| 1 | // Copyright 2014 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 main |
| 6 | |
| 7 | import ( |
| 8 | "errors" |
| 9 | "flag" |
| 10 | "fmt" |
| 11 | "go/build" |
| 12 | "go/types" |
| 13 | "io/ioutil" |
| 14 | "os" |
| 15 | "path/filepath" |
| 16 | "strings" |
| 17 | ) |
| 18 | |
| 19 | var ( |
| 20 | source = flag.String("s", "", "only consider packages from src, where src is one of the supported compilers") |
| 21 | verbose = flag.Bool("v", false, "verbose mode") |
| 22 | ) |
| 23 | |
| 24 | // lists of registered sources and corresponding importers |
| 25 | var ( |
| 26 | sources []string |
| 27 | importers []types.Importer |
| 28 | errImportFailed = errors.New("import failed") |
| 29 | ) |
| 30 | |
| 31 | func usage() { |
| 32 | fmt.Fprintln(os.Stderr, "usage: godex [flags] {path|qualifiedIdent}") |
| 33 | flag.PrintDefaults() |
| 34 | os.Exit(2) |
| 35 | } |
| 36 | |
| 37 | func report(msg string) { |
| 38 | fmt.Fprintln(os.Stderr, "error: "+msg) |
| 39 | os.Exit(2) |
| 40 | } |
| 41 | |
| 42 | func main() { |
| 43 | flag.Usage = usage |
| 44 | flag.Parse() |
| 45 | |
| 46 | if flag.NArg() == 0 { |
| 47 | report("no package name, path, or file provided") |
| 48 | } |
| 49 | |
| 50 | var imp types.Importer = new(tryImporters) |
| 51 | if *source != "" { |
| 52 | imp = lookup(*source) |
| 53 | if imp == nil { |
| 54 | report("source (-s argument) must be one of: " + strings.Join(sources, ", ")) |
| 55 | } |
| 56 | } |
| 57 | |
| 58 | for _, arg := range flag.Args() { |
| 59 | path, name := splitPathIdent(arg) |
| 60 | logf("\tprocessing %q: path = %q, name = %s\n", arg, path, name) |
| 61 | |
| 62 | // generate possible package path prefixes |
| 63 | // (at the moment we do this for each argument - should probably cache the generated prefixes) |
| 64 | prefixes := make(chan string) |
| 65 | go genPrefixes(prefixes, !filepath.IsAbs(path) && !build.IsLocalImport(path)) |
| 66 | |
| 67 | // import package |
| 68 | pkg, err := tryPrefixes(prefixes, path, imp) |
| 69 | if err != nil { |
| 70 | logf("\t=> ignoring %q: %s\n", path, err) |
| 71 | continue |
| 72 | } |
| 73 | |
| 74 | // filter objects if needed |
| 75 | var filter func(types.Object) bool |
| 76 | if name != "" { |
| 77 | filter = func(obj types.Object) bool { |
| 78 | // TODO(gri) perhaps use regular expression matching here? |
| 79 | return obj.Name() == name |
| 80 | } |
| 81 | } |
| 82 | |
| 83 | // print contents |
| 84 | print(os.Stdout, pkg, filter) |
| 85 | } |
| 86 | } |
| 87 | |
| 88 | func logf(format string, args ...interface{}) { |
| 89 | if *verbose { |
| 90 | fmt.Fprintf(os.Stderr, format, args...) |
| 91 | } |
| 92 | } |
| 93 | |
| 94 | // splitPathIdent splits a path.name argument into its components. |
| 95 | // All but the last path element may contain dots. |
| 96 | func splitPathIdent(arg string) (path, name string) { |
| 97 | if i := strings.LastIndex(arg, "."); i >= 0 { |
| 98 | if j := strings.LastIndex(arg, "/"); j < i { |
| 99 | // '.' is not part of path |
| 100 | path = arg[:i] |
| 101 | name = arg[i+1:] |
| 102 | return |
| 103 | } |
| 104 | } |
| 105 | path = arg |
| 106 | return |
| 107 | } |
| 108 | |
| 109 | // tryPrefixes tries to import the package given by (the possibly partial) path using the given importer imp |
| 110 | // by prepending all possible prefixes to path. It returns with the first package that it could import, or |
| 111 | // with an error. |
