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// Copyright 2011 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 gcimporter implements Import for gc-generated object files.
package gcimporter // import "go/internal/gcimporter"
import (
"bufio"
"fmt"
"go/build"
"go/token"
"go/types"
"io/ioutil"
"os"
"path/filepath"
"strings"
)
// debugging/development support
const debug = false
var pkgExts = [...]string{".a", ".o"}
// FindPkg returns the filename and unique package id for an import
// path based on package information provided by build.Import (using
// the build.Default build.Context). A relative srcDir is interpreted
// relative to the current working directory.
// If no file was found, an empty filename is returned.
//
func FindPkg(path, srcDir string) (filename, id string) {
if path == "" {
return
}
var noext string
switch {
default:
// "x" -> "$GOPATH/pkg/$GOOS_$GOARCH/x.ext", "x"
// Don't require the source files to be present.
if abs, err := filepath.Abs(srcDir); err == nil { // see issue 14282
srcDir = abs
}
bp, _ := build.Import(path, srcDir, build.FindOnly|build.AllowBinary)
if bp.PkgObj == "" {
id = path // make sure we have an id to print in error message
return
}
noext = strings.TrimSuffix(bp.PkgObj, ".a")
id = bp.ImportPath
case build.IsLocalImport(path):
// "./x" -> "/this/directory/x.ext", "/this/directory/x"
noext = filepath.Join(srcDir, path)
id = noext
case filepath.IsAbs(path):
// for completeness only - go/build.Import
// does not support absolute imports
// "/x" -> "/x.ext", "/x"
noext = path
id = path
}
if false { // for debugging
if path != id {
fmt.Printf("%s -> %s\n", path, id)
}
}
// try extensions
for _, ext := range pkgExts {
filename = noext + ext
if f, err := os.Stat(filename); err == nil && !f.IsDir() {
return
}
}
filename = "" // not found
return
}
// Import imports a gc-generated package given its import path and srcDir, adds
// the corresponding package object to the packages map, and returns the object.
// The packages map must contain all packages already imported.
//
func Import(packages map[string]*types.Package, path, srcDir string) (pkg *types.Package, err error) {
filename, id := FindPkg(path, srcDir)
if filename == "" {
if path == "unsafe" {
return types.Unsafe, nil
}
err = fmt.Errorf("can't find import: %q", id)
return
}
// no need to re-import if the package was imported completely before
if pkg = packages[id]; pkg != nil && pkg.Complete() {
return
}
// open file
f, err := os.Open(filename)
if err != nil {
return
}
defer func() {
f.Close()
if err != nil {
// add file name to error
err = fmt.Errorf("%s: %v", filename, err)
}
}()
var hdr string
buf := bufio.NewReader(f)
if hdr, err = FindExportData(buf); err != nil {
return
}
switch hdr {
case "$$\n":
err = fmt.Errorf("import %q: old export format no longer supported (recompile library)", path)
case "$$B\n":
var data []byte
data, err = ioutil.ReadAll(buf)
if err == nil {
// TODO(gri): allow clients of go/importer to provide a FileSet.
// Or, define a new standard go/types/gcexportdata package.
fset := token.NewFileSet()
_, pkg, err = BImportData(fset, packages, data, id)
return
}
default:
err = fmt.Errorf("unknown export data header: %q", hdr)
}
return
}
func deref(typ types.Type) types.Type {
if p, _ := typ.(*types.Pointer); p != nil {
return p.Elem()
}
return typ
}
type byPath []*types.Package
func (a byPath) Len() int { return len(a) }
func (a byPath) Swap(i, j int) { a[i], a[j] = a[j], a[i] }
func (a byPath) Less(i, j int) bool { return a[i].Path() < a[j].Path() }
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