ignoredPaths, "v", "mod")
+ }
+
+ for _, p := range ignoredPaths {
+ full := filepath.Join(w.root.Path, p)
+ if fi, err := os.Stat(full); err == nil {
+ w.ignoredDirs = append(w.ignoredDirs, fi)
+ if w.opts.Logf != nil {
+ w.opts.Logf("Directory added to ignore list: %s", full)
+ }
+ } else if w.opts.Logf != nil {
+ w.opts.Logf("Error statting ignored directory: %v", err)
+ }
+ }
+}
+
+// getIgnoredDirs reads an optional config file at <path>/.goimportsignore
+// of relative directories to ignore when scanning for go files.
+// The provided path is one of the $GOPATH entries with "src" appended.
+func (w *walker) getIgnoredDirs(path string) []string {
+ file := filepath.Join(path, ".goimportsignore")
+ slurp, err := ioutil.ReadFile(file)
+ if w.opts.Logf != nil {
+ if err != nil {
+ w.opts.Logf("%v", err)
+ } else {
+ w.opts.Logf("Read %s", file)
+ }
+ }
+ if err != nil {
+ return nil
+ }
+
+ var ignoredDirs []string
+ bs := bufio.NewScanner(bytes.NewReader(slurp))
+ for bs.Scan() {
+ line := strings.TrimSpace(bs.Text())
+ if line == "" || strings.HasPrefix(line, "#") {
+ continue
+ }
+ ignoredDirs = append(ignoredDirs, line)
+ }
+ return ignoredDirs
+}
+
+// shouldSkipDir reports whether the file should be skipped or not.
+func (w *walker) shouldSkipDir(fi os.FileInfo, dir string) bool {
+ for _, ignoredDir := range w.ignoredDirs {
+ if os.SameFile(fi, ignoredDir) {
+ return true
+ }
+ }
+ if w.skip != nil {
+ // Check with the user specified callback.
+ return w.skip(w.root, dir)
+ }
+ return false
+}
+
+// walk walks through the given path.
+func (w *walker) walk(path string, typ os.FileMode) error {
+ dir := filepath.Dir(path)
+ if typ.IsRegular() {
+ if dir == w.root.Path && (w.root.Type == RootGOROOT || w.root.Type == RootGOPATH) {
+ // Doesn't make sense to have regular files
+ // directly in your $GOPATH/src or $GOROOT/src.
+ return fastwalk.ErrSkipFiles
+ }
+ if !strings.HasSuffix(path, ".go") {
+ return nil
+ }
+
+ w.add(w.root, dir)
+ return fastwalk.ErrSkipFiles
+ }
+ if typ == os.ModeDir {
+ base := filepath.Base(path)
+ if base == "" || base[0] == '.' || base[0] == '_' ||
+ base == "testdata" ||
+ (w.root.Type == RootGOROOT && w.opts.ModulesEnabled && base == "vendor") ||
+ (!w.opts.ModulesEnabled && base == "node_modules") {
+ return filepath.SkipDir
+ }
+ fi, err := os.Lstat(path)
+ if err == nil && w.shouldSkipDir(fi, path) {
+ return filepath.SkipDir
+ }
+ return nil
+ }
+ if typ == os.ModeSymlink {
+ base := filepath.Base(path)
+ if strings.HasPrefix(base, ".#") {
+ // Emacs noise.
+ return nil
+ }
+ fi, err := os.Lstat(path)
+ if err != nil {
+ // Just ignore it.
+ return nil
+ }
+ if w.shouldTraverse(dir, fi) {
+ return fastwalk.ErrTraverseLink
+ }
+ }
+ return nil
+}
+
+// shouldTraverse reports whether the symlink fi, found in dir,
+// should be followed. It makes sure symlinks were never visited
+// before to avoid symlink loops.
+func (w *walker) shouldTraverse(dir string, fi os.FileInfo) bool {
+ path := filepath.Join(dir, fi.Name())
+ target, err := filepath.EvalSymlinks(path)
+ if err != nil {
+ return false
+ }
+ ts, err := os.Stat(target)
+ if err != nil {
+ fmt.Fprintln(os.Stderr, err)
+ return false
+ }
+ if !ts.IsDir() {
+ return false
+ }
+ if w.shouldSkipDir(ts, dir) {
+ return false
+ }
+ // Check for symlink loops by statting each directory component
+ // and seeing if any are the same file as ts.
+ for {
+ parent := filepath.Dir(path)
+ if parent == path {
+ // Made it to the root without seeing a cycle.
+ // Use this symlink.
+ return true
+ }
+ parentInfo, err := os.Stat(parent)
+ if err != nil {
+ return false
+ }
+ if os.SameFile(ts, parentInfo) {
+ // Cycle. Don't traverse.
+ return false
+ }
+ path = parent
+ }
+
+}