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. make test runs the committed seed corpus; make fuzz fuzzes for
one minute, by hand only.

Parser bug: MaxDecompressedSize did not bound decompression. The zstd
decoder decoded a payload under 128 KiB in full, each frame up to its
own 64 GiB limit, before the LimitReader read any of it. It now decodes
synchronously, only what the LimitReader reads, with MaxDecompressedSize
as its limit. Regression seeds: a frame claiming 8 GiB, and two frames
each under the limit and together over it.

Model: opus-5-5

Makefile

@@ -13,7 +13,7 @@ GOLDFLAGS += -X main.Version=$(VERSION)
 GOLDFLAGS += -X main.Gitrev=$(GITREV_BUILD)
 GOFLAGS := -ldflags "$(GOLDFLAGS)"
 
-.PHONY: bootstrap setup docker default run ci test check lint fmt fmt-check fmt-check-go fmt-check-md hooks fixme
+.PHONY: bootstrap setup docker default run ci test fuzz check lint fmt fmt-check fmt-check-go fmt-check-md hooks fixme
 
 default: fmt test
 
@@ -32,6 +32,9 @@ ci: test
 test:
 	@script/test
 
+fuzz:
+	@script/fuzz
+
 $(PROTOC_GEN_GO):
 	test -e $(PROTOC_GEN_GO) || go install -v google.golang.org/protobuf/cmd/protoc-gen-go@v1.28.1
 

README.md

@@ -44,6 +44,9 @@ provide:
   such as `script/docker`
 - `script/test` — run the test suite (`go test`), regenerating the protobuf code
   first if it is stale
+- `script/fuzz` — fuzz the manifest parser for one minute; run by hand
+  (`make fuzz`), never by CI, while `script/test` runs its committed seed corpus
+  as ordinary tests
 - `script/lint` — run `golangci-lint` and verify `gofmt` cleanliness
 - `script/fmt` — format all code and docs (writes): `gofumpt`,
   `golangci-lint run --fix`, and `script/prettier --write`
@@ -417,8 +420,8 @@ proto `go_package` option. Which is canonical?
       matching Scanner
 - [ ] Add `--deterministic` flag or make it default — omit `createdAt`, sort
       files (pending design question answer)
-- [x] Wire `--version` flag properly: `--version` and `-V` print the same line
+- [ ] Wire `--version` flag properly (currently only a `version` subcommand
-      as the `version` subcommand, and `-v` means verbose
+      exists; top-level `--version` shows urfave/cli generic output)
 - [ ] Add retry logic to `fetch` — currently no retries on transient HTTP
       errors; needs exponential backoff
 - [ ] `fetch` command uses bare `http.Get` with no timeout — needs `http.Client`

TODO.md

@@ -24,8 +24,11 @@ only thing left of the `chore/align-repo-policies` branch is the list below.
 
 # Completed Steps
 
-- 2026-09-21: fixed the `-v` collision between `--verbose` and `--version`;
+- 2026-10-03: added `FuzzNewManifestFromReader` and its seed corpus, which
-  verbose owns `-v`, and version answers to `--version` and `-V` (#64)
+  `make test` runs, plus `make fuzz` for a one-minute run by hand; the zstd
+  decoder now decodes only as many bytes as the parser reads, and has
+  `MaxDecompressedSize` as its limit, so neither a frame claiming a large size
+  nor several frames together can make the parser allocate past that limit (#65)
 - 2026-10-03: pinned the CLI error messages by driving the functions that emit
   them in `internal/cli/errmsg_test.go`, and made the freshen mtime-presence
   test distinguish an absent mtime from the epoch (#87)
@@ -128,7 +131,7 @@ only thing left of the `chore/align-repo-policies` branch is the list below.
       rate-limit Checker progress output; add --deterministic flag or default;
       wire top-level --version properly
 - Testing:
-    - Fuzz NewManifestFromReader; end-to-end tests for freshen and fetch
+    - End-to-end tests for freshen and fetch
 - Documentation:
     - Promote docs/FORMAT.md as primary spec reference; audit error messages;
       document the signature scheme fully

