OpenCores
URL https://opencores.org/ocsvn/openrisc/openrisc/trunk

Subversion Repositories openrisc

[/] [openrisc/] [trunk/] [gnu-dev/] [or1k-gcc/] [libgo/] [go/] [html/] [template/] [escape.go] - Blame information for rev 801

Go to most recent revision | Details | Compare with Previous | View Log

Line No. Rev Author Line
1 747 jeremybenn 
// Copyright 2011 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 template
6 
 
7 
import (
8 
        "bytes"
9 
        "fmt"
10 
        "html"
11 
        "text/template"
12 
        "text/template/parse"
13 
)
14 
 
15 
// escapeTemplates rewrites the named templates, which must be
16 
// associated with t, to guarantee that the output of any of the named
17 
// templates is properly escaped.  Names should include the names of
18 
// all templates that might be Executed but need not include helper
19 
// templates.  If no error is returned, then the named templates have
20 
// been modified.  Otherwise the named templates have been rendered
21 
// unusable.
22 
func escapeTemplates(tmpl *Template, names ...string) error {
23 
        e := newEscaper(tmpl)
24 
        for _, name := range names {
25 
                c, _ := e.escapeTree(context{}, name, 0)
26 
                var err error
27 
                if c.err != nil {
28 
                        err, c.err.Name = c.err, name
29 
                } else if c.state != stateText {
30 
                        err = &Error{ErrEndContext, name, 0, fmt.Sprintf("ends in a non-text context: %v", c)}
31 
                }
32 
                if err != nil {
33 
                        // Prevent execution of unsafe templates.
34 
                        for _, name := range names {
35 
                                if t := tmpl.set[name]; t != nil {
36 
                                        t.text.Tree = nil
37 
                                }
38 
                        }
39 
                        return err
40 
                }
41 
                tmpl.escaped = true
42 
        }
43 
        e.commit()
44 
        return nil
45 
}
46 
 
47 
// funcMap maps command names to functions that render their inputs safe.
48 
var funcMap = template.FuncMap{
49 
        "exp_template_html_attrescaper":     attrEscaper,
50 
        "exp_template_html_commentescaper":  commentEscaper,
51 
        "exp_template_html_cssescaper":      cssEscaper,
52 
        "exp_template_html_cssvaluefilter":  cssValueFilter,
53 
        "exp_template_html_htmlnamefilter":  htmlNameFilter,
54 
        "exp_template_html_htmlescaper":     htmlEscaper,
55 
        "exp_template_html_jsregexpescaper": jsRegexpEscaper,
56 
        "exp_template_html_jsstrescaper":    jsStrEscaper,
57 
        "exp_template_html_jsvalescaper":    jsValEscaper,
58 
        "exp_template_html_nospaceescaper":  htmlNospaceEscaper,
59 
        "exp_template_html_rcdataescaper":   rcdataEscaper,
60 
        "exp_template_html_urlescaper":      urlEscaper,
61 
        "exp_template_html_urlfilter":       urlFilter,
62 
        "exp_template_html_urlnormalizer":   urlNormalizer,
63 
}
64 
 
65 
// equivEscapers matches contextual escapers to equivalent template builtins.
66 
var equivEscapers = map[string]string{
67 
        "exp_template_html_attrescaper":    "html",
68 
        "exp_template_html_htmlescaper":    "html",
69 
        "exp_template_html_nospaceescaper": "html",
70 
        "exp_template_html_rcdataescaper":  "html",
71 
        "exp_template_html_urlescaper":     "urlquery",
72 
        "exp_template_html_urlnormalizer":  "urlquery",
73 
}
74 
 
75 
// escaper collects type inferences about templates and changes needed to make
76 
// templates injection safe.
77 
type escaper struct {
78 
        tmpl *Template
79 
        // output[templateName] is the output context for a templateName that
80 
        // has been mangled to include its input context.
81 
        output map[string]context
82 
        // derived[c.mangle(name)] maps to a template derived from the template
83 
        // named name templateName for the start context c.
84 
        derived map[string]*template.Template
85 
        // called[templateName] is a set of called mangled template names.
86 
        called map[string]bool
87 
        // xxxNodeEdits are the accumulated edits to apply during commit.
88 
        // Such edits are not applied immediately in case a template set
89 
        // executes a given template in different escaping contexts.
90 
        actionNodeEdits   map[*parse.ActionNode][]string
91 
        templateNodeEdits map[*parse.TemplateNode]string
92 
        textNodeEdits     map[*parse.TextNode][]byte
93 
}
94 
 
