Merge de243b05f3 into 881bdc289f

common/big.go

@@ -116,14 +116,19 @@ func FirstBitSet(v *big.Int) int {
 //
 // Returns the bytes of a big integer with the size specified by **base**
 // Attempts to pad the byte array with zeros.
+//
+// Note that input arg **num** is expected to be non-nil;
+// nil argument will result in runtime panic.
 func BigToBytes(num *big.Int, base int) []byte {
-	ret := make([]byte, base/8)
+	bytes := num.Bytes()
+	blen := len(bytes)
+	bpb := base / 8
 
-	if len(num.Bytes()) > base/8 {
-		return num.Bytes()
+	if blen > bpb {
+		return bytes
 	}
-
-	return append(ret[:len(ret)-len(num.Bytes())], num.Bytes()...)
+	padBuf := make([]byte, bpb)
+	return append(padBuf[:bpb-blen], bytes...)
 }
 
 // Big copy

common/bytes.go

@@ -14,7 +14,6 @@
 // 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 common contains various helper functions.
 package common
 
 import (
@@ -61,60 +60,29 @@ func NumberToBytes(num interface{}, bits int) []byte {
 	return buf.Bytes()[buf.Len()-(bits/8):]
 }
 
-// Bytes to number
-//
-// Attempts to cast a byte slice to a unsigned integer
+// Converts byte slice to a unsigned integer. Bytes are
+// interpreted as big-endian image of unsigned 64bit integer.
+// Slices less than 8 bytes are left padded before conversion;
+// For slices larger than 8 bytes the trailing bytes are ignored.
 func BytesToNumber(b []byte) uint64 {
-	var number uint64
+	var data = LeftPadBytes(b, 8)
 
-	// Make sure the buffer is 64bits
-	data := make([]byte, 8)
-	data = append(data[:len(b)], b...)
+	var n uint64
+	n |= uint64(data[0]) << 56
+	n |= uint64(data[1]) << 48
+	n |= uint64(data[2]) << 40
+	n |= uint64(data[3]) << 32
+	n |= uint64(data[4]) << 24
+	n |= uint64(data[5]) << 16
+	n |= uint64(data[6]) << 8
+	n |= uint64(data[7])
 
-	buf := bytes.NewReader(data)
-	err := binary.Read(buf, binary.BigEndian, &number)
-	if err != nil {
-		fmt.Println("BytesToNumber failed:", err)
-	}
-
-	return number
+	return n
 }
 
-// Read variable int
-//
-// Read a variable length number in big endian byte order
-func ReadVarInt(buff []byte) (ret uint64) {
-	switch l := len(buff); {
-	case l > 4:
-		d := LeftPadBytes(buff, 8)
-		binary.Read(bytes.NewReader(d), binary.BigEndian, &ret)
-	case l > 2:
-		var num uint32
-		d := LeftPadBytes(buff, 4)
-		binary.Read(bytes.NewReader(d), binary.BigEndian, &num)
-		ret = uint64(num)
-	case l > 1:
-		var num uint16
-		d := LeftPadBytes(buff, 2)
-		binary.Read(bytes.NewReader(d), binary.BigEndian, &num)
-		ret = uint64(num)
-	default:
-		var num uint8
-		binary.Read(bytes.NewReader(buff), binary.BigEndian, &num)
-		ret = uint64(num)
-	}
-
-	return
-}
-
-// Copy bytes
-//
 // Returns an exact copy of the provided bytes
 func CopyBytes(b []byte) (copiedBytes []byte) {
-	copiedBytes = make([]byte, len(b))
-	copy(copiedBytes, b)
-
-	return
+	return append([]byte{}, b...)
 }
 
 func HasHexPrefix(str string) bool {
@@ -137,7 +105,7 @@ func Hex2Bytes(str string) []byte {
 	return h
 }
 