internal/cli/entry_test.go

@@ -27,7 +27,6 @@ const (
 	testManifest    = "/manifest.mf"
 	testFlagBase    = "--base"
 	testFlagNoExtra = "--no-extra-files"
-	testFlagVersion = "--version"
 )
 
 var errSimulatedWrite = errors.New("simulated write failure")
@@ -103,7 +102,7 @@ func TestVersionCommand(t *testing.T) {
 	t.Parallel()
 
 	fs := afero.NewMemMapFs()
-	opts := testOpts([]string{testApp, cmdVersion}, fs)
+	opts := testOpts([]string{testApp, "version"}, fs)
 
 	exitCode := runCLI(opts)
 
@@ -114,110 +113,6 @@ func TestVersionCommand(t *testing.T) {
 	assert.Contains(t, stdout, "abc123")
 }
 
-// TestVFlagCollision covers the -v/--verbose vs --version flag interaction
-// (issue #64). Verbose owns -v; version answers to --version and -V. None of
-// these invocations may produce a parser error, and the two ways of asking
-// for the version must print the same thing.
-func TestVFlagCollision(t *testing.T) {
-	t.Parallel()
-
-	// Invocations that must print the version and exit 0.
-	versionCases := map[string][]string{
-		"long version flag":        {testApp, testFlagVersion},
-		"short version flag":       {testApp, "-V"},
-		"verbose then version":     {testApp, "-v", testFlagVersion},
-		"long verbose and version": {testApp, "--verbose", testFlagVersion},
-	}
-
-	for name, args := range versionCases {
-		t.Run(name, func(t *testing.T) {
-			t.Parallel()
-
-			opts := testOpts(args, afero.NewMemMapFs())
-			exitCode := runCLI(opts)
-
-			assert.Equal(t, 0, exitCode, "stderr: %s", testStderr(t, opts))
-			assert.Contains(t, testStdout(t, opts), mfer.Version)
-			assert.NotContains(t, testStderr(t, opts), "two forms of the same flag")
-		})
-	}
-
-	// Invocations that must enable verbose and exit 0 without a parser error.
-	verboseCases := map[string][]string{
-		"short verbose flag": {testApp, "-v"},
-		"long verbose flag":  {testApp, "--verbose"},
-	}
-
-	for name, args := range verboseCases {
-		t.Run(name, func(t *testing.T) {
-			t.Parallel()
-
-			opts := testOpts(args, afero.NewMemMapFs())
-			exitCode := runCLI(opts)
-
-			assert.Equal(t, 0, exitCode, "stderr: %s", testStderr(t, opts))
-			assert.Contains(t, testStdout(t, opts), cmdGenerate,
-				"root should show help listing subcommands")
-			assert.Empty(t, testStderr(t, opts))
-		})
-	}
-}
-
-// TestVersionFlagAndCommandMatch asserts that "mfer --version" and
-// "mfer version" produce identical output (issue #64).
-func TestVersionFlagAndCommandMatch(t *testing.T) {
-	t.Parallel()
-
-	flagOpts := testOpts([]string{testApp, testFlagVersion}, afero.NewMemMapFs())
-	require.Equal(t, 0, runCLI(flagOpts))
-
-	cmdOpts := testOpts([]string{testApp, cmdVersion}, afero.NewMemMapFs())
-	require.Equal(t, 0, runCLI(cmdOpts))
-
-	assert.Equal(t, testStdout(t, flagOpts), testStdout(t, cmdOpts))
-}
-
-// TestVerbosityFlagsBeforeSubcommand asserts that -q and -v given before the
-// subcommand name take effect in that subcommand (issue #64).
-func TestVerbosityFlagsBeforeSubcommand(t *testing.T) {
-	t.Parallel()
-
-	t.Run("quiet before fetch hides the banner", func(t *testing.T) {
-		t.Parallel()
-
-		opts := testOpts([]string{testApp, "-q", cmdFetch}, afero.NewMemMapFs())
-
-		assert.Equal(t, 1, runCLI(opts))
-		assert.Contains(t, testStderr(t, opts), errURLRequired.Error())
-		assert.NotContains(t, testStdout(t, opts), banner)
-	})
-
-	t.Run("verbose twice before fetch enables debug logging", func(t *testing.T) {
-		t.Parallel()
-
-		opts := testOpts([]string{testApp, "-v", "-v", cmdFetch}, afero.NewMemMapFs())
-
-		assert.Equal(t, 1, runCLI(opts))
-		assert.Contains(t, testStderr(t, opts), "fetchManifestOperation()")
-	})
-
-	t.Run("quiet before export hides the manifest summary", func(t *testing.T) {
-		t.Parallel()
-
-		fs := afero.NewMemMapFs()
-		manifest := buildTestManifest(t, map[string][]byte{"a.txt": []byte("a")})
-		require.NoError(t, afero.WriteFile(fs, testManifest, manifest, 0o644))
-
-		loud := testOpts([]string{testApp, cmdExport, testManifest}, fs)
-		require.Equal(t, 0, runCLI(loud))
-		assert.Contains(t, testStderr(t, loud), "loaded manifest")
-
-		quiet := testOpts([]string{testApp, "-q", cmdExport, testManifest}, fs)
-		require.Equal(t, 0, runCLI(quiet))
-		assert.NotContains(t, testStderr(t, quiet), "loaded manifest")
-	})
-}
-
 func TestHelpCommand(t *testing.T) {
 	t.Parallel()
 

