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-rw-r--r--modules/templates/scopedtmpl/scopedtmpl.go239
1 files changed, 239 insertions, 0 deletions
diff --git a/modules/templates/scopedtmpl/scopedtmpl.go b/modules/templates/scopedtmpl/scopedtmpl.go
new file mode 100644
index 0000000..2722ba9
--- /dev/null
+++ b/modules/templates/scopedtmpl/scopedtmpl.go
@@ -0,0 +1,239 @@
+// Copyright 2023 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package scopedtmpl
+
+import (
+ "fmt"
+ "html/template"
+ "io"
+ "reflect"
+ "sync"
+ texttemplate "text/template"
+ "text/template/parse"
+ "unsafe"
+)
+
+type TemplateExecutor interface {
+ Execute(wr io.Writer, data any) error
+}
+
+type ScopedTemplate struct {
+ all *template.Template
+ parseFuncs template.FuncMap // this func map is only used for parsing templates
+ frozen bool
+
+ scopedMu sync.RWMutex
+ scopedTemplateSets map[string]*scopedTemplateSet
+}
+
+func NewScopedTemplate() *ScopedTemplate {
+ return &ScopedTemplate{
+ all: template.New(""),
+ parseFuncs: template.FuncMap{},
+ scopedTemplateSets: map[string]*scopedTemplateSet{},
+ }
+}
+
+func (t *ScopedTemplate) Funcs(funcMap template.FuncMap) {
+ if t.frozen {
+ panic("cannot add new functions to frozen template set")
+ }
+ t.all.Funcs(funcMap)
+ for k, v := range funcMap {
+ t.parseFuncs[k] = v
+ }
+}
+
+func (t *ScopedTemplate) New(name string) *template.Template {
+ if t.frozen {
+ panic("cannot add new template to frozen template set")
+ }
+ return t.all.New(name)
+}
+
+func (t *ScopedTemplate) Freeze() {
+ t.frozen = true
+ // reset the exec func map, then `escapeTemplate` is safe to call `Execute` to do escaping
+ m := template.FuncMap{}
+ for k := range t.parseFuncs {
+ m[k] = func(v ...any) any { return nil }
+ }
+ t.all.Funcs(m)
+}
+
+func (t *ScopedTemplate) Executor(name string, funcMap template.FuncMap) (TemplateExecutor, error) {
+ t.scopedMu.RLock()
+ scopedTmplSet, ok := t.scopedTemplateSets[name]
+ t.scopedMu.RUnlock()
+
+ if !ok {
+ var err error
+ t.scopedMu.Lock()
+ if scopedTmplSet, ok = t.scopedTemplateSets[name]; !ok {
+ if scopedTmplSet, err = newScopedTemplateSet(t.all, name); err == nil {
+ t.scopedTemplateSets[name] = scopedTmplSet
+ }
+ }
+ t.scopedMu.Unlock()
+ if err != nil {
+ return nil, err
+ }
+ }
+
+ if scopedTmplSet == nil {
+ return nil, fmt.Errorf("template %s not found", name)
+ }
+ return scopedTmplSet.newExecutor(funcMap), nil
+}
+
+type scopedTemplateSet struct {
+ name string
+ htmlTemplates map[string]*template.Template
+ textTemplates map[string]*texttemplate.Template
+ execFuncs map[string]reflect.Value
+}
+
+func escapeTemplate(t *template.Template) error {
+ // force the Golang HTML template to complete the escaping work
+ err := t.Execute(io.Discard, nil)
+ if _, ok := err.(*template.Error); ok {
+ return err
+ }
+ return nil
+}
+
+//nolint:unused
+type htmlTemplate struct {
+ escapeErr error
+ text *texttemplate.Template
+}
+
+//nolint:unused
+type textTemplateCommon struct {
+ tmpl map[string]*template.Template // Map from name to defined templates.
+ muTmpl sync.RWMutex // protects tmpl
+ option struct {
+ missingKey int
+ }
+ muFuncs sync.RWMutex // protects parseFuncs and execFuncs
+ parseFuncs texttemplate.FuncMap
+ execFuncs map[string]reflect.Value
+}
+
+//nolint:unused
+type textTemplate struct {
+ name string
+ *parse.Tree
+ *textTemplateCommon
+ leftDelim string
+ rightDelim string
+}
+
+func ptr[T, P any](ptr *P) *T {
+ // https://pkg.go.dev/unsafe#Pointer
+ // (1) Conversion of a *T1 to Pointer to *T2.
+ // Provided that T2 is no larger than T1 and that the two share an equivalent memory layout,
+ // this conversion allows reinterpreting data of one type as data of another type.
