Add AST check to catch calls, remove regex for block and template

Makefile

@@ -339,11 +339,14 @@ update-template:
 		exit 1; \
 	fi
 	src="$$(go env GOROOT)/src"; \
-	cp "$$src/text/template/exec.go" "$$src/text/template/funcs.go" "$$src/text/template/template.go" "$$src/text/template/option.go" template/gotext/; \
+	rm -f template/gotext/*.go template/gotext/fmtsort/*.go; \
-	cp "$$src/internal/fmtsort/sort.go" template/gotext/fmtsort/; \
+	for f in $$(go list -f '{{range .GoFiles}}{{.}} {{end}}' text/template); do cp "$$src/text/template/$$f" template/gotext/; done; \
+	for f in $$(go list -f '{{range .GoFiles}}{{.}} {{end}}' internal/fmtsort); do cp "$$src/internal/fmtsort/$$f" template/gotext/fmtsort/; done; \
+	sed -i 's/^package template$$/package gotext/' template/gotext/*.go; \
+	sed -i 's#"internal/fmtsort"#"heckel.io/ntfy/v2/template/gotext/fmtsort"#' template/gotext/*.go; \
 	( cd template/gotext && for p in patches/*.patch; do echo "Applying $$p"; git apply "$$p" || exit 1; done )
 	go env GOVERSION > template/gotext/GENERATED_FROM
-	@echo "Regenerated template/gotext/ from $(TEMPLATE_GO_VERSION); review with 'git diff'."
+	@echo "Regenerated template/gotext/ from $(TEMPLATE_GO_VERSION) (files enumerated via 'go list'); review with 'git diff'."
 
 template-check: FORCE
 	@if [ "$$(cat template/gotext/GENERATED_FROM)" != "$(TEMPLATE_GO_VERSION)" ]; then \
@@ -355,17 +358,20 @@ template-check: FORCE
 		exit 0; \
 	fi
 	@tmp=$$(mktemp -d); src="$$(go env GOROOT)/src"; \
-	mkdir -p "$$tmp/gotext/fmtsort" "$$tmp/patches"; \
+	mkdir -p "$$tmp/gotext/fmtsort"; \
-	cp "$$src/text/template/exec.go" "$$src/text/template/funcs.go" "$$src/text/template/template.go" "$$src/text/template/option.go" "$$tmp/gotext/"; \
+	for f in $$(go list -f '{{range .GoFiles}}{{.}} {{end}}' text/template); do cp "$$src/text/template/$$f" "$$tmp/gotext/"; done; \
-	cp "$$src/internal/fmtsort/sort.go" "$$tmp/gotext/fmtsort/"; \
+	for f in $$(go list -f '{{range .GoFiles}}{{.}} {{end}}' internal/fmtsort); do cp "$$src/internal/fmtsort/$$f" "$$tmp/gotext/fmtsort/"; done; \
-	cp template/gotext/patches/*.patch "$$tmp/patches/"; \
+	sed -i 's/^package template$$/package gotext/' "$$tmp/gotext/"*.go; \
-	( cd "$$tmp/gotext" && for p in "$$tmp"/patches/*.patch; do git apply "$$p" || exit 1; done ); \
+	sed -i 's#"internal/fmtsort"#"heckel.io/ntfy/v2/template/gotext/fmtsort"#' "$$tmp/gotext/"*.go; \
-	ok=1; \
+	cp template/gotext/patches/*.patch "$$tmp/"; \
-	for f in exec.go funcs.go template.go option.go fmtsort/sort.go; do \
+	( cd "$$tmp/gotext" && for p in "$$tmp"/*.patch; do git apply "$$p" || exit 1; done ); \
-		diff -q "$$tmp/gotext/$$f" "template/gotext/$$f" >/dev/null 2>&1 || { echo "DRIFT: template/gotext/$$f differs from GOROOT+patches"; ok=0; }; \
+	if diff -rq -x 'README.md' -x 'GENERATED_FROM' -x 'patches' "$$tmp/gotext" template/gotext >/dev/null 2>&1; then \
-	done; \
+		rm -rf "$$tmp"; \
-	rm -rf "$$tmp"; \
+	else \
-	if [ "$$ok" != 1 ]; then echo "ERROR: template/gotext/ drifted from GOROOT+patches. Run 'make update-template' on Go $(TEMPLATE_GO_VERSION)."; exit 1; fi
+		echo "ERROR: template/gotext/ drifted from GOROOT+patches (or its file set changed). Run 'make update-template' on Go $(TEMPLATE_GO_VERSION):"; \
+		diff -rq -x 'README.md' -x 'GENERATED_FROM' -x 'patches' "$$tmp/gotext" template/gotext; \
+		rm -rf "$$tmp"; exit 1; \
+	fi
 
 # go-check is advisory only (never fails): it warns when the pinned Go (.go-version) is behind the
 # latest upstream release, so template/gotext doesn't silently fall behind on text/template fixes.

docs/publish.md

@@ -3224,6 +3224,11 @@ You can use the following features in your templates:
 A good way to experiment with Go templates is the **[Go Template Playground](https://repeatit.io)**. It is _highly recommended_ to test
 your templates there first ([example for Grafana alert](https://repeatit.io/#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)).
 