internal/cli/errmsg_test.go

@@ -5,7 +5,6 @@ import (
 	"bytes"
 	"context"
 	"flag"
-	"io"
 	"net/http"
 	"net/http/httptest"
 	"os"
@@ -17,7 +16,6 @@ import (
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 	urfcli "github.com/urfave/cli/v2"
-	"sneak.berlin/go/mfer/internal/log"
 	"sneak.berlin/go/mfer/mfer"
 )
 
@@ -38,16 +36,12 @@ const (
 	msgFpB = "BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB"
 )
 
-// runLocked runs fn while holding runMu and with the process-global logger
+// runLocked runs fn while holding runMu, so operations that write to the
-// pointed at io.Discard, so fn's log lines neither race the other CLI runs
+// process-global logger do not race the other CLI runs.
-// nor land in the last run's buffers, which its test may still be reading.
 func runLocked(fn func() error) error {
 	runMu.Lock()
 	defer runMu.Unlock()
 
-	log.SetOutput(io.Discard, io.Discard)
-	log.Init()
-
 	return fn()
 }
 

internal/cli/mfer.go

@@ -19,7 +19,6 @@ const (
 	cmdCheck    = "check"
 	cmdExport   = "export"
 	cmdFetch    = "fetch"
-	cmdVersion  = "version"
 
 	flagProgress = "progress"
 
@@ -69,12 +68,6 @@ func (mfa *CLIApp) VersionString() string {
 	return mfer.Version
 }
 
-// printVersion writes the version line shared by the --version flag and the
-// version subcommand, so both produce identical output.
-func (mfa *CLIApp) printVersion() {
-	_, _ = fmt.Fprintf(mfa.Stdout, "%s version %s\n", mfa.appname, mfa.VersionString())
-}
-
 func (mfa *CLIApp) printBanner() {
 	if log.GetLevel() <= log.InfoLevel {
 		_, _ = fmt.Fprintln(mfa.Stdout, banner)
@@ -85,34 +78,20 @@ func (mfa *CLIApp) printBanner() {
 	}
 }
 
-// setVerbosity sets the log level from -v and -q, given before the subcommand
-// name (the root's copies), after it (the subcommand's own copies), or both.
-// urfave/cli reads a flag from the nearest command that defines it, so each
-// command in the lineage is asked. The highest -v count wins rather than the
-// sum, because a subcommand without its own copies reads the root's.
 func (mfa *CLIApp) setVerbosity(c *cli.Context) {
 	_, present := os.LookupEnv("MFER_DEBUG")
 
