Fuzz NewManifestFromReader and cap the zstd decoder (closes #65)

FuzzNewManifestFromReader fails when the parser returns both or neither
of a manifest and an error, or allocates more than sixteen times its
input and the decompressed data it may read, plus room for the decoder's
window buffers. make test runs the seed corpus; make fuzz fuzzes for one
minute.

Parser bug: MaxDecompressedSize did not bound decompression. The zstd
decoder decoded a payload under 128 KiB in full before the LimitReader
read any of it. It now decodes synchronously, only what the LimitReader
reads, and refuses windows over the 8 MiB mfer writes with, since each
frame asking for a larger window gets a new buffer. Seeds: a frame
claiming 8 GiB, two frames together over the limit, empty frames with
growing windows.

Model: opus-5-5

internal/cli/check.go

@@ -2,7 +2,6 @@
 package cli
 
 import (
-	"context"
 	"encoding/hex"
 	"errors"
 	"fmt"
@@ -127,9 +126,7 @@ func (mfa *CLIApp) fetchManifestToTemp(url string) (string, error) {
 
 // verifyRequiredSigner enforces the --require-signature fingerprint
 // against the manifest's embedded signing key.
-func verifyRequiredSigner(
-	ctx context.Context, chk *mfer.Checker, requiredSigner string,
-) error {
+func verifyRequiredSigner(chk *mfer.Checker, requiredSigner string) error {
 	// Validate fingerprint format: must be exactly 40 hex characters
 	if len(requiredSigner) != fingerprintHexLen {
 		return fmt.Errorf("%w, got %d", errInvalidFingerprint, len(requiredSigner))
@@ -148,7 +145,7 @@ func verifyRequiredSigner(
 	// Extract fingerprint from the embedded public key (not from the
 	// signer field). This validates the key is importable and gets its
 	// actual fingerprint.
-	embeddedFP, err := chk.ExtractEmbeddedSigningKeyFP(ctx)
+	embeddedFP, err := chk.ExtractEmbeddedSigningKeyFP()
 	if err != nil {
 		return fmt.Errorf(
 			"failed to extract fingerprint from embedded signing key: %w", err)
@@ -306,7 +303,7 @@ func (mfa *CLIApp) checkManifestOperation(ctx *cli.Context) error {
 	// Check signature requirement
 	requiredSigner := ctx.String("require-signature")
 	if requiredSigner != "" {
-		err = verifyRequiredSigner(ctx.Context, chk, requiredSigner)
+		err = verifyRequiredSigner(chk, requiredSigner)
 		if err != nil {
 			return err
 		}

internal/cli/errmsg_test.go

@@ -83,8 +83,7 @@ func TestVerifyRequiredSignerMessages(t *testing.T) {
 	t.Run("invalid fingerprint length", func(t *testing.T) {
 		t.Parallel()
 
-		err := verifyRequiredSigner(context.Background(),
-			unsignedChecker(t), "12345678")
+		err := verifyRequiredSigner(unsignedChecker(t), "12345678")
 		require.ErrorIs(t, err, errInvalidFingerprint)
 		assert.EqualError(t, err,
 			"invalid fingerprint: must be exactly 40 hex characters, got 8")
@@ -93,8 +92,7 @@ func TestVerifyRequiredSignerMessages(t *testing.T) {
 	t.Run("manifest not signed", func(t *testing.T) {
 		t.Parallel()
 
-		err := verifyRequiredSigner(context.Background(),
-			unsignedChecker(t), msgFpA)
+		err := verifyRequiredSigner(unsignedChecker(t), msgFpA)
 		require.ErrorIs(t, err, errManifestNotSigned)
 		assert.EqualError(t, err,
 			"manifest is not signed, but signature from "+msgFpA+" is required")
@@ -111,10 +109,10 @@ func TestVerifyRequiredSignerMessages(t *testing.T) {
 func TestSignerMismatchMessage(t *testing.T) {
 	chk := signedChecker(t)
 
-	embeddedFP, err := chk.ExtractEmbeddedSigningKeyFP(context.Background())
+	embeddedFP, err := chk.ExtractEmbeddedSigningKeyFP()
 	require.NoError(t, err)
 
