ubi/item_updater_ubi.cpp - openbmc/openpower-pnor-code-mgmt - Gitiles

 #include "config.h"

 #include "item_updater_ubi.hpp"

 #include "activation_ubi.hpp"
 #include "serialize.hpp"
 #include "utils.hpp"
 #include "version.hpp"
 #include "xyz/openbmc_project/Common/error.hpp"

 #include <experimental/filesystem>
 #include <fstream>
 #include <phosphor-logging/elog-errors.hpp>
 #include <phosphor-logging/log.hpp>
 #include <queue>
 #include <string>
 #include <xyz/openbmc_project/Software/Version/server.hpp>

 namespace openpower
 {
 namespace software
 {
 namespace updater
 {

 // When you see server:: you know we're referencing our base class
 namespace server = sdbusplus::xyz::openbmc_project::Software::server;
 namespace fs = std::experimental::filesystem;

 using namespace sdbusplus::xyz::openbmc_project::Common::Error;
 using namespace phosphor::logging;

 constexpr auto squashFSImage = "pnor.xz.squashfs";

 std::unique_ptr<Activation> ItemUpdaterUbi::createActivationObject(
     const std::string& path, const std::string& versionId,
     const std::string& extVersion,
     sdbusplus::xyz::openbmc_project::Software::server::Activation::Activations
         activationStatus,
     AssociationList& assocs)
 {
     return std::make_unique<ActivationUbi>(
         bus, path, *this, versionId, extVersion, activationStatus, assocs);
 }

 std::unique_ptr<Version> ItemUpdaterUbi::createVersionObject(
     const std::string& objPath, const std::string& versionId,
     const std::string& versionString,
     sdbusplus::xyz::openbmc_project::Software::server::Version::VersionPurpose
         versionPurpose,
     const std::string& filePath)
 {
     auto version = std::make_unique<Version>(
         bus, objPath, *this, versionId, versionString, versionPurpose, filePath,
         std::bind(&ItemUpdaterUbi::erase, this, std::placeholders::_1));
     version->deleteObject = std::make_unique<Delete>(bus, objPath, *version);
     return version;
 }

 bool ItemUpdaterUbi::validateImage(const std::string& path)
 {
     return validateSquashFSImage(path) == 0;
 }

 void ItemUpdaterUbi::processPNORImage()
 {
     // Read pnor.toc from folders under /media/
     // to get Active Software Versions.
     for (const auto& iter : fs::directory_iterator(MEDIA_DIR))
     {
         auto activationState = server::Activation::Activations::Active;

         static const auto PNOR_RO_PREFIX_LEN = strlen(PNOR_RO_PREFIX);
         static const auto PNOR_RW_PREFIX_LEN = strlen(PNOR_RW_PREFIX);

         // Check if the PNOR_RO_PREFIX is the prefix of the iter.path
         if (0 ==
             iter.path().native().compare(0, PNOR_RO_PREFIX_LEN, PNOR_RO_PREFIX))
         {
             // The versionId is extracted from the path
             // for example /media/pnor-ro-2a1022fe.
             auto id = iter.path().native().substr(PNOR_RO_PREFIX_LEN);
             auto pnorTOC = iter.path() / PNOR_TOC_FILE;
             if (!fs::is_regular_file(pnorTOC))
             {
                 log<level::ERR>("Failed to read pnorTOC.",
                                 entry("FILENAME=%s", pnorTOC.c_str()));
                 ItemUpdaterUbi::erase(id);
                 continue;
             }
             auto keyValues = Version::getValue(
                 pnorTOC, {{"version", ""}, {"extended_version", ""}});
             auto& version = keyValues.at("version");
             if (version.empty())
             {
                 log<level::ERR>("Failed to read version from pnorTOC",
                                 entry("FILENAME=%s", pnorTOC.c_str()));
                 activationState = server::Activation::Activations::Invalid;
             }

             auto& extendedVersion = keyValues.at("extended_version");
             if (extendedVersion.empty())
             {
                 log<level::ERR>("Failed to read extendedVersion from pnorTOC",
                                 entry("FILENAME=%s", pnorTOC.c_str()));
                 activationState = server::Activation::Activations::Invalid;
             }

             auto purpose = server::Version::VersionPurpose::Host;
             auto path = fs::path(SOFTWARE_OBJPATH) / id;
             AssociationList associations = {};

             if (activationState == server::Activation::Activations::Active)
             {
                 // Create an association to the host inventory item
                 associations.emplace_back(std::make_tuple(
                     ACTIVATION_FWD_ASSOCIATION, ACTIVATION_REV_ASSOCIATION,
                     HOST_INVENTORY_PATH));

