func TestEvalSQLSubstring(t *testing.T) {
	evalCases := []struct {
		s           string
		startIdx    int
		length      int
		resExpected string
		errExpected error
	}{
		{"abcd", 1, 1, "a", nil},
		{"abcd", -1, 1, "a", nil},
		{"abcd", 999, 999, "", nil},
		{"", 999, 999, "", nil},
		{"测试abc", 1, 1, "测", nil},
		{"测试abc", 5, 5, "c", nil},
	}

	for i, tc := range evalCases {

			canonicalizedETag: "",
		},
		{
			etag:              "\"\"\"abc\"",
			canonicalizedETag: "abc",
		},
		{
			etag:              "abcd",
			canonicalizedETag: "abcd",
		},
		{
			etag:              "abcd\"\"",
			canonicalizedETag: "abcd",
		},
	}
	for _, test := range testCases {
		etag := canonicalizeETag(test.etag)
		if test.canonicalizedETag != etag {

        INTERFACES.put("samr", samr.getSyntax());
        INTERFACES.put("netdfs", netdfs.getSyntax());
        INTERFACES.put("netlogon", "12345678-1234-abcd-ef00-01234567cffb:1.0");
        INTERFACES.put("wkssvc", "6BFFD098-A112-3610-9833-46C3F87E345A:1.0");
        INTERFACES.put("samr", "12345778-1234-ABCD-EF00-0123456789AC:1.0");
    }


    /**
     * Add an interface to the registry
     * 
     * @param name
     * @param syntax

[
	uuid(12345778-1234-abcd-ef00-0123456789ab),
	version(0.0)
]
interface lsarpc
{
	import "../rpc.idl";

	typedef struct {
		uint32_t length;
		uint16_t impersonation_level;
		uint8_t context_mode;
		uint8_t effective_only;
	} LsarQosInfo;

	typedef struct {
		uint32_t length;
		uint8_t *root_directory;
		unicode_string *object_name;
		uint32_t attributes;
		uint32_t security_descriptor;

[
	uuid(12345778-1234-abcd-ef00-0123456789ab),
	version(0.0)
]
interface lsarpc
{
	import "../rpc.idl";

	typedef struct {
		uint32_t length;
		uint16_t impersonation_level;
		uint8_t context_mode;
		uint8_t effective_only;
	} LsarQosInfo;

	typedef struct {
		uint32_t length;
		uint8_t *root_directory;
		unicode_string *object_name;
		uint32_t attributes;
		uint32_t security_descriptor;

# Usage

```go
package main

import (
	"fmt"

	"github.com/smallnest/ringbuffer"
)

func main() {
	rb := ringbuffer.New(1024)

	// write
	rb.Write([]byte("abcd"))
	fmt.Println(rb.Length())
	fmt.Println(rb.Free())

	// read
	buf := make([]byte, 4)
	rb.Read(buf)
	fmt.Println(string(buf))
}
```