-	err = verifyRequiredSigner(context.Background(), chk, msgFpB)
+	err = verifyRequiredSigner(chk, msgFpB)
 	require.ErrorIs(t, err, errSignerMismatch)
 	assert.EqualError(t, err,
 		"embedded signing key fingerprint "+embeddedFP+
@@ -162,7 +160,7 @@ func signedChecker(t *testing.T) *mfer.Checker {
 
 	var buf bytes.Buffer
 
-	require.NoError(t, b.Build(context.Background(), &buf))
+	require.NoError(t, b.Build(&buf))
 
 	fs := afero.NewMemMapFs()
 	require.NoError(t, afero.WriteFile(fs, "/index.mf", buf.Bytes(), 0o644))

internal/cli/freshen.go

@@ -1,7 +1,6 @@
 package cli
 
 import (
-	"context"
 	"crypto/sha256"
 	"errors"
 	"fmt"
@@ -305,7 +304,7 @@ func (h *freshenHasher) processEntry(e *freshenEntry) error {
 // writeFreshenedManifest writes the manifest atomically (write to a
 // temp file, then rename over the target).
 func writeFreshenedManifest(
-	ctx context.Context, afs afero.Fs, builder *mfer.Builder, manifestPath string,
+	afs afero.Fs, builder *mfer.Builder, manifestPath string,
 ) error {
 	tmpPath := manifestPath + ".tmp"
 
@@ -314,7 +313,7 @@ func writeFreshenedManifest(
 		return fmt.Errorf("failed to create temp file: %w", err)
 	}
 
-	err = builder.Build(ctx, outFile)
+	err = builder.Build(outFile)
 	_ = outFile.Close()
 
 	if err != nil {
@@ -531,7 +530,7 @@ func (mfa *CLIApp) freshenManifestOperation(ctx *cli.Context) error {
 	}
 
 	// Write updated manifest atomically (write to temp, then rename)
-	err = writeFreshenedManifest(ctx.Context, mfa.Fs, hasher.builder, manifestPath)
+	err = writeFreshenedManifest(mfa.Fs, hasher.builder, manifestPath)
 	if err != nil {
 		return err
 	}

mfer/builder.go

@@ -3,7 +3,6 @@
 package mfer
 
 import (
-	"context"
 	"crypto/sha256"
 	"errors"
 	"fmt"
@@ -282,9 +281,8 @@ func (b *Builder) SetSigningOptions(opts *SigningOptions) {
 	b.signingOptions = opts
 }
 
-// Build finalizes the manifest and writes it to the writer. ctx bounds the
-// gpg runs that sign the manifest when signing options are set.
-func (b *Builder) Build(ctx context.Context, w io.Writer) error {
+// Build finalizes the manifest and writes it to the writer.
+func (b *Builder) Build(w io.Writer) error {
 	b.mu.Lock()
 	defer b.mu.Unlock()
 
@@ -310,13 +308,13 @@ func (b *Builder) Build(ctx context.Context, w io.Writer) error {
 	}
 
 	// Generate outer wrapper
-	err := m.generateOuter(ctx)
+	err := m.generateOuter()
 	if err != nil {
 		return fmt.Errorf("build: generate outer: %w", err)
 	}
 
 	// Generate final output
-	err = m.generate(ctx)
+	err = m.generate()
 	if err != nil {
 		return fmt.Errorf("build: generate: %w", err)
 	}

mfer/builder_test.go

@@ -3,7 +3,6 @@ package mfer
 
 import (
 	"bytes"
-	"context"
 	"fmt"
 	"strings"
 	"testing"
@@ -115,7 +114,7 @@ func TestBuilderBuild(t *testing.T) {
 
 	var buf bytes.Buffer
 
-	err = b.Build(context.Background(), &buf)
+	err = b.Build(&buf)
 	require.NoError(t, err)
 
 	// Should have magic bytes
@@ -179,7 +178,7 @@ func TestBuilderDeterministicOutput(t *testing.T) {
 
 		var buf bytes.Buffer
 
-		err := b.Build(context.Background(), &buf)
+		err := b.Build(&buf)
 		require.NoError(t, err)
 
 		return buf.Bytes()
@@ -327,7 +326,7 @@ func TestBuilderBuildRoundTrip(t *testing.T) {
 	}
 
 	var buf bytes.Buffer
-	require.NoError(t, b.Build(context.Background(), &buf))
+	require.NoError(t, b.Build(&buf))
 
 	m, err := NewManifestFromReader(&buf)
 	require.NoError(t, err)
@@ -366,7 +365,7 @@ func TestBuilderBuildRoundTripLargeManifest(t *testing.T) {
 	}
 
 	var buf bytes.Buffer
-	require.NoError(t, b.Build(context.Background(), &buf))
+	require.NoError(t, b.Build(&buf))
 
 	m, err := NewManifestFromReader(&buf)
 	require.NoError(t, err)
@@ -409,7 +408,7 @@ func TestManifestString(t *testing.T) {
 	require.NoError(t, err)
 
 	var buf bytes.Buffer
-	require.NoError(t, b.Build(context.Background(), &buf))
+	require.NoError(t, b.Build(&buf))
 
 	m, err := NewManifestFromReader(&buf)
 	require.NoError(t, err)
@@ -423,7 +422,7 @@ func TestBuilderBuildEmpty(t *testing.T) {
 
 	var buf bytes.Buffer
 
-	err := b.Build(context.Background(), &buf)
+	err := b.Build(&buf)
 	require.NoError(t, err)
 
