| 1 | // Copyright 2015 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 | // The fiximports command fixes import declarations to use the canonical |
| 6 | // import path for packages that have an "import comment" as defined by |
| 7 | // https://golang.org/s/go14customimport. |
| 8 | // |
| 9 | // # Background |
| 10 | // |
| 11 | // The Go 1 custom import path mechanism lets the maintainer of a |
| 12 | // package give it a stable name by which clients may import and "go |
| 13 | // get" it, independent of the underlying version control system (such |
| 14 | // as Git) or server (such as github.com) that hosts it. Requests for |
| 15 | // the custom name are redirected to the underlying name. This allows |
| 16 | // packages to be migrated from one underlying server or system to |
| 17 | // another without breaking existing clients. |
| 18 | // |
| 19 | // Because this redirect mechanism creates aliases for existing |
| 20 | // packages, it's possible for a single program to import the same |
| 21 | // package by its canonical name and by an alias. The resulting |
| 22 | // executable will contain two copies of the package, which is wasteful |
| 23 | // at best and incorrect at worst. |
| 24 | // |
| 25 | // To avoid this, "go build" reports an error if it encounters a special |
| 26 | // comment like the one below, and if the import path in the comment |
| 27 | // does not match the path of the enclosing package relative to |
| 28 | // GOPATH/src: |
| 29 | // |
| 30 | // $ grep ^package $GOPATH/src/github.com/bob/vanity/foo/foo.go |
| 31 | // package foo // import "vanity.com/foo" |
| 32 | // |
| 33 | // The error from "go build" indicates that the package canonically |
| 34 | // known as "vanity.com/foo" is locally installed under the |
| 35 | // non-canonical name "github.com/bob/vanity/foo". |
| 36 | // |
| 37 | // # Usage |
| 38 | // |
| 39 | // When a package that you depend on introduces a custom import comment, |
| 40 | // and your workspace imports it by the non-canonical name, your build |
| 41 | // will stop working as soon as you update your copy of that package |
| 42 | // using "go get -u". |
| 43 | // |
| 44 | // The purpose of the fiximports tool is to fix up all imports of the |
| 45 | // non-canonical path within a Go workspace, replacing them with imports |
| 46 | // of the canonical path. Following a run of fiximports, the workspace |
| 47 | // will no longer depend on the non-canonical copy of the package, so it |
| 48 | // should be safe to delete. It may be necessary to run "go get -u" |
| 49 | // again to ensure that the package is locally installed under its |
| 50 | // canonical path, if it was not already. |
| 51 | // |
| 52 | // The fiximports tool operates locally; it does not make HTTP requests |
| 53 | // and does not discover new custom import comments. It only operates |
| 54 | // on non-canonical packages present in your workspace. |
| 55 | // |
| 56 | // The -baddomains flag is a list of domain names that should always be |
| 57 | // considered non-canonical. You can use this if you wish to make sure |
| 58 | // that you no longer have any dependencies on packages from that |
| 59 | // domain, even those that do not yet provide a canonical import path |
| 60 | // comment. For example, the default value of -baddomains includes the |
| 61 | // moribund code hosting site code.google.com, so fiximports will report |
| 62 | // an error for each import of a package from this domain remaining |
| 63 | // after canonicalization. |
| 64 | // |
| 65 | // To see the changes fiximports would make without applying them, use |
| 66 | // the -n flag. |
| 67 | package main |
| 68 | |
| 69 | import ( |
| 70 | "bytes" |
| 71 | "encoding/json" |
| 72 | "flag" |
| 73 | "fmt" |
| 74 | "go/ast" |
| 75 | "go/build" |
| 76 | "go/format" |
