michael@0: # Copyright (c) 2012 The Chromium Authors. All rights reserved.
michael@0: # Use of this source code is governed by a BSD-style license that can be
michael@0: # found in the LICENSE file.
michael@0: 
michael@0: """A wrapper for subprocess to make calling shell commands easier."""
michael@0: 
michael@0: 
michael@0: import logging
michael@0: import subprocess
michael@0: 
michael@0: 
michael@0: def RunCmd(args, cwd=None):
michael@0:   """Opens a subprocess to execute a program and returns its return value.
michael@0: 
michael@0:   Args:
michael@0:     args: A string or a sequence of program arguments. The program to execute is
michael@0:       the string or the first item in the args sequence.
michael@0:     cwd: If not None, the subprocess's current directory will be changed to
michael@0:       |cwd| before it's executed.
michael@0: 
michael@0:   Returns:
michael@0:     Return code from the command execution.
michael@0:   """
michael@0:   logging.info(str(args) + ' ' + (cwd or ''))
michael@0:   p = subprocess.Popen(args=args, cwd=cwd)
michael@0:   return p.wait()
michael@0: 
michael@0: 
michael@0: def GetCmdOutput(args, cwd=None, shell=False):
michael@0:   """Open a subprocess to execute a program and returns its output.
michael@0: 
michael@0:   Args:
michael@0:     args: A string or a sequence of program arguments. The program to execute is
michael@0:       the string or the first item in the args sequence.
michael@0:     cwd: If not None, the subprocess's current directory will be changed to
michael@0:       |cwd| before it's executed.
michael@0:     shell: Whether to execute args as a shell command.
michael@0: 
michael@0:   Returns:
michael@0:     Captures and returns the command's stdout.
michael@0:     Prints the command's stderr to logger (which defaults to stdout).
michael@0:   """
michael@0:   logging.info(str(args) + ' ' + (cwd or ''))
michael@0:   p = subprocess.Popen(args=args, cwd=cwd, stdout=subprocess.PIPE,
michael@0:                        stderr=subprocess.PIPE, shell=shell)
michael@0:   stdout, stderr = p.communicate()
michael@0:   if stderr:
michael@0:     logging.critical(stderr)
michael@0:   logging.info(stdout[:4096])  # Truncate output longer than 4k.
michael@0:   return stdout