1 // Copyright 2012 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 // +build !cmd_go_bootstrap 6 7 // This code is compiled into the real 'go' binary, but it is not 8 // compiled into the binary that is built during all.bash, so as 9 // to avoid needing to build net (and thus use cgo) during the 10 // bootstrap process. 11 12 package main 13 14 import ( 15 "encoding/xml" 16 "fmt" 17 "io" 18 "strings" 19 ) 20 21 // charsetReader returns a reader for the given charset. Currently 22 // it only supports UTF-8 and ASCII. Otherwise, it returns a meaningful 23 // error which is printed by go get, so the user can find why the package 24 // wasn't downloaded if the encoding is not supported. Note that, in 25 // order to reduce potential errors, ASCII is treated as UTF-8 (i.e. characters 26 // greater than 0x7f are not rejected). 27 func charsetReader(charset string, input io.Reader) (io.Reader, error) { 28 switch strings.ToLower(charset) { 29 case "ascii": 30 return input, nil 31 default: 32 return nil, fmt.Errorf("can't decode XML document using charset %q", charset) 33 } 34 } 35 36 // parseMetaGoImports returns meta imports from the HTML in r. 37 // Parsing ends at the end of the <head> section or the beginning of the <body>. 38 func parseMetaGoImports(r io.Reader) (imports []metaImport, err error) { 39 d := xml.NewDecoder(r) 40 d.CharsetReader = charsetReader 41 d.Strict = false 42 var t xml.Token 43 for { 44 t, err = d.RawToken() 45 if err != nil { 46 if err == io.EOF || len(imports) > 0 { 47 err = nil 48 } 49 return 50 } 51 if e, ok := t.(xml.StartElement); ok && strings.EqualFold(e.Name.Local, "body") { 52 return 53 } 54 if e, ok := t.(xml.EndElement); ok && strings.EqualFold(e.Name.Local, "head") { 55 return 56 } 57 e, ok := t.(xml.StartElement) 58 if !ok || !strings.EqualFold(e.Name.Local, "meta") { 59 continue 60 } 61 if attrValue(e.Attr, "name") != "go-import" { 62 continue 63 } 64 if f := strings.Fields(attrValue(e.Attr, "content")); len(f) == 3 { 65 imports = append(imports, metaImport{ 66 Prefix: f[0], 67 VCS: f[1], 68 RepoRoot: f[2], 69 }) 70 } 71 } 72 } 73 74 // attrValue returns the attribute value for the case-insensitive key 75 // `name', or the empty string if nothing is found. 76 func attrValue(attrs []xml.Attr, name string) string { 77 for _, a := range attrs { 78 if strings.EqualFold(a.Name.Local, name) { 79 return a.Value 80 } 81 } 82 return "" 83 } 84
