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Viewing changes to src/go/src/code.google.com/p/go.tools/go/gccgoimporter/importer.go

  • Committer: Victor Palau
  • Date: 2015-03-11 14:24:42 UTC
  • Revision ID: vtuson@gmail.com-20150311142442-f2pxp111c8ynv232
public release

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src/go/src/code.google.com/p/go.tools/go/gccgoimporter/importer.go
 
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// Copyright 2013 The Go Authors. All rights reserved.
 
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// Use of this source code is governed by a BSD-style
 
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// license that can be found in the LICENSE file.
 
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// Package gccgoimporter implements Import for gccgo-generated object files.
 
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package gccgoimporter
 
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import (
 
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        "debug/elf"
 
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        "fmt"
 
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        "io"
 
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        "os"
 
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        "path/filepath"
 
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        "strings"
 
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        "code.google.com/p/go.tools/go/types"
 
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)
 
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// Locate the file from which to read export data.
 
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// This is intended to replicate the logic in gofrontend.
 
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func findExportFile(searchpaths []string, pkgpath string) (string, error) {
 
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        for _, spath := range searchpaths {
 
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                pkgfullpath := filepath.Join(spath, pkgpath)
 
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                pkgdir, name := filepath.Split(pkgfullpath)
 
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                for _, filepath := range [...]string{
 
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                        pkgfullpath,
 
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                        pkgfullpath + ".gox",
 
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                        pkgdir + "lib" + name + ".so",
 
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                        pkgdir + "lib" + name + ".a",
 
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                        pkgfullpath + ".o",
 
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                } {
 
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                        fi, err := os.Stat(filepath)
 
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                        if err == nil && !fi.IsDir() {
 
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                                return filepath, nil
 
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                        }
 
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                }
 
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        }
 
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        return "", fmt.Errorf("%s: could not find export data (tried %s)", pkgpath, strings.Join(searchpaths, ":"))
 
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}
 
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// Opens the export data file at the given path. If this is an ELF file,
 
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// searches for and opens the .go_export section.
 
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// This is intended to replicate the logic in gofrontend, although it doesn't handle archive files yet.
 
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func openExportFile(fpath string) (reader io.ReadSeeker, closer io.Closer, err error) {
 
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        f, err := os.Open(fpath)
 
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        if err != nil {
 
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                return
 
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        }
 
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        closer = f
 
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        var magic [4]byte
 
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        _, err = f.ReadAt(magic[:], 0)
 
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        if err != nil {
 
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                f.Close()
 
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                return
 
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        }
 
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        if string(magic[:]) == "v1;\n" {
 
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                // Raw export data.
 
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                reader = f
 
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                return
 
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        }
 
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        ef, err := elf.NewFile(f)
 
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        if err != nil {
 
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                f.Close()
 
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                return
 
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        }
 
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        sec := ef.Section(".go_export")
 
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        if sec == nil {
 
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                err = fmt.Errorf("%s: .go_export section not found", fpath)
 
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                f.Close()
 
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                return
 
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        }
 
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        reader = sec.Open()
 
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        return
 
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}
 
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func GetImporter(searchpaths []string) types.Importer {
 
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        return func(imports map[string]*types.Package, pkgpath string) (pkg *types.Package, err error) {
 
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                if pkgpath == "unsafe" {
 
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                        return types.Unsafe, nil
 
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                }
 
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                fpath, err := findExportFile(searchpaths, pkgpath)
 
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                if err != nil {
 
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                        return
 
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                }
 
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                reader, closer, err := openExportFile(fpath)
 
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                if err != nil {
 
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                        return
 
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                }
 
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                defer closer.Close()
 
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                var p parser
 
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                p.init(fpath, reader, imports)
 
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                pkg = p.parsePackage()
 
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                return
 
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        }
 
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}