// 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 $GOROOT.
package gopathwalk
import (
"bufio"
"bytes"
"fmt"
"go/build"
"io/ioutil"
"log"
"os"
"path/filepath"
"strings"
"golang.org/x/tools/internal/fastwalk"
)
// Options controls the behavior of a Walk call.
type Options struct {
Debug bool // Enable debug logging
ModulesEnabled bool // Search module caches. Also disables legacy goimports ignore rules.
}
// RootType indicates the type of a Root.
type RootType int
const (
RootUnknown RootType = iota
RootGOROOT
RootGOPATH
RootCurrentModule
RootModuleCache
RootOther
)
// A Root is a starting point for a Walk.
type Root struct {
Path string
Type RootType
}
// SrcDirsRoots returns the roots from build.Default.SrcDirs(). Not modules-compatible.
func SrcDirsRoots(ctx *build.Context) []Root {
var roots []Root
roots = append(roots, Root{filepath.Join(ctx.GOROOT, "src"), RootGOROOT})
for _, p := range filepath.SplitList(ctx.GOPATH) {
roots = append(roots, Root{filepath.Join(p, "src"), RootGOPATH})
}
return roots
}
// Walk walks Go source directories ($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) {
for _, root := range roots {
walkDir(root, add, opts)
}
}
func walkDir(root Root, add func(Root, string), opts Options) {
if _, err := os.Stat(root.Path); os.IsNotExist(err) {
if opts.Debug {
log.Printf("skipping nonexistant directory: %v", root.Path)
}
return
}
if opts.Debug {
log.Printf("scanning %s", root.Path)
}
w := &walker{
root: root,
add: add,
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.Debug {
log.Printf("scanned %s", root.Path)
}
}
// 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.
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.Debug {
log.Printf("Directory added to ignore list: %s", full)
}
} else if w.opts.Debug {
log.Printf("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.Debug {
if err != nil {
log.Print(err)
} else {
log.Printf("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
}
func (w *walker) shouldSkipDir(fi os.FileInfo) bool {
for _, ignoredDir := range w.ignoredDirs {
if os.SameFile(fi, ignoredDir) {
return true
}
}
return false
}
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.SkipFiles
}
if !strings.HasSuffix(path, ".go") {
return nil
}
w.add(w.root, dir)
return fastwalk.SkipFiles
}
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) {
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.TraverseLink
}
}
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) {
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
}
}
