sysutil.py #1

'mpptg module initializer and generic utilities'
__revision__ = '$Id: //depot/devuser/jsmith/tcdev_1.5.X/lib/mpptg/__init__.py#6 $'
__metaclass__ = type

import os
import sys
import re
import marshal
import cPickle


class PlatformError(Exception):
    'Used to indicate an unsupported platform'
    def __init__(self, platform):
        Exception.__init__(self, platform)
        self.platform = platform
        
    def __str__(self):
        return 'unsupported: ' + self.platform

class CommandError(Exception):
    'Base class for command runtime exceptions'

class SerializeError(CommandError):
    'Used to indicate serialization errors '
    def __init__(self, cmd):
        CommandError.__init__(self, cmd)
        self.cmd = cmd

    def __str__(self):
        return 'bad serialization when running: ' + self.cmd
        
class StderrError(CommandError):
    'Used to indicate error output from a command'
    def __init__(self, cmd, errlines, output):
        CommandError.__init__(self, cmd, errlines, output)
        self.cmd = cmd
        self.errlines = errlines
        self.output = output

    def __str__(self):
        return 'error output when running: ' + self.cmd + '\n' + ''.join(self.errlines)


def expandvars(instr, varblock):
    'string expandvars(string input, dictionary varlist)'
    if sys.platform == 'win32':
        var = re.compile(r'%(\w+)%')
        instr = var.sub(r'${\1}', instr)
    keeper = os.environ
    os.environ = varblock
    outstr = os.path.expandvars(instr)
    os.environ = keeper
    return outstr


def syscmd(cmd, inputlines=False, mode='t', running=False,
           serialize=False, prereaderr=False, serialver=0):
    'Run a system command'
    serializers = {'marshal': marshal, 'pickle': cPickle}
    
    # Marshalling requires binary streams and running must be turned off
    if serialize:
        mode = 'b'
        running = False
        serializer = serializers[serialize]

    # Get the current value of the Python buffering environment so it can be
    #   restored.  Set Python to unbuffered if running output was requested.
    pythonbuffering = os.environ.get('PYTHONUNBUFFERED')
    if running:
        os.environ['PYTHONUNBUFFERED'] = '1'

    (stdin, stdout, stderr) = os.popen3(cmd, mode)
    
    # Restore the Python buffering to the previous value         
    if pythonbuffering:
        os.environ['PYTHONUNBUFFERED'] = pythonbuffering

    if inputlines:
        if serialize:
            serializer.dump(inputlines, stdin, serialver)
        else:
            stdin.writelines(inputlines)
    stdin.close()

    errlines = list()
    if prereaderr:
        errlines = stderr.readlines()

    outlines = list()
    if running:
        while 1:
            line = stdout.readline()
            if not line:
                break
            sys.stdout.write(line)
            outlines.append(line)
    elif serialize:
        while 1:
            try:
                item = serializer.load(stdout)
                outlines.append(item)
            except EOFError:
                break
            except ValueError:
                stdout.close()
                stderr.close()
                raise SerializeError(cmd)
    else:
        outlines = stdout.readlines()
    stdout.close()
    
    errlines += stderr.readlines()
    stderr.close()
    
    if errlines:
        raise StderrError(cmd, errlines, outlines)

    return outlines