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fs_mgr_overlayfs: Make all string constants constexpr 

According to https://abseil.io/tips/140, string constants should be
constexpr char array or string_view object. This avoids subtle bugs due
to the toolchain shuffling object initialization order between/within
compilation units.

string_view has bad interoperability between C APIs as many of those
functions require string values to be null-terminated. Thus we can only
rely on good old c-string constants.

This change groups all string constants together and change them all to
constexpr char array for consistent style.
Also remove some duplicated method definition.

Test: adb-remount-test
Change-Id: I1ed57e6dc24ce3750e72c5538c388a6872cd2b40
This commit is contained in:
Yi-Yo Chiang 2023-07-21 16:19:13 +08:00
parent 6b57c885d3
commit b2e0edcaae
3 changed files with 36 additions and 128 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

117
fs_mgr/fs_mgr_overlayfs_control.cpp
View File

@ -71,15 +71,18 @@ namespace {
constexpr char kDataScratchSizeMbProp[] = "fs_mgr.overlayfs.data_scratch_size_mb";
constexpr char kPhysicalDevice[] = "/dev/block/by-name/";
constexpr char kScratchImageMetadata[] = "/metadata/gsi/remount/lp_metadata";
constexpr char kMkF2fs[] = "/system/bin/make_f2fs";
constexpr char kMkExt4[] = "/system/bin/mke2fs";
// Return true if everything is mounted, but before adb is started. Right
// after 'trigger load_persist_props_action' is done.
static bool fs_mgr_boot_completed() {
return android::base::GetBoolProperty("ro.persistent_properties.ready", false);
}
constexpr auto kPhysicalDevice = "/dev/block/by-name/";
constexpr char kScratchImageMetadata[] = "/metadata/gsi/remount/lp_metadata";
// Note: this is meant only for recovery/first-stage init.
static bool ScratchIsOnData() {
// The scratch partition of DSU is managed by gsid.
@ -131,7 +134,7 @@ static bool fs_mgr_rm_all(const std::string& path, bool* change = nullptr, int l
}
std::string fs_mgr_overlayfs_setup_dir(const std::string& dir) {
auto top = dir + kOverlayTopDir;
auto top = dir + "/" + kOverlayTopDir;
AutoSetFsCreateCon createcon(kOverlayfsFileContext);
if (!createcon.Ok()) {
@ -290,7 +293,7 @@ OverlayfsTeardownResult fs_mgr_overlayfs_teardown_scratch(const std::string& ove
bool fs_mgr_overlayfs_teardown_one(const std::string& overlay, const std::string& mount_point,
bool* change, bool* should_destroy_scratch = nullptr) {
const auto top = overlay + kOverlayTopDir;
const auto top = overlay + "/" + kOverlayTopDir;
if (!fs_mgr_access(top)) {
if (should_destroy_scratch) *should_destroy_scratch = true;
@ -300,7 +303,7 @@ bool fs_mgr_overlayfs_teardown_one(const std::string& overlay, const std::string
auto cleanup_all = mount_point.empty();
const auto partition_name = android::base::Basename(mount_point);
const auto oldpath = top + (cleanup_all ? "" : ("/" + partition_name));
const auto newpath = cleanup_all ? overlay + "/." + (kOverlayTopDir + 1) + ".teardown"
const auto newpath = cleanup_all ? overlay + "/." + kOverlayTopDir + ".teardown"
: top + "/." + partition_name + ".teardown";
auto ret = fs_mgr_rm_all(newpath);
if (!rename(oldpath.c_str(), newpath.c_str())) {
@ -346,72 +349,6 @@ bool fs_mgr_overlayfs_teardown_one(const std::string& overlay, const std::string
return ret;
}
// Mount kScratchMountPoint
bool MountScratch(const std::string& device_path, bool readonly = false) {
if (readonly) {
if (!fs_mgr_access(device_path)) {
LOG(ERROR) << "Path does not exist: " << device_path;
return false;
}
} else if (!fs_mgr_rw_access(device_path)) {
LOG(ERROR) << "Path does not exist or is not readwrite: " << device_path;
return false;
}
std::vector<const char*> filesystem_candidates;
if (fs_mgr_is_f2fs(device_path)) {
