[release-branch.go1.16] text/template: add lock for Template.tmpl to fix data race
This adds a new lock protecting "tmpl".
This is a copy of https://golang.org/cl/257817 by Andreas Fleig,
updated for current tip, and updated to start running the
html/template TestEscapeRace test.
Thanks to @bep for providing the test case.
For #39807
Fixes #47042
Change-Id: Ic8874484290283a49116812eeaffb8608346dc70
Reviewed-on: https://go-review.googlesource.com/c/go/+/316669
Trust: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
(cherry picked from commit 496d7c691481966fd6ea806205aa025698a172af)
Reviewed-on: https://go-review.googlesource.com/c/go/+/348580
Reviewed-by: Emmanuel Odeke <emmanuel@orijtech.com>
diff --git a/src/html/template/exec_test.go b/src/html/template/exec_test.go
index 7d1bef1..8885873 100644
--- a/src/html/template/exec_test.go
+++ b/src/html/template/exec_test.go
@@ -1720,8 +1720,6 @@
`
func TestEscapeRace(t *testing.T) {
- t.Skip("this test currently fails with -race; see issue #39807")
-
tmpl := New("")
_, err := tmpl.New("templ.html").Parse(raceText)
if err != nil {
diff --git a/src/text/template/exec.go b/src/text/template/exec.go
index 19154fc..ba01a15 100644
--- a/src/text/template/exec.go
+++ b/src/text/template/exec.go
@@ -179,10 +179,7 @@
// A template may be executed safely in parallel, although if parallel
// executions share a Writer the output may be interleaved.
func (t *Template) ExecuteTemplate(wr io.Writer, name string, data interface{}) error {
- var tmpl *Template
- if t.common != nil {
- tmpl = t.tmpl[name]
- }
+ tmpl := t.Lookup(name)
if tmpl == nil {
return fmt.Errorf("template: no template %q associated with template %q", name, t.name)
}
@@ -230,6 +227,8 @@
return ""
}
var b strings.Builder
+ t.muTmpl.RLock()
+ defer t.muTmpl.RUnlock()
for name, tmpl := range t.tmpl {
if tmpl.Tree == nil || tmpl.Root == nil {
continue
@@ -401,7 +400,7 @@
func (s *state) walkTemplate(dot reflect.Value, t *parse.TemplateNode) {
s.at(t)
- tmpl := s.tmpl.tmpl[t.Name]
+ tmpl := s.tmpl.Lookup(t.Name)
if tmpl == nil {
s.errorf("template %q not defined", t.Name)
}
diff --git a/src/text/template/exec_test.go b/src/text/template/exec_test.go
index 1a129ed..78abc25 100644
--- a/src/text/template/exec_test.go
+++ b/src/text/template/exec_test.go
@@ -12,6 +12,7 @@
"io"
"reflect"
"strings"
+ "sync"
"testing"
)
@@ -1710,3 +1711,40 @@
t.Errorf("%s", err)
}
}
+
+// Issue 39807: data race in html/template & text/template
+func TestIssue39807(t *testing.T) {
+ var wg sync.WaitGroup
+
+ tplFoo, err := New("foo").Parse(`{{ template "bar" . }}`)
+ if err != nil {
+ t.Error(err)
+ }
+
+ tplBar, err := New("bar").Parse("bar")
+ if err != nil {
+ t.Error(err)
+ }
+
+ gofuncs := 10
+ numTemplates := 10
+
+ for i := 1; i <= gofuncs; i++ {
+ wg.Add(1)
+ go func() {
+ defer wg.Done()
+ for j := 0; j < numTemplates; j++ {
+ _, err := tplFoo.AddParseTree(tplBar.Name(), tplBar.Tree)
+ if err != nil {
+ t.Error(err)
+ }
+ err = tplFoo.Execute(io.Discard, nil)
+ if err != nil {
+ t.Error(err)
+ }
+ }
+ }()
+ }
+
+ wg.Wait()
+}
diff --git a/src/text/template/template.go b/src/text/template/template.go
index ec26eb4..fd74d45 100644
--- a/src/text/template/template.go
+++ b/src/text/template/template.go
@@ -13,6 +13,7 @@
// common holds the information shared by related templates.
type common struct {
tmpl map[string]*Template // Map from name to defined templates.
+ muTmpl sync.RWMutex // protects tmpl
option option
// We use two maps, one for parsing and one for execution.
// This separation makes the API cleaner since it doesn't
@@ -88,6 +89,8 @@
if t.common == nil {
return nt, nil
}
+ t.muTmpl.RLock()
+ defer t.muTmpl.RUnlock()
for k, v := range t.tmpl {
if k == t.name {
nt.tmpl[t.name] = nt
@@ -124,6 +127,8 @@
// its definition. If it has been defined and already has that name, the existing
// definition is replaced; otherwise a new template is created, defined, and returned.
func (t *Template) AddParseTree(name string, tree *parse.Tree) (*Template, error) {
+ t.muTmpl.Lock()
+ defer t.muTmpl.Unlock()
t.init()
nt := t
if name != t.name {
@@ -142,6 +147,8 @@
return nil
}
// Return a slice so we don't expose the map.
+ t.muTmpl.RLock()
+ defer t.muTmpl.RUnlock()
m := make([]*Template, 0, len(t.tmpl))
for _, v := range t.tmpl {
m = append(m, v)
@@ -182,6 +189,8 @@
if t.common == nil {
return nil
}
+ t.muTmpl.RLock()
+ defer t.muTmpl.RUnlock()
return t.tmpl[name]
}