-func Hex2BytesFixed(str string, flen int) []byte {
+func HexToBytesFixed(str string, flen int) []byte {
 	h, _ := hex.DecodeString(str)
 	if len(h) == flen {
 		return h

common/bytes_test.go

@@ -39,47 +39,59 @@ func (s *BytesSuite) TestNumberToBytes(c *checker.C) {
 }
 
 func (s *BytesSuite) TestBytesToNumber(c *checker.C) {
-	datasmall := []byte{0xe9, 0x38, 0xe9, 0x38}
-	datalarge := []byte{0xe9, 0x38, 0xe9, 0x38, 0xe9, 0x38, 0xe9, 0x38}
+	data := [][]byte{
+		// check for zero-len
+		[]byte{},
+		// check for len < 8
+		[]byte{0xfe},
+		[]byte{0xca, 0xfe},
+		[]byte{0xca, 0xfe, 0xba, 0xbe},
+		// check case len < 8
+		[]byte{0x7f, 0x6f, 0x5f, 0x4f, 0x3f, 0x2f, 0x1f, 0x0f},
+		// check case len = 8
+		[]byte{0x7f, 0x6f, 0x5f, 0x4f, 0x3f, 0x2f, 0x1f, 0x0f, 0xba, 0xdc, 0x0d},
+	}
+	expected := []uint64{
+		0x0,
+		0xfe,
+		0xcafe,
+		0xcafebabe,
+		0x7f6f5f4f3f2f1f0f,
+		0x7f6f5f4f3f2f1f0f,
+	}
 
-	var expsmall uint64 = 0xe938e938
-	var explarge uint64 = 0x0
+	// assert-test-invariants:
+	c.Assert(len(data[0]), checker.Equals, 0)
+	c.Assert(len(data[1]), checker.Equals, 1)
+	c.Assert(len(data[2]), checker.Equals, 2)
+	c.Assert(len(data[3]), checker.Equals, 4)
+	c.Assert(len(data[4]), checker.Equals, 8)
+	c.Assert(len(data[5]), checker.Equals, 11)
 
-	ressmall := BytesToNumber(datasmall)
-	reslarge := BytesToNumber(datalarge)
+	c.Assert(len(expected), checker.Equals, len(data))
 
-	c.Assert(ressmall, checker.Equals, expsmall)
-	c.Assert(reslarge, checker.Equals, explarge)
-
-}
-
-func (s *BytesSuite) TestReadVarInt(c *checker.C) {
-	data8 := []byte{1, 2, 3, 4, 5, 6, 7, 8}
-	data4 := []byte{1, 2, 3, 4}
-	data2 := []byte{1, 2}
-	data1 := []byte{1}
-
-	exp8 := uint64(72623859790382856)
-	exp4 := uint64(16909060)
-	exp2 := uint64(258)
-	exp1 := uint64(1)
-
-	res8 := ReadVarInt(data8)
-	res4 := ReadVarInt(data4)
-	res2 := ReadVarInt(data2)
-	res1 := ReadVarInt(data1)
-
-	c.Assert(res8, checker.Equals, exp8)
-	c.Assert(res4, checker.Equals, exp4)
-	c.Assert(res2, checker.Equals, exp2)
-	c.Assert(res1, checker.Equals, exp1)
+	for i := 0; i < len(data); i++ {
+		have := BytesToNumber(data[i])
+		c.Assert(have, checker.Equals, expected[i])
+	}
 }
 
 func (s *BytesSuite) TestCopyBytes(c *checker.C) {
-	data1 := []byte{1, 2, 3, 4}
-	exp1 := []byte{1, 2, 3, 4}
-	res1 := CopyBytes(data1)
-	c.Assert(res1, checker.DeepEquals, exp1)
+	data := [][]byte{
+		[]byte{0x00, 0x7f, 0x80, 0xff}, // interesting bytes
+		[]byte{},                       // empty case
+	}
+
+	// test
+	for i := 0; i < len(data); i++ {
+		have := CopyBytes(data[i])
+		if data[i] != nil {
+			// make sure we're not just returning the input arg
+			c.Assert(&have, checker.Not(checker.Equals), &data[i])
+		}
+		// verify deep copy
+		c.Assert(have, checker.DeepEquals, data[i])
+	}
 }
 
 func (s *BytesSuite) TestIsHex(c *checker.C) {

common/pkgdoc.go

@@ -0,0 +1,18 @@
+// Copyright 2014 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 common contains various helper functions.
+package common