                 // Create an active association since this image is active
                 createActiveAssociation(path);
             }

             // Create Activation instance for this version.
             activations.insert(
                 std::make_pair(id, std::make_unique<ActivationUbi>(
                                        bus, path, *this, id, extendedVersion,
                                        activationState, associations)));

             // If Active, create RedundancyPriority instance for this version.
             if (activationState == server::Activation::Activations::Active)
             {
                 uint8_t priority = std::numeric_limits<uint8_t>::max();
                 if (!restoreFromFile(id, priority))
                 {
                     log<level::ERR>("Unable to restore priority from file.",
                                     entry("VERSIONID=%s", id.c_str()));
                 }
                 activations.find(id)->second->redundancyPriority =
                     std::make_unique<RedundancyPriorityUbi>(
                         bus, path, *(activations.find(id)->second), priority);
             }

             // Create Version instance for this version.
             auto versionPtr = std::make_unique<Version>(
                 bus, path, *this, id, version, purpose, "",
                 std::bind(&ItemUpdaterUbi::erase, this, std::placeholders::_1));
             versionPtr->deleteObject =
                 std::make_unique<Delete>(bus, path, *versionPtr);
             versions.insert(std::make_pair(id, std::move(versionPtr)));
         }
         else if (0 == iter.path().native().compare(0, PNOR_RW_PREFIX_LEN,
                                                    PNOR_RW_PREFIX))
         {
             auto id = iter.path().native().substr(PNOR_RW_PREFIX_LEN);
             auto roDir = PNOR_RO_PREFIX + id;
             if (!fs::is_directory(roDir))
             {
                 log<level::ERR>("No corresponding read-only volume found.",
                                 entry("DIRNAME=%s", roDir.c_str()));
                 ItemUpdaterUbi::erase(id);
             }
         }
     }

     // Look at the RO symlink to determine if there is a functional image
     auto id = determineId(PNOR_RO_ACTIVE_PATH);
     if (!id.empty())
     {
         updateFunctionalAssociation(id);
     }
     return;
 }

 int ItemUpdaterUbi::validateSquashFSImage(const std::string& filePath)
 {
     auto file = fs::path(filePath) / squashFSImage;
     if (fs::is_regular_file(file))
     {
         return 0;
     }
     else
     {
         log<level::ERR>("Failed to find the SquashFS image.");
         return -1;
     }
 }

 void ItemUpdaterUbi::removeReadOnlyPartition(const std::string& versionId)
 {
     auto serviceFile = "obmc-flash-bios-ubiumount-ro@" + versionId + ".service";

     // Remove the read-only partitions.
     auto method = bus.new_method_call(SYSTEMD_BUSNAME, SYSTEMD_PATH,
                                       SYSTEMD_INTERFACE, "StartUnit");
     method.append(serviceFile, "replace");
     bus.call_noreply(method);
 }

 void ItemUpdaterUbi::removeReadWritePartition(const std::string& versionId)
 {
     auto serviceFile = "obmc-flash-bios-ubiumount-rw@" + versionId + ".service";

     // Remove the read-write partitions.
     auto method = bus.new_method_call(SYSTEMD_BUSNAME, SYSTEMD_PATH,
                                       SYSTEMD_INTERFACE, "StartUnit");
     method.append(serviceFile, "replace");
     bus.call_noreply(method);
 }

 void ItemUpdaterUbi::reset()
 {
     utils::hiomapdSuspend(bus);

     constexpr static auto patchDir = "/usr/local/share/pnor";
     if (fs::is_directory(patchDir))
     {
         for (const auto& iter : fs::directory_iterator(patchDir))
         {
             fs::remove_all(iter);
         }
     }

     // Clear the read-write partitions.
     for (const auto& it : activations)
     {
         auto rwDir = PNOR_RW_PREFIX + it.first;
         if (fs::is_directory(rwDir))
         {
             for (const auto& iter : fs::directory_iterator(rwDir))
             {
                 fs::remove_all(iter);
             }
         }
     }