filesystem_candidates = {"f2fs", "ext4"};
} else if (fs_mgr_is_ext4(device_path)) {
filesystem_candidates = {"ext4", "f2fs"};
} else {
LOG(ERROR) << "Scratch partition is not f2fs or ext4";
return false;
}
AutoSetFsCreateCon createcon(kOverlayfsFileContext);
if (!createcon.Ok()) {
return false;
}
if (mkdir(kScratchMountPoint, 0755) && (errno != EEXIST)) {
PERROR << "create " << kScratchMountPoint;
return false;
}
FstabEntry entry;
entry.blk_device = device_path;
entry.mount_point = kScratchMountPoint;
entry.flags = MS_NOATIME | MS_RDONLY;
if (!readonly) {
entry.flags &= ~MS_RDONLY;
entry.flags |= MS_SYNCHRONOUS;
entry.fs_options = "nodiscard";
fs_mgr_set_blk_ro(device_path, false);
}
// check_fs requires apex runtime library
if (fs_mgr_overlayfs_already_mounted("/data", false)) {
entry.fs_mgr_flags.check = true;
}
bool mounted = false;
for (auto fs_type : filesystem_candidates) {
entry.fs_type = fs_type;
if (fs_mgr_do_mount_one(entry) == 0) {
mounted = true;
break;
}
}
if (!createcon.Restore()) {
return false;
}
if (!mounted) {
rmdir(kScratchMountPoint);
return false;
}
return true;
}
const std::string kMkF2fs("/system/bin/make_f2fs");
const std::string kMkExt4("/system/bin/mke2fs");
// Note: The scratch partition of DSU is managed by gsid, and should be initialized during
// first-stage-mount. Just check if the DM device for DSU scratch partition is created or not.
static std::string GetDsuScratchDevice() {
@ -456,14 +393,14 @@ bool MakeScratchFilesystem(const std::string& scratch_device) {
// thus do not rely on fsck to correct problems that could creep in.
auto fs_type = ""s;
auto command = ""s;
if (!access(kMkF2fs.c_str(), X_OK) && fs_mgr_filesystem_available("f2fs")) {
if (!access(kMkF2fs, X_OK) && fs_mgr_filesystem_available("f2fs")) {
fs_type = "f2fs";
command = kMkF2fs + " -w ";
command = kMkF2fs + " -w "s;
command += std::to_string(getpagesize());
command += " -f -d1 -l" + android::base::Basename(kScratchMountPoint);
} else if (!access(kMkExt4.c_str(), X_OK) && fs_mgr_filesystem_available("ext4")) {
} else if (!access(kMkExt4, X_OK) && fs_mgr_filesystem_available("ext4")) {
fs_type = "ext4";
command = kMkExt4 + " -F -b 4096 -t ext4 -m 0 -O has_journal -M " + kScratchMountPoint;
command = kMkExt4 + " -F -b 4096 -t ext4 -m 0 -O has_journal -M "s + kScratchMountPoint;
} else {
LERROR << "No supported mkfs command or filesystem driver available, supported filesystems "
"are: f2fs, ext4";
@ -697,7 +634,7 @@ bool fs_mgr_overlayfs_setup_scratch(const Fstab& fstab) {
// If the partition exists, assume first that it can be mounted.
if (partition_exists) {
if (MountScratch(scratch_device)) {
if (fs_mgr_access(std::string(kScratchMountPoint) + kOverlayTopDir) ||
if (fs_mgr_access(kScratchMountPoint + "/"s + kOverlayTopDir) ||
fs_mgr_filesystem_has_space(kScratchMountPoint)) {
return true;
}
@ -717,32 +654,6 @@ bool fs_mgr_overlayfs_setup_scratch(const Fstab& fstab) {
return MountScratch(scratch_device);
}
// NOTE: OverlayfsSetupAllowed() must be "stricter" than OverlayfsTeardownAllowed().
// Setup is allowed only if teardown is also allowed.
bool OverlayfsSetupAllowed(bool verbose = false) {
if (!kAllowOverlayfs) {
if (verbose) {
LOG(ERROR) << "Overlayfs remounts can only be used in debuggable builds";
}
return false;
}
// Check mandatory kernel patches.
if (fs_mgr_overlayfs_valid() == OverlayfsValidResult::kNotSupported) {
if (verbose) {
LOG(ERROR) << "Kernel does not support overlayfs";
}
return false;
}
// in recovery or fastbootd, not allowed!
if (fs_mgr_in_recovery()) {
if (verbose) {
LOG(ERROR) << "Unsupported overlayfs setup from recovery";
}
return false;
}
return true;
}
constexpr bool OverlayfsTeardownAllowed() {
// Never allow on non-debuggable build.
return kAllowOverlayfs;