+!!! info
+    A few Go template features are disabled for user-supplied templates: `{{define}}`, `{{template}}`,
+    `{{block}}`, and `{{call}}` are not allowed. Templates also run with a short execution time limit --
+    a template that loops too long is stopped and rejected with an HTTP 400 error.
+
 ### Template functions
 ntfy supports a subset of the **[Sprig template functions](publish/template-functions.md)** (originally copied from [Sprig](https://github.com/Masterminds/sprig),
 thank you to the Sprig developers 🙏). This is useful for advanced message templating and for transforming the data provided through the JSON payload.

server/errors.go

@@ -136,7 +136,7 @@ var (
 	errHTTPBadRequestTemplateMessageTooLarge         = &errHTTP{40041, http.StatusBadRequest, "invalid request: message or title is too large after replacing template", "https://ntfy.sh/docs/publish/#message-templating", nil}
 	errHTTPBadRequestTemplateMessageNotJSON          = &errHTTP{40042, http.StatusBadRequest, "invalid request: message body must be JSON if templating is enabled", "https://ntfy.sh/docs/publish/#message-templating", nil}
 	errHTTPBadRequestTemplateInvalid                 = &errHTTP{40043, http.StatusBadRequest, "invalid request: could not parse template", "https://ntfy.sh/docs/publish/#message-templating", nil}
-	errHTTPBadRequestTemplateDisallowedFunctionCalls = &errHTTP{40044, http.StatusBadRequest, "invalid request: template contains disallowed function calls, e.g. template, call, or define", "https://ntfy.sh/docs/publish/#message-templating", nil}
+	errHTTPBadRequestTemplateDisallowedFunctionCalls = &errHTTP{40044, http.StatusBadRequest, "invalid request: template contains disallowed function calls, e.g. template, call, define, or block", "https://ntfy.sh/docs/publish/#message-templating", nil}
 	errHTTPBadRequestTemplateExecuteFailed           = &errHTTP{40045, http.StatusBadRequest, "invalid request: template execution failed", "https://ntfy.sh/docs/publish/#message-templating", nil}
 	errHTTPBadRequestTemplateExecutionTimeout        = &errHTTP{40055, http.StatusBadRequest, "invalid request: template execution timed out", "https://ntfy.sh/docs/publish/#message-templating", nil}
 	errHTTPBadRequestInvalidUsername                 = &errHTTP{40046, http.StatusBadRequest, "invalid request: invalid username", "", nil}

server/server.go

@@ -150,10 +150,7 @@ var (
 	templatesFs  embed.FS // Contains template config files (e.g. grafana.yml, github.yml, ...)
 	templatesDir = "templates"
 
-	// templateDisallowedRegex tests a template for disallowed expressions. While not really dangerous, they
+	templateNameRegex = regexp.MustCompile(`^[-_A-Za-z0-9]+$`)
-	// are not useful, and seem potentially troublesome.
-	templateDisallowedRegex = regexp.MustCompile(`(?m)\{\{-?\s*(call|template|define)\b`)
-	templateNameRegex       = regexp.MustCompile(`^[-_A-Za-z0-9]+$`)
 )
 
 const (

server/server_template.go

@@ -7,6 +7,7 @@ import (
 	"os"
 	"path/filepath"
 	"strings"
+	"text/template/parse"
 	"time"
 
 	"gopkg.in/yaml.v2"
@@ -105,9 +106,6 @@ func (s *Server) renderTemplateFromParams(m *model.Message, peekedBody string, p
 
 // renderTemplate renders a template with the given JSON source data.
 func (s *Server) renderTemplate(name, tpl, source string) (string, error) {
-	if templateDisallowedRegex.MatchString(tpl) {
-		return "", errHTTPBadRequestTemplateDisallowedFunctionCalls
-	}
 	var data any
 	if err := json.Unmarshal([]byte(source), &data); err != nil {
 		return "", errHTTPBadRequestTemplateMessageNotJSON
@@ -116,6 +114,9 @@ func (s *Server) renderTemplate(name, tpl, source string) (string, error) {
 	if err != nil {
 		return "", errHTTPBadRequestTemplateInvalid.Wrap("%s", err.Error())
 	}
+	if templateUsesDisallowedFeatures(t) {
+		return "", errHTTPBadRequestTemplateDisallowedFunctionCalls
+	}
 	t.SetExecutionDeadline(time.Now().Add(templateMaxExecutionTime)) // Bail out of runaway templates (GHSA-rhwf-xgc9-m9fp)
 	var buf bytes.Buffer
 	limitWriter := util.NewLimitWriter(&buf, util.NewFixedLimiter(templateMaxOutputBytes))
@@ -127,3 +128,59 @@ func (s *Server) renderTemplate(name, tpl, source string) (string, error) {
 	}
 	return strings.TrimSpace(strings.ReplaceAll(buf.String(), "\\n", "\n")), nil // replace any remaining "\n" (those outside of template curly braces) with newlines
 }
+
+// templateUsesDisallowedFeatures reports whether the parsed template defines or invokes a
+// sub-template ({{define}}/{{block}}/{{template}}) or uses the {{call}} builtin. None are useful for
+// ntfy's JSON-data templates. Checking the parse tree (rather than the raw string) catches every
+// syntactic form -- e.g. {{if call .x}} or {{$y := call .x}} -- that a regex would miss.
+func templateUsesDisallowedFeatures(t *gotext.Template) bool {
+	if len(t.Templates()) > 1 { // {{define}}/{{block}} create additional associated templates
+		return true
+	}
+	return treeContainsDisallowedNode(t.Root)
+}
+
+// treeContainsDisallowedNode reports whether the parse tree contains a {{template}}/{{block}}
+// invocation or a {{call}} builtin, descending into pipes and command arguments (where {{call}} can
+// appear anywhere a function is allowed).
+func treeContainsDisallowedNode(node parse.Node) bool {
+	switch n := node.(type) {
+	case *parse.ListNode:
+		if n == nil {
+			return false
+		}
+		for _, child := range n.Nodes {
+			if treeContainsDisallowedNode(child) {
+				return true
+			}
+		}
+	case *parse.ActionNode:
+		return treeContainsDisallowedNode(n.Pipe)
+	case *parse.RangeNode:
+		return treeContainsDisallowedNode(n.Pipe) || treeContainsDisallowedNode(n.List) || treeContainsDisallowedNode(n.ElseList)
+	case *parse.IfNode:
+		return treeContainsDisallowedNode(n.Pipe) || treeContainsDisallowedNode(n.List) || treeContainsDisallowedNode(n.ElseList)
+	case *parse.WithNode:
+		return treeContainsDisallowedNode(n.Pipe) || treeContainsDisallowedNode(n.List) || treeContainsDisallowedNode(n.ElseList)
+	case *parse.TemplateNode: // {{template}} or {{block}} invocation
+		return true
+	case *parse.PipeNode:
+		if n == nil {
+			return false
+		}
+		for _, cmd := range n.Cmds {
+			if treeContainsDisallowedNode(cmd) {
+				return true
+			}
+		}
+	case *parse.CommandNode:
+		for _, arg := range n.Args {
+			if treeContainsDisallowedNode(arg) {
+				return true
+			}
+		}
+	case *parse.IdentifierNode: // a function name; {{call}} is the disallowed builtin
+		return n.Ident == "call"
+	}
+	return false
+}

