From 8ffb773f43c8dc54801ca1d111854e7e881c93c9 Mon Sep 17 00:00:00 2001 From: Frédéric Guillot Date: Sun, 19 Nov 2017 21:10:04 -0800 Subject: First commit --- vendor/golang.org/x/net/html/charset/charset.go | 257 ++++++++++++++++++++++++ 1 file changed, 257 insertions(+) create mode 100644 vendor/golang.org/x/net/html/charset/charset.go (limited to 'vendor/golang.org/x/net/html/charset/charset.go') diff --git a/vendor/golang.org/x/net/html/charset/charset.go b/vendor/golang.org/x/net/html/charset/charset.go new file mode 100644 index 0000000..13bed15 --- /dev/null +++ b/vendor/golang.org/x/net/html/charset/charset.go @@ -0,0 +1,257 @@ +// 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 charset provides common text encodings for HTML documents. +// +// The mapping from encoding labels to encodings is defined at +// https://encoding.spec.whatwg.org/. +package charset // import "golang.org/x/net/html/charset" + +import ( + "bytes" + "fmt" + "io" + "mime" + "strings" + "unicode/utf8" + + "golang.org/x/net/html" + "golang.org/x/text/encoding" + "golang.org/x/text/encoding/charmap" + "golang.org/x/text/encoding/htmlindex" + "golang.org/x/text/transform" +) + +// Lookup returns the encoding with the specified label, and its canonical +// name. It returns nil and the empty string if label is not one of the +// standard encodings for HTML. Matching is case-insensitive and ignores +// leading and trailing whitespace. Encoders will use HTML escape sequences for +// runes that are not supported by the character set. +func Lookup(label string) (e encoding.Encoding, name string) { + e, err := htmlindex.Get(label) + if err != nil { + return nil, "" + } + name, _ = htmlindex.Name(e) + return &htmlEncoding{e}, name +} + +type htmlEncoding struct{ encoding.Encoding } + +func (h *htmlEncoding) NewEncoder() *encoding.Encoder { + // HTML requires a non-terminating legacy encoder. We use HTML escapes to + // substitute unsupported code points. + return encoding.HTMLEscapeUnsupported(h.Encoding.NewEncoder()) +} + +// DetermineEncoding determines the encoding of an HTML document by examining +// up to the first 1024 bytes of content and the declared Content-Type. +// +// See http://www.whatwg.org/specs/web-apps/current-work/multipage/parsing.html#determining-the-character-encoding +func DetermineEncoding(content []byte, contentType string) (e encoding.Encoding, name string, certain bool) { + if len(content) > 1024 { + content = content[:1024] + } + + for _, b := range boms { + if bytes.HasPrefix(content, b.bom) { + e, name = Lookup(b.enc) + return e, name, true + } + } + + if _, params, err := mime.ParseMediaType(contentType); err == nil { + if cs, ok := params["charset"]; ok { + if e, name = Lookup(cs); e != nil { + return e, name, true + } + } + } + + if len(content) > 0 { + e, name = prescan(content) + if e != nil { + return e, name, false + } + } + + // Try to detect UTF-8. + // First eliminate any partial rune at the end. + for i := len(content) - 1; i >= 0 && i > len(content)-4; i-- { + b := content[i] + if b < 0x80 { + break + } + if utf8.RuneStart(b) { + content = content[:i] + break + } + } + hasHighBit := false + for _, c := range content { + if c >= 0x80 { + hasHighBit = true + break + } + } + if hasHighBit && utf8.Valid(content) { + return encoding.Nop, "utf-8", false + } + + // TODO: change default depending on user's locale? + return charmap.Windows1252, "windows-1252", false +} + +// NewReader returns an io.Reader that converts the content of r to UTF-8. +// It calls DetermineEncoding to find out what r's encoding is. +func NewReader(r io.Reader, contentType string) (io.Reader, error) { + preview := make([]byte, 1024) + n, err := io.ReadFull(r, preview) + switch { + case err == io.ErrUnexpectedEOF: + preview = preview[:n] + r = bytes.NewReader(preview) + case err != nil: + return nil, err + default: + r = io.MultiReader(bytes.NewReader(preview), r) + } + + if e, _, _ := DetermineEncoding(preview, contentType); e != encoding.Nop { + r = transform.NewReader(r, e.NewDecoder()) + } + return r, nil +} + +// NewReaderLabel returns a reader that converts from the specified charset to +// UTF-8. It uses Lookup to find the encoding that corresponds to label, and +// returns an error if Lookup returns nil. It is suitable for use as +// encoding/xml.Decoder's CharsetReader function. +func NewReaderLabel(label string, input io.Reader) (io.Reader, error) { + e, _ := Lookup(label) + if e == nil { + return nil, fmt.Errorf("unsupported charset: %q", label) + } + return transform.NewReader(input, e.NewDecoder()), nil +} + +func prescan(content []byte) (e encoding.Encoding, name string) { + z := html.NewTokenizer(bytes.NewReader(content)) + for { + switch z.Next() { + case html.ErrorToken: + return nil, "" + + case html.StartTagToken, html.SelfClosingTagToken: + tagName, hasAttr := z.TagName() + if !bytes.Equal(tagName, []byte("meta")) { + continue + } + attrList := make(map[string]bool) + gotPragma := false + + const ( + dontKnow = iota + doNeedPragma + doNotNeedPragma + ) + needPragma := dontKnow + + name = "" + e = nil + for hasAttr { + var key, val []byte + key, val, hasAttr = z.TagAttr() + ks := string(key) + if attrList[ks] { + continue + } + attrList[ks] = true + for i, c := range val { + if 'A' <= c && c <= 'Z' { + val[i] = c + 0x20 + } + } + + switch ks { + case "http-equiv": + if bytes.Equal(val, []byte("content-type")) { + gotPragma = true + } + + case "content": + if e == nil { + name = fromMetaElement(string(val)) + if name != "" { + e, name = Lookup(name) + if e != nil { + needPragma = doNeedPragma + } + } + } + + case "charset": + e, name = Lookup(string(val)) + needPragma = doNotNeedPragma + } + } + + if needPragma == dontKnow || needPragma == doNeedPragma && !gotPragma { + continue + } + + if strings.HasPrefix(name, "utf-16") { + name = "utf-8" + e = encoding.Nop + } + + if e != nil { + return e, name + } + } + } +} + +func fromMetaElement(s string) string { + for s != "" { + csLoc := strings.Index(s, "charset") + if csLoc == -1 { + return "" + } + s = s[csLoc+len("charset"):] + s = strings.TrimLeft(s, " \t\n\f\r") + if !strings.HasPrefix(s, "=") { + continue + } + s = s[1:] + s = strings.TrimLeft(s, " \t\n\f\r") + if s == "" { + return "" + } + if q := s[0]; q == '"' || q == '\'' { + s = s[1:] + closeQuote := strings.IndexRune(s, rune(q)) + if closeQuote == -1 { + return "" + } + return s[:closeQuote] + } + + end := strings.IndexAny(s, "; \t\n\f\r") + if end == -1 { + end = len(s) + } + return s[:end] + } + return "" +} + +var boms = []struct { + bom []byte + enc string +}{ + {[]byte{0xfe, 0xff}, "utf-16be"}, + {[]byte{0xff, 0xfe}, "utf-16le"}, + {[]byte{0xef, 0xbb, 0xbf}, "utf-8"}, +} -- cgit v1.2.3