| 77 | "go/parser" |
| 78 | "go/token" |
| 79 | exec "golang.org/x/sys/execabs" |
| 80 | "io" |
| 81 | "io/ioutil" |
| 82 | "log" |
| 83 | "os" |
| 84 | "path" |
| 85 | "path/filepath" |
| 86 | "sort" |
| 87 | "strconv" |
| 88 | "strings" |
| 89 | ) |
| 90 | |
| 91 | // flags |
| 92 | var ( |
| 93 | dryrun = flag.Bool("n", false, "dry run: show changes, but don't apply them") |
| 94 | badDomains = flag.String("baddomains", "code.google.com", |
| 95 | "a comma-separated list of domains from which packages should not be imported") |
| 96 | replaceFlag = flag.String("replace", "", |
| 97 | "a comma-separated list of noncanonical=canonical pairs of package paths. If both items in a pair end with '...', they are treated as path prefixes.") |
| 98 | ) |
| 99 | |
| 100 | // seams for testing |
| 101 | var ( |
| 102 | stderr io.Writer = os.Stderr |
| 103 | writeFile = ioutil.WriteFile |
| 104 | ) |
| 105 | |
| 106 | const usage = `fiximports: rewrite import paths to use canonical package names. |
| 107 | |
| 108 | Usage: fiximports [-n] package... |
| 109 | |
| 110 | The package... arguments specify a list of packages |
| 111 | in the style of the go tool; see "go help packages". |
| 112 | Hint: use "all" or "..." to match the entire workspace. |
| 113 | |
| 114 | For details, see https://pkg.go.dev/golang.org/x/tools/cmd/fiximports |
| 115 | |
| 116 | Flags: |
| 117 | -n: dry run: show changes, but don't apply them |
| 118 | -baddomains a comma-separated list of domains from which packages |
| 119 | should not be imported |
| 120 | ` |
| 121 | |
| 122 | func main() { |
| 123 | flag.Parse() |
| 124 | |
| 125 | if len(flag.Args()) == 0 { |
| 126 | fmt.Fprint(stderr, usage) |
| 127 | os.Exit(1) |
| 128 | } |
| 129 | if !fiximports(flag.Args()...) { |
| 130 | os.Exit(1) |
| 131 | } |
| 132 | } |
| 133 | |
| 134 | type canonicalName struct{ path, name string } |
| 135 | |
| 136 | // fiximports fixes imports in the specified packages. |
| 137 | // Invariant: a false result implies an error was already printed. |
| 138 | func fiximports(packages ...string) bool { |
| 139 | // importedBy is the transpose of the package import graph. |
| 140 | importedBy := make(map[string]map[*build.Package]bool) |
| 141 | |
| 142 | // addEdge adds an edge to the import graph. |
| 143 | addEdge := func(from *build.Package, to string) { |
| 144 | if to == "C" || to == "unsafe" { |
| 145 | return // fake |
| 146 | } |
| 147 | pkgs := importedBy[to] |
| 148 | if pkgs == nil { |
| 149 | pkgs = make(map[*build.Package]bool) |
| 150 | importedBy[to] = pkgs |
| 151 | } |
| 152 | pkgs[from] = true |
| 153 | } |
| 154 | |
| 155 | // List metadata for all packages in the workspace. |
| 156 | pkgs, err := list("...") |
| 157 | if err != nil { |
| 158 | fmt.Fprintf(stderr, "importfix: %v\n", err) |
| 159 | return false |
| 160 | } |
| 161 | |
| 162 | // packageName maps each package's path to its name. |
| 163 | packageName := make(map[string]string) |
| 164 | for _, p := range pkgs { |
| 165 | packageName[p.ImportPath] = p.Package.Name |
| 166 | } |
| 167 | |
| 168 | // canonical maps each non-canonical package path to |
| 169 | // its canonical path and name. |
| 170 | // A present nil value indicates that the canonical package |
| 171 | // is unknown: hosted on a bad domain with no redirect. |
| 172 | canonical := make(map[string]canonicalName) |
| 173 | domains := strings.Split(*badDomains, ",") |
| 174 | |
| 175 | type replaceItem struct { |
| 176 | old, new string |
| 177 | matchPrefix bool |
| 178 | } |
| 179 | var replace []replaceItem |
| 180 | for _, pair := range strings.Split(*replaceFlag, ",") { |
| 181 | if pair == "" { |
| 182 | continue |
| 183 | } |
| 184 | words := strings.Split(pair, "=") |
| 185 | if len(words) != 2 { |
| 186 | fmt.Fprintf(stderr, "importfix: -replace: %q is not of the form \"canonical=noncanonical\".\n", pair) |