server/server_test.go

@@ -3660,6 +3660,70 @@ func TestServer_MessageTemplate_ExecutionTimeout(t *testing.T) {
 	})
 }
 
+// TestServer_MessageTemplate_DataDrivenNestedRange_TimesOut is the regression for the exact hole the
+// old write-triggered TimeoutWriter missed: a nested {{range}} over a JSON array field with a
+// no-output body calls no function, so only the executor's wall-clock deadline can stop it
+// (GHSA-rhwf-xgc9-m9fp).
+func TestServer_MessageTemplate_DataDrivenNestedRange_TimesOut(t *testing.T) {
+	forEachBackend(t, func(t *testing.T, databaseURL string) {
+		t.Parallel()
+		s := newTestServer(t, newTestConfig(t, databaseURL))
+		elems := make([]string, 1000)
+		for i := range elems {
+			elems[i] = "0"
+		}
+		jsonBody := `{"a":[` + strings.Join(elems, ",") + `]}`
+		msg := `{{range .a}}{{range $.a}}{{range $.a}}{{$x := .}}{{end}}{{end}}{{end}}done`
+		start := time.Now()
+		response := request(t, s, "POST", "/mytopic", jsonBody, map[string]string{
+			"X-Message":  msg,
+			"X-Template": "1",
+		})
+		elapsed := time.Since(start)
+		require.Equal(t, 400, response.Code)
+		require.Equal(t, 40055, toHTTPError(t, response.Body.String()).Code)
+		require.Less(t, elapsed, 500*time.Millisecond, "data-driven nested range should be cut off by the deadline (took %s)", elapsed)
+	})
+}
+
+// TestServer_MessageTemplate_ExpensiveFunctionLoop_TimesOut ensures the deadline also bounds loops
+// whose body calls an expensive function (hashing a large string), where a single call between
+// deadline checks could otherwise overshoot (GHSA-rhwf-xgc9-m9fp).
+func TestServer_MessageTemplate_ExpensiveFunctionLoop_TimesOut(t *testing.T) {
+	forEachBackend(t, func(t *testing.T, databaseURL string) {
+		t.Parallel()
+		s := newTestServer(t, newTestConfig(t, databaseURL))
+		msg := `{{$big := repeat 990 "0123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789"}}{{range until 1000}}{{range until 1000}}{{$h := sha512sum $big}}{{end}}{{end}}`
+		start := time.Now()
+		response := request(t, s, "POST", "/mytopic", `{}`, map[string]string{
+			"X-Message":  msg,
+			"X-Template": "1",
+		})
+		elapsed := time.Since(start)
+		require.Equal(t, 400, response.Code)
+		require.Equal(t, 40055, toHTTPError(t, response.Body.String()).Code)
+		require.Less(t, elapsed, 1500*time.Millisecond, "expensive-function loop should be cut off by the deadline (took %s)", elapsed)
+	})
+}
+
+// TestServer_MessageTemplate_NestedLoopPoC_TimesOut is the exact proof-of-concept from the advisory:
+// a range over a runtime-computed slice, nested, must be bounded by the deadline (GHSA-rhwf-xgc9-m9fp).
+func TestServer_MessageTemplate_NestedLoopPoC_TimesOut(t *testing.T) {
+	forEachBackend(t, func(t *testing.T, databaseURL string) {
+		t.Parallel()
+		s := newTestServer(t, newTestConfig(t, databaseURL))
+		start := time.Now()
+		response := request(t, s, "POST", "/mytopic", `{}`, map[string]string{
+			"X-Message":  `{{$x := until 10000}}{{range $x}}{{range $x}}{{end}}{{end}}done`,
+			"X-Template": "1",
+		})
+		elapsed := time.Since(start)
+		require.Equal(t, 400, response.Code)
+		require.Equal(t, 40055, toHTTPError(t, response.Body.String()).Code)
+		require.Less(t, elapsed, 500*time.Millisecond, "advisory PoC should be cut off by the deadline (took %s)", elapsed)
+	})
+}
+
 func TestServer_MessageTemplate_GenuineError_NotTimeout(t *testing.T) {
 	forEachBackend(t, func(t *testing.T, databaseURL string) {
 		t.Parallel()
@@ -3810,11 +3874,18 @@ func TestServer_MessageTemplate_DisallowedCalls(t *testing.T) {
 			`{{- template ""}}`,
 			`{{-
 template ""}}`,
-			`{{      call abc}}`,
+			`{{ call "aa"}}`,
-			`{{      define "aa"}}`,
+			`{{define "aa"}}hi{{end}}`,
-			`We cannot {{define "aa"}}`,
+			`We cannot {{define "aa"}}hi{{end}}`,
 			`We cannot {{ call "aa"}}`,
 			`We cannot {{- template "aa"}}`,
+			`{{block "aa" .}}hi{{end}}`,
+			`We cannot {{- block "aa" .}}hi{{end}}`,
+			// call is a function, not a keyword, so it can hide in non-leading positions that a
+			// raw-string regex misses -- the parse-tree walk catches all of them.
+			`{{if call .x}}x{{end}}`,
+			`{{$y := call .x}}`,
+			`{{index (call .x) 0}}`,
 		}
 		for _, disallowedTemplate := range disallowedTemplates {
 			messageTemplate := disallowedTemplate