-	verbosity := 0
-	quiet := false
-
-	for _, ctx := range c.Lineage() {
-		verbosity = max(verbosity, ctx.Count("verbose"))
-		quiet = quiet || ctx.Bool("quiet")
-	}
-
 	switch {
 	case present:
 		log.EnableDebugLogging()
-	case quiet:
+	case c.Bool("quiet"):
 		log.SetLevel(log.ErrorLevel)
 	default:
-		log.SetLevelFromVerbosity(verbosity)
+		log.SetLevelFromVerbosity(c.Count("verbose"))
 	}
 }
 
-// commonFlags returns the -v and -q flags taken by the root and by the
+// commonFlags returns the flags shared by most commands (-v, -q)
-// generate, check, freshen and fetch subcommands.
 func commonFlags() []cli.Flag {
 	return []cli.Flag{
 		&cli.BoolFlag{
@@ -280,8 +259,6 @@ func (mfa *CLIApp) exportCommand() *cli.Command {
 		Usage:     "Export manifest contents as JSON",
 		ArgsUsage: "[manifest file or URL]",
 		Action: func(c *cli.Context) error {
-			mfa.setVerbosity(c)
-
 			return mfa.exportManifestOperation(c)
 		},
 	}
@@ -289,10 +266,10 @@ func (mfa *CLIApp) exportCommand() *cli.Command {
 
 func (mfa *CLIApp) versionCommand() *cli.Command {
 	return &cli.Command{
-		Name:  cmdVersion,
+		Name:  "version",
 		Usage: "Show version",
 		Action: func(_ *cli.Context) error {
-			mfa.printVersion()
+			_, _ = fmt.Fprintln(mfa.Stdout, mfa.VersionString())
 
 			return nil
 		},
@@ -348,21 +325,6 @@ func (mfa *CLIApp) run(args []string) {
 	log.SetOutput(mfa.Stdout, mfa.Stderr)
 	log.Init()
 
-	// -v means verbose, not version. urfave/cli's built-in version flag
-	// claims -v by default, which made "mfer -v --version" fail to parse and
-	// gave -v a different meaning at the root than on the generate, check,
-	// freshen and fetch subcommands, where it means verbose. Verbose is the
-	// more common meaning of -v in tools that offer both, so -v means verbose
-	// at the root too and the version flag takes the capital -V.
-	// VersionFlag and VersionPrinter are urfave/cli package globals; run() is
-	// serialized in tests, so assigning them here is safe.
-	cli.VersionFlag = &cli.BoolFlag{
-		Name:    cmdVersion,
-		Aliases: []string{"V"},
-		Usage:   "print the version",
-	}
-	cli.VersionPrinter = func(_ *cli.Context) { mfa.printVersion() }
-
 	mfa.app = &cli.App{
 		Name:                 mfa.appname,
 		Usage:                "Manifest generator",
@@ -370,13 +332,11 @@ func (mfa *CLIApp) run(args []string) {
 		EnableBashCompletion: true,
 		Writer:               mfa.Stdout,
 		ErrWriter:            mfa.Stderr,
-		Flags:                commonFlags(),
 		Action: func(c *cli.Context) error {
 			if c.Args().Len() > 0 {
 				return fmt.Errorf("%w %q", errUnknownCommand, c.Args().First())
 			}
 
-			mfa.setVerbosity(c)
 			mfa.printBanner()
 
 			return cli.ShowAppHelp(c)

mfer/deserialize.go

@@ -111,7 +111,15 @@ func (m *manifest) verifyOuterIntegrity() error {
 func (m *manifest) decompressInner() ([]byte, error) {
 	bb := bytes.NewBuffer(m.pbOuter.GetInnerMessage())
 
