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/*
* Copyright (C) 2015 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "read_elf.h"
#include <stdio.h>
#include <string.h>
#include <algorithm>
#include <base/file.h>
#include <base/logging.h>
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wunused-parameter"
#include <llvm/ADT/StringRef.h>
#include <llvm/Object/Binary.h>
#include <llvm/Object/ELFObjectFile.h>
#include <llvm/Object/ObjectFile.h>
#pragma clang diagnostic pop
#include <elf.h>
#include "utils.h"
static bool GetBuildIdFromNoteSection(const char* section, size_t section_size, BuildId* build_id) {
const char* p = section;
const char* end = p + section_size;
while (p < end) {
CHECK_LE(p + 12, end);
size_t namesz = *reinterpret_cast<const uint32_t*>(p);
p += 4;
size_t descsz = *reinterpret_cast<const uint32_t*>(p);
p += 4;
uint32_t type = *reinterpret_cast<const uint32_t*>(p);
p += 4;
namesz = ALIGN(namesz, 4);
descsz = ALIGN(descsz, 4);
CHECK_LE(p + namesz + descsz, end);
if ((type == NT_GNU_BUILD_ID) && (strcmp(p, ELF_NOTE_GNU) == 0)) {
std::fill(build_id->begin(), build_id->end(), 0);
memcpy(build_id->data(), p + namesz, std::min(build_id->size(), descsz));
return true;
}
p += namesz + descsz;
}
return false;
}
bool GetBuildIdFromNoteFile(const std::string& filename, BuildId* build_id) {
std::string content;
if (!android::base::ReadFileToString(filename, &content)) {
LOG(DEBUG) << "can't read note file " << filename;
return false;
}
if (GetBuildIdFromNoteSection(content.c_str(), content.size(), build_id) == false) {
LOG(DEBUG) << "can't read build_id from note file " << filename;
return false;
}
return true;
}
template <class ELFT>
bool GetBuildIdFromELFFile(const llvm::object::ELFFile<ELFT>* elf, BuildId* build_id) {
for (auto section_iterator = elf->begin_sections(); section_iterator != elf->end_sections();
++section_iterator) {
if (section_iterator->sh_type == SHT_NOTE) {
auto contents = elf->getSectionContents(&*section_iterator);
if (contents.getError()) {
LOG(DEBUG) << "read note section error";
continue;
}
if (GetBuildIdFromNoteSection(reinterpret_cast<const char*>(contents->data()),
contents->size(), build_id)) {
return true;
}
}
}
return false;
}
bool GetBuildIdFromElfFile(const std::string& filename, BuildId* build_id) {
auto owning_binary = llvm::object::createBinary(llvm::StringRef(filename));
if (owning_binary.getError()) {
PLOG(DEBUG) << "can't open file " << filename;
return false;
}
bool result = false;
llvm::object::Binary* binary = owning_binary.get().getBinary();
if (auto obj = llvm::dyn_cast<llvm::object::ObjectFile>(binary)) {
if (auto elf = llvm::dyn_cast<llvm::object::ELF32LEObjectFile>(obj)) {
result = GetBuildIdFromELFFile(elf->getELFFile(), build_id);
} else if (auto elf = llvm::dyn_cast<llvm::object::ELF64LEObjectFile>(obj)) {
result = GetBuildIdFromELFFile(elf->getELFFile(), build_id);
} else {
PLOG(DEBUG) << "unknown elf format in file " << filename;
}
}
if (!result) {
PLOG(DEBUG) << "can't read build_id from file " << filename;
}
return result;
}
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