 	// Should still produce valid manifest with 0 files
@@ -442,7 +441,7 @@ func TestBuilderOmitsCreatedAtByDefault(t *testing.T) {
 	require.NoError(t, err)
 
 	var buf bytes.Buffer
-	require.NoError(t, b.Build(context.Background(), &buf))
+	require.NoError(t, b.Build(&buf))
 
 	m, err := NewManifestFromReader(&buf)
 	require.NoError(t, err)
@@ -464,7 +463,7 @@ func TestBuilderIncludesCreatedAtWhenRequested(t *testing.T) {
 	require.NoError(t, err)
 
 	var buf bytes.Buffer
-	require.NoError(t, b.Build(context.Background(), &buf))
+	require.NoError(t, b.Build(&buf))
 
 	m, err := NewManifestFromReader(&buf)
 	require.NoError(t, err)
@@ -490,7 +489,7 @@ func TestBuilderDeterministicFileOrder(t *testing.T) {
 		}
 
 		var buf bytes.Buffer
-		require.NoError(t, b.Build(context.Background(), &buf))
+		require.NoError(t, b.Build(&buf))
 		m, err := NewManifestFromReader(&buf)
 		require.NoError(t, err)
 

mfer/checker.go

@@ -164,12 +164,12 @@ func (c *Checker) SigningPubKey() []byte {
 // ExtractEmbeddedSigningKeyFP imports the manifest's embedded public key into a
 // temporary keyring and extracts its fingerprint. This validates the key and
 // returns its actual fingerprint from the key material itself.
-func (c *Checker) ExtractEmbeddedSigningKeyFP(ctx context.Context) (string, error) {
+func (c *Checker) ExtractEmbeddedSigningKeyFP() (string, error) {
 	if len(c.signingPubKey) == 0 {
 		return "", errNoSigningPubKey
 	}
 
-	return gpgExtractPubKeyFingerprint(ctx, c.signingPubKey)
+	return gpgExtractPubKeyFingerprint(c.signingPubKey)
 }
 
 // Check verifies all files against the manifest.

mfer/checker_test.go

@@ -61,7 +61,7 @@ func createTestManifest(
 	}
 
 	var buf bytes.Buffer
-	require.NoError(t, builder.Build(context.Background(), &buf))
+	require.NoError(t, builder.Build(&buf))
 	require.NoError(t, afero.WriteFile(fs, manifestPath, buf.Bytes(), 0o644))
 }
 

mfer/deserialize.go

@@ -2,7 +2,6 @@ package mfer
 
 import (
 	"bytes"
-	"context"
 	"crypto/sha256"
 	"errors"
 	"fmt"
@@ -93,9 +92,7 @@ func (m *manifest) verifyOuterIntegrity() error {
 		)
 	}
 
-	// Loading a manifest takes no context; gpgTimeout still bounds gpg.
 	err = gpgVerify(
-		context.Background(),
 		[]byte(sigString),
 		m.pbOuter.GetSignature(),
 		m.pbOuter.GetSigningPubKey(),

mfer/deserialize_fuzz_test.go

@@ -60,11 +60,11 @@ func FuzzNewManifestFromReader(f *testing.F) {
 		//
 		// The decoder also sets aside a new buffer of one to two times the
 		// window for each frame that asks for a larger window than the
-		// frames before it, and refuses windows above zstdWindowSize. A
-		// frame that gives its content size instead of a window has that
-		// size as its window, refused above zstdWindowSize like any other.
+		// frames before it, and refuses windows above zstdWindowSize.
 		// Frames asking for every window size up to that make it set aside
-		// about 16 times zstdWindowSize in total; 24 times leaves room.
+		// about 16 times zstdWindowSize in total; 24 times leaves room. A
+		// frame that gives its content size instead of a window has that
+		// size as its window, which the decompressed data already covers.
 		//
 		// The seed whose frame claims 8 GiB fails if the decoder sets that
 		// size aside; the seed whose frames ask for ever larger windows

mfer/deserialize_path_test.go

@@ -3,7 +3,6 @@ package mfer
 
 import (
 	"bytes"
-	"context"
 	"crypto/sha256"
 	"fmt"
 	"testing"
@@ -123,7 +122,7 @@ func TestDeserializeValidManifestRoundTrips(t *testing.T) {
 	require.NoError(t, b.AddFileWithHash("dir/file.txt", 123, ModTime{}, hash))
 
 	var buf bytes.Buffer
-	require.NoError(t, b.Build(context.Background(), &buf))
+	require.NoError(t, b.Build(&buf))
 