| 187 | return false |
| 188 | } |
| 189 | replace = append(replace, replaceItem{ |
| 190 | old: strings.TrimSuffix(words[0], "..."), |
| 191 | new: strings.TrimSuffix(words[1], "..."), |
| 192 | matchPrefix: strings.HasSuffix(words[0], "...") && |
| 193 | strings.HasSuffix(words[1], "..."), |
| 194 | }) |
| 195 | } |
| 196 | |
| 197 | // Find non-canonical packages and populate importedBy graph. |
| 198 | for _, p := range pkgs { |
| 199 | if p.Error != nil { |
| 200 | msg := p.Error.Err |
| 201 | if strings.Contains(msg, "code in directory") && |
| 202 | strings.Contains(msg, "expects import") { |
| 203 | // don't show the very errors we're trying to fix |
| 204 | } else { |
| 205 | fmt.Fprintln(stderr, p.Error) |
| 206 | } |
| 207 | } |
| 208 | |
| 209 | for _, imp := range p.Imports { |
| 210 | addEdge(&p.Package, imp) |
| 211 | } |
| 212 | for _, imp := range p.TestImports { |
| 213 | addEdge(&p.Package, imp) |
| 214 | } |
| 215 | for _, imp := range p.XTestImports { |
| 216 | addEdge(&p.Package, imp) |
| 217 | } |
| 218 | |
| 219 | // Does package have an explicit import comment? |
| 220 | if p.ImportComment != "" { |
| 221 | if p.ImportComment != p.ImportPath { |
| 222 | canonical[p.ImportPath] = canonicalName{ |
| 223 | path: p.Package.ImportComment, |
| 224 | name: p.Package.Name, |
| 225 | } |
| 226 | } |
| 227 | } else { |
| 228 | // Is package matched by a -replace item? |
| 229 | var newPath string |
| 230 | for _, item := range replace { |
| 231 | if item.matchPrefix { |
| 232 | if strings.HasPrefix(p.ImportPath, item.old) { |
| 233 | newPath = item.new + p.ImportPath[len(item.old):] |
| 234 | break |
| 235 | } |
| 236 | } else if p.ImportPath == item.old { |
| 237 | newPath = item.new |
| 238 | break |
| 239 | } |
| 240 | } |
| 241 | if newPath != "" { |
| 242 | newName := packageName[newPath] |
| 243 | if newName == "" { |
| 244 | newName = filepath.Base(newPath) // a guess |
| 245 | } |
| 246 | canonical[p.ImportPath] = canonicalName{ |
| 247 | path: newPath, |
| 248 | name: newName, |
| 249 | } |
| 250 | continue |
| 251 | } |
| 252 | |
| 253 | // Is package matched by a -baddomains item? |
| 254 | for _, domain := range domains { |
| 255 | slash := strings.Index(p.ImportPath, "/") |
| 256 | if slash < 0 { |
| 257 | continue // no slash: standard package |
| 258 | } |
| 259 | if p.ImportPath[:slash] == domain { |
| 260 | // Package comes from bad domain and has no import comment. |
| 261 | // Report an error each time this package is imported. |
| 262 | canonical[p.ImportPath] = canonicalName{} |
| 263 | |
| 264 | // TODO(adonovan): should we make an HTTP request to |
| 265 | // see if there's an HTTP redirect, a "go-import" meta tag, |
| 266 | // or an import comment in the latest revision? |
| 267 | // It would duplicate a lot of logic from "go get". |
| 268 | } |
| 269 | break |
| 270 | } |
| 271 | } |
| 272 | } |
| 273 | |
| 274 | // Find all clients (direct importers) of canonical packages. |
| 275 | // These are the packages that need fixing up. |
| 276 | clients := make(map[*build.Package]bool) |
| 277 | for path := range canonical { |
| 278 | for client := range importedBy[path] { |
| 279 | clients[client] = true |
| 280 | } |
| 281 | } |
| 282 | |
| 283 | // Restrict rewrites to the set of packages specified by the user. |
| 284 | if len(packages) == 1 && (packages[0] == "all" || packages[0] == "...") { |
| 285 | // no restriction |
| 286 | } else { |
| 287 | pkgs, err := list(packages...) |
| 288 | if err != nil { |
| 289 | fmt.Fprintf(stderr, "importfix: %v\n", err) |
| 290 | return false |
| 291 | } |
| 292 | seen := make(map[string]bool) |
| 293 | for _, p := range pkgs { |
| 294 | seen[p.ImportPath] = true |
| 295 | } |
| 296 | for client := range clients { |
| 297 | if !seen[client.ImportPath] { |
