Yabin Cui | 568b82a | 2015-05-05 19:58:07 -0700 | [diff] [blame] | 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 | #include "read_elf.h" |
| 18 | |
| 19 | #include <stdio.h> |
| 20 | #include <string.h> |
| 21 | #include <algorithm> |
| 22 | #include <base/file.h> |
| 23 | #include <base/logging.h> |
| 24 | |
| 25 | #pragma clang diagnostic push |
| 26 | #pragma clang diagnostic ignored "-Wunused-parameter" |
| 27 | |
| 28 | #include <llvm/ADT/StringRef.h> |
| 29 | #include <llvm/Object/Binary.h> |
| 30 | #include <llvm/Object/ELFObjectFile.h> |
| 31 | #include <llvm/Object/ObjectFile.h> |
| 32 | |
| 33 | #pragma clang diagnostic pop |
| 34 | |
| 35 | #include <elf.h> |
| 36 | |
| 37 | #include "utils.h" |
| 38 | |
| 39 | static bool GetBuildIdFromNoteSection(const char* section, size_t section_size, BuildId* build_id) { |
| 40 | const char* p = section; |
| 41 | const char* end = p + section_size; |
| 42 | while (p < end) { |
| 43 | CHECK_LE(p + 12, end); |
| 44 | size_t namesz = *reinterpret_cast<const uint32_t*>(p); |
| 45 | p += 4; |
| 46 | size_t descsz = *reinterpret_cast<const uint32_t*>(p); |
| 47 | p += 4; |
| 48 | uint32_t type = *reinterpret_cast<const uint32_t*>(p); |
| 49 | p += 4; |
| 50 | namesz = ALIGN(namesz, 4); |
| 51 | descsz = ALIGN(descsz, 4); |
| 52 | CHECK_LE(p + namesz + descsz, end); |
| 53 | if ((type == NT_GNU_BUILD_ID) && (strcmp(p, ELF_NOTE_GNU) == 0)) { |
| 54 | std::fill(build_id->begin(), build_id->end(), 0); |
| 55 | memcpy(build_id->data(), p + namesz, std::min(build_id->size(), descsz)); |
| 56 | return true; |
| 57 | } |
| 58 | p += namesz + descsz; |
| 59 | } |
| 60 | return false; |
| 61 | } |
| 62 | |
| 63 | bool GetBuildIdFromNoteFile(const std::string& filename, BuildId* build_id) { |
| 64 | std::string content; |
| 65 | if (!android::base::ReadFileToString(filename, &content)) { |
| 66 | LOG(DEBUG) << "can't read note file " << filename; |
| 67 | return false; |
| 68 | } |
| 69 | if (GetBuildIdFromNoteSection(content.c_str(), content.size(), build_id) == false) { |
| 70 | LOG(DEBUG) << "can't read build_id from note file " << filename; |
| 71 | return false; |
| 72 | } |
| 73 | return true; |
| 74 | } |
| 75 | |
| 76 | template <class ELFT> |
| 77 | bool GetBuildIdFromELFFile(const llvm::object::ELFFile<ELFT>* elf, BuildId* build_id) { |
| 78 | for (auto section_iterator = elf->begin_sections(); section_iterator != elf->end_sections(); |
| 79 | ++section_iterator) { |
| 80 | if (section_iterator->sh_type == SHT_NOTE) { |
| 81 | auto contents = elf->getSectionContents(&*section_iterator); |
| 82 | if (contents.getError()) { |
| 83 | LOG(DEBUG) << "read note section error"; |
| 84 | continue; |
| 85 | } |
| 86 | if (GetBuildIdFromNoteSection(reinterpret_cast<const char*>(contents->data()), |
| 87 | contents->size(), build_id)) { |
| 88 | return true; |
| 89 | } |
| 90 | } |
| 91 | } |
| 92 | return false; |
| 93 | } |
| 94 | |
| 95 | bool GetBuildIdFromElfFile(const std::string& filename, BuildId* build_id) { |
| 96 | auto owning_binary = llvm::object::createBinary(llvm::StringRef(filename)); |
| 97 | if (owning_binary.getError()) { |
| 98 | PLOG(DEBUG) << "can't open file " << filename; |
| 99 | return false; |
| 100 | } |
| 101 | bool result = false; |
| 102 | llvm::object::Binary* binary = owning_binary.get().getBinary(); |
| 103 | if (auto obj = llvm::dyn_cast<llvm::object::ObjectFile>(binary)) { |
| 104 | if (auto elf = llvm::dyn_cast<llvm::object::ELF32LEObjectFile>(obj)) { |
| 105 | result = GetBuildIdFromELFFile(elf->getELFFile(), build_id); |
| 106 | } else if (auto elf = llvm::dyn_cast<llvm::object::ELF64LEObjectFile>(obj)) { |
| 107 | result = GetBuildIdFromELFFile(elf->getELFFile(), build_id); |
| 108 | } else { |
| 109 | PLOG(DEBUG) << "unknown elf format in file " << filename; |
| 110 | } |
| 111 | } |
| 112 | if (!result) { |
| 113 | PLOG(DEBUG) << "can't read build_id from file " << filename; |
| 114 | } |
| 115 | return result; |
| 116 | } |