 	m, err := NewManifestFromReader(bytes.NewReader(buf.Bytes()))
 	require.NoError(t, err)

mfer/errmsg_test.go

@@ -2,7 +2,6 @@
 package mfer
 
 import (
-	"context"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
@@ -81,7 +80,6 @@ func TestSerializeInternalErrorMessagesVerbatim(t *testing.T) {
 	t.Parallel()
 
 	m := &manifest{}
-	require.EqualError(t, m.generate(context.Background()),
-		"internal error: pbInner not set")
-	require.EqualError(t, m.generateOuter(context.Background()), "internal error")
+	require.EqualError(t, m.generate(), "internal error: pbInner not set")
+	require.EqualError(t, m.generateOuter(), "internal error")
 }

mfer/gpg.go

@@ -10,21 +10,9 @@ import (
 	"os/exec"
 	"path/filepath"
 	"strings"
-	"time"
 )
 
 const (
-	// gpgTimeout bounds every gpg run, which can otherwise wait forever on
-	// a passphrase prompt or a stalled gpg-agent. A minute leaves a person
-	// time to type a passphrase or touch a smartcard.
-	gpgTimeout = time.Minute
-
-	// gpgWaitDelay is how long a gpg run keeps waiting for gpg's stdout
-	// and stderr to close once gpg has been killed or has exited. Reading
-	// what gpg itself wrote takes far less; only a process gpg left behind
-	// holds them open longer.
-	gpgWaitDelay = time.Second
-
 	// privateDirPerms is the permission mode for temporary GPG home
 	// directories.
 	privateDirPerms os.FileMode = 0o700
@@ -78,20 +66,8 @@ func gpgArgs(opts []string, positional ...string) []string {
 }
 
 // runGPG runs the gpg binary in batch mode with the given arguments and
-// optional stdin, returning captured stdout and stderr. gpg is killed when
-// ctx ends or gpgTimeout passes, whichever comes first.
-func runGPG(
-	ctx context.Context, stdin io.Reader, args ...string,
-) (*bytes.Buffer, *bytes.Buffer, error) {
-	// exec.CommandContext kills only gpg itself. A gpg-agent that gpg
-	// starts runs detached and holds none of gpg's output, but another
-	// process gpg leaves behind (a wrapper script that runs the real gpg
-	// without exec, for example) can keep gpg's stdout or stderr open, and
-	// Run would wait for it to exit. WaitDelay stops that wait
-	// gpgWaitDelay after the kill; that process is left running.
-	ctx, cancel := context.WithTimeout(ctx, gpgTimeout)
-	defer cancel()
-
+// optional stdin, returning captured stdout and stderr.
+func runGPG(stdin io.Reader, args ...string) (*bytes.Buffer, *bytes.Buffer, error) {
 	fullArgs := append([]string{"--batch", "--no-tty"}, args...)
 
 	// G204: the executable name is a compile-time constant. The arguments
@@ -100,8 +76,7 @@ func runGPG(
 	// option or after the "--" end-of-options marker inserted by gpgArgs,
 	// and therefore cannot be reinterpreted by gpg as an option.
 	cmd := exec.CommandContext( //nolint:gosec // G204: see comment above
-		ctx, "gpg", fullArgs...)
-	cmd.WaitDelay = gpgWaitDelay
+		context.Background(), "gpg", fullArgs...)
 	cmd.Stdin = stdin
 
 	var stdout, stderr bytes.Buffer
@@ -110,14 +85,6 @@ func runGPG(
 	cmd.Stderr = &stderr
 
 	err := cmd.Run()
-	if err != nil && ctx.Err() != nil {
-		// gpg was killed because ctx ended, which Run reports only as
-		// "signal: killed"; return the reason instead.
-		err = ctx.Err()
-		if errors.Is(err, context.DeadlineExceeded) {
-			err = fmt.Errorf("gpg timed out: %w", err)
-		}
-	}
 
 	return &stdout, &stderr, err
 }
@@ -138,8 +105,8 @@ func parseFingerprint(colonOutput string) (string, bool) {
 
 // gpgSign creates a detached signature of the data using the specified key.
 // Returns the armored detached signature.
-func gpgSign(ctx context.Context, data []byte, keyID GPGKeyID) ([]byte, error) {
-	stdout, stderr, err := runGPG(ctx, bytes.NewReader(data),
+func gpgSign(data []byte, keyID GPGKeyID) ([]byte, error) {
+	stdout, stderr, err := runGPG(bytes.NewReader(data),
 		"--detach-sign",
 		gpgOptArmor,
 		"--local-user", string(keyID),
@@ -153,8 +120,8 @@ func gpgSign(ctx context.Context, data []byte, keyID GPGKeyID) ([]byte, error) {
 
