How to use

fstat

method

in

libcore.io.Os

public StructStat fstat(FileDescriptor fd) throws ErrnoException { return os.fstat(fd); }
public StructStatVfs fstatvfs(FileDescriptor fd) throws ErrnoException { return os.fstatvfs(fd); }

/**
 * Returns the length of this file in bytes.
 *
 * @return the file's length in bytes.
 * @throws IOException
 *             if this file is closed or some other I/O error occurs.
 */
public long length() throws IOException {
  try {
    return Libcore.os.fstat(fd).st_size;
  } catch (ErrnoException errnoException) {
    throw errnoException.rethrowAsIOException();
  }
}

public long size() throws IOException {
  checkOpen();
  try {
    return Libcore.os.fstat(fd).st_size;
  } catch (ErrnoException errnoException) {
    throw errnoException.rethrowAsIOException();
  }
}

/**
 * Use this to mmap the whole file read-only.
 */
public static MemoryMappedFile mmapRO(String path) throws ErrnoException {
  FileDescriptor fd = Libcore.os.open(path, O_RDONLY, 0);
  long size = Libcore.os.fstat(fd).st_size;
  long address = Libcore.os.mmap(0L, size, PROT_READ, MAP_SHARED, fd, 0);
  Libcore.os.close(fd);
  return new MemoryMappedFile(address, size);
}

public FileReader(String absolutePath) throws IOException {
  // We use IoBridge.open because callers might differentiate
  // between a FileNotFoundException and a general IOException.
  //
  // NOTE: This costs us an additional call to fstat(2) to test whether
  // "absolutePath" is a directory or not. We can eliminate it
  // at the cost of copying some code from IoBridge.open.
  try {
    fd = IoBridge.open(absolutePath, O_RDONLY);
  } catch (FileNotFoundException fnfe) {
    throw fnfe;
  }
  int capacity;
  try {
    final StructStat stat = Libcore.os.fstat(fd);
    // Like RAF & other APIs, we assume that the file size fits
    // into a 32 bit integer.
    capacity = (int) stat.st_size;
    if (capacity == 0) {
      unknownLength = true;
      capacity = 8192;
    }
  } catch (ErrnoException exception) {
    closeQuietly(fd);
    throw exception.rethrowAsIOException();
  }
  bytes = new byte[capacity];
}

@Override public void close(FileDescriptor fd) throws ErrnoException {
  try {
    if (S_ISSOCK(Libcore.os.fstat(fd).st_mode)) {
      if (isLingerSocket(fd)) {
        // If the fd is a socket with SO_LINGER set, we might block indefinitely.
        // We allow non-linger sockets so that apps can close their network
        // connections in methods like onDestroy which will run on the UI thread.
        BlockGuard.getThreadPolicy().onNetwork();
      }
      untagSocket(fd);
    }
  } catch (ErrnoException ignored) {
    // We're called via Socket.close (which doesn't ask for us to be called), so we
    // must not throw here, because Socket.close must not throw if asked to close an
    // already-closed socket. Also, the passed-in FileDescriptor isn't necessarily
    // a socket at all.
  }
  os.close(fd);
}

if (S_ISDIR(Libcore.os.fstat(fd).st_mode)) {
  throw new ErrnoException("open", EISDIR);

if (S_ISREG(Libcore.os.fstat(fd).st_mode) || ftruncateException.errno != EINVAL) {
  throw ftruncateException.rethrowAsIOException();

public long size() throws IOException {
  checkOpen();
  try {
    return Libcore.os.fstat(fd).st_size;
  } catch (ErrnoException errnoException) {
    throw errnoException.rethrowAsIOException();
  }
}

public long size() throws IOException {
  checkOpen();
  try {
    return Libcore.os.fstat(fd).st_size;
  } catch (ErrnoException errnoException) {
    throw errnoException.rethrowAsIOException();
  }
}

public long size() throws IOException {
  checkOpen();
  try {
    return Libcore.os.fstat(fd).st_size;
  } catch (ErrnoException errnoException) {
    throw errnoException.rethrowAsIOException();
  }
}

public long size() throws IOException {
  checkOpen();
  try {
    return Libcore.os.fstat(fd).st_size;
  } catch (ErrnoException errnoException) {
    throw errnoException.rethrowAsIOException();
  }
}

public long size() throws IOException {
  checkOpen();
  try {
    return Libcore.os.fstat(fd).st_size;
  } catch (ErrnoException errnoException) {
    throw errnoException.rethrowAsIOException();
  }
}

public long size() throws IOException {
  checkOpen();
  try {
    return Libcore.os.fstat(fd).st_size;
  } catch (ErrnoException errnoException) {
    throw errnoException.rethrowAsIOException();
  }
}

/**
 * Use this to mmap the whole file read-only.
 */
public static MemoryMappedFile mmapRO(String path) throws ErrnoException {
  FileDescriptor fd = Libcore.os.open(path, O_RDONLY, 0);
  long size = Libcore.os.fstat(fd).st_size;
  long address = Libcore.os.mmap(0L, size, PROT_READ, MAP_SHARED, fd, 0);
  Libcore.os.close(fd);
  return new MemoryMappedFile(address, size);
}

/**
 * Use this to mmap the whole file read-only.
 */
public static MemoryMappedFile mmapRO(String path) throws ErrnoException {
  FileDescriptor fd = Libcore.os.open(path, O_RDONLY, 0);
  long size = Libcore.os.fstat(fd).st_size;
  long address = Libcore.os.mmap(0L, size, PROT_READ, MAP_SHARED, fd, 0);
  Libcore.os.close(fd);
  return new MemoryMappedFile(address, size);
}

/**
 * Use this to mmap the whole file read-only.
 */
public static MemoryMappedFile mmapRO(String path) throws ErrnoException {
  FileDescriptor fd = Libcore.os.open(path, O_RDONLY, 0);
  long size = Libcore.os.fstat(fd).st_size;
  long address = Libcore.os.mmap(0L, size, PROT_READ, MAP_SHARED, fd, 0);
  Libcore.os.close(fd);
  return new MemoryMappedFile(address, size);
}

/**
 * Use this to mmap the whole file read-only.
 */
public static MemoryMappedFile mmapRO(String path) throws ErrnoException {
  FileDescriptor fd = Libcore.os.open(path, O_RDONLY, 0);
  long size = Libcore.os.fstat(fd).st_size;
  long address = Libcore.os.mmap(0L, size, PROT_READ, MAP_SHARED, fd, 0);
  Libcore.os.close(fd);
  return new MemoryMappedFile(address, size);
}

/**
 * Use this to mmap the whole file read-only.
 */
public static MemoryMappedFile mmapRO(String path) throws ErrnoException {
  FileDescriptor fd = Libcore.os.open(path, O_RDONLY, 0);
  long size = Libcore.os.fstat(fd).st_size;
  long address = Libcore.os.mmap(0L, size, PROT_READ, MAP_SHARED, fd, 0);
  Libcore.os.close(fd);
  return new MemoryMappedFile(address, size);
}

/**
 * Use this to mmap the whole file read-only.
 */
public static MemoryMappedFile mmapRO(String path) throws ErrnoException {
  FileDescriptor fd = Libcore.os.open(path, O_RDONLY, 0);
  long size = Libcore.os.fstat(fd).st_size;
  long address = Libcore.os.mmap(0L, size, PROT_READ, MAP_SHARED, fd, 0);
  Libcore.os.close(fd);
  return new MemoryMappedFile(address, size);
}