| 112 | func tryPrefixes(prefixes chan string, path string, imp types.Importer) (pkg *types.Package, err error) { |
| 113 | for prefix := range prefixes { |
| 114 | actual := path |
| 115 | if prefix == "" { |
| 116 | // don't use filepath.Join as it will sanitize the path and remove |
| 117 | // a leading dot and then the path is not recognized as a relative |
| 118 | // package path by the importers anymore |
| 119 | logf("\ttrying no prefix\n") |
| 120 | } else { |
| 121 | actual = filepath.Join(prefix, path) |
| 122 | logf("\ttrying prefix %q\n", prefix) |
| 123 | } |
| 124 | pkg, err = imp.Import(actual) |
| 125 | if err == nil { |
| 126 | break |
| 127 | } |
| 128 | logf("\t=> importing %q failed: %s\n", actual, err) |
| 129 | } |
| 130 | return |
| 131 | } |
| 132 | |
| 133 | // tryImporters is an importer that tries all registered importers |
| 134 | // successively until one of them succeeds or all of them failed. |
| 135 | type tryImporters struct{} |
| 136 | |
| 137 | func (t *tryImporters) Import(path string) (pkg *types.Package, err error) { |
| 138 | for i, imp := range importers { |
| 139 | logf("\t\ttrying %s import\n", sources[i]) |
| 140 | pkg, err = imp.Import(path) |
| 141 | if err == nil { |
| 142 | break |
| 143 | } |
| 144 | logf("\t\t=> %s import failed: %s\n", sources[i], err) |
| 145 | } |
| 146 | return |
| 147 | } |
| 148 | |
| 149 | type protector struct { |
| 150 | imp types.Importer |
| 151 | } |
| 152 | |
| 153 | func (p *protector) Import(path string) (pkg *types.Package, err error) { |
| 154 | defer func() { |
| 155 | if recover() != nil { |
| 156 | pkg = nil |
| 157 | err = errImportFailed |
| 158 | } |
| 159 | }() |
| 160 | return p.imp.Import(path) |
| 161 | } |
| 162 | |
| 163 | // protect protects an importer imp from panics and returns the protected importer. |
| 164 | func protect(imp types.Importer) types.Importer { |
| 165 | return &protector{imp} |
| 166 | } |
| 167 | |
| 168 | // register registers an importer imp for a given source src. |
| 169 | func register(src string, imp types.Importer) { |
| 170 | if lookup(src) != nil { |
| 171 | panic(src + " importer already registered") |
| 172 | } |
| 173 | sources = append(sources, src) |
| 174 | importers = append(importers, protect(imp)) |
| 175 | } |
| 176 | |
| 177 | // lookup returns the importer imp for a given source src. |
| 178 | func lookup(src string) types.Importer { |
| 179 | for i, s := range sources { |
| 180 | if s == src { |
| 181 | return importers[i] |
| 182 | } |
| 183 | } |
| 184 | return nil |
| 185 | } |
| 186 | |
| 187 | func genPrefixes(out chan string, all bool) { |
| 188 | out <- "" |
| 189 | if all { |
| 190 | platform := build.Default.GOOS + "_" + build.Default.GOARCH |
| 191 | dirnames := append([]string{build.Default.GOROOT}, filepath.SplitList(build.Default.GOPATH)...) |
| 192 | for _, dirname := range dirnames { |
| 193 | walkDir(filepath.Join(dirname, "pkg", platform), "", out) |
| 194 | } |
| 195 | } |
| 196 | close(out) |
| 197 | } |
| 198 | |
| 199 | func walkDir(dirname, prefix string, out chan string) { |
| 200 | fiList, err := ioutil.ReadDir(dirname) |
| 201 | if err != nil { |
| 202 | return |
| 203 | } |
| 204 | for _, fi := range fiList { |
| 205 | if fi.IsDir() && !strings.HasPrefix(fi.Name(), ".") { |
| 206 | prefix := filepath.Join(prefix, fi.Name()) |
| 207 | out <- prefix |
| 208 | walkDir(filepath.Join(dirname, fi.Name()), prefix, out) |
| 209 | } |
| 210 | } |
| 211 | } |
| 212 |
Members