| 1 | // Copyright 2013 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 | // Except for this comment and the import path, this file is a verbatim copy of the file |
| 6 | // with the same name in $GOROOT/src/go/internal/gccgoimporter. |
| 7 | |
| 8 | // Package gccgoimporter implements Import for gccgo-generated object files. |
| 9 | package gccgoimporter // import "golang.org/x/tools/go/internal/gccgoimporter" |
| 10 | |
| 11 | import ( |
| 12 | "debug/elf" |
| 13 | "fmt" |
| 14 | "go/types" |
| 15 | "io" |
| 16 | "os" |
| 17 | "path/filepath" |
| 18 | "strings" |
| 19 | ) |
| 20 | |
| 21 | // A PackageInit describes an imported package that needs initialization. |
| 22 | type PackageInit struct { |
| 23 | Name string // short package name |
| 24 | InitFunc string // name of init function |
| 25 | Priority int // priority of init function, see InitData.Priority |
| 26 | } |
| 27 | |
| 28 | // The gccgo-specific init data for a package. |
| 29 | type InitData struct { |
| 30 | // Initialization priority of this package relative to other packages. |
| 31 | // This is based on the maximum depth of the package's dependency graph; |
| 32 | // it is guaranteed to be greater than that of its dependencies. |
| 33 | Priority int |
| 34 | |
| 35 | // The list of packages which this package depends on to be initialized, |
| 36 | // including itself if needed. This is the subset of the transitive closure of |
| 37 | // the package's dependencies that need initialization. |
| 38 | Inits []PackageInit |
| 39 | } |
| 40 | |
| 41 | // Locate the file from which to read export data. |
| 42 | // This is intended to replicate the logic in gofrontend. |
| 43 | func findExportFile(searchpaths []string, pkgpath string) (string, error) { |
| 44 | for _, spath := range searchpaths { |
| 45 | pkgfullpath := filepath.Join(spath, pkgpath) |
| 46 | pkgdir, name := filepath.Split(pkgfullpath) |
| 47 | |
| 48 | for _, filepath := range [...]string{ |
| 49 | pkgfullpath, |
| 50 | pkgfullpath + ".gox", |
| 51 | pkgdir + "lib" + name + ".so", |
| 52 | pkgdir + "lib" + name + ".a", |
| 53 | pkgfullpath + ".o", |
| 54 | } { |
| 55 | fi, err := os.Stat(filepath) |
| 56 | if err == nil && !fi.IsDir() { |
| 57 | return filepath, nil |
| 58 | } |
| 59 | } |
| 60 | } |
| 61 | |
| 62 | return "", fmt.Errorf("%s: could not find export data (tried %s)", pkgpath, strings.Join(searchpaths, ":")) |
| 63 | } |
| 64 | |
| 65 | const ( |
| 66 | gccgov1Magic = "v1;\n" |
| 67 | gccgov2Magic = "v2;\n" |
| 68 | gccgov3Magic = "v3;\n" |
| 69 | goimporterMagic = "\n$$ " |
| 70 | archiveMagic = "!<ar" |
| 71 | ) |
| 72 | |
| 73 | // Opens the export data file at the given path. If this is an ELF file, |
| 74 | // searches for and opens the .go_export section. If this is an archive, |
| 75 | // reads the export data from the first member, which is assumed to be an ELF file. |
| 76 | // This is intended to replicate the logic in gofrontend. |
| 77 | func openExportFile(fpath string) (reader io.ReadSeeker, closer io.Closer, err error) { |
| 78 | f, err := os.Open(fpath) |
| 79 | if err != nil { |
| 80 | return |
| 81 | } |
| 82 | closer = f |
| 83 | defer func() { |
| 84 | if err != nil && closer != nil { |
| 85 | f.Close() |
| 86 | } |
| 87 | }() |
| 88 | |
| 89 | var magic [4]byte |
| 90 | _, err = f.ReadAt(magic[:], 0) |
| 91 | if err != nil { |
| 92 | return |
| 93 | } |
| 94 | |
| 95 | var elfreader io.ReaderAt |
| 96 | switch string(magic[:]) { |
| 97 | case gccgov1Magic, gccgov2Magic, gccgov3Magic, goimporterMagic: |
| 98 | // Raw export data. |
| 99 | reader = f |
| 100 | return |
| 101 | |
| 102 | case archiveMagic: |
| 103 | reader, err = arExportData(f) |
| 104 | return |
| 105 | |
| 106 | default: |
| 107 | elfreader = f |
| 108 | } |
| 109 | |
| 110 | ef, err := elf.NewFile(elfreader) |
| 111 | if err != nil { |
| 112 | return |
| 113 | } |
| 114 | |
| 115 | sec := ef.Section(".go_export") |
| 116 | if sec == nil { |
| 117 | err = fmt.Errorf("%s: .go_export section not found", fpath) |
| 118 | return |
| 119 | } |
| 120 | |
| 121 | reader = sec.Open() |
| 122 | return |
| 123 | } |
| 124 | |
| 125 | // An Importer resolves import paths to Packages. The imports map records |
| 126 | // packages already known, indexed by package path. |