template/gotext/README.md

@@ -34,9 +34,9 @@ config: Twilio, `cmd/serve.go`) keep using the standard library -- they are not
 
 | File | Origin |
 |------|--------|
-| `exec.go`, `funcs.go`, `template.go`, `option.go` | verbatim from `$(go env GOROOT)/src/text/template/` |
+| `*.go` (`exec.go`, `funcs.go`, `template.go`, `option.go`, `helper.go`, `doc.go`) | verbatim from `$(go env GOROOT)/src/text/template/`, enumerated with `go list` so files added/removed upstream are picked up automatically |
 | `fmtsort/sort.go` | verbatim from `$(go env GOROOT)/src/internal/fmtsort/` -- `exec.go` needs it, and `internal/...` packages can't be imported from outside GOROOT, so it comes along |
-| `patches/0001-exec-deadline.patch` | our only change (see below) |
+| `patches/0001-exec-deadline.patch` | our only real change (see below) |
 | `GENERATED_FROM` | the exact Go version `make update-template` last regenerated this copy from; provenance, written by that target |
 
 The Go toolchain version this copy is pinned to lives in the repo-root [`.go-version`](../../.go-version)
@@ -49,15 +49,20 @@ plain import.
 ## The patch
 
 `patches/` is a quilt-style ordered series (apply `0001-*`, then `0002-*`, ...). Today there is just
-`0001-exec-deadline.patch`, which is small and purely additive:
+`0001-exec-deadline.patch` -- small, purely additive, and touching only `exec.go`/`template.go`:
 
-- renames the package to `gotext` and rewrites the `internal/fmtsort` import to `heckel.io/ntfy/v2/template/gotext/fmtsort`
 - adds `deadline`/`steps` fields to the executor `state` and a `deadline` field + a
   `SetExecutionDeadline(time.Time)` method on `Template`
 - adds the amortized deadline check at the top of `state.walk`
 - adds the exported sentinel `ErrExecutionInterrupted` (detect with `errors.Is`)
 
-Keeping the patch tiny and additive is deliberate: it makes re-basing onto a new Go release cheap.
+Two *mechanical* transforms are applied by `make update-template` with `sed`, **not** the patch --
+renaming the package to `gotext`, and rewriting the `internal/fmtsort` import to
+`heckel.io/ntfy/v2/template/gotext/fmtsort`. Keeping them out of the patch means they apply to
+whatever files `go list` returns, so they survive upstream files being added or removed.
+
+Keeping the patch tiny (deadline logic only, on two stable files) is deliberate: it makes re-basing
+onto a new Go release cheap.
 
