| 1 | // Copyright 2011 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 | // This file is a reduced copy of $GOROOT/src/go/internal/gcimporter/gcimporter.go. |
| 6 | |
| 7 | // Package gcimporter provides various functions for reading |
| 8 | // gc-generated object files that can be used to implement the |
| 9 | // Importer interface defined by the Go 1.5 standard library package. |
| 10 | package gcimporter // import "golang.org/x/tools/internal/gcimporter" |
| 11 | |
| 12 | import ( |
| 13 | "bufio" |
| 14 | "bytes" |
| 15 | "fmt" |
| 16 | "go/build" |
| 17 | "go/token" |
| 18 | "go/types" |
| 19 | "io" |
| 20 | "io/ioutil" |
| 21 | "os" |
| 22 | "os/exec" |
| 23 | "path/filepath" |
| 24 | "strings" |
| 25 | "sync" |
| 26 | ) |
| 27 | |
| 28 | const ( |
| 29 | // Enable debug during development: it adds some additional checks, and |
| 30 | // prevents errors from being recovered. |
| 31 | debug = false |
| 32 | |
| 33 | // If trace is set, debugging output is printed to std out. |
| 34 | trace = false |
| 35 | ) |
| 36 | |
| 37 | var exportMap sync.Map // package dir → func() (string, bool) |
| 38 | |
| 39 | // lookupGorootExport returns the location of the export data |
| 40 | // (normally found in the build cache, but located in GOROOT/pkg |
| 41 | // in prior Go releases) for the package located in pkgDir. |
| 42 | // |
| 43 | // (We use the package's directory instead of its import path |
| 44 | // mainly to simplify handling of the packages in src/vendor |
| 45 | // and cmd/vendor.) |
| 46 | func lookupGorootExport(pkgDir string) (string, bool) { |
| 47 | f, ok := exportMap.Load(pkgDir) |
| 48 | if !ok { |
| 49 | var ( |
| 50 | listOnce sync.Once |
| 51 | exportPath string |
| 52 | ) |
| 53 | f, _ = exportMap.LoadOrStore(pkgDir, func() (string, bool) { |
| 54 | listOnce.Do(func() { |
| 55 | cmd := exec.Command("go", "list", "-export", "-f", "{{.Export}}", pkgDir) |
| 56 | cmd.Dir = build.Default.GOROOT |
| 57 | var output []byte |
| 58 | output, err := cmd.Output() |
| 59 | if err != nil { |
| 60 | return |
| 61 | } |
| 62 | |
| 63 | exports := strings.Split(string(bytes.TrimSpace(output)), "\n") |
| 64 | if len(exports) != 1 { |
| 65 | return |
| 66 | } |
| 67 | |
| 68 | exportPath = exports[0] |
| 69 | }) |
| 70 | |
| 71 | return exportPath, exportPath != "" |
| 72 | }) |
| 73 | } |
| 74 | |
| 75 | return f.(func() (string, bool))() |
| 76 | } |
| 77 | |
| 78 | var pkgExts = [...]string{".a", ".o"} |
| 79 | |
| 80 | // FindPkg returns the filename and unique package id for an import |
| 81 | // path based on package information provided by build.Import (using |
| 82 | // the build.Default build.Context). A relative srcDir is interpreted |
| 83 | // relative to the current working directory. |
| 84 | // If no file was found, an empty filename is returned. |
| 85 | func FindPkg(path, srcDir string) (filename, id string) { |
| 86 | if path == "" { |
| 87 | return |
| 88 | } |
| 89 | |
| 90 | var noext string |
| 91 | switch { |
| 92 | default: |
| 93 | // "x" -> "$GOPATH/pkg/$GOOS_$GOARCH/x.ext", "x" |
| 94 | // Don't require the source files to be present. |
| 95 | if abs, err := filepath.Abs(srcDir); err == nil { // see issue 14282 |
| 96 | srcDir = abs |
| 97 | } |
| 98 | bp, _ := build.Import(path, srcDir, build.FindOnly|build.AllowBinary) |
| 99 | if bp.PkgObj == "" { |
| 100 | var ok bool |
| 101 | if bp.Goroot && bp.Dir != "" { |
| 102 | filename, ok = lookupGorootExport(bp.Dir) |
| 103 | } |
| 104 | if !ok { |
| 105 | id = path // make sure we have an id to print in error message |
| 106 | return |
| 107 | } |
| 108 | } else { |
| 109 | noext = strings.TrimSuffix(bp.PkgObj, ".a") |
| 110 | id = bp.ImportPath |
| 111 | } |
| 112 | |
| 113 | case build.IsLocalImport(path): |
| 114 | // "./x" -> "/this/directory/x.ext", "/this/directory/x" |
| 115 | noext = filepath.Join(srcDir, path) |
| 116 | id = noext |
| 117 | |
| 118 | case filepath.IsAbs(path): |
| 119 | // for completeness only - go/build.Import |
| 120 | // does not support absolute imports |
| 121 | // "/x" -> "/x.ext", "/x" |
| 122 | noext = path |
| 123 | id = path |
| 124 | } |
| 125 | |
| 126 | if false { // for debugging |
| 127 | if path != id { |
| 128 | fmt.Printf("%s -> %s\n", path, id) |
| 129 | } |
| 130 | } |
| 131 | |
| 132 | if filename != "" { |
