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/*
**
** Copyright 2016, 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_apk.h"
#include <errno.h>
#include <stdio.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
#include <memory>
#include <android-base/file.h>
#include <android-base/logging.h>
#include <ziparchive/zip_archive.h>
#include "read_elf.h"
#include "utils.h"
std::map<ApkInspector::ApkOffset, std::unique_ptr<EmbeddedElf>> ApkInspector::embedded_elf_cache_;
EmbeddedElf* ApkInspector::FindElfInApkByOffset(const std::string& apk_path, uint64_t file_offset) {
// Already in cache?
ApkOffset ami(apk_path, file_offset);
auto it = embedded_elf_cache_.find(ami);
if (it != embedded_elf_cache_.end()) {
return it->second.get();
}
std::unique_ptr<EmbeddedElf> elf = FindElfInApkByOffsetWithoutCache(apk_path, file_offset);
EmbeddedElf* result = elf.get();
embedded_elf_cache_[ami] = std::move(elf);
return result;
}
std::unique_ptr<EmbeddedElf> ApkInspector::FindElfInApkByOffsetWithoutCache(const std::string& apk_path,
uint64_t file_offset) {
// Crack open the apk(zip) file and take a look.
if (!IsValidApkPath(apk_path)) {
return nullptr;
}
FileHelper fhelper = FileHelper::OpenReadOnly(apk_path);
if (!fhelper) {
return nullptr;
}
ArchiveHelper ahelper(fhelper.fd(), apk_path);
if (!ahelper) {
return nullptr;
}
ZipArchiveHandle &handle = ahelper.archive_handle();
// Iterate through the zip file. Look for a zip entry corresponding
// to an uncompressed blob whose range intersects with the mmap
// offset we're interested in.
void* iteration_cookie;
if (StartIteration(handle, &iteration_cookie, nullptr, nullptr) < 0) {
return nullptr;
}
ZipEntry zentry;
ZipString zname;
bool found = false;
int zrc;
while ((zrc = Next(iteration_cookie, &zentry, &zname)) == 0) {
if (zentry.method == kCompressStored &&
file_offset >= static_cast<uint64_t>(zentry.offset) &&
file_offset < static_cast<uint64_t>(zentry.offset + zentry.uncompressed_length)) {
// Found.
found = true;
break;
}
}
EndIteration(iteration_cookie);
if (!found) {
return nullptr;
}
// We found something in the zip file at the right spot. Is it an ELF?
if (lseek(fhelper.fd(), zentry.offset, SEEK_SET) != zentry.offset) {
PLOG(ERROR) << "lseek() failed in " << apk_path << " offset " << zentry.offset;
return nullptr;
}
std::string entry_name;
entry_name.resize(zname.name_length,'\0');
memcpy(&entry_name[0], zname.name, zname.name_length);
if (!IsValidElfFile(fhelper.fd())) {
LOG(ERROR) << "problems reading ELF from in " << apk_path << " entry '"
<< entry_name << "'";
return nullptr;
}
// Elf found: add EmbeddedElf to vector, update cache.
return std::unique_ptr<EmbeddedElf>(new EmbeddedElf(apk_path, entry_name, zentry.offset,
zentry.uncompressed_length));
}
std::unique_ptr<EmbeddedElf> ApkInspector::FindElfInApkByName(const std::string& apk_path,
const std::string& elf_filename) {
if (!IsValidApkPath(apk_path)) {
return nullptr;
}
FileHelper fhelper = FileHelper::OpenReadOnly(apk_path);
if (!fhelper) {
return nullptr;
}
ArchiveHelper ahelper(fhelper.fd(), apk_path);
if (!ahelper) {
return nullptr;
}
ZipArchiveHandle& handle = ahelper.archive_handle();
ZipEntry zentry;
int32_t rc = FindEntry(handle, ZipString(elf_filename.c_str()), &zentry);
if (rc != 0) {
LOG(ERROR) << "failed to find " << elf_filename << " in " << apk_path
<< ": " << ErrorCodeString(rc);
return nullptr;
}
if (zentry.method != kCompressStored || zentry.compressed_length != zentry.uncompressed_length) {
LOG(ERROR) << "shared library " << elf_filename << " in " << apk_path << " is compressed";
return nullptr;
}
return std::unique_ptr<EmbeddedElf>(new EmbeddedElf(apk_path, elf_filename, zentry.offset,
zentry.uncompressed_length));
}
bool IsValidApkPath(const std::string& apk_path) {
static const char zip_preamble[] = {0x50, 0x4b, 0x03, 0x04 };
if (!IsRegularFile(apk_path)) {
return false;
}
std::string mode = std::string("rb") + CLOSE_ON_EXEC_MODE;
FILE* fp = fopen(apk_path.c_str(), mode.c_str());
if (fp == nullptr) {
return false;
}
char buf[4];
if (fread(buf, 4, 1, fp) != 1) {
fclose(fp);
return false;
}
fclose(fp);
return memcmp(buf, zip_preamble, 4) == 0;
}
// Refer file in apk in compliance with http://developer.android.com/reference/java/net/JarURLConnection.html.
std::string GetUrlInApk(const std::string& apk_path, const std::string& elf_filename) {
return apk_path + "!/" + elf_filename;
}
std::tuple<bool, std::string, std::string> SplitUrlInApk(const std::string& path) {
size_t pos = path.find("!/");
if (pos == std::string::npos) {
return std::make_tuple(false, "", "");
}
return std::make_tuple(true, path.substr(0, pos), path.substr(pos + 2));
}
bool GetBuildIdFromApkFile(const std::string& apk_path, const std::string& elf_filename,
BuildId* build_id) {
std::unique_ptr<EmbeddedElf> ee = ApkInspector::FindElfInApkByName(apk_path, elf_filename);
if (ee == nullptr) {
return false;
}
return GetBuildIdFromEmbeddedElfFile(apk_path, ee->entry_offset(), ee->entry_size(), build_id);
}
bool ParseSymbolsFromApkFile(const std::string& apk_path, const std::string& elf_filename,
const BuildId& expected_build_id,
std::function<void(const ElfFileSymbol&)> callback) {
std::unique_ptr<EmbeddedElf> ee = ApkInspector::FindElfInApkByName(apk_path, elf_filename);
if (ee == nullptr) {
return false;
}
return ParseSymbolsFromEmbeddedElfFile(apk_path, ee->entry_offset(), ee->entry_size(),
expected_build_id, callback);
}
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