| 298 | delete(clients, client) |
| 299 | } |
| 300 | } |
| 301 | } |
| 302 | |
| 303 | // Rewrite selected client packages. |
| 304 | ok := true |
| 305 | for client := range clients { |
| 306 | if !rewritePackage(client, canonical) { |
| 307 | ok = false |
| 308 | |
| 309 | // There were errors. |
| 310 | // Show direct and indirect imports of client. |
| 311 | seen := make(map[string]bool) |
| 312 | var direct, indirect []string |
| 313 | for p := range importedBy[client.ImportPath] { |
| 314 | direct = append(direct, p.ImportPath) |
| 315 | seen[p.ImportPath] = true |
| 316 | } |
| 317 | |
| 318 | var visit func(path string) |
| 319 | visit = func(path string) { |
| 320 | for q := range importedBy[path] { |
| 321 | qpath := q.ImportPath |
| 322 | if !seen[qpath] { |
| 323 | seen[qpath] = true |
| 324 | indirect = append(indirect, qpath) |
| 325 | visit(qpath) |
| 326 | } |
| 327 | } |
| 328 | } |
| 329 | |
| 330 | if direct != nil { |
| 331 | fmt.Fprintf(stderr, "\timported directly by:\n") |
| 332 | sort.Strings(direct) |
| 333 | for _, path := range direct { |
| 334 | fmt.Fprintf(stderr, "\t\t%s\n", path) |
| 335 | visit(path) |
| 336 | } |
| 337 | |
| 338 | if indirect != nil { |
| 339 | fmt.Fprintf(stderr, "\timported indirectly by:\n") |
| 340 | sort.Strings(indirect) |
| 341 | for _, path := range indirect { |
| 342 | fmt.Fprintf(stderr, "\t\t%s\n", path) |
| 343 | } |
| 344 | } |
| 345 | } |
| 346 | } |
| 347 | } |
| 348 | |
| 349 | return ok |
| 350 | } |
| 351 | |
| 352 | // Invariant: false result => error already printed. |
| 353 | func rewritePackage(client *build.Package, canonical map[string]canonicalName) bool { |
| 354 | ok := true |
| 355 | |
| 356 | used := make(map[string]bool) |
| 357 | var filenames []string |
| 358 | filenames = append(filenames, client.GoFiles...) |
| 359 | filenames = append(filenames, client.TestGoFiles...) |
| 360 | filenames = append(filenames, client.XTestGoFiles...) |
| 361 | var first bool |
| 362 | for _, filename := range filenames { |
| 363 | if !first { |
| 364 | first = true |
| 365 | fmt.Fprintf(stderr, "%s\n", client.ImportPath) |
| 366 | } |
| 367 | err := rewriteFile(filepath.Join(client.Dir, filename), canonical, used) |
| 368 | if err != nil { |
| 369 | fmt.Fprintf(stderr, "\tERROR: %v\n", err) |
| 370 | ok = false |
| 371 | } |
| 372 | } |
| 373 | |
| 374 | // Show which imports were renamed in this package. |
| 375 | var keys []string |
| 376 | for key := range used { |
| 377 | keys = append(keys, key) |
| 378 | } |
| 379 | sort.Strings(keys) |
| 380 | for _, key := range keys { |
| 381 | if p := canonical[key]; p.path != "" { |
| 382 | fmt.Fprintf(stderr, "\tfixed: %s -> %s\n", key, p.path) |
| 383 | } else { |
| 384 | fmt.Fprintf(stderr, "\tERROR: %s has no import comment\n", key) |
| 385 | ok = false |
| 386 | } |
| 387 | } |
| 388 | |
| 389 | return ok |
| 390 | } |
| 391 | |
| 392 | // rewrite reads, modifies, and writes filename, replacing all imports |
| 393 | // of packages P in canonical by canonical[P]. |
| 394 | // It records in used which canonical packages were imported. |
| 395 | // used[P]=="" indicates that P was imported but its canonical path is unknown. |
| 396 | func rewriteFile(filename string, canonical map[string]canonicalName, used map[string]bool) error { |
| 397 | fset := token.NewFileSet() |
| 398 | f, err := parser.ParseFile(fset, filename, nil, parser.ParseComments) |
| 399 | if err != nil { |
| 400 | return err |
| 401 | } |
| 402 | var changed bool |
| 403 | for _, imp := range f.Imports { |
| 404 | impPath, err := strconv.Unquote(imp.Path.Value) |
| 405 | if err != nil { |
| 406 | log.Printf("%s: bad import spec %q: %v", |
| 407 | fset.Position(imp.Pos()), imp.Path.Value, err) |
| 408 | continue |
| 409 | } |
| 410 | canon, ok := canonical[impPath] |
| 411 | if !ok { |
