internal/conv: fix wrong string to bytes implementation

internal/conv/string.go

@@ -8,8 +8,12 @@ import (
 // UnsafeStrToBytes uses unsafe to convert string into byte array. Returned bytes
 // must not be altered after this function is called as it will cause a segmentation fault.
 func UnsafeStrToBytes(s string) []byte {
-	var buf = *(*[]byte)(unsafe.Pointer(&s))
-	(*reflect.SliceHeader)(unsafe.Pointer(&buf)).Cap = len(s)
+	var buf []byte
+	sHdr := (*reflect.StringHeader)(unsafe.Pointer(&s))
+	bufHdr := (*reflect.SliceHeader)(unsafe.Pointer(&buf))
+	bufHdr.Data = sHdr.Data
+	bufHdr.Cap = sHdr.Len
+	bufHdr.Len = sHdr.Len
 	return buf
 }
 
@@ -18,6 +22,5 @@ func UnsafeStrToBytes(s string) []byte {
 // to be used generally, but for a specific pattern to delete keys
 // from a map.
 func UnsafeBytesToStr(b []byte) string {
-	hdr := (*reflect.StringHeader)(unsafe.Pointer(&b))
-	return *(*string)(unsafe.Pointer(hdr))
+	return *(*string)(unsafe.Pointer(&b))
 }

internal/conv/string_test.go

@@ -2,6 +2,7 @@ package conv
 
 import (
 	"runtime"
+	"strconv"
 	"testing"
 	"time"
 
@@ -45,3 +46,9 @@ func (s *StringSuite) TestUnsafeBytesToStr() {
 		s.Equal("abc", str)
 	}
 }
+
+func BenchmarkUnsafeStrToBytes(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		UnsafeStrToBytes(strconv.Itoa(i))
+	}
+}