| 133 | if f, err := os.Stat(filename); err == nil && !f.IsDir() { |
| 134 | return |
| 135 | } |
| 136 | } |
| 137 | |
| 138 | // try extensions |
| 139 | for _, ext := range pkgExts { |
| 140 | filename = noext + ext |
| 141 | if f, err := os.Stat(filename); err == nil && !f.IsDir() { |
| 142 | return |
| 143 | } |
| 144 | } |
| 145 | |
| 146 | filename = "" // not found |
| 147 | return |
| 148 | } |
| 149 | |
| 150 | // Import imports a gc-generated package given its import path and srcDir, adds |
| 151 | // the corresponding package object to the packages map, and returns the object. |
| 152 | // The packages map must contain all packages already imported. |
| 153 | func Import(packages map[string]*types.Package, path, srcDir string, lookup func(path string) (io.ReadCloser, error)) (pkg *types.Package, err error) { |
| 154 | var rc io.ReadCloser |
| 155 | var filename, id string |
| 156 | if lookup != nil { |
| 157 | // With custom lookup specified, assume that caller has |
| 158 | // converted path to a canonical import path for use in the map. |
| 159 | if path == "unsafe" { |
| 160 | return types.Unsafe, nil |
| 161 | } |
| 162 | id = path |
| 163 | |
| 164 | // No need to re-import if the package was imported completely before. |
| 165 | if pkg = packages[id]; pkg != nil && pkg.Complete() { |
| 166 | return |
| 167 | } |
| 168 | f, err := lookup(path) |
| 169 | if err != nil { |
| 170 | return nil, err |
| 171 | } |
| 172 | rc = f |
| 173 | } else { |
| 174 | filename, id = FindPkg(path, srcDir) |
| 175 | if filename == "" { |
| 176 | if path == "unsafe" { |
| 177 | return types.Unsafe, nil |
| 178 | } |
| 179 | return nil, fmt.Errorf("can't find import: %q", id) |
| 180 | } |
| 181 | |
| 182 | // no need to re-import if the package was imported completely before |
| 183 | if pkg = packages[id]; pkg != nil && pkg.Complete() { |
| 184 | return |
| 185 | } |
| 186 | |
| 187 | // open file |
| 188 | f, err := os.Open(filename) |
| 189 | if err != nil { |
| 190 | return nil, err |
| 191 | } |
| 192 | defer func() { |
| 193 | if err != nil { |
| 194 | // add file name to error |
| 195 | err = fmt.Errorf("%s: %v", filename, err) |
| 196 | } |
| 197 | }() |
| 198 | rc = f |
| 199 | } |
| 200 | defer rc.Close() |
| 201 | |
| 202 | var hdr string |
| 203 | var size int64 |
| 204 | buf := bufio.NewReader(rc) |
| 205 | if hdr, size, err = FindExportData(buf); err != nil { |
| 206 | return |
| 207 | } |
| 208 | |
| 209 | switch hdr { |
| 210 | case "$$B\n": |
| 211 | var data []byte |
| 212 | data, err = ioutil.ReadAll(buf) |
| 213 | if err != nil { |
| 214 | break |
| 215 | } |
| 216 | |
| 217 | // TODO(gri): allow clients of go/importer to provide a FileSet. |
| 218 | // Or, define a new standard go/types/gcexportdata package. |
| 219 | fset := token.NewFileSet() |
| 220 | |
| 221 | // The indexed export format starts with an 'i'; the older |
| 222 | // binary export format starts with a 'c', 'd', or 'v' |
| 223 | // (from "version"). Select appropriate importer. |
| 224 | if len(data) > 0 { |
| 225 | switch data[0] { |
| 226 | case 'i': |
| 227 | _, pkg, err := IImportData(fset, packages, data[1:], id) |
| 228 | return pkg, err |
| 229 | |
| 230 | case 'v', 'c', 'd': |
| 231 | _, pkg, err := BImportData(fset, packages, data, id) |
| 232 | return pkg, err |
| 233 | |
| 234 | case 'u': |
| 235 | _, pkg, err := UImportData(fset, packages, data[1:size], id) |
| 236 | return pkg, err |
| 237 | |
| 238 | default: |
| 239 | l := len(data) |
| 240 | if l > 10 { |
| 241 | l = 10 |
| 242 | } |
| 243 | return nil, fmt.Errorf("unexpected export data with prefix %q for path %s", string(data[:l]), id) |
| 244 | } |
| 245 | } |
| 246 | |
| 247 | default: |
| 248 | err = fmt.Errorf("unknown export data header: %q", hdr) |
| 249 | } |
| 250 | |
| 251 | return |
| 252 | } |
| 253 | |
| 254 | func deref(typ types.Type) types.Type { |
| 255 | if p, _ := typ.(*types.Pointer); p != nil { |
| 256 | return p.Elem() |
| 257 | } |
| 258 | return typ |
| 259 | } |
| 260 | |
| 261 | type byPath []*types.Package |
| 262 | |
| 263 | func (a byPath) Len() int { return len(a) } |
| 264 | func (a byPath) Swap(i, j int) { a[i], a[j] = a[j], a[i] } |
| 265 | func (a byPath) Less(i, j int) bool { return a[i].Path() < a[j].Path() } |
| 266 |
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