     // Clear the preserved partition.
     if (fs::is_directory(PNOR_PRSV))
     {
         for (const auto& iter : fs::directory_iterator(PNOR_PRSV))
         {
             fs::remove_all(iter);
         }
     }

     utils::hiomapdResume(bus);
 }

 bool ItemUpdaterUbi::isVersionFunctional(const std::string& versionId)
 {
     if (!fs::exists(PNOR_RO_ACTIVE_PATH))
     {
         return false;
     }

     fs::path activeRO = fs::read_symlink(PNOR_RO_ACTIVE_PATH);

     if (!fs::is_directory(activeRO))
     {
         return false;
     }

     if (activeRO.string().find(versionId) == std::string::npos)
     {
         return false;
     }

     // active PNOR is the version we're checking
     return true;
 }

 void ItemUpdaterUbi::freePriority(uint8_t value, const std::string& versionId)
 {
     // TODO openbmc/openbmc#1896 Improve the performance of this function
     for (const auto& intf : activations)
     {
         if (intf.second->redundancyPriority)
         {
             if (intf.second->redundancyPriority.get()->priority() == value &&
                 intf.second->versionId != versionId)
             {
                 intf.second->redundancyPriority.get()->priority(value + 1);
             }
         }
     }
 }

 bool ItemUpdaterUbi::erase(std::string entryId)
 {
     if (!ItemUpdater::erase(entryId))
     {
         return false;
     }

     // Remove priority persistence file
     removeFile(entryId);

     // Removing read-only and read-write partitions
     removeReadWritePartition(entryId);
     removeReadOnlyPartition(entryId);

     return true;
 }

 void ItemUpdaterUbi::deleteAll()
 {
     auto chassisOn = isChassisOn();

     for (const auto& activationIt : activations)
     {
         if (isVersionFunctional(activationIt.first) && chassisOn)
         {
             continue;
         }
         else
         {
             ItemUpdaterUbi::erase(activationIt.first);
         }
     }

     // Remove any remaining pnor-ro- or pnor-rw- volumes that do not match
     // the current version.
     auto method = bus.new_method_call(SYSTEMD_BUSNAME, SYSTEMD_PATH,
                                       SYSTEMD_INTERFACE, "StartUnit");
     method.append("obmc-flash-bios-cleanup.service", "replace");
     bus.call_noreply(method);
 }

 // TODO: openbmc/openbmc#1402 Monitor flash usage
 bool ItemUpdaterUbi::freeSpace()
 {
     bool isSpaceFreed = false;
     //  Versions with the highest priority in front
     std::priority_queue<std::pair<int, std::string>,
                         std::vector<std::pair<int, std::string>>,
                         std::less<std::pair<int, std::string>>>
         versionsPQ;

     std::size_t count = 0;
     for (const auto& iter : activations)
     {
         if (iter.second.get()->activation() ==
             server::Activation::Activations::Active)
         {
             count++;
             // Don't put the functional version on the queue since we can't
             // remove the "running" PNOR version if it allows multiple PNORs
             // But removing functional version if there is only one PNOR.
             if (ACTIVE_PNOR_MAX_ALLOWED > 1 &&
                 isVersionFunctional(iter.second->versionId))
             {
                 continue;
             }
             versionsPQ.push(std::make_pair(
                 iter.second->redundancyPriority.get()->priority(),
                 iter.second->versionId));
         }
     }

     // If the number of PNOR versions is over ACTIVE_PNOR_MAX_ALLOWED -1,
     // remove the highest priority one(s).
     while ((count >= ACTIVE_PNOR_MAX_ALLOWED) && (!versionsPQ.empty()))
     {
         erase(versionsPQ.top().second);
         versionsPQ.pop();
         count--;
         isSpaceFreed = true;
     }
     return isSpaceFreed;
 }

 std::string ItemUpdaterUbi::determineId(const std::string& symlinkPath)
 {
     if (!fs::exists(symlinkPath))
     {
         return {};
     }

     auto target = fs::canonical(symlinkPath).string();

     // check to make sure the target really exists
     if (!fs::is_regular_file(target + "/" + PNOR_TOC_FILE))
     {
         return {};
     }
     // Get the image <id> from the symlink target
     // for example /media/ro-2a1022fe
     static const auto PNOR_RO_PREFIX_LEN = strlen(PNOR_RO_PREFIX);
     return target.substr(PNOR_RO_PREFIX_LEN);
 }

 void GardResetUbi::reset()
 {
     // The GARD partition is currently misspelled "GUARD." This file path will
     // need to be updated in the future.
     auto path = fs::path(PNOR_PRSV_ACTIVE_PATH);
     path /= "GUARD";

     utils::hiomapdSuspend(bus);

     if (fs::is_regular_file(path))
     {
         fs::remove(path);
     }

     utils::hiomapdResume(bus);
 }

 } // namespace updater
 } // namespace software
 } // namespace openpower
	#include "config.h"

