common/bitutil: fix decompression corner cases; fuzz, test & bench

1 files changed, 152 insertions, 0 deletions

diff --git a/common/bitutil/compress_test.go b/common/bitutil/compress_test.go
new file mode 100644
index 000000000..ef38bc7b3
--- /dev/null
+++ b/common/bitutil/compress_test.go
@@ -0,0 +1,152 @@
+// Copyright 2017 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package bitutil
+
+import (
+	"bytes"
+	"math/rand"
+	"testing"
+
+	"github.com/ethereum/go-ethereum/common/hexutil"
+)
+
+// Tests that data compression and decompression works correctly.
+func TestCompressCycle(t *testing.T) {
+	tests := []string{
+		// Tests generated by go-fuzz to maximize code coverage
+		"0x000000000000000000",
+		"0xef0400",
+		"0xdf7070533534333636313639343638373532313536346c1bc33339343837313070706336343035336336346c65fefb3930393233383838ac2f65fefb",
+		"0x7b64000000",
+		"0x000034000000000000",
+		"0x0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000f0000000000000000000",
+		"0x4912385c0e7b64000000",
+		"0x000034000000000000000000000000000000",
+		"0x00",
+		"0x000003e834ff7f0000",
+		"0x0000",
+		"0x0000000000000000000000000000000000000000000000000000000000ff00",
+		"0x895f0c6a020f850c6a020f85f88df88d",
+		"0xdf7070533534333636313639343638373432313536346c1bc3315aac2f65fefb",
+		"0x0000000000",
+		"0xdf70706336346c65fefb",
+		"0x00006d643634000000",
+		"0xdf7070533534333636313639343638373532313536346c1bc333393438373130707063363430353639343638373532313536346c1bc333393438336336346c65fe",
+	}
+	for i, tt := range tests {
+		data := hexutil.MustDecode(tt)
+
+		proc, err := DecompressBytes(CompressBytes(data), len(data))
+		if err != nil {
+			t.Errorf("test %d: failed to decompress compressed data: %v", i, err)
+			continue
+		}
+		if !bytes.Equal(data, proc) {
+			t.Errorf("test %d: compress/decompress mismatch: have %x, want %x", i, proc, data)
+		}
+	}
+}
+
+// Tests that data decompression works
+func TestDecompress(t *testing.T) {
+	tests := []struct {
+		size  int
+		input string
+		fail  error
+	}{
+		{size: 0, input: "0x"},
+
+		// Crashers generated by go-fuzz
+		{size: 0, input: "0x0020", fail: ErrUnreferencedData},
+		{size: 0, input: "0x30", fail: ErrUnreferencedData},
+		{size: 1, input: "0x00", fail: ErrUnreferencedData},
+		{size: 2, input: "0x07", fail: ErrMissingData},
+		{size: 1024, input: "0x8000", fail: ErrZeroContent},
+
+		// Tests generated by go-fuzz to maximize code coverage
+		{size: 29490, input: "0x343137343733323134333839373334323073333930783e3078333930783e70706336346c65303e", fail: ErrMissingData},
+		{size: 59395, input: "0x00", fail: ErrUnreferencedData},
+		{size: 52574, input: "0x70706336346c65c0de", fail: ErrExceededTarget},
+		{size: 42264, input: "0x07", fail: ErrMissingData},
+		{size: 52, input: "0xa5045bad48f4", fail: ErrExceededTarget},
+		{size: 52574, input: "0xc0de", fail: ErrMissingData},
+		{size: 52574, input: "0x"},
+		{size: 29490, input: "0x34313734373332313433383937333432307333393078073034333839373334323073333930783e3078333937333432307333393078073061333930783e70706336346c65303e", fail: ErrMissingData},
+		{size: 29491, input: "0x3973333930783e30783e", fail: ErrMissingData},
+
+		{size: 1024, input: "0x808080608080"},
+		{size: 1024, input: "0x808470705e3632383337363033313434303137393130306c6580ef46806380635a80"},
+		{size: 1024, input: "0x8080808070"},
+		{size: 1024, input: "0x808070705e36346c6580ef46806380635a80"},
+		{size: 1024, input: "0x80808046802680"},
+		{size: 1024, input: "0x4040404035"},
+		{size: 1024, input: "0x4040bf3ba2b3f684402d353234373438373934409fe5b1e7ada94ebfd7d0505e27be4035"},
+		{size: 1024, input: "0x404040bf3ba2b3f6844035"},
+		{size: 1024, input: "0x40402d35323437343837393440bfd7d0505e27be4035"},
+	}
+	for i, tt := range tests {
+		data := hexutil.MustDecode(tt.input)
+
+		orig, err := DecompressBytes(data, tt.size)
+		if err != tt.fail {
+			t.Errorf("test %d: failure mismatch: have %v, want %v", i, err, tt.fail)
+		}
+		if err != nil {
+			continue
+		}
+		if comp := CompressBytes(orig); !bytes.Equal(comp, data) {
+			t.Errorf("test %d: decompress/compress mismatch: have %x, want %x", i, comp, data)
+		}
+	}
+}
+
+// Crude benchmark for compressing random slices of bytes.
+func BenchmarkCompress1KBVerySparse(b *testing.B) { benchmarkCompress(b, 1024, 0.0001) }
+func BenchmarkCompress2KBVerySparse(b *testing.B) { benchmarkCompress(b, 2048, 0.0001) }
+func BenchmarkCompress4KBVerySparse(b *testing.B) { benchmarkCompress(b, 4096, 0.0001) }
+
+func BenchmarkCompress1KBSparse(b *testing.B) { benchmarkCompress(b, 1024, 0.001) }
+func BenchmarkCompress2KBSparse(b *testing.B) { benchmarkCompress(b, 2048, 0.001) }
+func BenchmarkCompress4KBSparse(b *testing.B) { benchmarkCompress(b, 4096, 0.001) }
+
+func BenchmarkCompress1KBDense(b *testing.B) { benchmarkCompress(b, 1024, 0.1) }
+func BenchmarkCompress2KBDense(b *testing.B) { benchmarkCompress(b, 2048, 0.1) }
+func BenchmarkCompress4KBDense(b *testing.B) { benchmarkCompress(b, 4096, 0.1) }
+
+func BenchmarkCompress1KBSaturated(b *testing.B) { benchmarkCompress(b, 1024, 0.5) }
+func BenchmarkCompress2KBSaturated(b *testing.B) { benchmarkCompress(b, 2048, 0.5) }
+func BenchmarkCompress4KBSaturated(b *testing.B) { benchmarkCompress(b, 4096, 0.5) }
+
+func benchmarkCompress(b *testing.B, bytes int, fill float64) {
+	// Generate a random slice of bytes to compress
+	random := rand.NewSource(0) // reproducible and comparable
+
+	data := make([]byte, bytes)
+	bits := int(float64(bytes) * 8 * fill)
+
+	for i := 0; i < bits; i++ {
+		idx := random.Int63() % int64(len(data))
+		bit := uint(random.Int63() % 8)
+		data[idx] |= 1 << bit
+	}
+	// Reset the benchmark and measure compression/decompression
+	b.ResetTimer()
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		DecompressBytes(CompressBytes(data), len(data))
+	}
+}