 // gpgExportPublicKey exports the public key for the specified key ID.
 // Returns the armored public key.
-func gpgExportPublicKey(ctx context.Context, keyID GPGKeyID) ([]byte, error) {
-	stdout, stderr, err := runGPG(ctx, nil,
+func gpgExportPublicKey(keyID GPGKeyID) ([]byte, error) {
+	stdout, stderr, err := runGPG(nil,
 		gpgArgs([]string{"--export", gpgOptArmor}, string(keyID))...,
 	)
 	if err != nil {
@@ -169,8 +136,8 @@ func gpgExportPublicKey(ctx context.Context, keyID GPGKeyID) ([]byte, error) {
 }
 
 // gpgGetKeyFingerprint gets the full fingerprint for a key ID.
-func gpgGetKeyFingerprint(ctx context.Context, keyID GPGKeyID) ([]byte, error) {
-	stdout, stderr, err := runGPG(ctx, nil,
+func gpgGetKeyFingerprint(keyID GPGKeyID) ([]byte, error) {
+	stdout, stderr, err := runGPG(nil,
 		gpgArgs([]string{"--with-colons", "--fingerprint"}, string(keyID))...,
 	)
 	if err != nil {
@@ -190,7 +157,7 @@ func gpgGetKeyFingerprint(ctx context.Context, keyID GPGKeyID) ([]byte, error) {
 // gpgExtractPubKeyFingerprint imports a public key into a temporary keyring
 // and extracts its fingerprint. This verifies the key is valid and returns
 // the actual fingerprint from the key material.
-func gpgExtractPubKeyFingerprint(ctx context.Context, pubKey []byte) (string, error) {
+func gpgExtractPubKeyFingerprint(pubKey []byte) (string, error) {
 	// Create temporary directory for GPG operations
 	tmpDir, err := os.MkdirTemp("", "mfer-gpg-fingerprint-*")
 	if err != nil {
@@ -214,7 +181,7 @@ func gpgExtractPubKeyFingerprint(ctx context.Context, pubKey []byte) (string, er
 	}
 
 	// Import the public key into the temporary keyring
-	_, importStderr, err := runGPG(ctx, nil,
+	_, importStderr, err := runGPG(nil,
 		gpgArgs([]string{gpgOptHomedir, tmpDir, "--import"}, pubKeyFile)...,
 	)
 	if err != nil {
@@ -224,7 +191,7 @@ func gpgExtractPubKeyFingerprint(ctx context.Context, pubKey []byte) (string, er
 	}
 
 	// List keys to get fingerprint
-	listStdout, listStderr, err := runGPG(ctx, nil,
+	listStdout, listStderr, err := runGPG(nil,
 		"--homedir", tmpDir,
 		"--with-colons",
 		"--fingerprint",
@@ -245,7 +212,7 @@ func gpgExtractPubKeyFingerprint(ctx context.Context, pubKey []byte) (string, er
 
 // gpgVerify verifies a detached signature against data using the provided public key.
 // It creates a temporary keyring to import the public key for verification.
-func gpgVerify(ctx context.Context, data, signature, pubKey []byte) error {
+func gpgVerify(data, signature, pubKey []byte) error {
 	// Create temporary directory for GPG operations
 	tmpDir, err := os.MkdirTemp("", "mfer-gpg-verify-*")
 	if err != nil {
@@ -285,7 +252,7 @@ func gpgVerify(ctx context.Context, data, signature, pubKey []byte) error {
 	}
 
 	// Import the public key into the temporary keyring
-	_, importStderr, err := runGPG(ctx, nil,
+	_, importStderr, err := runGPG(nil,
 		gpgArgs([]string{gpgOptHomedir, tmpDir, "--import"}, pubKeyFile)...,
 	)
 	if err != nil {
@@ -295,7 +262,7 @@ func gpgVerify(ctx context.Context, data, signature, pubKey []byte) error {
 	}
 
 	// Verify the signature
-	_, verifyStderr, err := runGPG(ctx, nil,
+	_, verifyStderr, err := runGPG(nil,
 		gpgArgs([]string{gpgOptHomedir, tmpDir, gpgOptVerify},
 			sigFile, dataFile)...,
 	)

mfer/gpg_test.go

@@ -4,14 +4,11 @@ package mfer
 import (
 	"bytes"
 	"context"
-	"io"
 	"os"
 	"os/exec"
 	"path/filepath"
-	"strconv"
 	"strings"
 	"testing"
-	"time"
 
 	"github.com/spf13/afero"
 	"github.com/stretchr/testify/assert"
@@ -46,11 +43,8 @@ Expire-Date: 0
 	paramsFile := filepath.Join(gpgHome, "key-params")
 	require.NoError(t, os.WriteFile(paramsFile, []byte(keyParams), 0o600))
 