| 127 | // An importer must determine the canonical package path and check imports |
| 128 | // to see if it is already present in the map. If so, the Importer can return |
| 129 | // the map entry. Otherwise, the importer must load the package data for the |
| 130 | // given path into a new *Package, record it in imports map, and return the |
| 131 | // package. |
| 132 | type Importer func(imports map[string]*types.Package, path, srcDir string, lookup func(string) (io.ReadCloser, error)) (*types.Package, error) |
| 133 | |
| 134 | func GetImporter(searchpaths []string, initmap map[*types.Package]InitData) Importer { |
| 135 | return func(imports map[string]*types.Package, pkgpath, srcDir string, lookup func(string) (io.ReadCloser, error)) (pkg *types.Package, err error) { |
| 136 | // TODO(gri): Use srcDir. |
| 137 | // Or not. It's possible that srcDir will fade in importance as |
| 138 | // the go command and other tools provide a translation table |
| 139 | // for relative imports (like ./foo or vendored imports). |
| 140 | if pkgpath == "unsafe" { |
| 141 | return types.Unsafe, nil |
| 142 | } |
| 143 | |
| 144 | var reader io.ReadSeeker |
| 145 | var fpath string |
| 146 | var rc io.ReadCloser |
| 147 | if lookup != nil { |
| 148 | if p := imports[pkgpath]; p != nil && p.Complete() { |
| 149 | return p, nil |
| 150 | } |
| 151 | rc, err = lookup(pkgpath) |
| 152 | if err != nil { |
| 153 | return nil, err |
| 154 | } |
| 155 | } |
| 156 | if rc != nil { |
| 157 | defer rc.Close() |
| 158 | rs, ok := rc.(io.ReadSeeker) |
| 159 | if !ok { |
| 160 | return nil, fmt.Errorf("gccgo importer requires lookup to return an io.ReadSeeker, have %T", rc) |
| 161 | } |
| 162 | reader = rs |
| 163 | fpath = "<lookup " + pkgpath + ">" |
| 164 | // Take name from Name method (like on os.File) if present. |
| 165 | if n, ok := rc.(interface{ Name() string }); ok { |
| 166 | fpath = n.Name() |
| 167 | } |
| 168 | } else { |
| 169 | fpath, err = findExportFile(searchpaths, pkgpath) |
| 170 | if err != nil { |
| 171 | return nil, err |
| 172 | } |
| 173 | |
| 174 | r, closer, err := openExportFile(fpath) |
| 175 | if err != nil { |
| 176 | return nil, err |
| 177 | } |
| 178 | if closer != nil { |
| 179 | defer closer.Close() |
| 180 | } |
| 181 | reader = r |
| 182 | } |
| 183 | |
| 184 | var magics string |
| 185 | magics, err = readMagic(reader) |
| 186 | if err != nil { |
| 187 | return |
| 188 | } |
| 189 | |
| 190 | if magics == archiveMagic { |
| 191 | reader, err = arExportData(reader) |
| 192 | if err != nil { |
| 193 | return |
| 194 | } |
| 195 | magics, err = readMagic(reader) |
| 196 | if err != nil { |
| 197 | return |
| 198 | } |
| 199 | } |
| 200 | |
| 201 | switch magics { |
| 202 | case gccgov1Magic, gccgov2Magic, gccgov3Magic: |
| 203 | var p parser |
| 204 | p.init(fpath, reader, imports) |
| 205 | pkg = p.parsePackage() |
| 206 | if initmap != nil { |
| 207 | initmap[pkg] = p.initdata |
| 208 | } |
| 209 | |
| 210 | // Excluded for now: Standard gccgo doesn't support this import format currently. |
| 211 | // case goimporterMagic: |
| 212 | // var data []byte |
| 213 | // data, err = ioutil.ReadAll(reader) |
| 214 | // if err != nil { |
| 215 | // return |
| 216 | // } |
| 217 | // var n int |
| 218 | // n, pkg, err = importer.ImportData(imports, data) |
| 219 | // if err != nil { |
| 220 | // return |
| 221 | // } |
| 222 | |
| 223 | // if initmap != nil { |
| 224 | // suffixreader := bytes.NewReader(data[n:]) |
| 225 | // var p parser |
| 226 | // p.init(fpath, suffixreader, nil) |
| 227 | // p.parseInitData() |
| 228 | // initmap[pkg] = p.initdata |
| 229 | // } |
| 230 | |
| 231 | default: |
| 232 | err = fmt.Errorf("unrecognized magic string: %q", magics) |
| 233 | } |
| 234 | |
| 235 | return |
| 236 | } |
| 237 | } |
| 238 | |
| 239 | // readMagic reads the four bytes at the start of a ReadSeeker and |
| 240 | // returns them as a string. |
| 241 | func readMagic(reader io.ReadSeeker) (string, error) { |
| 242 | var magic [4]byte |
| 243 | if _, err := reader.Read(magic[:]); err != nil { |
| 244 | return "", err |
| 245 | } |
| 246 | if _, err := reader.Seek(0, io.SeekStart); err != nil { |
| 247 | return "", err |
| 248 | } |
| 249 | return string(magic[:]), nil |
| 250 | } |
| 251 |
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