testing: fix -run behavior with fuzz tests

This change fixes some issues with -run, and
the subsequent command line output when running
in verbose mode. It replaces CorpusEntry.Name
with CorpusEntry.Path, and refactors the code
accordingly.

This change also adds a lot of additional tests
which check explicit command line output when
fuzz targets are run without fuzzing. This will
be important to avoid regressions.

Updates #48149

Change-Id: If34b1f51db646317b7b51c3c38ae53231d01f568
Reviewed-on: https://go-review.googlesource.com/c/go/+/354632
Trust: Katie Hockman <katie@golang.org>
Run-TryBot: Katie Hockman <katie@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Jay Conrod <jayconrod@google.com>

2 files changed, 44 insertions, 40 deletions

diff --git a/src/internal/fuzz/fuzz.go b/src/internal/fuzz/fuzz.go
index f660052911..a8bbd60b1c 100644
--- a/src/internal/fuzz/fuzz.go
+++ b/src/internal/fuzz/fuzz.go
@@ -141,14 +141,14 @@ func CoordinateFuzzing(ctx context.Context, opts CoordinateFuzzingOpts) (err err
 		if c.crashMinimizing == nil || crashWritten {
 			return
 		}
-		fileName, werr := writeToCorpus(c.crashMinimizing.entry.Data, opts.CorpusDir)
+		werr := writeToCorpus(&c.crashMinimizing.entry, opts.CorpusDir)
 		if werr != nil {
 			err = fmt.Errorf("%w\n%v", err, werr)
 			return
 		}
 		if err == nil {
 			err = &crashError{
-				name: filepath.Base(fileName),
+				path: c.crashMinimizing.entry.Path,
 				err:  errors.New(c.crashMinimizing.crasherMsg),
 			}
 		}
@@ -230,7 +230,8 @@ func CoordinateFuzzing(ctx context.Context, opts CoordinateFuzzingOpts) (err err
 
 			if result.crasherMsg != "" {
 				if c.warmupRun() && result.entry.IsSeed {
-					fmt.Fprintf(c.opts.Log, "found a crash while testing seed corpus entry: %q\n", result.entry.Parent)
+					target := filepath.Base(c.opts.CorpusDir)
+					fmt.Fprintf(c.opts.Log, "found a crash while testing seed corpus entry: %s/%s\n", target, testName(result.entry.Parent))
 					stop(errors.New(result.crasherMsg))
 					break
 				}
@@ -249,11 +250,11 @@ func CoordinateFuzzing(ctx context.Context, opts CoordinateFuzzingOpts) (err err
 				} else if !crashWritten {
 					// Found a crasher that's either minimized or not minimizable.
 					// Write to corpus and stop.
-					fileName, err := writeToCorpus(result.entry.Data, opts.CorpusDir)
+					err := writeToCorpus(&result.entry, opts.CorpusDir)
 					if err == nil {
 						crashWritten = true
 						err = &crashError{
-							name: filepath.Base(fileName),
+							path: result.entry.Path,
 							err:  errors.New(result.crasherMsg),
 						}
 					}
@@ -262,7 +263,7 @@ func CoordinateFuzzing(ctx context.Context, opts CoordinateFuzzingOpts) (err err
 							c.opts.Log,
 							"DEBUG new crasher, elapsed: %s, id: %s, parent: %s, gen: %d, size: %d, exec time: %s\n",
 							c.elapsed(),
-							fileName,
+							result.entry.Path,
 							result.entry.Parent,
 							result.entry.Generation,
 							len(result.entry.Data),
@@ -315,12 +316,11 @@ func CoordinateFuzzing(ctx context.Context, opts CoordinateFuzzingOpts) (err err
 						// Update the coordinator's coverage mask and save the value.
 						inputSize := len(result.entry.Data)
 						if opts.CacheDir != "" {
-							filename, err := writeToCorpus(result.entry.Data, opts.CacheDir)
+							err := writeToCorpus(&result.entry, opts.CacheDir)
 							if err != nil {
 								stop(err)
 							}
 							result.entry.Data = nil
-							result.entry.Name = filename
 						}
 						c.updateCoverage(keepCoverage)
 						c.corpus.entries = append(c.corpus.entries, result.entry)
@@ -331,7 +331,7 @@ func CoordinateFuzzing(ctx context.Context, opts CoordinateFuzzingOpts) (err err
 								c.opts.Log,
 								"DEBUG new interesting input, elapsed: %s, id: %s, parent: %s, gen: %d, new bits: %d, total bits: %d, size: %d, exec time: %s\n",
 								c.elapsed(),
-								result.entry.Name,
+								result.entry.Path,
 								result.entry.Parent,
 								result.entry.Generation,
 								countBits(keepCoverage),
@@ -347,7 +347,7 @@ func CoordinateFuzzing(ctx context.Context, opts CoordinateFuzzingOpts) (err err
 							c.opts.Log,
 							"DEBUG worker reported interesting input that doesn't expand coverage, elapsed: %s, id: %s, parent: %s, canMinimize: %t\n",
 							c.elapsed(),
-							result.entry.Name,
+							result.entry.Path,
 							result.entry.Parent,
 							result.canMinimize,
 						)
@@ -397,7 +397,7 @@ func CoordinateFuzzing(ctx context.Context, opts CoordinateFuzzingOpts) (err err
 // of the file where the input causing the crasher was saved. The testing
 // framework uses this to report a command to re-run that specific input.
 type crashError struct {
-	name string
+	path string
 	err  error
 }
 