95 
// newEscaper creates a blank escaper for the given set.
96 
func newEscaper(t *Template) *escaper {
97 
        return &escaper{
98 
                t,
99 
                map[string]context{},
100 
                map[string]*template.Template{},
101 
                map[string]bool{},
102 
                map[*parse.ActionNode][]string{},
103 
                map[*parse.TemplateNode]string{},
104 
                map[*parse.TextNode][]byte{},
105 
        }
106 
}
107 
 
108 
// filterFailsafe is an innocuous word that is emitted in place of unsafe values
109 
// by sanitizer functions. It is not a keyword in any programming language,
110 
// contains no special characters, is not empty, and when it appears in output
111 
// it is distinct enough that a developer can find the source of the problem
112 
// via a search engine.
113 
const filterFailsafe = "ZgotmplZ"
114 
 
115 
// escape escapes a template node.
116 
func (e *escaper) escape(c context, n parse.Node) context {
117 
        switch n := n.(type) {
118 
        case *parse.ActionNode:
119 
                return e.escapeAction(c, n)
120 
        case *parse.IfNode:
121 
                return e.escapeBranch(c, &n.BranchNode, "if")
122 
        case *parse.ListNode:
123 
                return e.escapeList(c, n)
124 
        case *parse.RangeNode:
125 
                return e.escapeBranch(c, &n.BranchNode, "range")
126 
        case *parse.TemplateNode:
127 
                return e.escapeTemplate(c, n)
128 
        case *parse.TextNode:
129 
                return e.escapeText(c, n)
130 
        case *parse.WithNode:
131 
                return e.escapeBranch(c, &n.BranchNode, "with")
132 
        }
133 
        panic("escaping " + n.String() + " is unimplemented")
134 
}
135 
 
136 
// escapeAction escapes an action template node.
137 
func (e *escaper) escapeAction(c context, n *parse.ActionNode) context {
138 
        if len(n.Pipe.Decl) != 0 {
139 
                // A local variable assignment, not an interpolation.
140 
                return c
141 
        }
142 
        c = nudge(c)
143 
        s := make([]string, 0, 3)
144 
        switch c.state {
145 
        case stateError:
146 
                return c
147 
        case stateURL, stateCSSDqStr, stateCSSSqStr, stateCSSDqURL, stateCSSSqURL, stateCSSURL:
148 
                switch c.urlPart {
149 
                case urlPartNone:
150 
                        s = append(s, "exp_template_html_urlfilter")
151 
                        fallthrough
152 
                case urlPartPreQuery:
153 
                        switch c.state {
154 
                        case stateCSSDqStr, stateCSSSqStr:
155 
                                s = append(s, "exp_template_html_cssescaper")
156 
                        default:
157 
                                s = append(s, "exp_template_html_urlnormalizer")
158 
                        }
159 
                case urlPartQueryOrFrag:
160 
                        s = append(s, "exp_template_html_urlescaper")
161 
                case urlPartUnknown:
162 
                        return context{
163 
                                state: stateError,
164 
                                err:   errorf(ErrAmbigContext, n.Line, "%s appears in an ambiguous URL context", n),
165 
                        }
166 
                default:
167 
                        panic(c.urlPart.String())
168 
                }
169 
        case stateJS:
170 
                s = append(s, "exp_template_html_jsvalescaper")
171 
                // A slash after a value starts a div operator.
172 
                c.jsCtx = jsCtxDivOp
173 
        case stateJSDqStr, stateJSSqStr:
174 
                s = append(s, "exp_template_html_jsstrescaper")
175 
        case stateJSRegexp:
176 
                s = append(s, "exp_template_html_jsregexpescaper")
177 
        case stateCSS:
178 
                s = append(s, "exp_template_html_cssvaluefilter")
179 
        case stateText:
180 
                s = append(s, "exp_template_html_htmlescaper")
181 
        case stateRCDATA:
182 
                s = append(s, "exp_template_html_rcdataescaper")
183 
        case stateAttr:
184 
                // Handled below in delim check.
185 
        case stateAttrName, stateTag:
186 
                c.state = stateAttrName
187 
                s = append(s, "exp_template_html_htmlnamefilter")
188 
        default:
189 
                if isComment(c.state) {
190 
                        s = append(s, "exp_template_html_commentescaper")
191 
                } else {
192 
                        panic("unexpected state " + c.state.String())
193 
                }
194 
        }
195 
        switch c.delim {
196 
        case delimNone:
197 
                // No extra-escaping needed for raw text content.
198 
        case delimSpaceOrTagEnd:
199 
                s = append(s, "exp_template_html_nospaceescaper")
200 
        default:
201 
                s = append(s, "exp_template_html_attrescaper")
202 
        }
203 
        e.editActionNode(n, s)
204 
        return c
205 
}
206 
 
