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