-	zr, err := zstd.NewReader(bb)
+	// By default the decoder decodes a payload under 128 KiB in full,
+	// each frame up to the decoder's limit, before the LimitReader below
+	// reads any of it. Decoding synchronously and never in full makes it decode
+	// only what the LimitReader asks for. Its limit caps the window that
+	// a frame header can make it set aside.
+	zr, err := zstd.NewReader(bb,
+		zstd.WithDecoderConcurrency(1),
+		zstd.WithDecodeBuffersBelow(0),
+		zstd.WithDecoderMaxMemory(uint64(MaxDecompressedSize)))
 	if err != nil {
 		return nil, fmt.Errorf("deserialize: zstd reader: %w", err)
 	}

mfer/deserialize_fuzz_test.go

@@ -0,0 +1,75 @@
+//nolint:testpackage // white-box tests exercise unexported internals
+package mfer
+
+import (
+	"bytes"
+	"runtime"
+	"testing"
+
+	"google.golang.org/protobuf/proto"
+)
+
+// FuzzNewManifestFromReader feeds arbitrary bytes to the manifest parser.
+// `make test` runs it on the seed corpus in
+// testdata/fuzz/FuzzNewManifestFromReader; `make fuzz` searches for new
+// inputs.
+//
+// For every input the parser must return a manifest or an error, not both
+// and not neither, and must not allocate more than a fixed multiple of its
+// input and of the decompressed data it may read, plus room for the
+// decoder's window. A panic or a hang fails the test on its own.
+func FuzzNewManifestFromReader(f *testing.F) {
+	// A signed manifest makes the parser write the key and signature to a
+	// temporary directory and run gpg on them. With gpg off the PATH and
+	// temporary files kept in the test's own directory, no process is
+	// started and nothing is written elsewhere; such input ends in an
+	// error instead.
+	f.Setenv("PATH", "")
+	f.Setenv("TMPDIR", f.TempDir())
+
+	f.Fuzz(func(t *testing.T, data []byte) {
+		var before, after runtime.MemStats
+
+		runtime.ReadMemStats(&before)
+
+		m, err := NewManifestFromReader(bytes.NewReader(data))
+
+		runtime.ReadMemStats(&after)
+
+		if (m == nil) == (err == nil) {
+			t.Fatalf("got manifest %p and error %v, want exactly one", m, err)
+		}
+
+		// The parser reads at most the declared size plus one byte of
+		// decompressed data, and never more than MaxDecompressedSize.
+		decompressed := uint64(MaxDecompressedSize)
+
+		outer := new(MFFileOuter)
+		if validateMagic(data) &&
+			proto.Unmarshal(data[len(MAGIC):], outer) == nil {
+			size := outer.GetSize()
+			if size > 0 && size < MaxDecompressedSize {
+				decompressed = uint64(size) + 1
+			}
+		}
+
+		// It also keeps a few copies of its input, and the decoder sets
+		// aside a window that a frame header sizes, up to a little over
+		// MaxDecompressedSize. Buffers grow by copying, so reaching those
+		// sizes allocates a few times them in total: sixteen times the
+		// input and the decompressed data, plus twice MaxDecompressedSize
+		// for the window, leaves room for that. The seed whose frame
+		// claims 8 GiB fails if the decoder sets that size aside; the seed
+		// whose two frames together exceed MaxDecompressedSize fails if
+		// the decoder decodes them in full instead of stopping at the
+		// declared size.
+		limit := 16*(uint64(len(data))+decompressed) +
+			2*uint64(MaxDecompressedSize)
+
+		allocated := after.TotalAlloc - before.TotalAlloc
+		if allocated > limit {
+			t.Fatalf("allocated %d bytes for %d bytes of input, limit %d",
+				allocated, len(data), limit)
+		}
+	})
+}

mfer/testdata/fuzz/FuzzNewManifestFromReader/empty

@@ -0,0 +1,2 @@
+go test fuzz v1
+[]byte("")