@@ -409,8 +409,8 @@ func (e *crashError) Unwrap() error {
 	return e.err
 }
 
-func (e *crashError) CrashName() string {
-	return e.name
+func (e *crashError) CrashPath() string {
+	return e.path
 }
 
 type corpus struct {
@@ -426,14 +426,14 @@ type corpus struct {
 type CorpusEntry = struct {
 	Parent string
 
-	// Name is the name of the corpus file, if the entry was loaded from the
-	// seed corpus. It can be used with -run. For entries added with f.Add and
-	// entries generated by the mutator, Name is empty and Data is populated.
-	Name string
+	// Path is the path of the corpus file, if the entry was loaded from disk.
+	// For other entries, including seed values provided by f.Add, Path is the
+	// name of the test, e.g. seed#0 or its hash.
+	Path string
 
-	// Data is the raw input data. Data should only be populated for initial
-	// seed values added with f.Add. For on-disk corpus files, Data will
-	// be nil.
+	// Data is the raw input data. Data should only be populated for seed
+	// values. For on-disk corpus files, Data will be nil, as it will be loaded
+	// from disk using Path.
 	Data []byte
 
 	// Values is the unmarshaled values from a corpus file.
@@ -452,7 +452,7 @@ func CorpusEntryData(ce CorpusEntry) ([]byte, error) {
 		return ce.Data, nil
 	}
 
-	return os.ReadFile(ce.Name)
+	return os.ReadFile(ce.Path)
 }
 
 type fuzzInput struct {
@@ -616,7 +616,7 @@ type coordinator struct {
 }
 
 func newCoordinator(opts CoordinateFuzzingOpts) (*coordinator, error) {
-	// Make sure all of the seed corpus given by f.Add has marshalled data.
+	// Make sure all of the seed corpus has marshalled data.
 	for i := range opts.Seed {
 		if opts.Seed[i].Data == nil && opts.Seed[i].Values != nil {
 			opts.Seed[i].Data = marshalCorpusFile(opts.Seed[i].Values...)
@@ -673,7 +673,7 @@ func newCoordinator(opts CoordinateFuzzingOpts) (*coordinator, error) {
 		data := marshalCorpusFile(vals...)
 		h := sha256.Sum256(data)
 		name := fmt.Sprintf("%x", h[:4])
-		c.corpus.entries = append(c.corpus.entries, CorpusEntry{Name: name, Data: data})
+		c.corpus.entries = append(c.corpus.entries, CorpusEntry{Path: name, Data: data})
 	}
 