26
fs_mgr/fs_mgr_overlayfs_mount.cpp
View File

@ -62,13 +62,16 @@ using namespace android::storage_literals;
constexpr char kPreferCacheBackingStorageProp[] = "fs_mgr.overlayfs.prefer_cache_backing_storage";
constexpr char kCacheMountPoint[] = "/cache";
constexpr char kPhysicalDevice[] = "/dev/block/by-name/";
constexpr char kLowerdirOption[] = "lowerdir=";
constexpr char kUpperdirOption[] = "upperdir=";
bool fs_mgr_access(const std::string& path) {
return access(path.c_str(), F_OK) == 0;
}
const auto kLowerdirOption = "lowerdir=";
const auto kUpperdirOption = "upperdir=";
bool fs_mgr_in_recovery() {
// Check the existence of recovery binary instead of using the compile time
// __ANDROID_RECOVERY__ macro.
@ -89,8 +92,6 @@ bool fs_mgr_is_dsu_running() {
return android::gsi::IsGsiRunning();
}
const auto kCacheMountPoint = "/cache";
static bool IsABDevice() {
return !android::base::GetProperty("ro.boot.slot_suffix", "").empty();
}
@ -141,8 +142,6 @@ bool fs_mgr_filesystem_has_space(const std::string& mount_point) {
(static_cast<uint64_t>(vst.f_bfree) * vst.f_frsize) >= kSizeThreshold;
}
const auto kPhysicalDevice = "/dev/block/by-name/";
static bool fs_mgr_update_blk_device(FstabEntry* entry) {
if (entry->fs_mgr_flags.logical) {
fs_mgr_update_logical_partition(entry);
@ -155,7 +154,7 @@ static bool fs_mgr_update_blk_device(FstabEntry* entry) {
}
// special case for system-as-root (taimen and others)
auto blk_device = std::string(kPhysicalDevice) + "system";
auto blk_device = kPhysicalDevice + "system"s;
if (!fs_mgr_access(blk_device)) {
blk_device += fs_mgr_get_slot_suffix();
if (!fs_mgr_access(blk_device)) {
@ -237,7 +236,7 @@ static std::string fs_mgr_get_overlayfs_candidate(const std::string& mount_point
if (!fs_mgr_is_dir(mount_point)) return "";
const auto base = android::base::Basename(mount_point) + "/";
for (const auto& overlay_mount_point : OverlayMountPoints()) {
auto dir = overlay_mount_point + kOverlayTopDir + "/" + base;
auto dir = overlay_mount_point + "/" + kOverlayTopDir + "/" + base;
auto upper = dir + kUpperName;
if (!fs_mgr_is_dir(upper)) continue;
auto work = dir + kWorkName;
@ -527,7 +526,7 @@ static bool fs_mgr_overlayfs_mount(const FstabEntry& entry) {
}
// Mount kScratchMountPoint
static bool MountScratch(const std::string& device_path, bool readonly = false) {
bool MountScratch(const std::string& device_path, bool readonly) {
if (readonly) {
if (!fs_mgr_access(device_path)) {
LOG(ERROR) << "Path does not exist: " << device_path;
@ -589,9 +588,6 @@ static bool MountScratch(const std::string& device_path, bool readonly = false)
return true;
}
const std::string kMkF2fs("/system/bin/make_f2fs");
const std::string kMkExt4("/system/bin/mke2fs");
// Note: The scratch partition of DSU is managed by gsid, and should be initialized during
// first-stage-mount. Just check if the DM device for DSU scratch partition is created or not.
static std::string GetDsuScratchDevice() {
@ -633,7 +629,7 @@ static std::string GetBootScratchDevice() {
// NOTE: OverlayfsSetupAllowed() must be "stricter" than OverlayfsTeardownAllowed().
// Setup is allowed only if teardown is also allowed.
bool OverlayfsSetupAllowed(bool verbose = false) {
bool OverlayfsSetupAllowed(bool verbose) {
if (!kAllowOverlayfs) {
if (verbose) {
LOG(ERROR) << "Overlayfs remounts can only be used in debuggable builds";
@ -737,7 +733,7 @@ static void TryMountScratch() {
if (!MountScratch(scratch_device, true /* readonly */)) {
return;
}
auto has_overlayfs_dir = fs_mgr_access(std::string(kScratchMountPoint) + kOverlayTopDir);
auto has_overlayfs_dir = fs_mgr_access(kScratchMountPoint + "/"s + kOverlayTopDir);
fs_mgr_overlayfs_umount_scratch();
if (has_overlayfs_dir) {
MountScratch(scratch_device);