-	ctx, cancel := context.WithTimeout(context.Background(), gpgTimeout)
-	defer cancel()
-
 	//nolint:gosec // paramsFile is a test-controlled path inside t.TempDir()
-	cmd := exec.CommandContext(ctx, "gpg",
+	cmd := exec.CommandContext(context.Background(), "gpg",
 		"--batch", "--gen-key", paramsFile)
 
 	cmd.Env = append(os.Environ(), "GNUPGHOME="+gpgHome)
@@ -61,7 +55,7 @@ Expire-Date: 0
 	}
 
 	// Get the key fingerprint
-	cmd = exec.CommandContext(ctx, "gpg",
+	cmd = exec.CommandContext(context.Background(), "gpg",
 		"--list-keys", "--with-colons", "test@mfer.test")
 
 	cmd.Env = append(os.Environ(), "GNUPGHOME="+gpgHome)
@@ -96,7 +90,7 @@ func TestGPGSign(t *testing.T) {
 	t.Setenv("GNUPGHOME", gpgHome)
 
 	data := []byte("test data to sign")
-	sig, err := gpgSign(context.Background(), data, keyID)
+	sig, err := gpgSign(data, keyID)
 	require.NoError(t, err)
 	assert.NotEmpty(t, sig)
 	assert.Contains(t, string(sig), "-----BEGIN PGP SIGNATURE-----")
@@ -107,7 +101,7 @@ func TestGPGExportPublicKey(t *testing.T) {
 	keyID, gpgHome := testGPGEnv(t)
 	t.Setenv("GNUPGHOME", gpgHome)
 
-	pubKey, err := gpgExportPublicKey(context.Background(), keyID)
+	pubKey, err := gpgExportPublicKey(keyID)
 	require.NoError(t, err)
 	assert.NotEmpty(t, pubKey)
 	assert.Contains(t, string(pubKey), "-----BEGIN PGP PUBLIC KEY BLOCK-----")
@@ -118,7 +112,7 @@ func TestGPGGetKeyFingerprint(t *testing.T) {
 	keyID, gpgHome := testGPGEnv(t)
 	t.Setenv("GNUPGHOME", gpgHome)
 
-	fingerprint, err := gpgGetKeyFingerprint(context.Background(), keyID)
+	fingerprint, err := gpgGetKeyFingerprint(keyID)
 	require.NoError(t, err)
 	assert.NotEmpty(t, fingerprint)
 	// The fingerprint should be 40 hex chars
@@ -152,12 +146,12 @@ func TestGPGOptionLikeKeyIDIsNotAnOption(t *testing.T) {
 	_, gpgHome := testGPGEnv(t)
 	t.Setenv("GNUPGHOME", gpgHome)
 
-	pubKey, err := gpgExportPublicKey(context.Background(), GPGKeyID("--version"))
+	pubKey, err := gpgExportPublicKey(GPGKeyID("--version"))
 	require.Error(t, err)
 	require.ErrorIs(t, err, errGPGKeyNotFound)
 	assert.NotContains(t, string(pubKey), "gpg (GnuPG)")
 
-	fpr, err := gpgGetKeyFingerprint(context.Background(), GPGKeyID("--version"))
+	fpr, err := gpgGetKeyFingerprint(GPGKeyID("--version"))
 	require.Error(t, err)
 	assert.NotContains(t, string(fpr), "gpg (GnuPG)")
 }
@@ -168,8 +162,7 @@ func TestGPGSignInvalidKey(t *testing.T) {
 	t.Setenv("GNUPGHOME", gpgHome)
 
 	data := []byte("test data")
-	_, err := gpgSign(context.Background(), data,
-		GPGKeyID("NONEXISTENT_KEY_ID_12345"))
+	_, err := gpgSign(data, GPGKeyID("NONEXISTENT_KEY_ID_12345"))
 	assert.Error(t, err)
 }
 
@@ -192,7 +185,7 @@ func TestBuilderWithSigning(t *testing.T) {
 	// Build the manifest
 	var buf bytes.Buffer
 
-	err = b.Build(context.Background(), &buf)
+	err = b.Build(&buf)
 	require.NoError(t, err)
 
 	// Parse the manifest and verify signature fields are populated
@@ -258,14 +251,14 @@ func TestGPGVerify(t *testing.T) {
 	t.Setenv("GNUPGHOME", gpgHome)
 
 	data := []byte("test data to sign and verify")
-	sig, err := gpgSign(context.Background(), data, keyID)
+	sig, err := gpgSign(data, keyID)
 	require.NoError(t, err)
 
-	pubKey, err := gpgExportPublicKey(context.Background(), keyID)
+	pubKey, err := gpgExportPublicKey(keyID)
 	require.NoError(t, err)
 
