Merge "libdm: Implement zero and linear targets." (d9b581e9) · Commits · e / os / android_system_core

fs_mgr/libdm/dm.cpp

+3 −0

Original line number	Diff line number	Diff line
		@@ -114,6 +114,9 @@ bool DeviceMapper::LoadTableAndActivate(const std::string& name, const DmTable&
		io->data_size = ioctl_buffer.size();
		io->data_start = sizeof(struct dm_ioctl);
		io->target_count = static_cast<uint32_t>(table.num_targets());
		if (table.readonly()) {
		io->flags \|= DM_READONLY_FLAG;
		}
		if (ioctl(fd_, DM_TABLE_LOAD, io)) {
		PLOG(ERROR) << "DM_TABLE_LOAD failed";
		return false;

fs_mgr/libdm/dm_table.cpp

+21 −4

Original line number	Diff line number	Diff line
		@@ -22,7 +22,8 @@
		namespace android {
		namespace dm {

		bool DmTable::AddTarget(std::unique_ptr<DmTarget>&& /* target */) {
		bool DmTable::AddTarget(std::unique_ptr<DmTarget>&& target) {
		targets_.push_back(std::move(target));
		return true;
		}

		@@ -31,6 +32,14 @@ bool DmTable::RemoveTarget(std::unique_ptr<DmTarget>&& /* target */) {
		}

		bool DmTable::valid() const {
		if (targets_.empty()) {
		LOG(ERROR) << "Device-mapper table must have at least one target.";
		return "";
		}
		if (targets_[0]->start() != 0) {
		LOG(ERROR) << "Device-mapper table must start at logical sector 0.";
		return "";
		}
		return true;
		}

		@@ -38,15 +47,23 @@ uint64_t DmTable::num_sectors() const {
		return valid() ? num_sectors_ : 0;
		}

		// Returns a string represnetation of the table that is ready to be passed
		// down to the kernel for loading
		// Returns a string representation of the table that is ready to be passed
		// down to the kernel for loading.
		//
		// Implementation must verify there are no gaps in the table, table starts
		// with sector == 0, and iterate over each target to get its table
		// serialized.
		std::string DmTable::Serialize() const {
		if (!valid()) {
		return "";
		}

		std::string table;
		for (const auto& target : targets_) {
		table += target->Serialize();
		}
		return table;
		}

		} // namespace dm
		} // namespace android

fs_mgr/libdm/dm_target.cpp

+36 −1

Original line number	Diff line number	Diff line
		@@ -19,6 +19,41 @@
		#include <android-base/logging.h>
		#include <android-base/macros.h>

		#include <libdm/dm.h>

		namespace android {
		namespace dm {} // namespace dm
		namespace dm {

		std::string DmTarget::Serialize() const {
		// Create a string containing a dm_target_spec, parameter data, and an
		// explicit null terminator.
		std::string data(sizeof(dm_target_spec), '\0');
		data += GetParameterString();
		data.push_back('\0');

		// The kernel expects each target to be 8-byte aligned.
		size_t padding = DM_ALIGN(data.size()) - data.size();
		for (size_t i = 0; i < padding; i++) {
		data.push_back('\0');
		}

		// Finally fill in the dm_target_spec.
		struct dm_target_spec* spec = reinterpret_cast<struct dm_target_spec*>(&data[0]);
		spec->sector_start = start();
		spec->length = size();
		strlcpy(spec->target_type, name().c_str(), sizeof(spec->target_type));
		spec->next = (uint32_t)data.size();
		return data;
		}

		std::string DmTargetZero::GetParameterString() const {
		// The zero target type has no additional parameters.
		return "";
		}

		std::string DmTargetLinear::GetParameterString() const {
		return block_device_ + " " + std::to_string(physical_sector_);
		}

		} // namespace dm
		} // namespace android

fs_mgr/libdm/include/libdm/dm_table.h

+7 −1

Original line number	Diff line number	Diff line
		@@ -30,7 +30,7 @@ namespace dm {

		class DmTable {
		public:
		DmTable() : num_sectors_(0){};
		DmTable() : num_sectors_(0), readonly_(false) {}

		// Adds a target to the device mapper table for a range specified in the target object.
		// The function will return 'true' if the target was successfully added and doesn't overlap with
		@@ -59,6 +59,9 @@ class DmTable {
		// as part of the DM_TABLE_LOAD ioctl.
		std::string Serialize() const;

		void set_readonly(bool readonly) { readonly_ = readonly; }
		bool readonly() const { return readonly_; }

		~DmTable() = default;

		private:
		@@ -70,6 +73,9 @@ class DmTable {
		// Total size in terms of # of sectors, as calculated by looking at the last and the first
		// target in 'target_'.
		uint64_t num_sectors_;

		// True if the device should be read-only; false otherwise.
		bool readonly_;
		};

		} // namespace dm

fs_mgr/libdm/include/libdm/dm_target.h

+29 −2

Original line number	Diff line number	Diff line
		@@ -55,7 +55,7 @@ class DmTarget {
		virtual ~DmTarget() = default;

		// Returns name of the target.
		virtual const std::string& name() const = 0;
		virtual std::string name() const = 0;

		// Return the first logical sector represented by this target.
		uint64_t start() const { return start_; }
		@@ -67,7 +67,12 @@ class DmTarget {
		// Function that converts this object to a string of arguments that can
		// be passed to the kernel for adding this target in a table. Each target (e.g. verity, linear)
		// must implement this, for it to be used on a device.
		virtual std::string Serialize() const = 0;
		std::string Serialize() const;

		protected:
		// Get the parameter string that is passed to the end of the dm_target_spec
		// for this target type.
		virtual std::string GetParameterString() const = 0;

		private:
		// logical sector number start and total length (in terms of 512-byte sectors) represented
		@@ -75,6 +80,28 @@ class DmTarget {
		uint64_t start_, length_;
		};

		class DmTargetZero final : public DmTarget {
		public:
		DmTargetZero(uint64_t start, uint64_t length) : DmTarget(start, length) {}

		std::string name() const override { return "zero"; }
		std::string GetParameterString() const override;
		};

		class DmTargetLinear final : public DmTarget {
		public:
		DmTargetLinear(uint64_t start, uint64_t length, const std::string& block_device,
		uint64_t physical_sector)
		: DmTarget(start, length), block_device_(block_device), physical_sector_(physical_sector) {}

		std::string name() const override { return "linear"; }
		std::string GetParameterString() const override;

		private:
		std::string block_device_;
		uint64_t physical_sector_;
		};

		} // namespace dm
		} // namespace android