libgo/go/cmd/go/internal/load/icfg.go

   1 // Copyright 2017 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 package load
   6
   7 import (
   8         "bytes"
   9         "encoding/json"
  10         "errors"
  11         "io/ioutil"
  12 )
  13
  14 // DebugDeprecatedImportcfg is installed as the undocumented -debug-deprecated-importcfg build flag.
  15 // It is useful for debugging subtle problems in the go command logic but not something
  16 // we want users to depend on. The hope is that the "deprecated" will make that clear.
  17 // We intend to remove this flag in Go 1.11.
  18 var DebugDeprecatedImportcfg debugDeprecatedImportcfgFlag
  19
  20 type debugDeprecatedImportcfgFlag struct {
  21         enabled bool
  22         Import  map[string]string
  23         Pkg     map[string]*debugDeprecatedImportcfgPkg
  24 }
  25
  26 type debugDeprecatedImportcfgPkg struct {
  27         Dir    string
  28         Import map[string]string
  29 }
  30
  31 var (
  32         debugDeprecatedImportcfgMagic = []byte("# debug-deprecated-importcfg\n")
  33         errImportcfgSyntax            = errors.New("malformed syntax")
  34 )
  35
  36 func (f *debugDeprecatedImportcfgFlag) String() string { return "" }
  37
  38 func (f *debugDeprecatedImportcfgFlag) Set(x string) error {
  39         if x == "" {
  40                 *f = debugDeprecatedImportcfgFlag{}
  41                 return nil
  42         }
  43         data, err := ioutil.ReadFile(x)
  44         if err != nil {
  45                 return err
  46         }
  47
  48         if !bytes.HasPrefix(data, debugDeprecatedImportcfgMagic) {
  49                 return errImportcfgSyntax
  50         }
  51         data = data[len(debugDeprecatedImportcfgMagic):]
  52
  53         f.Import = nil
  54         f.Pkg = nil
  55         if err := json.Unmarshal(data, &f); err != nil {
  56                 return errImportcfgSyntax
  57         }
  58         f.enabled = true
  59         return nil
  60 }
  61
  62 func (f *debugDeprecatedImportcfgFlag) lookup(parent *Package, path string) (dir, newPath string) {
  63         newPath = path
  64         if p := f.Import[path]; p != "" {
  65                 newPath = p
  66         }
  67         if parent != nil {
  68                 if p1 := f.Pkg[parent.ImportPath]; p1 != nil {
  69                         if p := p1.Import[path]; p != "" {
  70                                 newPath = p
  71                         }
  72                 }
  73         }
  74         if p2 := f.Pkg[newPath]; p2 != nil {
  75                 return p2.Dir, newPath
  76         }
  77         return "", ""
  78 }