mfer/testdata/fuzz/FuzzNewManifestFromReader/magic-then-garbage

@@ -0,0 +1,2 @@
+go test fuzz v1
+[]byte("ZNAVSRFGy[i\x04\xe5O\x82A\x1d\xf4\xb0\xe2z7:U\xee\xa3\xf9\xd6m\xacZ\x9b\xce\x1d\xd9/{@\x1d\xa5y[i\x04\xe5O\x82A\x1d\xf4\xb0\xe2z7:U\xee\xa3\xf9\xd6m\xacZ\x9b\xce\x1d\xd9/{@\x1d\xa5")

mfer/testdata/fuzz/FuzzNewManifestFromReader/minimal

@@ -0,0 +1,2 @@
+go test fuzz v1
+[]byte("ZNAVSRFG\xa8\x06\x01\xb0\x06\x01\xb8\x06V\xc2\x06 \xa3\xf7\x97\xa7\xf3\x87:\x90)\\ӊj\xb9\xf7\xfaTJ\x1b\xe7:\xee\xbe\"V\xe0:\x8d(Z\xd6%\xca\x06\x10\x93\x85\vpu\x85\xe4\x04\xe4\x95\x1a=\xdc\x1f\x05\xa3\xba\fc(\xb5/\xfd\x04\x00\xb1\x02\x00\xa0\x06\x01\xaa\x06=\n\x05a.txt\x10\x01\x1a$\n\"\x12 ʗ\x81\x12\xca\x1b\xbd\xca\xfa\xc21\xb3\x9a#\xdcM\xa7\x86\xef\xf8\x14|Nr\xb9\x80w\x85\xaf\xeeH\xbb\xf2\x12\v\b\x80\x92\xb8Ø\xfe\xff\xff\xff\x01\xb2\x06\x10\x93\x85\vpu\x85\xe4\x04\xe4\x95\x1a=\xdc\x1f\x05\xa3s\xeeG\x80")

mfer/testdata/fuzz/FuzzNewManifestFromReader/signed

@@ -0,0 +1,2 @@
+go test fuzz v1
+[]byte("ZNAVSRFG\xa8\x06\x01\xb0\x06\x01\xb8\x06V\xc2\x06 \xa3\xf7\x97\xa7\xf3\x87:\x90)\\ӊj\xb9\xf7\xfaTJ\x1b\xe7:\xee\xbe\"V\xe0:\x8d(Z\xd6%\xca\x06\x10\x93\x85\vpu\x85\xe4\x04\xe4\x95\x1a=\xdc\x1f\x05\xa3\xba\fc(\xb5/\xfd\x04\x00\xb1\x02\x00\xa0\x06\x01\xaa\x06=\n\x05a.txt\x10\x01\x1a$\n\"\x12 ʗ\x81\x12\xca\x1b\xbd\xca\xfa\xc21\xb3\x9a#\xdcM\xa7\x86\xef\xf8\x14|Nr\xb9\x80w\x85\xaf\xeeH\xbb\xf2\x12\v\b\x80\x92\xb8Ø\xfe\xff\xff\xff\x01\xb2\x06\x10\x93\x85\vpu\x85\xe4\x04\xe4\x95\x1a=\xdc\x1f\x05\xa3s\xeeG\x80\xca\f\xe8\x03-----BEGIN PGP SIGNATURE-----\n\niQEzBAABCgAdFiEET1Yr+4Y/3GtRtO6IhypRF2zvI64FAmrBIXAACgkQhypRF2zv\nI67BQAf/QrpX2MjY15YGMGkjR5oIhnx/YV96aGYZyZThzb+l/R/N75iVFVkhX21d\nZhQqdCsORrodTPAXic2g2UGVXP9PhNMh7n6Wm3LsvQYjrRQGrQnqtCkut+3tUt8K\n7pt4OAnnwRSieaVImA1COmzxIrQQKNOs6UkgmAstGuPV0XZoeDiSG8TUYJ/vieCn\np5hC0FFXtzfw4NtkxSmkewE0xBxIwFCA/RfSHCGH3m5K+tRz41vMEgGbL1iEp6+V\nuBaoEc4hqCgEt+Af2pA8VHfqeu2vKiwggOpYpaILXZKVqH9+tWHL1EBv9t0vTsYE\n9D57euuR9+kOdngYNPieP1yn5dOSHg==\n=kvgL\n-----END PGP SIGNATURE-----\n\xd2\f(4F562BFB863FDC6B51B4EE88872A51176CEF23AE\xda\f\xb5\a-----BEGIN PGP PUBLIC KEY BLOCK-----\n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\nKoTjp4nxgQGy5WmeBzs4Hdm/\n=TCB8\n-----END PGP PUBLIC KEY BLOCK-----\n")