 ## Updating (when bumping the Go toolchain)
 

template/gotext/doc.go

@@ -0,0 +1,502 @@
+// Copyright 2011 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 template implements data-driven templates for generating textual output.
+
+To generate HTML output, see [html/template], which has the same interface
+as this package but automatically secures HTML output against certain attacks.
+
+Templates are executed by applying them to a data structure. Annotations in the
+template refer to elements of the data structure (typically a field of a struct
+or a key in a map) to control execution and derive values to be displayed.
+Execution of the template walks the structure and sets the cursor, represented
+by a period '.' and called "dot", to the value at the current location in the
+structure as execution proceeds.
+
+The security model used by this package assumes that template authors are
+trusted. The package does not auto-escape output, so injecting code into
+a template can lead to arbitrary code execution if the template is executed
+by an untrusted source.
+
+The input text for a template is UTF-8-encoded text in any format.
+"Actions"--data evaluations or control structures--are delimited by
+"{{" and "}}"; all text outside actions is copied to the output unchanged.
+
+Once parsed, a template may be executed safely in parallel, although if parallel
+executions share a Writer the output may be interleaved.
+
+Here is a trivial example that prints "17 items are made of wool".
+
+	type Inventory struct {
+		Material string
+		Count    uint
+	}
+	sweaters := Inventory{"wool", 17}
+	tmpl, err := template.New("test").Parse("{{.Count}} items are made of {{.Material}}")
+	if err != nil { panic(err) }
+	err = tmpl.Execute(os.Stdout, sweaters)
+	if err != nil { panic(err) }
+
+More intricate examples appear below.
+
+Text and spaces
+
+By default, all text between actions is copied verbatim when the template is
+executed. For example, the string " items are made of " in the example above
+appears on standard output when the program is run.
+
+However, to aid in formatting template source code, if an action's left
+delimiter (by default "{{") is followed immediately by a minus sign and white
+space, all trailing white space is trimmed from the immediately preceding text.
+Similarly, if the right delimiter ("}}") is preceded by white space and a minus
+sign, all leading white space is trimmed from the immediately following text.
+In these trim markers, the white space must be present:
+"{{- 3}}" is like "{{3}}" but trims the immediately preceding text, while
+"{{-3}}" parses as an action containing the number -3.
+
+For instance, when executing the template whose source is
+
+	"{{23 -}} < {{- 45}}"
+
+the generated output would be
+
+	"23<45"
+
+For this trimming, the definition of white space characters is the same as in Go:
+space, horizontal tab, carriage return, and newline.
+
+Actions
+
+Here is the list of actions. "Arguments" and "pipelines" are evaluations of
+data, defined in detail in the corresponding sections that follow.
+
+*/
+//	{{/* a comment */}}
+//	{{- /* a comment with white space trimmed from preceding and following text */ -}}
+//		A comment; discarded. May contain newlines.
+//		Comments do not nest and must start and end at the
+//		delimiters, as shown here.
+/*
+
+	{{pipeline}}
+		The default textual representation (the same as would be
+		printed by fmt.Print) of the value of the pipeline is copied
+		to the output.
+
+	{{if pipeline}} T1 {{end}}
+		If the value of the pipeline is empty, no output is generated;
+		otherwise, T1 is executed. The empty values are false, 0, any
+		nil pointer or interface value, and any array, slice, map, or
+		string of length zero.
+		Dot is unaffected.
+
+	{{if pipeline}} T1 {{else}} T0 {{end}}
+		If the value of the pipeline is empty, T0 is executed;
+		otherwise, T1 is executed. Dot is unaffected.
+
+	{{if pipeline}} T1 {{else if pipeline}} T0 {{end}}
+		To simplify the appearance of if-else chains, the else action
+		of an if may include another if directly; the effect is exactly
+		the same as writing
+			{{if pipeline}} T1 {{else}}{{if pipeline}} T0 {{end}}{{end}}
+
+	{{range pipeline}} T1 {{end}}
+		The value of the pipeline must be an array, slice, map, iter.Seq,
+		iter.Seq2, integer or channel.
+		If the value of the pipeline has length zero, nothing is output;
+		otherwise, dot is set to the successive elements of the array,
+		slice, or map and T1 is executed. If the value is a map and the
+		keys are of basic type with a defined order, the elements will be
+		visited in sorted key order.
+
+	{{range pipeline}} T1 {{else}} T0 {{end}}
+		The value of the pipeline must be an array, slice, map, iter.Seq,
+		iter.Seq2, integer or channel.
+		If the value of the pipeline has length zero, dot is unaffected and
+		T0 is executed; otherwise, dot is set to the successive elements
+		of the array, slice, or map and T1 is executed.
+
+	{{break}}
+		The innermost {{range pipeline}} loop is ended early, stopping the
+		current iteration and bypassing all remaining iterations.
+
+	{{continue}}
+		The current iteration of the innermost {{range pipeline}} loop is
+		stopped, and the loop starts the next iteration.
+
+	{{template "name"}}
+		The template with the specified name is executed with nil data.
+
+	{{template "name" pipeline}}
+		The template with the specified name is executed with dot set
+		to the value of the pipeline.
+
+	{{block "name" pipeline}} T1 {{end}}
+		A block is shorthand for defining a template
+			{{define "name"}} T1 {{end}}
+		and then executing it in place
+			{{template "name" pipeline}}
+		The typical use is to define a set of root templates that are
+		then customized by redefining the block templates within.
+
+	{{with pipeline}} T1 {{end}}
+		If the value of the pipeline is empty, no output is generated;
+		otherwise, dot is set to the value of the pipeline and T1 is
+		executed.
+
+	{{with pipeline}} T1 {{else}} T0 {{end}}
+		If the value of the pipeline is empty, dot is unaffected and T0
+		is executed; otherwise, dot is set to the value of the pipeline
+		and T1 is executed.
+
+	{{with pipeline}} T1 {{else with pipeline}} T0 {{end}}
+		To simplify the appearance of with-else chains, the else action
+		of a with may include another with directly; the effect is exactly
