#
#
# Licensed to the Apache Software Foundation (ASF) under one
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# to you under the Apache License, Version 2.0 (the
# "License"); you may not use this file except in compliance
# with the License.  You may obtain a copy of the License at
#
#   http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing,
# software distributed under the License is distributed on an
# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
# KIND, either express or implied.  See the License for the
# specific language governing permissions and limitations
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#
#
# executable.py -- Utilities for dealing with external executables
#

import os
import subprocess

def exists(file):
  """Is this an executable file?"""
  return os.path.isfile(file) and os.access(file, os.X_OK)

def find(file, dirs=None):
  """Search for an executable in a given list of directories.
     If no directories are given, search according to the PATH
     environment variable."""
  if not dirs:
    dirs = os.environ["PATH"].split(os.pathsep)
  for path in dirs:
    if is_executable(os.path.join(path, file)):
      return os.path.join(path, file)
    elif is_executable(os.path.join(path, "%s.exe" % file)):
      return os.path.join(path, "%s.exe" % file)
  return None

def output(cmd, strip=None):
  """Run a command and collect all output"""
  # Check that cmd is in PATH (otherwise we'd get a generic OSError later)
  import distutils.spawn
  if isinstance(cmd, str):
    cmdname = cmd
  elif isinstance(cmd, list):
    cmdname = cmd[0]
  if distutils.spawn.find_executable(cmdname) is None:
    return None

  # Run it
  (output, empty_stderr) = subprocess.Popen(cmd, stdout=subprocess.PIPE, \
                             stderr=subprocess.STDOUT).communicate()
  if strip:
    return output.strip()
  else:
    return output

def run(cmd):
  """Run a command"""
  exit_code = os.system(cmd)
  assert(not exit_code)