一个关于VTS VtsKernelCheckpointTest、VtsKernelCheckpointTest测项失败的代码分析
作者：互联网
如刚才实验，烧录GSI之后，本来已经被格式化为ext4的metadata分区，又被格式化为无格式的分区。
我这边继续Check发现，在替换GSI的SOP中，fastboot –w选项如果在bootloader执行，会清userdata、cache、metadata分区为无格式分区，而后进入recovery再次格式化成ext4。
FLOW如下：
a. fastboot程序-w选项如果在loader中执行会传命令给loader清userdata,cache,metadata分区
https://android.googlesource.com/platform/system/core/+/refs/heads/master/fastboot/fastboot.cpp
if (wants_wipe) {
if (force_flash) {
CancelSnapshotIfNeeded();
}
std::vector<std::string> partitions = { "userdata", "cache", "metadata" };
for (const auto& partition : partitions) {
std::string partition_type;
if (fb->GetVar("partition-type:" + partition, &partition_type) != fastboot::SUCCESS) {
continue;
}
if (partition_type.empty()) continue;
fb->Erase(partition);
if (partition == "userdata" && set_fbe_marker) {
fprintf(stderr, "setting FBE marker on initial userdata...\n");
std::string initial_userdata_dir = create_fbemarker_tmpdir();
fb_perform_format(partition, 1, partition_type, "", initial_userdata_dir, fs_options);
delete_fbemarker_tmpdir(initial_userdata_dir);
} else {
fb_perform_format(partition, 1, partition_type, "", "", fs_options);
}
}
}
b. bootloader根据fastboot传下的分区列表清除对应分区。
c. recovery收到wipe=data会格式化userdata,cache,metadata分区为ext4格式.
https://android.googlesource.com/platform/bootable/recovery/+/refs/heads/master/recovery.cpp
case Device::WIPE_DATA:
save_current_log = true;
if (ui->IsTextVisible()) {
if (ask_to_wipe_data(device)) {
WipeData(device, false);
}
} else {
WipeData(device, false);
return Device::NO_ACTION;
}
break;
但是目前的情况是做完fastboot –w选项之后，发现userdata,cache都被格式化为ext4格式，而metadata分区未被格式化，所以猜想recovery没有格式化metadata，
进一步看code可以看到，recovery中如果要格式化metadata，需要volume_for_mount_point返回非空指针，
https://android.googlesource.com/platform/bootable/recovery/+/refs/heads/master/install/wipe_data.cpp
bool WipeData(Device* device, bool convert_fbe) {
RecoveryUI* ui = device->GetUI();
ui->Print("\n-- Wiping data...\n");
if (!FinishPendingSnapshotMerges(device)) {
ui->Print("Unable to check update status or complete merge, cannot wipe partitions.\n");
return false;
}
bool success = device->PreWipeData();
if (success) {
success &= EraseVolume(DATA_ROOT, ui, convert_fbe);
bool has_cache = volume_for_mount_point("/cache") != nullptr;
if (has_cache) {
success &= EraseVolume(CACHE_ROOT, ui, false);
}
if (volume_for_mount_point(METADATA_ROOT) != nullptr) {
success &= EraseVolume(METADATA_ROOT, ui, false);
}
}
if (success) {
success &= device->PostWipeData();
}
ui->Print("Data wipe %s.\n", success ? "complete" : "failed");
return success;
}
而volume_for_mount_point调用GetEntryForMountPoint，根据entry.mount_point判断METADATA是否存在，如果存在就返回METADATA的挂载路径，
然后EraseVolume函数会umount设备，再调用wipe_block_device清数据以及调用/system/bin/mke2fs格式化。
https://android.googlesource.com/platform/bootable/recovery/+/refs/heads/master/install/wipe_data.cpp
static bool EraseVolume(const char* volume, RecoveryUI* ui, bool convert_fbe) {
bool is_cache = (strcmp(volume, CACHE_ROOT) == 0);
bool is_data = (strcmp(volume, DATA_ROOT) == 0);
ui->SetBackground(RecoveryUI::ERASING);
ui->SetProgressType(RecoveryUI::INDETERMINATE);
std::vector<saved_log_file> log_files;
if (is_cache) {
// If we're reformatting /cache, we load any past logs (i.e. "/cache/recovery/last_*") and the
// current log ("/cache/recovery/log") into memory, so we can restore them after the reformat.
log_files = ReadLogFilesToMemory();
}
ui->Print("Formatting %s...\n", volume);
ensure_path_unmounted(volume);
int result;
if (is_data && convert_fbe) {
constexpr const char* CONVERT_FBE_DIR = "/tmp/convert_fbe";
constexpr const char* CONVERT_FBE_FILE = "/tmp/convert_fbe/convert_fbe";
// Create convert_fbe breadcrumb file to signal init to convert to file based encryption, not
// full disk encryption.
if (mkdir(CONVERT_FBE_DIR, 0700) != 0) {
PLOG(ERROR) << "Failed to mkdir " << CONVERT_FBE_DIR;
return false;
}
FILE* f = fopen(CONVERT_FBE_FILE, "wbe");
if (!f) {
PLOG(ERROR) << "Failed to convert to file encryption";
return false;
}
fclose(f);
result = format_volume(volume, CONVERT_FBE_DIR);
remove(CONVERT_FBE_FILE);
rmdir(CONVERT_FBE_DIR);
} else {
result = format_volume(volume);
}
if (is_cache) {
RestoreLogFilesAfterFormat(log_files);
}
return (result == 0);
}
因为目前看到metadata未被格式化，因此有可能类entry中没有metadata分区相关信息，所以继续查找entry的fstab如何获取的，
在fs_mgr_fstab.cpp中可以看到if(access(/system/bin/recovery, F_OK))表示当前是recovery启动，则读取recovery.fstab作为default_fstab_path。
https://android.googlesource.com/platform/system/core/+/refs/heads/master/fs_mgr/fs_mgr_fstab.cpp
// Loads the fstab file and combines with fstab entries passed in from device tree.
bool ReadDefaultFstab(Fstab* fstab) {
Fstab dt_fstab;
ReadFstabFromDt(&dt_fstab, false);
*fstab = std::move(dt_fstab);
std::string default_fstab_path;
// Use different fstab paths for normal boot and recovery boot, respectively
if (access("/system/bin/recovery", F_OK) == 0) {
default_fstab_path = "/etc/recovery.fstab";
} else { // normal boot
default_fstab_path = GetFstabPath();
}
Fstab default_fstab;
if (!default_fstab_path.empty()) {
ReadFstabFromFile(default_fstab_path, &default_fstab);
} else {
LINFO << __FUNCTION__ << "(): failed to find device default fstab";
}
for (auto&& entry : default_fstab) {
fstab->emplace_back(std::move(entry));
}
return !fstab->empty();
}
如果需要Check一下recovery.fstab中的内容，因为recovery.fstab是从在AN目录下打包过去的，所以在device下看到recovery有3张fstab，检查发现，3张表都是没有metadata分区的。
所以要看一下这里加上metadata后是否可以。
标签：cache,recovery,fstab,partition,VTS,ui,测项,metadata,VtsKernelCheckpointTest 来源： https://www.cnblogs.com/smilingsusu/p/14032434.html