path: root/bitbake/lib/bb/pysh/interp.py

# interp.py - shell interpreter for pysh.
#
# Copyright 2007 Patrick Mezard
#
# This software may be used and distributed according to the terms
# of the GNU General Public License, incorporated herein by reference.

"""Implement the shell interpreter.

Most references are made to "The Open Group Base Specifications Issue 6".
<http://www.opengroup.org/onlinepubs/009695399/utilities/xcu_chap02.html>
"""
# TODO: document the fact input streams must implement fileno() so Popen will work correctly.
# it requires non-stdin stream to be implemented as files. Still to be tested...
# DOC: pathsep is used in PATH instead of ':'. Clearly, there are path syntax issues here.
# TODO: stop command execution upon error.
# TODO: sort out the filename/io_number mess. It should be possible to use filenames only.
# TODO: review subshell implementation
# TODO: test environment cloning for non-special builtins
# TODO: set -x should not rebuild commands from tokens, assignments/redirections are lost
# TODO: unit test for variable assignment
# TODO: test error management wrt error type/utility type
# TODO: test for binary output everywhere
# BUG: debug-parsing does not pass log file to PLY. Maybe a PLY upgrade is necessary.
import base64
import cPickle as pickle
import errno
import glob
import os
import re
import subprocess
import sys
import tempfile

try:
    s = set()
    del s
except NameError:
    from Set import Set as set

import builtin
from sherrors import *
import pyshlex
import pyshyacc

def mappend(func, *args, **kargs):
    """Like map but assume func returns a list. Returned lists are merged into
    a single one.
    """
    return reduce(lambda a,b: a+b, map(func, *args, **kargs), [])

class FileWrapper:
    """File object wrapper to ease debugging.
    
    Allow mode checking and implement file duplication through a simple 
    reference counting scheme. Not sure the latter is really useful since
    only real file descriptors can be used.
    """
    def __init__(self, mode, file, close=True):
        if mode not in ('r', 'w', 'a'):
            raise IOError('invalid mode: %s' % mode)
        self._mode = mode
        self._close = close
        if isinstance(file, FileWrapper):
            if file._refcount[0] <= 0:
                raise IOError(0, 'Error')
            self._refcount = file._refcount
            self._refcount[0] += 1
            self._file = file._file
        else:
            self._refcount = [1]
            self._file = file
        
    def dup(self):
        return FileWrapper(self._mode, self, self._close)
        
    def fileno(self):
        """fileno() should be only necessary for input streams."""
        return self._file.fileno()
        
    def read(self, size=-1):
        if self._mode!='r':
            raise IOError(0, 'Error')
        return self._file.read(size)
        
    def readlines(self, *args, **kwargs):
        return self._file.readlines(*args, **kwargs)
        
    def write(self, s):
        if self._mode not in ('w', 'a'):
            raise IOError(0, 'Error')
        return self._file.write(s)
        
    def flush(self):
        self._file.flush()
        
    def close(self):        
        if not self._refcount:
            return
        assert  self._refcount[0] > 0
        
        self._refcount[0] -= 1    
        if self._refcount[0] == 0:
            self._mode = 'c'
            if self._close:
                self._file.close()
        self._refcount = None
                
    def mode(self):
        return self._mode

    def __getattr__(self, name):
        if name == 'name':
            self.name = getattr(self._file, name)
            return self.name
        else:
            raise AttributeError(name)

    def __del__(self):
        self.close()
               
               
def win32_open_devnull(mode):
    return open('NUL', mode)
    
        
class Redirections:
    """Stores open files and their mapping to pseudo-sh file descriptor.
    """
    # BUG: redirections are not handled correctly: 1>&3 2>&3 3&g