dvc/dvc/executor.py

import sys
import subprocess

from dvc.exceptions import DvcException


class ExecutorError(DvcException):
    def __init__(self, msg):
        DvcException.__init__(self, msg)


class Executor:
    @staticmethod
    def exec_cmd(cmd, stdout_file=None, stderr_file=None, cwd=None):
        stdout, stdout_fd = Executor.output_file(stdout_file)
        stderr, stderr_fd = Executor.output_file(stderr_file)

        try:
            p = subprocess.Popen(cmd,
                                 cwd=cwd,
                                 stdout=stdout,
                                 stderr=stderr)
            out, err = map(lambda s: s.decode().strip('\n\r') if s else '', p.communicate())

            return p.returncode, out, err
        except Exception as ex:
            return 1, None, str(ex)
        finally:
            if stderr_fd:
                stderr_fd.close()
            if stdout_fd:
                stdout_fd.close()
        pass

    @staticmethod
    def output_file(output_file, default_output=None):
        output_fd = None
        if output_file is not None:
            if output_file == '-':
                output = default_output
            else:
                output_fd = open(output_file, 'w')
                output = output_fd
        else:
            output = subprocess.PIPE
        return output, output_fd

    @staticmethod
    def exec_cmd_only_success(cmd, stdout_file=None, stderr_file=None, cwd=None):
        code, out, err = Executor.exec_cmd(cmd, stdout_file=stdout_file, stderr_file=stderr_file, cwd=cwd)
        if code != 0:
            raise Executor._build_executor_error(cmd, err)
        return out

    @staticmethod
    def _build_executor_error(cmd, out):
        return ExecutorError('Git command error ({}):\n{}'.format(' '.join(cmd), out))