1// Copyright 2018 The Go Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style
3// license that can be found in the LICENSE file.
4
5// Package gopathwalk is like filepath.Walk but specialized for finding Go
6// packages, particularly in $GOPATH and $GOROOT.
7package gopathwalk
8
9import (
10 "bufio"
11 "bytes"
12 "fmt"
13 "go/build"
14 "io/ioutil"
15 "log"
16 "os"
17 "path/filepath"
18 "strings"
19
20 "golang.org/x/tools/internal/fastwalk"
21)
22
23// Options controls the behavior of a Walk call.
24type Options struct {
25 Debug bool // Enable debug logging
26 ModulesEnabled bool // Search module caches. Also disables legacy goimports ignore rules.
27}
28
29// RootType indicates the type of a Root.
30type RootType int
31
32const (
33 RootUnknown RootType = iota
34 RootGOROOT
35 RootGOPATH
36 RootCurrentModule
37 RootModuleCache
38 RootOther
39)
40
41// A Root is a starting point for a Walk.
42type Root struct {
43 Path string
44 Type RootType
45}
46
47// SrcDirsRoots returns the roots from build.Default.SrcDirs(). Not modules-compatible.
48func SrcDirsRoots(ctx *build.Context) []Root {
49 var roots []Root
50 roots = append(roots, Root{filepath.Join(ctx.GOROOT, "src"), RootGOROOT})
51 for _, p := range filepath.SplitList(ctx.GOPATH) {
52 roots = append(roots, Root{filepath.Join(p, "src"), RootGOPATH})
53 }
54 return roots
55}
56
57// Walk walks Go source directories ($GOROOT, $GOPATH, etc) to find packages.
58// For each package found, add will be called (concurrently) with the absolute
59// paths of the containing source directory and the package directory.
60// add will be called concurrently.
61func Walk(roots []Root, add func(root Root, dir string), opts Options) {
62 for _, root := range roots {
63 walkDir(root, add, opts)
64 }
65}
66
67func walkDir(root Root, add func(Root, string), opts Options) {
68 if _, err := os.Stat(root.Path); os.IsNotExist(err) {
69 if opts.Debug {
70 log.Printf("skipping nonexistant directory: %v", root.Path)
71 }
72 return
73 }
74 if opts.Debug {
75 log.Printf("scanning %s", root.Path)
76 }
77 w := &walker{
78 root: root,
79 add: add,
80 opts: opts,
81 }
82 w.init()
83 if err := fastwalk.Walk(root.Path, w.walk); err != nil {
84 log.Printf("gopathwalk: scanning directory %v: %v", root.Path, err)
85 }
86
87 if opts.Debug {
88 log.Printf("scanned %s", root.Path)
89 }
90}
91
92// walker is the callback for fastwalk.Walk.
93type walker struct {
94 root Root // The source directory to scan.
95 add func(Root, string) // The callback that will be invoked for every possible Go package dir.
96 opts Options // Options passed to Walk by the user.
97
98 ignoredDirs []os.FileInfo // The ignored directories, loaded from .goimportsignore files.
99}
100
101// init initializes the walker based on its Options.
102func (w *walker) init() {
103 var ignoredPaths []string
104 if w.root.Type == RootModuleCache {
105 ignoredPaths = []string{"cache"}
106 }
107 if !w.opts.ModulesEnabled && w.root.Type == RootGOPATH {
108 ignoredPaths = w.getIgnoredDirs(w.root.Path)
109 ignoredPaths = append(ignoredPaths, "v", "mod")
110 }
111
112 for _, p := range ignoredPaths {
113 full := filepath.Join(w.root.Path, p)
114 if fi, err := os.Stat(full); err == nil {
115 w.ignoredDirs = append(w.ignoredDirs, fi)
116 if w.opts.Debug {
117 log.Printf("Directory added to ignore list: %s", full)
118 }
119 } else if w.opts.Debug {
120 log.Printf("Error statting ignored directory: %v", err)
121 }
122 }
123}
124
125// getIgnoredDirs reads an optional config file at <path>/.goimportsignore
126// of relative directories to ignore when scanning for go files.
