1/*
2 * Copyright (C) 2008 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17/*
18 * Functions for interpreting LEB128 (little endian base 128) values
19 */
20
21#include "Leb128.h"
22
23/*
24 * Reads an unsigned LEB128 value, updating the given pointer to point
25 * just past the end of the read value and also indicating whether the
26 * value was syntactically valid. The only syntactically *invalid*
27 * values are ones that are five bytes long where the final byte has
28 * any but the low-order four bits set. Additionally, if the limit is
29 * passed as non-NULL and bytes would need to be read past the limit,
30 * then the read is considered invalid.
31 */
32int readAndVerifyUnsignedLeb128(const u1** pStream, const u1* limit,
33        bool* okay) {
34    const u1* ptr = *pStream;
35    int result = readUnsignedLeb128(pStream);
36
37    if (((limit != NULL) && (*pStream > limit))
38            || (((*pStream - ptr) == 5) && (ptr[4] > 0x0f))) {
39        *okay = false;
40    }
41
42    return result;
43}
44
45/*
46 * Reads a signed LEB128 value, updating the given pointer to point
47 * just past the end of the read value and also indicating whether the
48 * value was syntactically valid. The only syntactically *invalid*
49 * values are ones that are five bytes long where the final byte has
50 * any but the low-order four bits set. Additionally, if the limit is
51 * passed as non-NULL and bytes would need to be read past the limit,
52 * then the read is considered invalid.
53 */
54int readAndVerifySignedLeb128(const u1** pStream, const u1* limit,
55        bool* okay) {
56    const u1* ptr = *pStream;
57    int result = readSignedLeb128(pStream);
58
59    if (((limit != NULL) && (*pStream > limit))
60            || (((*pStream - ptr) == 5) && (ptr[4] > 0x0f))) {
61        *okay = false;
62    }
63
64    return result;
65}
66