207 
// ensurePipelineContains ensures that the pipeline has commands with
208 
// the identifiers in s in order.
209 
// If the pipeline already has some of the sanitizers, do not interfere.
210 
// For example, if p is (.X | html) and s is ["escapeJSVal", "html"] then it
211 
// has one matching, "html", and one to insert, "escapeJSVal", to produce
212 
// (.X | escapeJSVal | html).
213 
func ensurePipelineContains(p *parse.PipeNode, s []string) {
214 
        if len(s) == 0 {
215 
                return
216 
        }
217 
        n := len(p.Cmds)
218 
        // Find the identifiers at the end of the command chain.
219 
        idents := p.Cmds
220 
        for i := n - 1; i >= 0; i-- {
221 
                if cmd := p.Cmds[i]; len(cmd.Args) != 0 {
222 
                        if id, ok := cmd.Args[0].(*parse.IdentifierNode); ok {
223 
                                if id.Ident == "noescape" {
224 
                                        return
225 
                                }
226 
                                continue
227 
                        }
228 
                }
229 
                idents = p.Cmds[i+1:]
230 
        }
231 
        dups := 0
232 
        for _, id := range idents {
233 
                if escFnsEq(s[dups], (id.Args[0].(*parse.IdentifierNode)).Ident) {
234 
                        dups++
235 
                        if dups == len(s) {
236 
                                return
237 
                        }
238 
                }
239 
        }
240 
        newCmds := make([]*parse.CommandNode, n-len(idents), n+len(s)-dups)
241 
        copy(newCmds, p.Cmds)
242 
        // Merge existing identifier commands with the sanitizers needed.
243 
        for _, id := range idents {
244 
                i := indexOfStr((id.Args[0].(*parse.IdentifierNode)).Ident, s, escFnsEq)
245 
                if i != -1 {
246 
                        for _, name := range s[:i] {
247 
                                newCmds = appendCmd(newCmds, newIdentCmd(name))
248 
                        }
249 
                        s = s[i+1:]
250 
                }
251 
                newCmds = appendCmd(newCmds, id)
252 
        }
253 
        // Create any remaining sanitizers.
254 
        for _, name := range s {
255 
                newCmds = appendCmd(newCmds, newIdentCmd(name))
256 
        }
257 
        p.Cmds = newCmds
258 
}
259 
 
260 
// redundantFuncs[a][b] implies that funcMap[b](funcMap[a](x)) == funcMap[a](x)
261 
// for all x.
262 
var redundantFuncs = map[string]map[string]bool{
263 
        "exp_template_html_commentescaper": {
264 
                "exp_template_html_attrescaper":    true,
265 
                "exp_template_html_nospaceescaper": true,
266 
                "exp_template_html_htmlescaper":    true,
267 
        },
268 
        "exp_template_html_cssescaper": {
269 
                "exp_template_html_attrescaper": true,
270 
        },
271 
        "exp_template_html_jsregexpescaper": {
272 
                "exp_template_html_attrescaper": true,
273 
        },
274 
        "exp_template_html_jsstrescaper": {
275 
                "exp_template_html_attrescaper": true,
276 
        },
277 
        "exp_template_html_urlescaper": {
278 
                "exp_template_html_urlnormalizer": true,
279 
        },
280 
}
281 
 
282 
// appendCmd appends the given command to the end of the command pipeline
283 
// unless it is redundant with the last command.
284 
func appendCmd(cmds []*parse.CommandNode, cmd *parse.CommandNode) []*parse.CommandNode {
285 
        if n := len(cmds); n != 0 {
286 
                last, ok := cmds[n-1].Args[0].(*parse.IdentifierNode)
287 
                next, _ := cmd.Args[0].(*parse.IdentifierNode)
288 
                if ok && redundantFuncs[last.Ident][next.Ident] {
289 
                        return cmds
290 
                }
291 
        }
292 
        return append(cmds, cmd)
293 
}
294 
 