mfer/testdata/fuzz/FuzzNewManifestFromReader/size-above-payload

@@ -0,0 +1,2 @@
+go test fuzz v1
+[]byte("ZNAVSRFG\xa8\x06\x01\xb0\x06\x01\xb8\x06!\xc2\x06 \x91\x90*\xa5>\fݐ \x87\xbeaL\xc1\x05?\x0eR\xc18\xa4eՕ\xa95\xb9KʺoZ\xca\x06\x10\x93\x85\vpu\x85\xe4\x04\xe4\x95\x1a=\xdc\x1f\x05\xa3\xba\f-(\xb5/\xfd\x04\x00\x01\x01\x00\xa0\x06\x01\xaa\x06\a\n\x05a.txt\xb2\x06\x10\x93\x85\vpu\x85\xe4\x04\xe4\x95\x1a=\xdc\x1f\x05\xa3a[k'")

mfer/testdata/fuzz/FuzzNewManifestFromReader/size-below-payload

@@ -0,0 +1,2 @@
+go test fuzz v1
+[]byte("ZNAVSRFG\xa8\x06\x01\xb0\x06\x01\xb8\x06\x1f\xc2\x06 \x91\x90*\xa5>\fݐ \x87\xbeaL\xc1\x05?\x0eR\xc18\xa4eՕ\xa95\xb9KʺoZ\xca\x06\x10\x93\x85\vpu\x85\xe4\x04\xe4\x95\x1a=\xdc\x1f\x05\xa3\xba\f-(\xb5/\xfd\x04\x00\x01\x01\x00\xa0\x06\x01\xaa\x06\a\n\x05a.txt\xb2\x06\x10\x93\x85\vpu\x85\xe4\x04\xe4\x95\x1a=\xdc\x1f\x05\xa3a[k'")

mfer/testdata/fuzz/FuzzNewManifestFromReader/truncated-at-172

@@ -0,0 +1,2 @@
+go test fuzz v1
+[]byte("ZNAVSRFG\xa8\x06\x01\xb0\x06\x01\xb8\x06V\xc2\x06 \xa3\xf7\x97\xa7\xf3\x87:\x90)\\ӊj\xb9\xf7\xfaTJ\x1b\xe7:\xee\xbe\"V\xe0:\x8d(Z\xd6%\xca\x06\x10\x93\x85\vpu\x85\xe4\x04\xe4\x95\x1a=\xdc\x1f\x05\xa3\xba\fc(\xb5/\xfd\x04\x00\xb1\x02\x00\xa0\x06\x01\xaa\x06=\n\x05a.txt\x10\x01\x1a$\n\"\x12 ʗ\x81\x12\xca\x1b\xbd\xca\xfa\xc21\xb3\x9a#\xdcM\xa7\x86\xef\xf8\x14|Nr\xb9\x80w\x85\xaf\xeeH\xbb\xf2\x12\v\b\x80\x92\xb8Ø\xfe\xff\xff\xff\x01\xb2\x06\x10\x93\x85\vpu\x85\xe4\x04\xe4\x95\x1a=\xdc\x1f\x05\xa3s\xeeG")

mfer/testdata/fuzz/FuzzNewManifestFromReader/truncated-at-20

@@ -0,0 +1,2 @@
+go test fuzz v1
+[]byte("ZNAVSRFG\xa8\x06\x01\xb0\x06\x01\xb8\x06V\xc2\x06 ")