21
fs_mgr/fs_mgr_overlayfs_mount.h
View File

@ -20,9 +20,12 @@
#include <fstab/fstab.h>
bool fs_mgr_overlayfs_already_mounted(const std::string& mount_point, bool overlay_only = true);
bool fs_mgr_wants_overlayfs(android::fs_mgr::FstabEntry* entry);
android::fs_mgr::Fstab fs_mgr_overlayfs_candidate_list(const android::fs_mgr::Fstab& fstab);
constexpr char kOverlayfsFileContext[] = "u:object_r:overlayfs_file:s0";
constexpr char kScratchMountPoint[] = "/mnt/scratch";
constexpr char kOverlayTopDir[] = "overlay";
constexpr char kUpperName[] = "upper";
constexpr char kWorkName[] = "work";
#if ALLOW_ADBD_DISABLE_VERITY
constexpr bool kAllowOverlayfs = true;
@ -45,18 +48,16 @@ class AutoSetFsCreateCon final {
bool restored_ = false;
};
constexpr auto kScratchMountPoint = "/mnt/scratch";
constexpr char kOverlayfsFileContext[] = "u:object_r:overlayfs_file:s0";
constexpr auto kUpperName = "upper";
constexpr auto kWorkName = "work";
constexpr auto kOverlayTopDir = "/overlay";
bool fs_mgr_is_dsu_running();
bool fs_mgr_in_recovery();
bool fs_mgr_access(const std::string& path);
bool fs_mgr_rw_access(const std::string& path);
bool fs_mgr_filesystem_has_space(const std::string& mount_point);
const std::string fs_mgr_mount_point(const std::string& mount_point);
bool OverlayfsSetupAllowed(bool verbose = false);
bool MountScratch(const std::string& device_path, bool readonly = false);
bool fs_mgr_overlayfs_umount_scratch();
std::vector<const std::string> OverlayMountPoints();
bool fs_mgr_overlayfs_already_mounted(const std::string& mount_point, bool overlay_only = true);
bool fs_mgr_wants_overlayfs(android::fs_mgr::FstabEntry* entry);
android::fs_mgr::Fstab fs_mgr_overlayfs_candidate_list(const android::fs_mgr::Fstab& fstab);