| 412 | continue // import path is canonical |
| 413 | } |
| 414 | |
| 415 | used[impPath] = true |
| 416 | |
| 417 | if canon.path == "" { |
| 418 | // The canonical path is unknown (a -baddomain). |
| 419 | // Show the offending import. |
| 420 | // TODO(adonovan): should we show the actual source text? |
| 421 | fmt.Fprintf(stderr, "\t%s:%d: import %q\n", |
| 422 | shortPath(filename), |
| 423 | fset.Position(imp.Pos()).Line, impPath) |
| 424 | continue |
| 425 | } |
| 426 | |
| 427 | changed = true |
| 428 | |
| 429 | imp.Path.Value = strconv.Quote(canon.path) |
| 430 | |
| 431 | // Add a renaming import if necessary. |
| 432 | // |
| 433 | // This is a guess at best. We can't see whether a 'go |
| 434 | // get' of the canonical import path would have the same |
| 435 | // name or not. Assume it's the last segment. |
| 436 | newBase := path.Base(canon.path) |
| 437 | if imp.Name == nil && newBase != canon.name { |
| 438 | imp.Name = &ast.Ident{Name: canon.name} |
| 439 | } |
| 440 | } |
| 441 | |
| 442 | if changed && !*dryrun { |
| 443 | var buf bytes.Buffer |
| 444 | if err := format.Node(&buf, fset, f); err != nil { |
| 445 | return fmt.Errorf("%s: couldn't format file: %v", filename, err) |
| 446 | } |
| 447 | return writeFile(filename, buf.Bytes(), 0644) |
| 448 | } |
| 449 | |
| 450 | return nil |
| 451 | } |
| 452 | |
| 453 | // listPackage is a copy of cmd/go/list.Package. |
| 454 | // It has more fields than build.Package and we need some of them. |
| 455 | type listPackage struct { |
| 456 | build.Package |
| 457 | Error *packageError // error loading package |
| 458 | } |
| 459 | |
| 460 | // A packageError describes an error loading information about a package. |
| 461 | type packageError struct { |
| 462 | ImportStack []string // shortest path from package named on command line to this one |
| 463 | Pos string // position of error |
| 464 | Err string // the error itself |
| 465 | } |
| 466 | |
| 467 | func (e packageError) Error() string { |
| 468 | if e.Pos != "" { |
| 469 | return e.Pos + ": " + e.Err |
| 470 | } |
| 471 | return e.Err |
| 472 | } |
| 473 | |
| 474 | // list runs 'go list' with the specified arguments and returns the |
| 475 | // metadata for matching packages. |
| 476 | func list(args ...string) ([]*listPackage, error) { |
| 477 | cmd := exec.Command("go", append([]string{"list", "-e", "-json"}, args...)...) |
| 478 | cmd.Stdout = new(bytes.Buffer) |
| 479 | cmd.Stderr = stderr |
| 480 | if err := cmd.Run(); err != nil { |
| 481 | return nil, err |
| 482 | } |
| 483 | |
| 484 | dec := json.NewDecoder(cmd.Stdout.(io.Reader)) |
| 485 | var pkgs []*listPackage |
| 486 | for { |
| 487 | var p listPackage |
| 488 | if err := dec.Decode(&p); err == io.EOF { |
| 489 | break |
| 490 | } else if err != nil { |
| 491 | return nil, err |
| 492 | } |
| 493 | pkgs = append(pkgs, &p) |
| 494 | } |
| 495 | return pkgs, nil |
| 496 | } |
| 497 | |
| 498 | // cwd contains the current working directory of the tool. |
| 499 | // |
| 500 | // It is initialized directly so that its value will be set for any other |
| 501 | // package variables or init functions that depend on it, such as the gopath |
| 502 | // variable in main_test.go. |
| 503 | var cwd string = func() string { |
| 504 | cwd, err := os.Getwd() |
| 505 | if err != nil { |
| 506 | log.Fatalf("os.Getwd: %v", err) |
| 507 | } |
| 508 | return cwd |
| 509 | }() |
| 510 | |
| 511 | // shortPath returns an absolute or relative name for path, whatever is shorter. |
| 512 | // Plundered from $GOROOT/src/cmd/go/build.go. |
| 513 | func shortPath(path string) string { |
| 514 | if rel, err := filepath.Rel(cwd, path); err == nil && len(rel) < len(path) { |
| 515 | return rel |
| 516 | } |
| 517 | return path |
| 518 | } |
| 519 |
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