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#!/usr/bin/env python
# Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
#
# Use of this source code is governed by a BSD-style license
# that can be found in the LICENSE file in the root of the source
# tree. An additional intellectual property rights grant can be found
# in the file PATENTS. All contributing project authors may
# be found in the AUTHORS file in the root of the source tree.
import os
import subprocess
import sys
_DEFAULT_PADDING = 4
class HelperError(Exception):
"""Exception raised for errors in the helper."""
pass
def zero_pad(number, padding=_DEFAULT_PADDING):
"""Converts an int into a zero padded string.
Args:
number(int): The number to convert.
padding(int): The number of chars in the output. Note that if you pass for
example number=23456 and padding=4, the output will still be '23456',
i.e. it will not be cropped. If you pass number=2 and padding=4, the
return value will be '0002'.
Return:
(string): The zero padded number converted to string.
"""
return str(number).zfill(padding)
def run_shell_command(cmd_list, fail_msg=None):
"""Executes a command.
Args:
cmd_list(list): Command list to execute.
fail_msg(string): Message describing the error in case the command fails.
Return:
(string): The standard output from running the command.
Raise:
HelperError: If command fails.
"""
process = subprocess.Popen(cmd_list, stdout=subprocess.PIPE,
stderr=subprocess.PIPE)
output, error = process.communicate()
if process.returncode != 0:
if fail_msg:
print >> sys.stderr, fail_msg
raise HelperError('Failed to run %s: command returned %d and printed '
'%s and %s' % (' '.join(cmd_list), process.returncode,
output, error))
return output.strip()
def perform_action_on_all_files(directory, file_pattern, file_extension,
start_number, action, **kwargs):
"""Function that performs a given action on all files matching a pattern.
It is assumed that the files are named file_patternxxxx.file_extension, where
xxxx are digits. The file names start from
file_patern0..start_number>.file_extension.
Args:
directory(string): The directory where the files live.
file_pattern(string): The name pattern of the files.
file_extension(string): The files' extension.
start_number(int): From where to start to count frames.
action(function): The action to be performed over the files. Must return
False if the action failed, True otherwise.
Return:
(bool): Whether performing the action over all files was successful or not.
"""
file_prefix = os.path.join(directory, file_pattern)
file_exists = True
file_number = start_number
errors = False
while file_exists:
zero_padded_file_number = zero_pad(file_number)
file_name = file_prefix + zero_padded_file_number + '.' + file_extension
if os.path.isfile(file_name):
if not action(file_name=file_name, **kwargs):
errors = True
break
file_number += 1
else:
file_exists = False
return not errors
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