mfer/testdata/fuzz/FuzzNewManifestFromReader/truncated-at-4

@@ -0,0 +1,2 @@
+go test fuzz v1
+[]byte("ZNAV")

mfer/testdata/fuzz/FuzzNewManifestFromReader/truncated-at-8

@@ -0,0 +1,2 @@
+go test fuzz v1
+[]byte("ZNAVSRFG")

mfer/testdata/fuzz/FuzzNewManifestFromReader/truncated-at-86

@@ -0,0 +1,2 @@
+go test fuzz v1
+[]byte("ZNAVSRFG\xa8\x06\x01\xb0\x06\x01\xb8\x06V\xc2\x06 \xa3\xf7\x97\xa7\xf3\x87:\x90)\\ӊj\xb9\xf7\xfaTJ\x1b\xe7:\xee\xbe\"V\xe0:\x8d(Z\xd6%\xca\x06\x10\x93\x85\vpu\x85\xe4\x04\xe4\x95\x1a=\xdc\x1f\x05\xa3\xba\fc(\xb5/\xfd\x04\x00\xb1\x02\x00\xa0\x06\x01")

mfer/testdata/fuzz/FuzzNewManifestFromReader/wrong-magic

@@ -0,0 +1,2 @@
+go test fuzz v1
+[]byte("ZNAVSRFX\xa8\x06\x01\xb0\x06\x01\xb8\x06V\xc2\x06 \xa3\xf7\x97\xa7\xf3\x87:\x90)\\ӊj\xb9\xf7\xfaTJ\x1b\xe7:\xee\xbe\"V\xe0:\x8d(Z\xd6%\xca\x06\x10\x93\x85\vpu\x85\xe4\x04\xe4\x95\x1a=\xdc\x1f\x05\xa3\xba\fc(\xb5/\xfd\x04\x00\xb1\x02\x00\xa0\x06\x01\xaa\x06=\n\x05a.txt\x10\x01\x1a$\n\"\x12 ʗ\x81\x12\xca\x1b\xbd\xca\xfa\xc21\xb3\x9a#\xdcM\xa7\x86\xef\xf8\x14|Nr\xb9\x80w\x85\xaf\xeeH\xbb\xf2\x12\v\b\x80\x92\xb8Ø\xfe\xff\xff\xff\x01\xb2\x06\x10\x93\x85\vpu\x85\xe4\x04\xe4\x95\x1a=\xdc\x1f\x05\xa3s\xeeG\x80")

mfer/testdata/fuzz/FuzzNewManifestFromReader/zstd-frame-claims-8gib

@@ -0,0 +1,2 @@
+go test fuzz v1
+[]byte("ZNAVSRFG\xa8\x06\x01\xb0\x06\x01\xb8\x06\x01\xc2\x06 \xd6aQ\xa4\x85\xc0+\xbb\xca\x11\x11\a<\x019\x97\xb3\xbb3\xd0 \xd5U\xfa!\xaeAf<N@\x9d\xca\x06\x10\x93\x85\vpu\x85\xe4\x04\xe4\x95\x1a=\xdc\x1f\x05\xa3\xba\f\x12(\xb5/\xfd\xc0\x00\x00\x00\x00\x00\x02\x00\x00\x00\v\x00\x00\x00")

script/fuzz

@@ -0,0 +1,17 @@
+#!/bin/sh
+# script/fuzz: fuzz the manifest parser for one minute. Run by hand only:
+# script/test already runs the committed seed corpus as ordinary tests,
+# and CI never fuzzes. An input that fails is written to
+# mfer/testdata/fuzz/FuzzNewManifestFromReader/; once the parser is fixed,
+# commit it there as a regression seed.
+set -eu
+
+ROOT="$(cd "$(dirname "$0")/.." && pwd -P)"
+
+main() {
+    cd "$ROOT"
+    go test -run '^$' -fuzz '^FuzzNewManifestFromReader$' \
+        -fuzztime 1m -parallel 2 ./mfer
+}
+
+main "$@"