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// Copyright 2018 The Chromium OS Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
// DiskQuota - manages the kernel's quota-related operations.
#include <cstdint>
#include <memory>
#include <string>
#include <base/macros.h>
#include "cryptohome/homedirs.h"
#include "cryptohome/platform.h"
namespace cryptohome {
// This is the constant that is usually fed to the |home| parameter in
// ArcDiskQuota's constructor.
constexpr char kArcDiskHome[] = "/home";
// This class handles quota-related query from ARC++, and only designed to be
// called from within the container. The main reason is that IsQuotaSupported
// only makes sense from within the container since it counts the number of
// mounted android-data and only makes sense when the current user's
// android-data is mounted (which depends strictly on the container startup
// sequence: android-data is explicitly mounted before this function is called
// in installd, which is defined in init).
// This class only caches the device file that contains the home directory,
// since the device file won't change throughout Cryptohome lifetime. On the
// other hand, IsQuotaSupported is not cached here (please see the comments in
// IsQuotaSupported for the more detailed explanation).
class ArcDiskQuota {
// Parameters
// homedirs - The mockable Cryptohome homedirs
// platform - The mockable Cryptohome platform
// home - The path to the home directory, e.g., /home
ArcDiskQuota(HomeDirs* homedirs,
Platform* platform,
const base::FilePath& home);
ArcDiskQuota(const ArcDiskQuota&) = delete;
ArcDiskQuota& operator=(const ArcDiskQuota&) = delete;
virtual ~ArcDiskQuota();
// Initializing by looking for the right quota mounted device that hosts
// Android's /data. Not thread-safe.
virtual void Initialize();
// Whether or not cryptohome supports quota-based stats. This function returns
// true when all the following conditions are true:
// 1. There is a /dev file mounted as /home
// 2. The dev file above is mounted with quota option enabled
// 3. There is exactly 1 android-data mounted.
// Before multiple Android user is supported, make sure to call this
// function (once) from Android container (i.e., during installd
// initialization) before asking for curspace. Moreover, this function
// shouldn't be called too often since it iterates through filesystem and
// might potentially be expensive.
// Caching note: This function is intentionally not cached in cryptohome, but
// should be cached in installd instead, since cryptohome lifetime is
// different from container's (and the android-data directory). However,
// caching this during installd's initialization might produce false negative
// during installd's lifetime. For example in the case when cryptohome
// concurrently cleans up old users due to low storage event - which might
// reduce the number of android-data from more than 1 to 1. However, this case
// should be rare and even if that happens, installd still works correctly
// using non-quota path.
// On the other hand, false positive is not desired (since triggering quota
// path on multiple user will gave undesired result). Fortunately, caching
// this function in installd won't result to false positive because installd
// is restarted after everytime android-data is mounted as /data - and hence,
// there won't be a case where new android-data is mounted in the middle of
// installd lifetime.
virtual bool IsQuotaSupported() const;
// Get the current disk space usage for an android uid (a shifted uid).
// Returns -1 if quotactl fails.
virtual int64_t GetCurrentSpaceForUid(uid_t android_uid) const;
// Get the current disk space usage for an android gid (a shifted gid).
// Returns -1 if quotactl fails.
virtual int64_t GetCurrentSpaceForGid(gid_t android_gid) const;
// Get the current disk space usage for a project ID.
// Returns -1 if quotactl fails.
virtual int64_t GetCurrentSpaceForProjectId(int project_id) const;
// The constants below describes the ranges of valid ID to query (based on
// what is tracked by installd).These numbers are from
// system/core/libcutils/include/private/android_filesystem_config.h in
// Android codebase.
// The smallest UID in Android that is tracked by installd. This is set to be
// the minimum possible uid that Android process can have.
static constexpr uid_t kAndroidUidStart = 0;
// The largest UID in Android that is tracked by installd. This is from
// AID_APP_END in android_filesystem_config.h.
static constexpr uid_t kAndroidUidEnd = 19999;
// The following section describes the GID that are tracked by installd.
// Installd tracks different kinds of GID types: Cache, External, Shared, and
// other Android processes GID that are smaller than Cache GID. The smallest
// amongst them is 0 and the largest is Shared hence the covered range is
// between 0 and AID_SHARED_GID_END (inclusive).
// The smallest GID in Android that is tracked by installd. This is set to be
// the minimum possible gid that Android process can have.
static constexpr gid_t kAndroidGidStart = 0;
// The largest GID in Android that is tracked by installd. This is from
// AID_SHARED_GID_END in android_filesystem_config.h.
static constexpr gid_t kAndroidGidEnd = 59999;
// Helper function to parse dev file that contains Android's /data.
base::FilePath GetDevice();
HomeDirs* homedirs_;
Platform* platform_;
const base::FilePath home_;
base::FilePath device_;
friend class ArcDiskQuotaTest;
} // namespace cryptohome