+		the same as writing
+			{{with pipeline}} T1 {{else}}{{with pipeline}} T0 {{end}}{{end}}
+
+
+Arguments
+
+An argument is a simple value, denoted by one of the following.
+
+	- A boolean, string, character, integer, floating-point, imaginary
+	  or complex constant in Go syntax. These behave like Go's untyped
+	  constants. Note that, as in Go, whether a large integer constant
+	  overflows when assigned or passed to a function can depend on whether
+	  the host machine's ints are 32 or 64 bits.
+	- The keyword nil, representing an untyped Go nil.
+	- The character '.' (period):
+
+		.
+
+	  The result is the value of dot.
+	- A variable name, which is a (possibly empty) alphanumeric string
+	  preceded by a dollar sign, such as
+
+		$piOver2
+
+	  or
+
+		$
+
+	  The result is the value of the variable.
+	  Variables are described below.
+	- The name of a field of the data, which must be a struct, preceded
+	  by a period, such as
+
+		.Field
+
+	  The result is the value of the field. Field invocations may be
+	  chained:
+
+	    .Field1.Field2
+
+	  Fields can also be evaluated on variables, including chaining:
+
+	    $x.Field1.Field2
+	- The name of a key of the data, which must be a map, preceded
+	  by a period, such as
+
+		.Key
+
+	  The result is the map element value indexed by the key.
+	  Key invocations may be chained and combined with fields to any
+	  depth:
+
+	    .Field1.Key1.Field2.Key2
+
+	  Although the key must be an alphanumeric identifier, unlike with
+	  field names they do not need to start with an upper case letter.
+	  Keys can also be evaluated on variables, including chaining:
+
+	    $x.key1.key2
+	- The name of a niladic method of the data, preceded by a period,
+	  such as
+
+		.Method
+
+	  The result is the value of invoking the method with dot as the
+	  receiver, dot.Method(). Such a method must have one return value (of
+	  any type) or two return values, the second of which is an error.
+	  If it has two and the returned error is non-nil, execution terminates
+	  and an error is returned to the caller as the value of Execute.
+	  Method invocations may be chained and combined with fields and keys
+	  to any depth:
+
+	    .Field1.Key1.Method1.Field2.Key2.Method2
+
+	  Methods can also be evaluated on variables, including chaining:
+
+	    $x.Method1.Field
+	- The name of a niladic function, such as
+
+		fun
+
+	  The result is the value of invoking the function, fun(). The return
+	  types and values behave as in methods. Functions and function
+	  names are described below.
+	- A parenthesized instance of one the above, for grouping. The result
+	  may be accessed by a field or map key invocation.
+
+		print (.F1 arg1) (.F2 arg2)
+		(.StructValuedMethod "arg").Field
+
+Arguments may evaluate to any type; if they are pointers the implementation
+automatically indirects to the base type when required.
+If an evaluation yields a function value, such as a function-valued
+field of a struct, the function is not invoked automatically, but it
+can be used as a truth value for an if action and the like. To invoke
+it, use the call function, defined below.
+
+Pipelines
+
+A pipeline is a possibly chained sequence of "commands". A command is a simple
+value (argument) or a function or method call, possibly with multiple arguments:
+
+	Argument
+		The result is the value of evaluating the argument.
+	.Method [Argument...]
+		The method can be alone or the last element of a chain but,
+		unlike methods in the middle of a chain, it can take arguments.
+		The result is the value of calling the method with the
+		arguments:
+			dot.Method(Argument1, etc.)
+	functionName [Argument...]
+		The result is the value of calling the function associated
+		with the name:
+			function(Argument1, etc.)
+		Functions and function names are described below.
+
+A pipeline may be "chained" by separating a sequence of commands with pipeline
+characters '|'. In a chained pipeline, the result of each command is
+passed as the last argument of the following command. The output of the final
+command in the pipeline is the value of the pipeline.
+
+The output of a command will be either one value or two values, the second of
+which has type error. If that second value is present and evaluates to
+non-nil, execution terminates and the error is returned to the caller of
+Execute.
+
+Variables
+
+A pipeline inside an action may initialize a variable to capture the result.
+The initialization has syntax
+
+	$variable := pipeline
+
+where $variable is the name of the variable. An action that declares a
+variable produces no output.
+
+Variables previously declared can also be assigned, using the syntax
+
+	$variable = pipeline
+
+If a "range" action initializes a variable, the variable is set to the
+successive elements of the iteration. Also, a "range" may declare two
+variables, separated by a comma:
+
+	range $index, $element := pipeline
+
+in which case $index and $element are set to the successive values of the
+array/slice index or map key and element, respectively. Note that if there is
+only one variable, it is assigned the element; this is opposite to the
+convention in Go range clauses.
+
+A variable's scope extends to the "end" action of the control structure ("if",
+"with", or "range") in which it is declared, or to the end of the template if
+there is no such control structure. A template invocation does not inherit
+variables from the point of its invocation.
+
+When execution begins, $ is set to the data argument passed to Execute, that is,
+to the starting value of dot.
+
+Examples
+
+Here are some example one-line templates demonstrating pipelines and variables.
+All produce the quoted word "output":
+
+	{{"\"output\""}}
+		A string constant.
+	{{`"output"`}}
+		A raw string constant.
+	{{printf "%q" "output"}}
+		A function call.
+	{{"output" | printf "%q"}}
+		A function call whose final argument comes from the previous
+		command.
+	{{printf "%q" (print "out" "put")}}
+		A parenthesized argument.
+	{{"put" | printf "%s%s" "out" | printf "%q"}}
+		A more elaborate call.
+	{{"output" | printf "%s" | printf "%q"}}
+		A longer chain.
+	{{with "output"}}{{printf "%q" .}}{{end}}
+		A with action using dot.
+	{{with $x := "output" | printf "%q"}}{{$x}}{{end}}
+		A with action that creates and uses a variable.