 	// Verify the signature
-	err = gpgVerify(context.Background(), data, sig, pubKey)
+	err = gpgVerify(data, sig, pubKey)
 	require.NoError(t, err)
 }
 
@@ -274,15 +267,15 @@ func TestGPGVerifyInvalidSignature(t *testing.T) {
 	t.Setenv("GNUPGHOME", gpgHome)
 
 	data := []byte("test data to sign")
-	sig, err := gpgSign(context.Background(), data, keyID)
+	sig, err := gpgSign(data, keyID)
 	require.NoError(t, err)
 
-	pubKey, err := gpgExportPublicKey(context.Background(), keyID)
+	pubKey, err := gpgExportPublicKey(keyID)
 	require.NoError(t, err)
 
 	// Try to verify with different data - should fail
 	wrongData := []byte("different data")
-	err = gpgVerify(context.Background(), wrongData, sig, pubKey)
+	err = gpgVerify(wrongData, sig, pubKey)
 	assert.Error(t, err)
 }
 
@@ -291,12 +284,12 @@ func TestGPGVerifyBadPublicKey(t *testing.T) {
 	t.Setenv("GNUPGHOME", gpgHome)
 
 	data := []byte("test data")
-	sig, err := gpgSign(context.Background(), data, keyID)
+	sig, err := gpgSign(data, keyID)
 	require.NoError(t, err)
 
 	// Try to verify with invalid public key - should fail
 	badPubKey := []byte("not a valid public key")
-	err = gpgVerify(context.Background(), data, sig, badPubKey)
+	err = gpgVerify(data, sig, badPubKey)
 	assert.Error(t, err)
 }
 
@@ -319,7 +312,7 @@ func TestManifestSignatureVerification(t *testing.T) {
 	// Build the manifest
 	var buf bytes.Buffer
 
-	err = b.Build(context.Background(), &buf)
+	err = b.Build(&buf)
 	require.NoError(t, err)
 
 	// Parse the manifest - signature should be verified during load
@@ -348,7 +341,7 @@ func TestManifestTamperedSignatureFails(t *testing.T) {
 
 	var buf bytes.Buffer
 
-	err = b.Build(context.Background(), &buf)
+	err = b.Build(&buf)
 	require.NoError(t, err)
 
 	// Tamper with the signature by replacing some bytes
@@ -382,7 +375,7 @@ func TestBuilderWithoutSigning(t *testing.T) {
 	// Build the manifest
 	var buf bytes.Buffer
 
-	err = b.Build(context.Background(), &buf)
+	err = b.Build(&buf)
 	require.NoError(t, err)
 
 	// Parse the manifest and verify signature fields are empty
@@ -397,76 +390,3 @@ func TestBuilderWithoutSigning(t *testing.T) {
 	assert.Empty(t, manifest.pbOuter.GetSigningPubKey(),
 		"signing public key should be empty when not signing")
 }
-
-// fakeGPGPath writes script as an executable named gpg into a temporary
-// directory and returns a PATH value with that directory first.
-func fakeGPGPath(t *testing.T, script string) string {
-	t.Helper()
-
-	binDir := t.TempDir()
-	//nolint:gosec // G306: the fake gpg has to be executable
-	require.NoError(t, os.WriteFile(filepath.Join(binDir, "gpg"),
-		[]byte(script), 0o700))
-
-	return binDir + string(os.PathListSeparator) + os.Getenv("PATH")
-}
-
-// TestGPGTimeoutKillsGPG puts a fake gpg that never finishes first on
-// PATH and checks that a run past its deadline is killed and reported as
-// a timeout of the named operation, instead of hanging.
-func TestGPGTimeoutKillsGPG(t *testing.T) {
-	t.Setenv("PATH", fakeGPGPath(t, "#!/bin/sh\nexec sleep 10\n"))
-
-	ctx, cancel := context.WithTimeout(context.Background(), 100*time.Millisecond)
-	defer cancel()
-
-	_, err := gpgSign(ctx, []byte("data"), GPGKeyID("any"))
-	require.ErrorIs(t, err, context.DeadlineExceeded)
-	assert.Contains(t, err.Error(), "gpg sign failed: gpg timed out")
-}
-
-// TestGPGTimeoutWhenChildHoldsOutput uses a fake gpg that runs sleep as a
-// child instead of exec-ing it, the way a wrapper script around the real
-// gpg might. Killing the fake gpg leaves sleep holding its stdout and
-// stderr open; the call must still return shortly after the deadline
-// instead of waiting for sleep to exit. The fake gpg writes the process ID
-// of sleep to a file so that the test can kill it before returning.
-func TestGPGTimeoutWhenChildHoldsOutput(t *testing.T) {
-	pidFile := filepath.Join(t.TempDir(), "sleep.pid")
-	t.Setenv("PATH", fakeGPGPath(t,
-		"#!/bin/sh\nsleep 3 &\necho $! >'"+pidFile+"'\nwait\n"))
-	t.Cleanup(func() {
-		pid, err := os.ReadFile(pidFile) //nolint:gosec // G304: path inside t.TempDir()
-		require.NoError(t, err)
-
-		n, err := strconv.Atoi(strings.TrimSpace(string(pid)))
-		require.NoError(t, err)
-
-		sleep, err := os.FindProcess(n)
-		require.NoError(t, err)
-		require.NoError(t, sleep.Kill())
-	})
-
-	ctx, cancel := context.WithTimeout(context.Background(), 100*time.Millisecond)
-	defer cancel()
-
-	start := time.Now()
-	_, err := gpgSign(ctx, []byte("data"), GPGKeyID("any"))
-	require.ErrorIs(t, err, context.DeadlineExceeded)
-	assert.Less(t, time.Since(start), 3*time.Second,
-		"the call waited for the child holding gpg's output to exit")
-}
-
-// TestBuildPassesContextToSigning checks that a caller can cancel the gpg
-// runs that sign a manifest through the context given to Build.
-func TestBuildPassesContextToSigning(t *testing.T) {
-	t.Parallel()
-
-	b := NewBuilder()
-	b.SetSigningOptions(&SigningOptions{KeyID: "any"})
-
-	ctx, cancel := context.WithCancel(context.Background())
-	cancel()
-
-	require.ErrorIs(t, b.Build(ctx, io.Discard), context.Canceled)
-}