 	return c, nil
@@ -956,7 +956,7 @@ func ReadCorpus(dir string, types []reflect.Type) ([]CorpusEntry, error) {
 			errs = append(errs, fmt.Errorf("%q: %v", filename, err))
 			continue
 		}
-		corpus = append(corpus, CorpusEntry{Name: filename, Values: vals})
+		corpus = append(corpus, CorpusEntry{Path: filename, Values: vals})
 	}
 	if len(errs) > 0 {
 		return corpus, &MalformedCorpusError{errs: errs}
@@ -979,7 +979,7 @@ func readCorpusData(data []byte, types []reflect.Type) ([]interface{}, error) {
 // provided.
 func CheckCorpus(vals []interface{}, types []reflect.Type) error {
 	if len(vals) != len(types) {
-		return fmt.Errorf("wrong number of values in corpus entry: %d, want %d", len(vals), len(types))
+		return fmt.Errorf("wrong number of values in corpus entry %v: want %v", vals, types)
 	}
 	for i := range types {
 		if reflect.TypeOf(vals[i]) != types[i] {
@@ -989,21 +989,25 @@ func CheckCorpus(vals []interface{}, types []reflect.Type) error {
 	return nil
 }
 
-// writeToCorpus atomically writes the given bytes to a new file in testdata.
-// If the directory does not exist, it will create one. If the file already
-// exists, writeToCorpus will not rewrite it. writeToCorpus returns the
-// file's name, or an error if it failed.
-func writeToCorpus(b []byte, dir string) (name string, err error) {
-	sum := fmt.Sprintf("%x", sha256.Sum256(b))
-	name = filepath.Join(dir, sum)
+// writeToCorpus atomically writes the given bytes to a new file in testdata. If
+// the directory does not exist, it will create one. If the file already exists,
+// writeToCorpus will not rewrite it. writeToCorpus sets entry.Path to the new
+// file that was just written or an error if it failed.
+func writeToCorpus(entry *CorpusEntry, dir string) (err error) {
+	sum := fmt.Sprintf("%x", sha256.Sum256(entry.Data))
+	entry.Path = filepath.Join(dir, sum)
 	if err := os.MkdirAll(dir, 0777); err != nil {
-		return "", err
+		return err
 	}
-	if err := ioutil.WriteFile(name, b, 0666); err != nil {
-		os.Remove(name) // remove partially written file
-		return "", err
+	if err := ioutil.WriteFile(entry.Path, entry.Data, 0666); err != nil {
+		os.Remove(entry.Path) // remove partially written file
+		return err
 	}
-	return name, nil
+	return nil
+}
+
+func testName(path string) string {
+	return filepath.Base(path)
 }
 
 func zeroValue(t reflect.Type) interface{} {
diff --git a/src/internal/fuzz/worker.go b/src/internal/fuzz/worker.go
index 1429decba8..0c428ed832 100644
--- a/src/internal/fuzz/worker.go
+++ b/src/internal/fuzz/worker.go
@@ -1029,7 +1029,7 @@ func (wc *workerClient) minimize(ctx context.Context, entryIn CorpusEntry, args
 		entryOut.Values, err = unmarshalCorpusFile(entryOut.Data)
 		h := sha256.Sum256(entryOut.Data)
 		name := fmt.Sprintf("%x", h[:4])
-		entryOut.Name = name
+		entryOut.Path = name
 		entryOut.Parent = entryIn.Parent
 		entryOut.Generation = entryIn.Generation
 		if err != nil {
@@ -1092,8 +1092,8 @@ func (wc *workerClient) fuzz(ctx context.Context, entryIn CorpusEntry, args fuzz
 		h := sha256.Sum256(dataOut)
 		name := fmt.Sprintf("%x", h[:4])
 		entryOut = CorpusEntry{
-			Name:       name,
-			Parent:     entryIn.Name,
+			Parent:     entryIn.Path,
+			Path:       name,
 			Data:       dataOut,
 			Generation: entryIn.Generation + 1,
 		}