+	{{with $x := "output"}}{{printf "%q" $x}}{{end}}
+		A with action that uses the variable in another action.
+	{{with $x := "output"}}{{$x | printf "%q"}}{{end}}
+		The same, but pipelined.
+
+Functions
+
+During execution functions are found in two function maps: first in the
+template, then in the global function map. By default, no functions are defined
+in the template but the Funcs method can be used to add them.
+
+Predefined global functions are named as follows.
+
+	and
+		Returns the boolean AND of its arguments by returning the
+		first empty argument or the last argument. That is,
+		"and x y" behaves as "if x then y else x."
+		Evaluation proceeds through the arguments left to right
+		and returns when the result is determined.
+	call
+		Returns the result of calling the first argument, which
+		must be a function, with the remaining arguments as parameters.
+		Thus "call .X.Y 1 2" is, in Go notation, dot.X.Y(1, 2) where
+		Y is a func-valued field, map entry, or the like.
+		The first argument must be the result of an evaluation
+		that yields a value of function type (as distinct from
+		a predefined function such as print). The function must
+		return either one or two result values, the second of which
+		is of type error. If the arguments don't match the function
+		or the returned error value is non-nil, execution stops.
+	html
+		Returns the escaped HTML equivalent of the textual
+		representation of its arguments. This function is unavailable
+		in html/template, with a few exceptions.
+	index
+		Returns the result of indexing its first argument by the
+		following arguments. Thus "index x 1 2 3" is, in Go syntax,
+		x[1][2][3]. Each indexed item must be a map, slice, or array.
+	slice
+		slice returns the result of slicing its first argument by the
+		remaining arguments. Thus "slice x 1 2" is, in Go syntax, x[1:2],
+		while "slice x" is x[:], "slice x 1" is x[1:], and "slice x 1 2 3"
+		is x[1:2:3]. The first argument must be a string, slice, or array.
+	js
+		Returns the escaped JavaScript equivalent of the textual
+		representation of its arguments.
+	len
+		Returns the integer length of its argument.
+	not
+		Returns the boolean negation of its single argument.
+	or
+		Returns the boolean OR of its arguments by returning the
+		first non-empty argument or the last argument, that is,
+		"or x y" behaves as "if x then x else y".
+		Evaluation proceeds through the arguments left to right
+		and returns when the result is determined.
+	print
+		An alias for fmt.Sprint
+	printf
+		An alias for fmt.Sprintf
+	println
+		An alias for fmt.Sprintln
+	urlquery
+		Returns the escaped value of the textual representation of
+		its arguments in a form suitable for embedding in a URL query.
+		This function is unavailable in html/template, with a few
+		exceptions.
+
+The boolean functions take any zero value to be false and a non-zero
+value to be true.
+
+There is also a set of binary comparison operators defined as
+functions:
+
+	eq
+		Returns the boolean truth of arg1 == arg2
+	ne
+		Returns the boolean truth of arg1 != arg2
+	lt
+		Returns the boolean truth of arg1 < arg2
+	le
+		Returns the boolean truth of arg1 <= arg2
+	gt
+		Returns the boolean truth of arg1 > arg2
+	ge
+		Returns the boolean truth of arg1 >= arg2
+
+For simpler multi-way equality tests, eq (only) accepts two or more
+arguments and compares the second and subsequent to the first,
+returning in effect
+
+	arg1==arg2 || arg1==arg3 || arg1==arg4 ...
+
+(Unlike with || in Go, however, eq is a function call and all the
+arguments will be evaluated.)
+
+The comparison functions work on any values whose type Go defines as
+comparable. For basic types such as integers, the rules are relaxed:
+size and exact type are ignored, so any integer value, signed or unsigned,
+may be compared with any other integer value. (The arithmetic value is compared,
+not the bit pattern, so all negative integers are less than all unsigned integers.)
+However, as usual, one may not compare an int with a float32 and so on.
+
+Associated templates
+
+Each template is named by a string specified when it is created. Also, each
+template is associated with zero or more other templates that it may invoke by
+name; such associations are transitive and form a name space of templates.
+
+A template may use a template invocation to instantiate another associated
+template; see the explanation of the "template" action above. The name must be
+that of a template associated with the template that contains the invocation.
+
+Nested template definitions
+
+When parsing a template, another template may be defined and associated with the
+template being parsed. Template definitions must appear at the top level of the
+template, much like global variables in a Go program.
+
+The syntax of such definitions is to surround each template declaration with a
+"define" and "end" action.
+
+The define action names the template being created by providing a string
+constant. Here is a simple example:
+
+	{{define "T1"}}ONE{{end}}
+	{{define "T2"}}TWO{{end}}
+	{{define "T3"}}{{template "T1"}} {{template "T2"}}{{end}}
+	{{template "T3"}}
+
+This defines two templates, T1 and T2, and a third T3 that invokes the other two
+when it is executed. Finally it invokes T3. If executed this template will
+produce the text
+
+	ONE TWO
+
+By construction, a template may reside in only one association. If it's
+necessary to have a template addressable from multiple associations, the
+template definition must be parsed multiple times to create distinct *Template
+values, or must be copied with [Template.Clone] or [Template.AddParseTree].
+
+Parse may be called multiple times to assemble the various associated templates;
+see [ParseFiles], [ParseGlob], [Template.ParseFiles] and [Template.ParseGlob]
+for simple ways to parse related templates stored in files.
+
+A template may be executed directly or through [Template.ExecuteTemplate], which executes
+an associated template identified by name. To invoke our example above, we
+might write,
+
+	err := tmpl.Execute(os.Stdout, "no data needed")
+	if err != nil {
+		log.Fatalf("execution failed: %s", err)
+	}
+
+or to invoke a particular template explicitly by name,
+
+	err := tmpl.ExecuteTemplate(os.Stdout, "T2", "no data needed")
+	if err != nil {
+		log.Fatalf("execution failed: %s", err)
+	}
+
+*/
+package gotext