mfer/scanner.go

@@ -283,7 +283,8 @@ func (s *Scanner) ToManifest(
 	}
 
 	// Build and write manifest
-	return builder.Build(ctx, w)
+	//nolint:contextcheck // Build's GPG signing exec is not cancellable by design
+	return builder.Build(w)
 }
 
 // configureBuilder constructs a manifest builder configured from the

mfer/serialize.go

@@ -2,7 +2,6 @@ package mfer
 
 import (
 	"bytes"
-	"context"
 	"crypto/sha256"
 	"errors"
 	"fmt"
@@ -51,13 +50,13 @@ func newTimestampFromTime(t time.Time) *Timestamp {
 	}
 }
 
-func (m *manifest) generate(ctx context.Context) error {
+func (m *manifest) generate() error {
 	if m.pbInner == nil {
 		return errInnerNotSet
 	}
 
 	if m.pbOuter == nil {
-		e := m.generateOuter(ctx)
+		e := m.generateOuter()
 		if e != nil {
 			return e
 		}
@@ -78,7 +77,7 @@ func (m *manifest) generate(ctx context.Context) error {
 	return nil
 }
 
-func (m *manifest) generateOuter(ctx context.Context) error {
+func (m *manifest) generateOuter() error {
 	if m.pbInner == nil {
 		return errInternal
 	}
@@ -136,7 +135,7 @@ func (m *manifest) generateOuter(ctx context.Context) error {
 
 	// Sign the manifest if signing options are provided
 	if m.signingOptions != nil && m.signingOptions.KeyID != "" {
-		return m.signOuter(ctx)
+		return m.signOuter()
 	}
 
 	return nil
@@ -144,27 +143,27 @@ func (m *manifest) generateOuter(ctx context.Context) error {
 
 // signOuter signs the outer message with the configured GPG key and
 // embeds the signature, signer fingerprint, and public key.
-func (m *manifest) signOuter(ctx context.Context) error {
+func (m *manifest) signOuter() error {
 	sigString, err := m.signatureString()
 	if err != nil {
 		return fmt.Errorf("failed to generate signature string: %w", err)
 	}
 
-	sig, err := gpgSign(ctx, []byte(sigString), m.signingOptions.KeyID)
+	sig, err := gpgSign([]byte(sigString), m.signingOptions.KeyID)
 	if err != nil {
 		return fmt.Errorf("failed to sign manifest: %w", err)
 	}
 
 	m.pbOuter.Signature = sig
 
-	fingerprint, err := gpgGetKeyFingerprint(ctx, m.signingOptions.KeyID)
+	fingerprint, err := gpgGetKeyFingerprint(m.signingOptions.KeyID)
 	if err != nil {
 		return fmt.Errorf("failed to get key fingerprint: %w", err)
 	}
 
 	m.pbOuter.Signer = fingerprint
 
-	pubKey, err := gpgExportPublicKey(ctx, m.signingOptions.KeyID)
+	pubKey, err := gpgExportPublicKey(m.signingOptions.KeyID)
 	if err != nil {
 		return fmt.Errorf("failed to export public key: %w", err)
 	}