+ return (*T)(unsafe.Pointer(ptr))
+}
+
+func newScopedTemplateSet(all *template.Template, name string) (*scopedTemplateSet, error) {
+ targetTmpl := all.Lookup(name)
+ if targetTmpl == nil {
+ return nil, fmt.Errorf("template %q not found", name)
+ }
+ if err := escapeTemplate(targetTmpl); err != nil {
+ return nil, fmt.Errorf("template %q has an error when escaping: %w", name, err)
+ }
+
+ ts := &scopedTemplateSet{
+ name: name,
+ htmlTemplates: map[string]*template.Template{},
+ textTemplates: map[string]*texttemplate.Template{},
+ }
+
+ htmlTmpl := ptr[htmlTemplate](all)
+ textTmpl := htmlTmpl.text
+ textTmplPtr := ptr[textTemplate](textTmpl)
+
+ textTmplPtr.muFuncs.Lock()
+ ts.execFuncs = map[string]reflect.Value{}
+ for k, v := range textTmplPtr.execFuncs {
+ ts.execFuncs[k] = v
+ }
+ textTmplPtr.muFuncs.Unlock()
+
+ var collectTemplates func(nodes []parse.Node)
+ var collectErr error // only need to collect the one error
+ collectTemplates = func(nodes []parse.Node) {
+ for _, node := range nodes {
+ if node.Type() == parse.NodeTemplate {
+ nodeTemplate := node.(*parse.TemplateNode)
+ subName := nodeTemplate.Name
+ if ts.htmlTemplates[subName] == nil {
+ subTmpl := all.Lookup(subName)
+ if subTmpl == nil {
+ // HTML template will add some internal templates like "$delimDoubleQuote" into the text template
+ ts.textTemplates[subName] = textTmpl.Lookup(subName)
+ } else if subTmpl.Tree == nil || subTmpl.Tree.Root == nil {
+ collectErr = fmt.Errorf("template %q has no tree, it's usually caused by broken templates", subName)
+ } else {
+ ts.htmlTemplates[subName] = subTmpl
+ if err := escapeTemplate(subTmpl); err != nil {
+ collectErr = fmt.Errorf("template %q has an error when escaping: %w", subName, err)
+ return
+ }
+ collectTemplates(subTmpl.Tree.Root.Nodes)
+ }
+ }
+ } else if node.Type() == parse.NodeList {
+ nodeList := node.(*parse.ListNode)
+ collectTemplates(nodeList.Nodes)
+ } else if node.Type() == parse.NodeIf {
+ nodeIf := node.(*parse.IfNode)
+ collectTemplates(nodeIf.BranchNode.List.Nodes)
+ if nodeIf.BranchNode.ElseList != nil {
+ collectTemplates(nodeIf.BranchNode.ElseList.Nodes)
+ }
+ } else if node.Type() == parse.NodeRange {
+ nodeRange := node.(*parse.RangeNode)
+ collectTemplates(nodeRange.BranchNode.List.Nodes)
+ if nodeRange.BranchNode.ElseList != nil {
+ collectTemplates(nodeRange.BranchNode.ElseList.Nodes)
+ }
+ } else if node.Type() == parse.NodeWith {
+ nodeWith := node.(*parse.WithNode)
+ collectTemplates(nodeWith.BranchNode.List.Nodes)
+ if nodeWith.BranchNode.ElseList != nil {
+ collectTemplates(nodeWith.BranchNode.ElseList.Nodes)
+ }
+ }
+ }
+ }
+ ts.htmlTemplates[name] = targetTmpl
+ collectTemplates(targetTmpl.Tree.Root.Nodes)
+ return ts, collectErr
+}
+
+func (ts *scopedTemplateSet) newExecutor(funcMap map[string]any) TemplateExecutor {
+ tmpl := texttemplate.New("")
+ tmplPtr := ptr[textTemplate](tmpl)
+ tmplPtr.execFuncs = map[string]reflect.Value{}
+ for k, v := range ts.execFuncs {
+ tmplPtr.execFuncs[k] = v
+ }
+ if funcMap != nil {
+ tmpl.Funcs(funcMap)
+ }
+ // after escapeTemplate, the html templates are also escaped text templates, so it could be added to the text template directly
+ for _, t := range ts.htmlTemplates {
+ _, _ = tmpl.AddParseTree(t.Name(), t.Tree)
+ }
+ for _, t := range ts.textTemplates {
+ _, _ = tmpl.AddParseTree(t.Name(), t.Tree)
+ }
+
+ // now the text template has all necessary escaped templates, so we can safely execute, just like what the html template does
+ return tmpl.Lookup(ts.name)
+}