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 */
readAndVerifyUnsignedLeb128(const u1 ** pStream,const u1 * limit,bool * okay)32 int 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 */
readAndVerifySignedLeb128(const u1 ** pStream,const u1 * limit,bool * okay)54 int 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