pkg/corpus: a separate package for the corpus functionality

pkg/fuzzer and syz-manager have a common corpus functionality that can
be well be unified.

Create a separate pkg/corpus package that would be used by both of them.
It will simplify further work of moving pkg/fuzzer to the host.

1 files changed, 56 insertions, 0 deletions

diff --git a/pkg/fuzzer/cover.go b/pkg/fuzzer/cover.go
new file mode 100644
index 000000000..cc18862bd
--- /dev/null
+++ b/pkg/fuzzer/cover.go
@@ -0,0 +1,56 @@
+// Copyright 2024 syzkaller project authors. All rights reserved.
+// Use of this source code is governed by Apache 2 LICENSE that can be found in the LICENSE file.
+
+package fuzzer
+
+import (
+	"sync"
+
+	"github.com/google/syzkaller/pkg/signal"
+)
+
+// Cover keeps track of the signal known to the fuzzer.
+type Cover struct {
+	mu        sync.RWMutex
+	maxSignal signal.Signal // max signal ever observed (including flakes)
+	newSignal signal.Signal // newly identified max signal
+}
+
+// Signal that should no longer be chased after.
+func (cover *Cover) AddMaxSignal(sign signal.Signal) {
+	cover.mu.Lock()
+	defer cover.mu.Unlock()
+	cover.maxSignal.Merge(sign)
+}
+
+func (cover *Cover) addRawMaxSignal(signal []uint32, prio uint8) signal.Signal {
+	cover.mu.Lock()
+	defer cover.mu.Unlock()
+	diff := cover.maxSignal.DiffRaw(signal, prio)
+	if diff.Empty() {
+		return diff
+	}
+	cover.maxSignal.Merge(diff)
+	cover.newSignal.Merge(diff)
+	return diff
+}
+
+func (cover *Cover) GrabNewSignal() signal.Signal {
+	cover.mu.Lock()
+	defer cover.mu.Unlock()
+	sign := cover.newSignal
+	cover.newSignal = nil
+	return sign
+}
+
+type CoverStat struct {
+	MaxSignal int
+}
+
+func (cover *Cover) Stat() CoverStat {
+	cover.mu.RLock()
+	defer cover.mu.RUnlock()
+	return CoverStat{
+		MaxSignal: len(cover.maxSignal),
+	}
+}