	#include "item_updater_ubi.hpp"

	#include "activation_ubi.hpp"
	#include "serialize.hpp"
	#include "utils.hpp"
	#include "version.hpp"
	#include "xyz/openbmc_project/Common/error.hpp"

	#include <experimental/filesystem>
	#include <fstream>
	#include <phosphor-logging/elog-errors.hpp>
	#include <phosphor-logging/log.hpp>
	#include <queue>
	#include <string>
	#include <xyz/openbmc_project/Software/Version/server.hpp>

	namespace openpower
	{
	namespace software
	{
	namespace updater
	{

	// When you see server:: you know we're referencing our base class
	namespace server = sdbusplus::xyz::openbmc_project::Software::server;
	namespace fs = std::experimental::filesystem;

	using namespace sdbusplus::xyz::openbmc_project::Common::Error;
	using namespace phosphor::logging;

	constexpr auto squashFSImage = "pnor.xz.squashfs";

	std::unique_ptr<Activation> ItemUpdaterUbi::createActivationObject(
	const std::string& path, const std::string& versionId,
	const std::string& extVersion,
	sdbusplus::xyz::openbmc_project::Software::server::Activation::Activations
	activationStatus,
	AssociationList& assocs)
	{
	return std::make_unique<ActivationUbi>(
	bus, path, *this, versionId, extVersion, activationStatus, assocs);
	}

	std::unique_ptr<Version> ItemUpdaterUbi::createVersionObject(
	const std::string& objPath, const std::string& versionId,
	const std::string& versionString,
	sdbusplus::xyz::openbmc_project::Software::server::Version::VersionPurpose
	versionPurpose,
	const std::string& filePath)
	{
	auto version = std::make_unique<Version>(
	bus, objPath, *this, versionId, versionString, versionPurpose, filePath,
	std::bind(&ItemUpdaterUbi::erase, this, std::placeholders::_1));
	version->deleteObject = std::make_unique<Delete>(bus, objPath, *version);
	return version;
	}

	bool ItemUpdaterUbi::validateImage(const std::string& path)
	{
	return validateSquashFSImage(path) == 0;
	}

	void ItemUpdaterUbi::processPNORImage()
	{
	// Read pnor.toc from folders under /media/
	// to get Active Software Versions.
	for (const auto& iter : fs::directory_iterator(MEDIA_DIR))
	{
	auto activationState = server::Activation::Activations::Active;

	static const auto PNOR_RO_PREFIX_LEN = strlen(PNOR_RO_PREFIX);
	static const auto PNOR_RW_PREFIX_LEN = strlen(PNOR_RW_PREFIX);

	// Check if the PNOR_RO_PREFIX is the prefix of the iter.path
	if (0 ==
	iter.path().native().compare(0, PNOR_RO_PREFIX_LEN, PNOR_RO_PREFIX))
	{
	// The versionId is extracted from the path
	// for example /media/pnor-ro-2a1022fe.
	auto id = iter.path().native().substr(PNOR_RO_PREFIX_LEN);
	auto pnorTOC = iter.path() / PNOR_TOC_FILE;
	if (!fs::is_regular_file(pnorTOC))
	{
	log<level::ERR>("Failed to read pnorTOC.",
	entry("FILENAME=%s", pnorTOC.c_str()));
	ItemUpdaterUbi::erase(id);
	continue;
	}
	auto keyValues = Version::getValue(
	pnorTOC, {{"version", ""}, {"extended_version", ""}});
	auto& version = keyValues.at("version");
	if (version.empty())
	{
	log<level::ERR>("Failed to read version from pnorTOC",
	entry("FILENAME=%s", pnorTOC.c_str()));
	activationState = server::Activation::Activations::Invalid;
	}

	auto& extendedVersion = keyValues.at("extended_version");
	if (extendedVersion.empty())
	{
	log<level::ERR>("Failed to read extendedVersion from pnorTOC",
	entry("FILENAME=%s", pnorTOC.c_str()));
	activationState = server::Activation::Activations::Invalid;
	}

	auto purpose = server::Version::VersionPurpose::Host;
	auto path = fs::path(SOFTWARE_OBJPATH) / id;
	AssociationList associations = {};

	if (activationState == server::Activation::Activations::Active)
	{
	// Create an association to the host inventory item
	associations.emplace_back(std::make_tuple(
	ACTIVATION_FWD_ASSOCIATION, ACTIVATION_REV_ASSOCIATION,
	HOST_INVENTORY_PATH));