127// The provided path is one of the $GOPATH entries with "src" appended.
128func (w *walker) getIgnoredDirs(path string) []string {
129 file := filepath.Join(path, ".goimportsignore")
130 slurp, err := ioutil.ReadFile(file)
131 if w.opts.Debug {
132 if err != nil {
133 log.Print(err)
134 } else {
135 log.Printf("Read %s", file)
136 }
137 }
138 if err != nil {
139 return nil
140 }
141
142 var ignoredDirs []string
143 bs := bufio.NewScanner(bytes.NewReader(slurp))
144 for bs.Scan() {
145 line := strings.TrimSpace(bs.Text())
146 if line == "" || strings.HasPrefix(line, "#") {
147 continue
148 }
149 ignoredDirs = append(ignoredDirs, line)
150 }
151 return ignoredDirs
152}
153
154func (w *walker) shouldSkipDir(fi os.FileInfo) bool {
155 for _, ignoredDir := range w.ignoredDirs {
156 if os.SameFile(fi, ignoredDir) {
157 return true
158 }
159 }
160 return false
161}
162
163func (w *walker) walk(path string, typ os.FileMode) error {
164 dir := filepath.Dir(path)
165 if typ.IsRegular() {
166 if dir == w.root.Path && (w.root.Type == RootGOROOT || w.root.Type == RootGOPATH) {
167 // Doesn't make sense to have regular files
168 // directly in your $GOPATH/src or $GOROOT/src.
169 return fastwalk.SkipFiles
170 }
171 if !strings.HasSuffix(path, ".go") {
172 return nil
173 }
174
175 w.add(w.root, dir)
176 return fastwalk.SkipFiles
177 }
178 if typ == os.ModeDir {
179 base := filepath.Base(path)
180 if base == "" || base[0] == '.' || base[0] == '_' ||
181 base == "testdata" ||
182 (w.root.Type == RootGOROOT && w.opts.ModulesEnabled && base == "vendor") ||
183 (!w.opts.ModulesEnabled && base == "node_modules") {
184 return filepath.SkipDir
185 }
186 fi, err := os.Lstat(path)
187 if err == nil && w.shouldSkipDir(fi) {
188 return filepath.SkipDir
189 }
190 return nil
191 }
192 if typ == os.ModeSymlink {
193 base := filepath.Base(path)
194 if strings.HasPrefix(base, ".#") {
195 // Emacs noise.
196 return nil
197 }
198 fi, err := os.Lstat(path)
199 if err != nil {
200 // Just ignore it.
201 return nil
202 }
203 if w.shouldTraverse(dir, fi) {
204 return fastwalk.TraverseLink
205 }
206 }
207 return nil
208}
209
210// shouldTraverse reports whether the symlink fi, found in dir,
211// should be followed. It makes sure symlinks were never visited
212// before to avoid symlink loops.
213func (w *walker) shouldTraverse(dir string, fi os.FileInfo) bool {
214 path := filepath.Join(dir, fi.Name())
215 target, err := filepath.EvalSymlinks(path)
216 if err != nil {
217 return false
218 }
219 ts, err := os.Stat(target)
220 if err != nil {
221 fmt.Fprintln(os.Stderr, err)
222 return false
223 }
224 if !ts.IsDir() {
225 return false
226 }
227 if w.shouldSkipDir(ts) {
228 return false
229 }
230 // Check for symlink loops by statting each directory component
231 // and seeing if any are the same file as ts.
232 for {
233 parent := filepath.Dir(path)
234 if parent == path {
235 // Made it to the root without seeing a cycle.
236 // Use this symlink.
237 return true
238 }
239 parentInfo, err := os.Stat(parent)
240 if err != nil {
241 return false
242 }
243 if os.SameFile(ts, parentInfo) {
244 // Cycle. Don't traverse.
245 return false
246 }
247 path = parent
248 }
249
250}