295 
// indexOfStr is the first i such that eq(s, strs[i]) or -1 if s was not found.
296 
func indexOfStr(s string, strs []string, eq func(a, b string) bool) int {
297 
        for i, t := range strs {
298 
                if eq(s, t) {
299 
                        return i
300 
                }
301 
        }
302 
        return -1
303 
}
304 
 
305 
// escFnsEq returns whether the two escaping functions are equivalent.
306 
func escFnsEq(a, b string) bool {
307 
        if e := equivEscapers[a]; e != "" {
308 
                a = e
309 
        }
310 
        if e := equivEscapers[b]; e != "" {
311 
                b = e
312 
        }
313 
        return a == b
314 
}
315 
 
316 
// newIdentCmd produces a command containing a single identifier node.
317 
func newIdentCmd(identifier string) *parse.CommandNode {
318 
        return &parse.CommandNode{
319 
                NodeType: parse.NodeCommand,
320 
                Args:     []parse.Node{parse.NewIdentifier(identifier)},
321 
        }
322 
}
323 
 
324 
// nudge returns the context that would result from following empty string
325 
// transitions from the input context.
326 
// For example, parsing:
327 
//     `
328 
// will end in context{stateBeforeValue, attrURL}, but parsing one extra rune:
329 
//     `
330 
// will end in context{stateURL, delimSpaceOrTagEnd, ...}.
331 
// There are two transitions that happen when the 'x' is seen:
332 
// (1) Transition from a before-value state to a start-of-value state without
333 
//     consuming any character.
334 
// (2) Consume 'x' and transition past the first value character.
335 
// In this case, nudging produces the context after (1) happens.
336 
func nudge(c context) context {
337 
        switch c.state {
338 
        case stateTag:
339 
                // In `
340 
                c.state = stateAttrName
341 
        case stateBeforeValue:
342 
                // In `
343 
                c.state, c.delim, c.attr = attrStartStates[c.attr], delimSpaceOrTagEnd, attrNone
344 
        case stateAfterName:
345 
                // In `
346 
                c.state, c.attr = stateAttrName, attrNone
347 
        }
348 
        return c
349 
}
350 
 
351 
// join joins the two contexts of a branch template node. The result is an
352 
// error context if either of the input contexts are error contexts, or if the
353 
// the input contexts differ.
354 
func join(a, b context, line int, nodeName string) context {
355 
        if a.state == stateError {
356 
                return a
357 
        }
358 
        if b.state == stateError {
359 
                return b
360 
        }
361 
        if a.eq(b) {
362 
                return a
363 
        }
364 
 
365 
        c := a
366 
        c.urlPart = b.urlPart
367 
        if c.eq(b) {
368 
                // The contexts differ only by urlPart.
369 
                c.urlPart = urlPartUnknown
370 
                return c
371 
        }
372 
 
373 
        c = a
374 
        c.jsCtx = b.jsCtx
375 
        if c.eq(b) {
376 
                // The contexts differ only by jsCtx.
377 
                c.jsCtx = jsCtxUnknown
378 
                return c
379 
        }
380 
 
381 
        // Allow a nudged context to join with an unnudged one.
382 
        // This means that
383 
        //
384 
        // ends in an unquoted value state even though the else branch
385 
        // ends in stateBeforeValue.
386 
        if c, d := nudge(a), nudge(b); !(c.eq(a) && d.eq(b)) {
387 
                if e := join(c, d, line, nodeName); e.state != stateError {
388 
                        return e
389 
                }
390 
        }
391 
 
392 
        return context{
393 
                state: stateError,
394 
                err:   errorf(ErrBranchEnd, line, "{{%s}} branches end in different contexts: %v, %v", nodeName, a, b),
395 
        }
396 
}
397 
 
398 
// escapeBranch escapes a branch template node: "if", "range" and "with".
399 
func (e *escaper) escapeBranch(c context, n *parse.BranchNode, nodeName string) context {
400 
        c0 := e.escapeList(c, n.List)
401 
        if nodeName == "range" && c0.state != stateError {
402 
                // The "true" branch of a "range" node can execute multiple times.
403 
                // We check that executing n.List once results in the same context
404 
                // as executing n.List twice.
405 
                c1, _ := e.escapeListConditionally(c0, n.List, nil)
406 
                c0 = join(c0, c1, n.Line, nodeName)
407 
                if c0.state == stateError {
408 
                        // Make clear that this is a problem on loop re-entry
409 
                        // since developers tend to overlook that branch when
410 
                        // debugging templates.
411 
                        c0.err.Line = n.Line
412 
                        c0.err.Description = "on range loop re-entry: " + c0.err.Description
413 
                        return c0
414 
                }
415 
        }
416 
        c1 := e.escapeList(c, n.ElseList)
417 
        return join(c0, c1, n.Line, nodeName)
418 
}
419 
 
