1# Copyright (c) 2013 The Chromium OS Authors. All rights reserved.
2# Use of this source code is governed by a BSD-style license that can be
3# found in the LICENSE file.
4
5from autotest_lib.client.common_lib import error
6
7
8def get_datetime_float(host):
9    """
10    Returns host's system time in seconds since epoch.
11
12    @param host: an Autotest host object.
13    @returns a float, timestamp since epoch in <seconds>.<nanoseconds>.
14
15    @raises TestError: if error reading datetime or converting its value
16                       from string to float.
17    """
18    r = host.run('date +%s.%N')
19    if r.exit_status > 0:
20        err = ('Error reading datetime from capturer (%r): %r' %
21               (r.exit_status, r.stderr))
22        raise error.TestError(err)
23    try:
24        return float(r.stdout)
25    except ValueError as e:
26        raise error.TestError('Error converting datetime string: %r', e)
27