1 /*
2  * Copyright (C) 2015 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 #ifndef SIMPLE_PERF_BUILD_ID_H_
18 #define SIMPLE_PERF_BUILD_ID_H_
19 
20 #include <string.h>
21 #include <algorithm>
22 #include <android-base/stringprintf.h>
23 
24 constexpr size_t BUILD_ID_SIZE = 20;
25 
26 // Shared libraries can have a section called .note.gnu.build-id, containing
27 // a ~20 bytes unique id. Build id is used to compare if two shared libraries
28 // are actually the same. BuildId class is the representation of build id in
29 // memory.
30 class BuildId {
31  public:
Size()32   static size_t Size() {
33     return BUILD_ID_SIZE;
34   }
35 
BuildId()36   BuildId() {
37     memset(data_, '\0', BUILD_ID_SIZE);
38   }
39 
40   // Copy build id from a byte array, like {0x76, 0x00, 0x32,...}.
BuildId(const void * data,size_t len)41   BuildId(const void* data, size_t len) : BuildId() {
42     memcpy(data_, data, std::min(len, BUILD_ID_SIZE));
43   }
44 
45   // Read build id from a hex string, like "7600329e31058e12b145d153ef27cd40e1a5f7b9".
BuildId(const std::string & s)46   explicit BuildId(const std::string& s) : BuildId() {
47     for (size_t i = 0; i < s.size() && i < BUILD_ID_SIZE * 2; i += 2) {
48       unsigned char ch = 0;
49       for (size_t j = i; j < i + 2; ++j) {
50         ch <<= 4;
51         if (s[j] >= '0' && s[j] <= '9') {
52           ch |= s[j] - '0';
53         } else if (s[j] >= 'a' && s[j] <= 'f') {
54           ch |= s[j] - 'a' + 10;
55         } else if (s[j] >= 'A' && s[j] <= 'F') {
56           ch |= s[j] - 'A' + 10;
57         }
58       }
59       data_[i / 2] = ch;
60     }
61   }
62 
Data()63   const unsigned char* Data() const {
64     return data_;
65   }
66 
ToString()67   std::string ToString() const {
68     std::string s = "0x";
69     for (size_t i = 0; i < BUILD_ID_SIZE; ++i) {
70       s += android::base::StringPrintf("%02x", data_[i]);
71     }
72     return s;
73   }
74 
75   bool operator==(const BuildId& build_id) const {
76     return memcmp(data_, build_id.data_, BUILD_ID_SIZE) == 0;
77   }
78 
79   bool operator!=(const BuildId& build_id) const {
80     return !(*this == build_id);
81   }
82 
IsEmpty()83   bool IsEmpty() const {
84     static BuildId empty_build_id;
85     return *this == empty_build_id;
86   }
87 
88  private:
89   unsigned char data_[BUILD_ID_SIZE];
90 };
91 
92 inline std::ostream& operator<<(std::ostream& os, const BuildId& build_id) {
93   os << build_id.ToString();
94   return os;
95 }
96 
97 #endif  // SIMPLE_PERF_BUILD_ID_H_
98