420 
// escapeList escapes a list template node.
421 
func (e *escaper) escapeList(c context, n *parse.ListNode) context {
422 
        if n == nil {
423 
                return c
424 
        }
425 
        for _, m := range n.Nodes {
426 
                c = e.escape(c, m)
427 
        }
428 
        return c
429 
}
430 
 
431 
// escapeListConditionally escapes a list node but only preserves edits and
432 
// inferences in e if the inferences and output context satisfy filter.
433 
// It returns the best guess at an output context, and the result of the filter
434 
// which is the same as whether e was updated.
435 
func (e *escaper) escapeListConditionally(c context, n *parse.ListNode, filter func(*escaper, context) bool) (context, bool) {
436 
        e1 := newEscaper(e.tmpl)
437 
        // Make type inferences available to f.
438 
        for k, v := range e.output {
439 
                e1.output[k] = v
440 
        }
441 
        c = e1.escapeList(c, n)
442 
        ok := filter != nil && filter(e1, c)
443 
        if ok {
444 
                // Copy inferences and edits from e1 back into e.
445 
                for k, v := range e1.output {
446 
                        e.output[k] = v
447 
                }
448 
                for k, v := range e1.derived {
449 
                        e.derived[k] = v
450 
                }
451 
                for k, v := range e1.called {
452 
                        e.called[k] = v
453 
                }
454 
                for k, v := range e1.actionNodeEdits {
455 
                        e.editActionNode(k, v)
456 
                }
457 
                for k, v := range e1.templateNodeEdits {
458 
                        e.editTemplateNode(k, v)
459 
                }
460 
                for k, v := range e1.textNodeEdits {
461 
                        e.editTextNode(k, v)
462 
                }
463 
        }
464 
        return c, ok
465 
}
466 
 
467 
// escapeTemplate escapes a {{template}} call node.
468 
func (e *escaper) escapeTemplate(c context, n *parse.TemplateNode) context {
469 
        c, name := e.escapeTree(c, n.Name, n.Line)
470 
        if name != n.Name {
471 
                e.editTemplateNode(n, name)
472 
        }
473 
        return c
474 
}
475 
 
476 
// escapeTree escapes the named template starting in the given context as
477 
// necessary and returns its output context.
478 
func (e *escaper) escapeTree(c context, name string, line int) (context, string) {
479 
        // Mangle the template name with the input context to produce a reliable
480 
        // identifier.
481 
        dname := c.mangle(name)
482 
        e.called[dname] = true
483 
        if out, ok := e.output[dname]; ok {
484 
                // Already escaped.
485 
                return out, dname
486 
        }
487 
        t := e.template(name)
488 
        if t == nil {
489 
                // Two cases: The template exists but is empty, or has never been mentioned at
490 
                // all. Distinguish the cases in the error messages.
491 
                if e.tmpl.set[name] != nil {
492 
                        return context{
493 
                                state: stateError,
494 
                                err:   errorf(ErrNoSuchTemplate, line, "%q is an incomplete or empty template", name),
495 
                        }, dname
496 
                }
497 
                return context{
498 
                        state: stateError,
499 
                        err:   errorf(ErrNoSuchTemplate, line, "no such template %q", name),
500 
                }, dname
501 
        }
502 
        if dname != name {
503 
                // Use any template derived during an earlier call to escapeTemplate
504 
                // with different top level templates, or clone if necessary.
505 
                dt := e.template(dname)
506 
                if dt == nil {
507 
                        dt = template.New(dname)
508 
                        dt.Tree = &parse.Tree{Name: dname, Root: cloneList(t.Root)}
509 
                        e.derived[dname] = dt
510 
                }
511 
                t = dt
512 
        }
513 
        return e.computeOutCtx(c, t), dname
514 
}
515 
 
