Android 设置存储修改

源码8.1

packages/apps/Settings/src/com/android/settings/deviceinfo/storage/StorageSummaryDonutPreferenceController.java

    /**
     * Updates the state of the donut preference for the next update using volume to summarize.
     * @param volume VolumeInfo to use to populate the informayion.
     */
    public void updateSizes(StorageVolumeProvider svp, VolumeInfo volume) {
        final long sharedDataSize = volume.getPath().getTotalSpace();
        long totalSize = svp.getPrimaryStorageSize();

        if (totalSize <= 0) {
            totalSize = sharedDataSize;
        }

        final long usedBytes = totalSize - volume.getPath().getFreeSpace();
        updateBytes(usedBytes, totalSize);
    }

svp.getPrimaryStorageSize() 等于获取/data的总大小 等于 fsstat.f_blocks * fsstat.f_frsize

    // StorageManager.java
    /** {@hide} */
    public long getPrimaryStorageSize() {
        return FileUtils.roundStorageSize(Environment.getDataDirectory().getTotalSpace());
    }

    public long getTotalSpace() {
        SecurityManager sm = System.getSecurityManager();
        if (sm != null) {
            sm.checkPermission(new RuntimePermission("getFileSystemAttributes"));
            sm.checkRead(path);
        }
        if (isInvalid()) {
            return 0L;
        }
        return fs.getSpace(this, FileSystem.SPACE_TOTAL);
    }

// libcore/ojluni/src/main/native/UnixFileSystem_md.c
// Android-changed: Name changed because of added thread policy check
JNIEXPORT jlong JNICALL
Java_java_io_UnixFileSystem_getSpace0(JNIEnv *env, jobject this,
                                      jobject file, jint t)
{   
    jlong rv = 0L;
    
    WITH_FIELD_PLATFORM_STRING(env, file, ids.path, path) {
        struct statvfs64 fsstat;
        memset(&fsstat, 0, sizeof(fsstat));
        if (statvfs64(path, &fsstat) == 0) {
            switch(t) {
            case java_io_FileSystem_SPACE_TOTAL:
                rv = jlong_mul(long_to_jlong(fsstat.f_frsize),
                               long_to_jlong(fsstat.f_blocks));
                break;
            case java_io_FileSystem_SPACE_FREE:
                rv = jlong_mul(long_to_jlong(fsstat.f_frsize),
                               long_to_jlong(fsstat.f_bfree));
                break;
            case java_io_FileSystem_SPACE_USABLE:
                rv = jlong_mul(long_to_jlong(fsstat.f_frsize),
                               long_to_jlong(fsstat.f_bavail));
                break;
            default:
                assert(0);
            }
        }
    } END_PLATFORM_STRING(env, path);
    return rv;
}

volume.getPath().getFreeSpace() 通过 dumpsys mount 也可以获取 path=/storage/emulated

# dumpsys mount
Disks:

Volumes:
  VolumeInfo{emulated}:
    type=EMULATED diskId=null partGuid=null mountFlags=PRIMARY|VISIBLE mountUserId=-1 state=MOUNTED
    fsType=null fsUuid=null fsLabel=null
    path=/storage/emulated internalPath=/data/media