	// Create an active association since this image is active
	createActiveAssociation(path);
	}

	// Create Activation instance for this version.
	activations.insert(
	std::make_pair(id, std::make_unique<ActivationUbi>(
	bus, path, *this, id, extendedVersion,
	activationState, associations)));

	// If Active, create RedundancyPriority instance for this version.
	if (activationState == server::Activation::Activations::Active)
	{
	uint8_t priority = std::numeric_limits<uint8_t>::max();
	if (!restoreFromFile(id, priority))
	{
	log<level::ERR>("Unable to restore priority from file.",
	entry("VERSIONID=%s", id.c_str()));
	}
	activations.find(id)->second->redundancyPriority =
	std::make_unique<RedundancyPriorityUbi>(
	bus, path, *(activations.find(id)->second), priority);
	}

	// Create Version instance for this version.
	auto versionPtr = std::make_unique<Version>(
	bus, path, *this, id, version, purpose, "",
	std::bind(&ItemUpdaterUbi::erase, this, std::placeholders::_1));
	versionPtr->deleteObject =
	std::make_unique<Delete>(bus, path, *versionPtr);
	versions.insert(std::make_pair(id, std::move(versionPtr)));
	}
	else if (0 == iter.path().native().compare(0, PNOR_RW_PREFIX_LEN,
	PNOR_RW_PREFIX))
	{
	auto id = iter.path().native().substr(PNOR_RW_PREFIX_LEN);
	auto roDir = PNOR_RO_PREFIX + id;
	if (!fs::is_directory(roDir))
	{
	log<level::ERR>("No corresponding read-only volume found.",
	entry("DIRNAME=%s", roDir.c_str()));
	ItemUpdaterUbi::erase(id);
	}
	}
	}

	// Look at the RO symlink to determine if there is a functional image
	auto id = determineId(PNOR_RO_ACTIVE_PATH);
	if (!id.empty())
	{
	updateFunctionalAssociation(id);
	}
	return;
	}

	int ItemUpdaterUbi::validateSquashFSImage(const std::string& filePath)
	{
	auto file = fs::path(filePath) / squashFSImage;
	if (fs::is_regular_file(file))
	{
	return 0;
	}
	else
	{
	log<level::ERR>("Failed to find the SquashFS image.");
	return -1;
	}
	}

	void ItemUpdaterUbi::removeReadOnlyPartition(const std::string& versionId)
	{
	auto serviceFile = "obmc-flash-bios-ubiumount-ro@" + versionId + ".service";

	// Remove the read-only partitions.
	auto method = bus.new_method_call(SYSTEMD_BUSNAME, SYSTEMD_PATH,
	SYSTEMD_INTERFACE, "StartUnit");
	method.append(serviceFile, "replace");
	bus.call_noreply(method);
	}

	void ItemUpdaterUbi::removeReadWritePartition(const std::string& versionId)
	{
	auto serviceFile = "obmc-flash-bios-ubiumount-rw@" + versionId + ".service";

	// Remove the read-write partitions.
	auto method = bus.new_method_call(SYSTEMD_BUSNAME, SYSTEMD_PATH,
	SYSTEMD_INTERFACE, "StartUnit");
	method.append(serviceFile, "replace");
	bus.call_noreply(method);
	}

	void ItemUpdaterUbi::reset()
	{
	utils::hiomapdSuspend(bus);

	constexpr static auto patchDir = "/usr/local/share/pnor";
	if (fs::is_directory(patchDir))
	{
	for (const auto& iter : fs::directory_iterator(patchDir))
	{
	fs::remove_all(iter);
	}
	}

	// Clear the read-write partitions.
	for (const auto& it : activations)
	{
	auto rwDir = PNOR_RW_PREFIX + it.first;
	if (fs::is_directory(rwDir))
	{
	for (const auto& iter : fs::directory_iterator(rwDir))
	{
	fs::remove_all(iter);
	}
	}
	}

