fix(actions): keep folded block scalars intact across serialization (#39787)

Folded (`>`) scalars in workflows gained blank lines and had spaces
turned into newlines every time Gitea re-serialized a job. This bumps
go-yaml to its main branch and drops our workarounds. The runner gets
the same change in https://gitea.com/gitea/runner/pulls/1321.

- go-yaml main fixes the accumulating blank lines
(https://github.com/yaml/go-yaml/pull/366) and the block scalar
indentation indicators (https://github.com/yaml/go-yaml/pull/414), so
`BlockSafeString` and the folded scalar requoting go away
- The job encoder no longer wraps lines, because go-yaml still wraps
more-indented lines of folded scalars and turns a space into a newline
- The fix applies to folded scalars anywhere in a workflow, including
workflow-level `env`

Fixes https://github.com/go-gitea/gitea/issues/39775
Co-authored-by: silverwind <me@silverwind.io>

modules/actions/jobparser/model.go

@@ -4,7 +4,6 @@
 package jobparser
 
 import (
-	"bytes"
 	"errors"
 	"fmt"
 	"strings"
@@ -65,44 +64,31 @@ func (w *SingleWorkflow) SetJob(id string, job *Job) error {
 	m := map[string]*Job{
 		id: job,
 	}
-	var buf bytes.Buffer
-	encoder := yaml.NewEncoder(&buf)
-	encoder.SetIndent(2)
-	if err := encoder.Encode(m); err != nil {
+	out, err := marshalYAML(m)
+	if err != nil {
 		return err
 	}
-	encoder.Close()
 
 	node := yaml.Node{}
-	if err := yaml.Unmarshal(buf.Bytes(), &node); err != nil {
+	if err := yaml.Unmarshal(out, &node); err != nil {
 		return err
 	}
 	if len(node.Content) != 1 || node.Content[0].Kind != yaml.MappingNode {
-		return fmt.Errorf("can not set job: %s", buf.String())
+		return fmt.Errorf("can not set job: %s", out)
 	}
 	w.RawJobs = *node.Content[0]
 	return nil
 }
 
 func (w *SingleWorkflow) Marshal() ([]byte, error) {
-	// Encode with the same indentation SetJob uses (2). yaml.Marshal's default
-	// indentation (4) makes the encoder emit multi-line block scalars (e.g. a
-	// `run:` step that begins with blank lines) with a wrong explicit indentation
-	// indicator (`run: |4`) that then fails to re-parse, which silently strands
-	// the job during concurrency evaluation. Keeping both encoders at indent 2
-	// makes the serialized single workflow round-trip.
-	var buf bytes.Buffer
-	enc := yaml.NewEncoder(&buf)
-	enc.SetIndent(2)
 	payload := *w
 	payload.RunName = "" // already interpolated into the run title, a runner would parse it as a template again
-	if err := enc.Encode(&payload); err != nil {
-		return nil, err
-	}
-	if err := enc.Close(); err != nil {
-		return nil, err
-	}
-	return buf.Bytes(), nil
+	return marshalYAML(&payload)
+}
+
+// marshalYAML never wraps lines, go-yaml wraps more-indented lines of folded scalars until https://github.com/yaml/go-yaml/pull/441 is released.
+func marshalYAML(v any) ([]byte, error) {
+	return yaml.Dump(v, yaml.WithV3Defaults(), yaml.WithIndent(2), yaml.WithLineWidth(-1))
 }
 
 type Job struct {
@@ -196,29 +182,18 @@ func (j *Job) DisplayName() string {
 	return util.EllipsisDisplayString(unescapeExpressions(j.Name), 255)
 }
 