516 
// computeOutCtx takes a template and its start context and computes the output
517 
// context while storing any inferences in e.
518 
func (e *escaper) computeOutCtx(c context, t *template.Template) context {
519 
        // Propagate context over the body.
520 
        c1, ok := e.escapeTemplateBody(c, t)
521 
        if !ok {
522 
                // Look for a fixed point by assuming c1 as the output context.
523 
                if c2, ok2 := e.escapeTemplateBody(c1, t); ok2 {
524 
                        c1, ok = c2, true
525 
                }
526 
                // Use c1 as the error context if neither assumption worked.
527 
        }
528 
        if !ok && c1.state != stateError {
529 
                return context{
530 
                        state: stateError,
531 
                        // TODO: Find the first node with a line in t.text.Tree.Root
532 
                        err: errorf(ErrOutputContext, 0, "cannot compute output context for template %s", t.Name()),
533 
                }
534 
        }
535 
        return c1
536 
}
537 
 
538 
// escapeTemplateBody escapes the given template assuming the given output
539 
// context, and returns the best guess at the output context and whether the
540 
// assumption was correct.
541 
func (e *escaper) escapeTemplateBody(c context, t *template.Template) (context, bool) {
542 
        filter := func(e1 *escaper, c1 context) bool {
543 
                if c1.state == stateError {
544 
                        // Do not update the input escaper, e.
545 
                        return false
546 
                }
547 
                if !e1.called[t.Name()] {
548 
                        // If t is not recursively called, then c1 is an
549 
                        // accurate output context.
550 
                        return true
551 
                }
552 
                // c1 is accurate if it matches our assumed output context.
553 
                return c.eq(c1)
554 
        }
555 
        // We need to assume an output context so that recursive template calls
556 
        // take the fast path out of escapeTree instead of infinitely recursing.
557 
        // Naively assuming that the input context is the same as the output
558 
        // works >90% of the time.
559 
        e.output[t.Name()] = c
560 
        return e.escapeListConditionally(c, t.Tree.Root, filter)
561 
}
562 
 
563 
// delimEnds maps each delim to a string of characters that terminate it.
564 
var delimEnds = [...]string{
565 
        delimDoubleQuote: `"`,
566 
        delimSingleQuote: "'",
567 
        // Determined empirically by running the below in various browsers.
568 
        // var div = document.createElement("DIV");
569 
        // for (var i = 0; i < 0x10000; ++i) {
570 
        //   div.innerHTML = "";
571 
        //   if (div.getElementsByTagName("SPAN")[0].title.indexOf("bar") < 0)
572 
        //     document.write("
U+" + i.toString(16));
573 
        // }
574 
        delimSpaceOrTagEnd: " \t\n\f\r>",
575 
}
576 
 
577 
var doctypeBytes = []byte("
578 
 
579 
// escapeText escapes a text template node.
580 
func (e *escaper) escapeText(c context, n *parse.TextNode) context {
581 
        s, written, i, b := n.Text, 0, 0, new(bytes.Buffer)
582 
        for i != len(s) {
583 
                c1, nread := contextAfterText(c, s[i:])
584 
                i1 := i + nread
585 
                if c.state == stateText || c.state == stateRCDATA {
586 
                        end := i1
587 
                        if c1.state != c.state {
588 
                                for j := end - 1; j >= i; j-- {
589 
                                        if s[j] == '<' {
590 
                                                end = j
591 
                                                break
592 
                                        }
593 
                                }
594 
                        }
595 
                        for j := i; j < end; j++ {
596 
                                if s[j] == '<' && !bytes.HasPrefix(s[j:], doctypeBytes) {
597 
                                        b.Write(s[written:j])
598 
                                        b.WriteString("<")
599 
                                        written = j + 1
600 
                                }
601 
                        }
602 
                } else if isComment(c.state) && c.delim == delimNone {
603 
                        switch c.state {
604 
                        case stateJSBlockCmt:
605 
                                // http://es5.github.com/#x7.4:
606 
                                // "Comments behave like white space and are
607 
                                // discarded except that, if a MultiLineComment
608 
                                // contains a line terminator character, then
609 
                                // the entire comment is considered to be a
610 
                                // LineTerminator for purposes of parsing by
611 
                                // the syntactic grammar."
612 
                                if bytes.IndexAny(s[written:i1], "\n\r\u2028\u2029") != -1 {
613 
                                        b.WriteByte('\n')
614 
                                } else {
615 
                                        b.WriteByte(' ')
616 
                                }
617 
                        case stateCSSBlockCmt:
618 
                                b.WriteByte(' ')
619 
                        }
620 
                        written = i1
621 
                }
622 
                if c.state != c1.state && isComment(c1.state) && c1.delim == delimNone {
623 
                        // Preserve the portion between written and the comment start.
624 
                        cs := i1 - 2
625 
                        if c1.state == stateHTMLCmt {
626 
                                // "