template/gotext/helper.go

@@ -0,0 +1,178 @@
+// Copyright 2011 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.
+
+// Helper functions to make constructing templates easier.
+
+package gotext
+
+import (
+	"fmt"
+	"io/fs"
+	"os"
+	"path"
+	"path/filepath"
+)
+
+// Functions and methods to parse templates.
+
+// Must is a helper that wraps a call to a function returning ([*Template], error)
+// and panics if the error is non-nil. It is intended for use in variable
+// initializations such as
+//
+//	var t = template.Must(template.New("name").Parse("text"))
+func Must(t *Template, err error) *Template {
+	if err != nil {
+		panic(err)
+	}
+	return t
+}
+
+// ParseFiles creates a new [Template] and parses the template definitions from
+// the named files. The returned template's name will have the base name and
+// parsed contents of the first file. There must be at least one file.
+// If an error occurs, parsing stops and the returned *Template is nil.
+//
+// When parsing multiple files with the same name in different directories,
+// the last one mentioned will be the one that results.
+// For instance, ParseFiles("a/foo", "b/foo") stores "b/foo" as the template
+// named "foo", while "a/foo" is unavailable.
+func ParseFiles(filenames ...string) (*Template, error) {
+	return parseFiles(nil, readFileOS, filenames...)
+}
+
+// ParseFiles parses the named files and associates the resulting templates with
+// t. If an error occurs, parsing stops and the returned template is nil;
+// otherwise it is t. There must be at least one file.
+// Since the templates created by ParseFiles are named by the base
+// (see [filepath.Base]) names of the argument files, t should usually have the
+// name of one of the (base) names of the files. If it does not, depending on
+// t's contents before calling ParseFiles, t.Execute may fail. In that
+// case use t.ExecuteTemplate to execute a valid template.
+//
+// When parsing multiple files with the same name in different directories,
+// the last one mentioned will be the one that results.
+func (t *Template) ParseFiles(filenames ...string) (*Template, error) {
+	t.init()
+	return parseFiles(t, readFileOS, filenames...)
+}
+
+// parseFiles is the helper for the method and function. If the argument
+// template is nil, it is created from the first file.
+func parseFiles(t *Template, readFile func(string) (string, []byte, error), filenames ...string) (*Template, error) {
+	if len(filenames) == 0 {
+		// Not really a problem, but be consistent.
+		return nil, fmt.Errorf("template: no files named in call to ParseFiles")
+	}
+	for _, filename := range filenames {
+		name, b, err := readFile(filename)
+		if err != nil {
+			return nil, err
+		}
+		s := string(b)
+		// First template becomes return value if not already defined,
+		// and we use that one for subsequent New calls to associate
+		// all the templates together. Also, if this file has the same name
+		// as t, this file becomes the contents of t, so
+		//  t, err := New(name).Funcs(xxx).ParseFiles(name)
+		// works. Otherwise we create a new template associated with t.
+		var tmpl *Template
+		if t == nil {
+			t = New(name)
+		}
+		if name == t.Name() {
+			tmpl = t
+		} else {
+			tmpl = t.New(name)
+		}
+		_, err = tmpl.Parse(s)
+		if err != nil {
+			return nil, err
+		}
+	}
+	return t, nil
+}
+
+// ParseGlob creates a new [Template] and parses the template definitions from
+// the files identified by the pattern. The files are matched according to the
+// semantics of [filepath.Match], and the pattern must match at least one file.
+// The returned template will have the [filepath.Base] name and (parsed)
+// contents of the first file matched by the pattern. ParseGlob is equivalent to
+// calling [ParseFiles] with the list of files matched by the pattern.
+//
+// When parsing multiple files with the same name in different directories,
+// the last one mentioned will be the one that results.
+func ParseGlob(pattern string) (*Template, error) {
+	return parseGlob(nil, pattern)
+}
+
+// ParseGlob parses the template definitions in the files identified by the
+// pattern and associates the resulting templates with t. The files are matched
+// according to the semantics of [filepath.Match], and the pattern must match at
+// least one file. ParseGlob is equivalent to calling [Template.ParseFiles] with
+// the list of files matched by the pattern.
+//
+// When parsing multiple files with the same name in different directories,
+// the last one mentioned will be the one that results.
+func (t *Template) ParseGlob(pattern string) (*Template, error) {
+	t.init()
+	return parseGlob(t, pattern)
+}
+
+// parseGlob is the implementation of the function and method ParseGlob.
+func parseGlob(t *Template, pattern string) (*Template, error) {
+	filenames, err := filepath.Glob(pattern)
+	if err != nil {
+		return nil, err
+	}
+	if len(filenames) == 0 {
+		return nil, fmt.Errorf("template: pattern matches no files: %#q", pattern)
+	}
+	return parseFiles(t, readFileOS, filenames...)
+}
+
+// ParseFS is like [Template.ParseFiles] or [Template.ParseGlob] but reads from the file system fsys
+// instead of the host operating system's file system.
+// It accepts a list of glob patterns (see [path.Match]).
+// (Note that most file names serve as glob patterns matching only themselves.)
+func ParseFS(fsys fs.FS, patterns ...string) (*Template, error) {
+	return parseFS(nil, fsys, patterns)
+}
+
+// ParseFS is like [Template.ParseFiles] or [Template.ParseGlob] but reads from the file system fsys
+// instead of the host operating system's file system.
+// It accepts a list of glob patterns (see [path.Match]).
+// (Note that most file names serve as glob patterns matching only themselves.)
+func (t *Template) ParseFS(fsys fs.FS, patterns ...string) (*Template, error) {
+	t.init()
+	return parseFS(t, fsys, patterns)
+}
+
+func parseFS(t *Template, fsys fs.FS, patterns []string) (*Template, error) {
+	var filenames []string
+	for _, pattern := range patterns {
+		list, err := fs.Glob(fsys, pattern)
+		if err != nil {
+			return nil, err
+		}
+		if len(list) == 0 {
+			return nil, fmt.Errorf("template: pattern matches no files: %#q", pattern)
+		}
+		filenames = append(filenames, list...)
+	}
+	return parseFiles(t, readFileFS(fsys), filenames...)
+}
+
+func readFileOS(file string) (name string, b []byte, err error) {
+	name = filepath.Base(file)
+	b, err = os.ReadFile(file)
+	return
+}
+
+func readFileFS(fsys fs.FS) func(string) (string, []byte, error) {
+	return func(file string) (name string, b []byte, err error) {
+		name = path.Base(file)
+		b, err = fs.ReadFile(fsys, file)
+		return
+	}
+}

template/gotext/patches/0001-exec-deadline.patch

@@ -1,17 +1,11 @@
 diff -ruN a/exec.go b/exec.go
---- a/exec.go	2026-07-08 15:38:43.551040811 +0200
+--- a/exec.go	2026-07-08 21:46:30.952555712 +0200
-+++ b/exec.go	2026-07-08 15:38:43.553556913 +0200
++++ b/exec.go	2026-07-08 21:46:30.953912265 +0200
-@@ -2,17 +2,19 @@
+@@ -7,12 +7,14 @@
- // Use of this source code is governed by a BSD-style
- // license that can be found in the LICENSE file.
- 
--package template
-+package gotext
- 
  import (
  	"errors"
  	"fmt"
--	"internal/fmtsort"
+-	"heckel.io/ntfy/v2/template/gotext/fmtsort"
  	"io"
  	"reflect"
  	"runtime"
@@ -79,42 +73,10 @@ diff -ruN a/exec.go b/exec.go
  	switch node := node.(type) {
  	case *parse.ActionNode:
  		// Do not pop variables so they persist until next end.
-diff -ruN a/funcs.go b/funcs.go
---- a/funcs.go	2026-07-08 15:38:43.551127782 +0200
-+++ b/funcs.go	2026-07-08 15:38:43.553627333 +0200
-@@ -2,7 +2,7 @@
- // Use of this source code is governed by a BSD-style
- // license that can be found in the LICENSE file.
- 
--package template
-+package gotext
- 
- import (
- 	"errors"
-diff -ruN a/option.go b/option.go
---- a/option.go	2026-07-08 15:38:43.551232856 +0200
-+++ b/option.go	2026-07-08 15:38:43.553688366 +0200
-@@ -4,7 +4,7 @@
- 
- // This file contains the code to handle template options.
- 
--package template
-+package gotext
- 
- import "strings"
- 
 diff -ruN a/template.go b/template.go
---- a/template.go	2026-07-08 15:38:43.551182684 +0200
+--- a/template.go	2026-07-08 21:46:30.952848382 +0200
-+++ b/template.go	2026-07-08 15:38:43.553660525 +0200
++++ b/template.go	2026-07-08 21:46:30.953952891 +0200
-@@ -2,20 +2,22 @@
+@@ -9,13 +9,15 @@
- // Use of this source code is governed by a BSD-style
- // license that can be found in the LICENSE file.
- 
--package template
-+package gotext
- 
- import (
- 	"maps"
  	"reflect"
  	"sync"
  	"text/template/parse"