1#!/usr/bin/env python
2# Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
3#
4# Use of this source code is governed by a BSD-style license
5# that can be found in the LICENSE file in the root of the source
6# tree. An additional intellectual property rights grant can be found
7# in the file PATENTS.  All contributing project authors may
8# be found in the AUTHORS file in the root of the source tree.
9
10import os
11import subprocess
12import sys
13
14_DEFAULT_PADDING = 4
15
16
17class HelperError(Exception):
18  """Exception raised for errors in the helper."""
19  pass
20
21
22def zero_pad(number, padding=_DEFAULT_PADDING):
23  """Converts an int into a zero padded string.
24
25  Args:
26    number(int): The number to convert.
27    padding(int): The number of chars in the output. Note that if you pass for
28      example number=23456 and padding=4, the output will still be '23456',
29      i.e. it will not be cropped. If you pass number=2 and padding=4, the
30      return value will be '0002'.
31  Return:
32    (string): The zero padded number converted to string.
33  """
34  return str(number).zfill(padding)
35
36
37def run_shell_command(cmd_list, fail_msg=None):
38  """Executes a command.
39
40  Args:
41    cmd_list(list): Command list to execute.
42    fail_msg(string): Message describing the error in case the command fails.
43
44  Return:
45    (string): The standard output from running the command.
46
47  Raise:
48    HelperError: If command fails.
49  """
50  process = subprocess.Popen(cmd_list, stdout=subprocess.PIPE,
51                             stderr=subprocess.PIPE)
52  output, error = process.communicate()
53  if process.returncode != 0:
54    if fail_msg:
55      print >> sys.stderr, fail_msg
56    raise HelperError('Failed to run %s: command returned %d and printed '
57                      '%s and %s' % (' '.join(cmd_list), process.returncode,
58                                     output, error))
59  return output.strip()
60
61
62def perform_action_on_all_files(directory, file_pattern, file_extension,
63                                start_number, action, **kwargs):
64  """Function that performs a given action on all files matching a pattern.
65
66  It is assumed that the files are named file_patternxxxx.file_extension, where
67  xxxx are digits. The file names start from
68  file_patern0..start_number>.file_extension.
69
70  Args:
71    directory(string): The directory where the files live.
72    file_pattern(string): The name pattern of the files.
73    file_extension(string): The files' extension.
74    start_number(int): From where to start to count frames.
75    action(function): The action to be performed over the files. Must return
76      False if the action failed, True otherwise.
77
78  Return:
79    (bool): Whether performing the action over all files was successful or not.
80  """
81  file_prefix = os.path.join(directory, file_pattern)
82  file_exists = True
83  file_number = start_number
84  errors = False
85
86  while file_exists:
87    zero_padded_file_number = zero_pad(file_number)
88    file_name = file_prefix + zero_padded_file_number + '.' + file_extension
89    if os.path.isfile(file_name):
90      if not action(file_name=file_name, **kwargs):
91        errors = True
92        break
93      file_number += 1
94    else:
95      file_exists = False
96  return not errors
97