	// Clear the preserved partition.
	if (fs::is_directory(PNOR_PRSV))
	{
	for (const auto& iter : fs::directory_iterator(PNOR_PRSV))
	{
	fs::remove_all(iter);
	}
	}

	utils::hiomapdResume(bus);
	}

	bool ItemUpdaterUbi::isVersionFunctional(const std::string& versionId)
	{
	if (!fs::exists(PNOR_RO_ACTIVE_PATH))
	{
	return false;
	}

	fs::path activeRO = fs::read_symlink(PNOR_RO_ACTIVE_PATH);

	if (!fs::is_directory(activeRO))
	{
	return false;
	}

	if (activeRO.string().find(versionId) == std::string::npos)
	{
	return false;
	}

	// active PNOR is the version we're checking
	return true;
	}

	void ItemUpdaterUbi::freePriority(uint8_t value, const std::string& versionId)
	{
	// TODO openbmc/openbmc#1896 Improve the performance of this function
	for (const auto& intf : activations)
	{
	if (intf.second->redundancyPriority)
	{
	if (intf.second->redundancyPriority.get()->priority() == value &&
	intf.second->versionId != versionId)
	{
	intf.second->redundancyPriority.get()->priority(value + 1);
	}
	}
	}
	}

	bool ItemUpdaterUbi::erase(std::string entryId)
	{
	if (!ItemUpdater::erase(entryId))
	{
	return false;
	}

	// Remove priority persistence file
	removeFile(entryId);

	// Removing read-only and read-write partitions
	removeReadWritePartition(entryId);
	removeReadOnlyPartition(entryId);

	return true;
	}

	void ItemUpdaterUbi::deleteAll()
	{
	auto chassisOn = isChassisOn();

	for (const auto& activationIt : activations)
	{
	if (isVersionFunctional(activationIt.first) && chassisOn)
	{
	continue;
	}
	else
	{
	ItemUpdaterUbi::erase(activationIt.first);
	}
	}

	// Remove any remaining pnor-ro- or pnor-rw- volumes that do not match
	// the current version.
	auto method = bus.new_method_call(SYSTEMD_BUSNAME, SYSTEMD_PATH,
	SYSTEMD_INTERFACE, "StartUnit");
	method.append("obmc-flash-bios-cleanup.service", "replace");
	bus.call_noreply(method);
	}

	// TODO: openbmc/openbmc#1402 Monitor flash usage
	bool ItemUpdaterUbi::freeSpace()
	{
	bool isSpaceFreed = false;
	// Versions with the highest priority in front
	std::priority_queue<std::pair<int, std::string>,
	std::vector<std::pair<int, std::string>>,
	std::less<std::pair<int, std::string>>>
	versionsPQ;

	std::size_t count = 0;
	for (const auto& iter : activations)
	{
	if (iter.second.get()->activation() ==
	server::Activation::Activations::Active)
	{
	count++;
	// Don't put the functional version on the queue since we can't
	// remove the "running" PNOR version if it allows multiple PNORs
	// But removing functional version if there is only one PNOR.
	if (ACTIVE_PNOR_MAX_ALLOWED > 1 &&
	isVersionFunctional(iter.second->versionId))
	{
	continue;
	}
	versionsPQ.push(std::make_pair(
	iter.second->redundancyPriority.get()->priority(),
	iter.second->versionId));
	}
	}

	// If the number of PNOR versions is over ACTIVE_PNOR_MAX_ALLOWED -1,
	// remove the highest priority one(s).
	while ((count >= ACTIVE_PNOR_MAX_ALLOWED) && (!versionsPQ.empty()))
	{
	erase(versionsPQ.top().second);
	versionsPQ.pop();
	count--;
	isSpaceFreed = true;
	}
	return isSpaceFreed;
	}

	std::string ItemUpdaterUbi::determineId(const std::string& symlinkPath)
	{
	if (!fs::exists(symlinkPath))
	{
	return {};
	}

	auto target = fs::canonical(symlinkPath).string();

	// check to make sure the target really exists
	if (!fs::is_regular_file(target + "/" + PNOR_TOC_FILE))
	{
	return {};
	}
	// Get the image <id> from the symlink target
	// for example /media/ro-2a1022fe
	static const auto PNOR_RO_PREFIX_LEN = strlen(PNOR_RO_PREFIX);
	return target.substr(PNOR_RO_PREFIX_LEN);
	}

	void GardResetUbi::reset()
	{
	// The GARD partition is currently misspelled "GUARD." This file path will
	// need to be updated in the future.
	auto path = fs::path(PNOR_PRSV_ACTIVE_PATH);
	path /= "GUARD";

	utils::hiomapdSuspend(bus);

	if (fs::is_regular_file(path))
	{
	fs::remove(path);
	}

	utils::hiomapdResume(bus);
	}

	} // namespace updater
	} // namespace software
	} // namespace openpower