134 lines
5.3 KiB
Go
134 lines
5.3 KiB
Go
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// Copyright 2016 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 gcexportdata provides functions for locating, reading, and
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// writing export data files containing type information produced by the
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// gc compiler. This package supports go1.7 export data format and all
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// later versions.
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//
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// Although it might seem convenient for this package to live alongside
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// go/types in the standard library, this would cause version skew
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// problems for developer tools that use it, since they must be able to
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// consume the outputs of the gc compiler both before and after a Go
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// update such as from Go 1.7 to Go 1.8. Because this package lives in
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// golang.org/x/tools, sites can update their version of this repo some
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// time before the Go 1.8 release and rebuild and redeploy their
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// developer tools, which will then be able to consume both Go 1.7 and
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// Go 1.8 export data files, so they will work before and after the
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// Go update. (See discussion at https://golang.org/issue/15651.)
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//
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package gcexportdata // import "golang.org/x/tools/go/gcexportdata"
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import (
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"bufio"
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"bytes"
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"fmt"
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"go/token"
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"go/types"
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"io"
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"io/ioutil"
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"golang.org/x/tools/go/internal/gcimporter"
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)
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// Find returns the name of an object (.o) or archive (.a) file
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// containing type information for the specified import path,
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// using the workspace layout conventions of go/build.
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// If no file was found, an empty filename is returned.
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//
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// A relative srcDir is interpreted relative to the current working directory.
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//
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// Find also returns the package's resolved (canonical) import path,
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// reflecting the effects of srcDir and vendoring on importPath.
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func Find(importPath, srcDir string) (filename, path string) {
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return gcimporter.FindPkg(importPath, srcDir)
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}
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// NewReader returns a reader for the export data section of an object
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// (.o) or archive (.a) file read from r. The new reader may provide
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// additional trailing data beyond the end of the export data.
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func NewReader(r io.Reader) (io.Reader, error) {
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buf := bufio.NewReader(r)
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_, err := gcimporter.FindExportData(buf)
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// If we ever switch to a zip-like archive format with the ToC
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// at the end, we can return the correct portion of export data,
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// but for now we must return the entire rest of the file.
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return buf, err
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}
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// Read reads export data from in, decodes it, and returns type
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// information for the package.
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// The package name is specified by path.
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// File position information is added to fset.
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//
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// Read may inspect and add to the imports map to ensure that references
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// within the export data to other packages are consistent. The caller
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// must ensure that imports[path] does not exist, or exists but is
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// incomplete (see types.Package.Complete), and Read inserts the
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// resulting package into this map entry.
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//
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// On return, the state of the reader is undefined.
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func Read(in io.Reader, fset *token.FileSet, imports map[string]*types.Package, path string) (*types.Package, error) {
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data, err := ioutil.ReadAll(in)
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if err != nil {
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return nil, fmt.Errorf("reading export data for %q: %v", path, err)
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}
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if bytes.HasPrefix(data, []byte("!<arch>")) {
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return nil, fmt.Errorf("can't read export data for %q directly from an archive file (call gcexportdata.NewReader first to extract export data)", path)
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}
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// The App Engine Go runtime v1.6 uses the old export data format.
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// TODO(adonovan): delete once v1.7 has been around for a while.
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if bytes.HasPrefix(data, []byte("package ")) {
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return gcimporter.ImportData(imports, path, path, bytes.NewReader(data))
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}
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// The indexed export format starts with an 'i'; the older
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// binary export format starts with a 'c', 'd', or 'v'
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// (from "version"). Select appropriate importer.
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if len(data) > 0 && data[0] == 'i' {
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_, pkg, err := gcimporter.IImportData(fset, imports, data[1:], path)
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return pkg, err
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}
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_, pkg, err := gcimporter.BImportData(fset, imports, data, path)
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return pkg, err
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}
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// Write writes encoded type information for the specified package to out.
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// The FileSet provides file position information for named objects.
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func Write(out io.Writer, fset *token.FileSet, pkg *types.Package) error {
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if _, err := io.WriteString(out, "i"); err != nil {
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return err
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}
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return gcimporter.IExportData(out, fset, pkg)
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}
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// ReadBundle reads an export bundle from in, decodes it, and returns type
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// information for the packages.
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// File position information is added to fset.
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//
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// ReadBundle may inspect and add to the imports map to ensure that references
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// within the export bundle to other packages are consistent.
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//
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// On return, the state of the reader is undefined.
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//
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// Experimental: This API is experimental and may change in the future.
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func ReadBundle(in io.Reader, fset *token.FileSet, imports map[string]*types.Package) ([]*types.Package, error) {
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data, err := ioutil.ReadAll(in)
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if err != nil {
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return nil, fmt.Errorf("reading export bundle: %v", err)
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}
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return gcimporter.IImportBundle(fset, imports, data)
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}
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// WriteBundle writes encoded type information for the specified packages to out.
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// The FileSet provides file position information for named objects.
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//
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// Experimental: This API is experimental and may change in the future.
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func WriteBundle(out io.Writer, fset *token.FileSet, pkgs []*types.Package) error {
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return gcimporter.IExportBundle(out, fset, pkgs)
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}
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