-// BlockSafeString works around https://github.com/yaml/go-yaml/issues/399, quoting a value whose
-// leading newline would cost a literal block scalar its indentation indicator.
-type BlockSafeString string
-
-func (s BlockSafeString) MarshalYAML() (any, error) {
-	if !strings.HasPrefix(string(s), "\n") {
-		return string(s), nil
-	}
-	return &yaml.Node{Kind: yaml.ScalarNode, Tag: "!!str", Style: yaml.DoubleQuotedStyle, Value: string(s)}, nil
-}
-
 type Step struct {
-	ID                 string          `yaml:"id,omitempty"`
-	If                 yaml.Node       `yaml:"if,omitempty"`
-	Name               BlockSafeString `yaml:"name,omitempty"`
-	Uses               string          `yaml:"uses,omitempty"`
-	Run                BlockSafeString `yaml:"run,omitempty"`
-	WorkingDirectory   string          `yaml:"working-directory,omitempty"`
-	Shell              string          `yaml:"shell,omitempty"`
-	Env                yaml.Node       `yaml:"env,omitempty"`
-	With               yaml.Node       `yaml:"with,omitempty"`
-	RawContinueOnError yaml.Node       `yaml:"continue-on-error,omitempty"` // raw: the runner evaluates it with the steps context
-	TimeoutMinutes     string          `yaml:"timeout-minutes,omitempty"`
+	ID                 string    `yaml:"id,omitempty"`
+	If                 yaml.Node `yaml:"if,omitempty"`
+	Name               string    `yaml:"name,omitempty"`
+	Uses               string    `yaml:"uses,omitempty"`
+	Run                string    `yaml:"run,omitempty"`
+	WorkingDirectory   string    `yaml:"working-directory,omitempty"`
+	Shell              string    `yaml:"shell,omitempty"`
+	Env                yaml.Node `yaml:"env,omitempty"`
+	With               yaml.Node `yaml:"with,omitempty"`
+	RawContinueOnError yaml.Node `yaml:"continue-on-error,omitempty"` // raw: the runner evaluates it with the steps context
+	TimeoutMinutes     string    `yaml:"timeout-minutes,omitempty"`
 }
 
 // UnmarshalYAML canonicalizes booleans like continue-on-error
@@ -240,9 +215,9 @@ func (s *Step) String() string {
 	}
 	return (&model.Step{
 		ID:   s.ID,
-		Name: string(s.Name),
+		Name: s.Name,
 		Uses: s.Uses,
-		Run:  string(s.Run),
+		Run:  s.Run,
 	}).String()
 }
 

modules/actions/jobparser/roundtrip_test.go

@@ -48,7 +48,7 @@ jobs:
 	_, origJob := sws[0].Job()
 	require.Len(t, origJob.Steps, 1)
 	const wantRun = "\n\necho start\necho done\n"
-	require.Equal(t, wantRun, string(origJob.Steps[0].Run))
+	require.Equal(t, wantRun, origJob.Steps[0].Run)
 
 	payload, err := sws[0].Marshal()
 	require.NoError(t, err)
@@ -63,7 +63,7 @@ jobs:
 	// the round-trip must preserve the run block byte-for-byte
 	_, gotJob := roundTripped[0].Job()
 	require.Len(t, gotJob.Steps, 1)
-	require.Equal(t, wantRun, string(gotJob.Steps[0].Run), "round-trip must preserve run content; got payload:\n%s", payload)
+	require.Equal(t, wantRun, gotJob.Steps[0].Run, "round-trip must preserve run content; got payload:\n%s", payload)
 }
 
 // Typing a step's continue-on-error as a bool used to reject the whole `jobs:` node.
@@ -104,3 +104,37 @@ jobs:
 		require.Equal(t, w, steps[i].RawContinueOnError, "step %d, payload:\n%s", i, payload)
 	}
 }
+
+// Folded (`>`) scalars in with/env used to gain blank lines and have spaces turned into newlines
+// on every Marshal -> Parse cycle.
+func TestSingleWorkflowRoundTripFoldedScalar(t *testing.T) {
+	const wf = `name: demo
+on: push
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: ./.github/actions/build
+        with:
+          cfg: >
+            begin
+              first "indented" line with path dir/Installer Scripts/some long path/another long path/some file name.xzy,
+              second "indented" line
+            end
+`
+	const want = "begin\n  first \"indented\" line with path dir/Installer Scripts/some long path/another long path/some file name.xzy,\n  second \"indented\" line\nend\n"
+	sws, err := Parse([]byte(wf))
+	require.NoError(t, err)
+	require.Len(t, sws, 1)
+	for range 3 {
+		payload, err := sws[0].Marshal()
+		require.NoError(t, err)
+		sws, err = Parse(payload)
+		require.NoError(t, err)
+		require.Len(t, sws, 1)
+	}
+	_, job := sws[0].Job()
+	var with map[string]string
+	require.NoError(t, job.Steps[0].With.Decode(&with))
+	require.Equal(t, want, with["cfg"])
+}

modules/actions/jobparser/testdata/prefixed_newline.out.yaml

@@ -7,5 +7,9 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - id: extract_tag
-        name: "\nExtract tag for variant"
-        run: "\necho Test\n"
+        name: |-
+
+          Extract tag for variant
+        run: |
+
+          echo Test