path: root/shellutils.py

"""shell/term utilities, useful to write some python scripts instead of shell
scripts.

:author:    Logilab
:copyright: 2000-2008 LOGILAB S.A. (Paris, FRANCE), all rights reserved.
:contact: http://www.logilab.fr/ -- mailto:contact@logilab.fr
:license: General Public License version 2 - http://www.gnu.org/licenses
"""
__docformat__ = "restructuredtext en"

import os
import glob
import shutil
import stat
import sys
import tempfile
import time
import fnmatch
import errno
from os.path import exists, isdir, islink, basename, join, walk

from logilab.common import STD_BLACKLIST
from logilab.common.proc import ProcInfo, NoSuchProcess


def chown(path, login=None, group=None):
    """Same as `os.chown` function but accepting user login or group name as
    argument. If login or group is omitted, it's left unchanged.

    Note: you must own the file to chown it (or be root). Otherwise OSError is raised. 
    """
    if login is None:
        uid = -1
    else:
        try:
            uid = int(login)
        except ValueError:
            import pwd
            uid = pwd.getpwnam(login).pw_uid
    if group is None:
        gid = -1
    else:
        try:
            gid = int(group)
        except ValueError:
            import grp
            gid = grp.getgrname(group).gr_gid
    os.chown(path, uid, gid)
        

def mv(source, destination, _action=shutil.move):
    """A shell-like mv, supporting wildcards.
    """
    sources = glob.glob(source)
    if len(sources) > 1:
        assert isdir(destination)
        for filename in sources:
            _action(filename, join(destination, basename(filename)))
    else:
        try:
            source = sources[0]
        except IndexError:
            raise OSError('No file matching %s' % source)
        if isdir(destination) and exists(destination):
            destination = join(destination, basename(source))
        try:
            _action(source, destination)
        except OSError, ex:
            raise OSError('Unable to move %r to %r (%s)' % (
                source, destination, ex))
        
def rm(*files):
    """A shell-like rm, supporting wildcards.
    """
    for wfile in files:
        for filename in glob.glob(wfile):
            if islink(filename):
                os.remove(filename)
            elif isdir(filename):
                shutil.rmtree(filename)
            else:
                os.remove(filename)
    
def cp(source, destination):
    """A shell-like cp, supporting wildcards.
    """
    mv(source, destination, _action=shutil.copy)


def find(directory, exts, exclude=False, blacklist=STD_BLACKLIST):
    """Recursivly find files ending with the given extensions from the directory.

    :type directory: str
    :param directory:
      directory where the search should start

    :type exts: basestring or list or tuple
    :param exts:
      extensions or lists or extensions to search

    :type exclude: boolean
    :param exts:
      if this argument is True, returning files NOT ending with the given
      extensions

    :type blacklist: list or tuple
    :param blacklist:
      optional list of files or directory to ignore, default to the value of
      `logilab.common.STD_BLACKLIST`

    :rtype: list
    :return:
      the list of all matching files
    """
    if isinstance(exts, basestring):
        exts = (exts,)
    if exclude:
        def match(filename, exts):
            for ext in exts:
                if filename.endswith(ext):
                    return False
            return True
    else:
        def match(filename, exts):
            for ext in exts:
                if filename.endswith(ext):
                    return True
            return False
    def func(files, directory, fnames):
        """walk handler"""
        # remove files/directories in the black list
        for norecurs in blacklist:
            try:
                fnames.remove(norecurs)
            except ValueError:
                continue
        for filename in fnames:
            src = join(directory, filename)
            if isdir(src):
                continue
            if match(filename, exts):
                files.append(src)
    files = []
    walk(directory, func, files)
    return files


def globfind(directory, pattern, blacklist=STD_BLACKLIST):
    """Recursively finds files matching glob `pattern` under `directory`.

    This is an alternative to `logilab.common.shellutils.find`.
    
    :type directory: str
    :param directory:
      directory where the search should start

    :type pattern: basestring
    :param pattern:
      the glob pattern (e.g *.py, foo*.py, etc.)

    :type blacklist: list or tuple
    :param blacklist:
      optional list of files or directory to ignore, default to the value of
      `logilab.common.STD_BLACKLIST`

    :rtype: iterator
    :return:
      iterator over the list of all matching files
    """
    for curdir, dirnames, filenames in os.walk(directory):
        for fname in fnmatch.filter(filenames, pattern):
            yield join(curdir, fname)
        for skipped in blacklist:
            if skipped in dirnames:
                dirnames.remove(skipped)

def unzip(archive, destdir):
    import zipfile
    if not exists(destdir):
        os.mkdir(destdir)
    zfobj = zipfile.ZipFile(archive)
    for name in zfobj.namelist():
        if name.endswith('/'):
            os.mkdir(join(destdir, name))
        else:
            outfile = open(join(destdir, name), 'wb')
            outfile.write(zfobj.read(name))
            outfile.close()

class Execute:
    """This is a deadlock safe version of popen2 (no stdin), that returns
    an object with errorlevel, out and err.
    """
    
    def __init__(self, command):
        outfile = tempfile.mktemp()
        errfile = tempfile.mktemp()
        self.status = os.system("( %s ) >%s 2>%s" %
                                (command, outfile, errfile)) >> 8
        self.out = open(outfile,"r").read()
        self.err = open(errfile,"r").read()
        os.remove(outfile)
        os.remove(errfile)

def acquire_lock(lock_file, max_try=10, delay=10, max_delay=3600):
    """Acquire a lock represented by a file on the file system

    If the process written in lock file doesn't exist anymore, we remove the
    lock file immediately
    If age of the lock_file is greater than max_delay, then we raise a UserWarning
    """
    count = abs(max_try)
    while count:
        try:
            fd = os.open(lock_file, os.O_EXCL | os.O_RDWR | os.O_CREAT)
            os.write(fd, str(os.getpid()))
            os.close(fd)
            return True
        except OSError, e:
            if e.errno == errno.EEXIST:
                try:
                    fd = open(lock_file, "r")
                    pid = int(fd.readline())
                    pi = ProcInfo(pid)
                    age = (time.time() - os.stat(lock_file)[stat.ST_MTIME])
                    if age / max_delay > 1 :
                        raise UserWarning("Command '%s' (pid %s) has locked the "
                                          "file '%s' for %s minutes"
                                          % (pi.name(), pid, lock_file, age/60))
                except UserWarning:
                    raise
                except NoSuchProcess:
                    os.remove(lock_file)
                except Exception:
                    # The try block is not essential. can be skipped.
                    # Note: ProcInfo object is only available for linux
                    # process information are not accessible...
                    # or lock_file is no more present...
                    pass
            else:
                raise
            count -= 1
            time.sleep(delay)
    else:
        raise Exception('Unable to acquire %s' % lock_file)

def release_lock(lock_file):
    """Release a lock represented by a file on the file system."""
    os.remove(lock_file)


class ProgressBar(object):
    """A simple text progression bar."""
    
    def __init__(self, nbops, size=20, stream=sys.stdout):
        self._fstr = '\r[%%-%ss]' % int(size)
        self._stream = stream
        self._total = nbops
        self._size = size
        self._current = 0
        self._progress = 0

    def update(self):
        """Update the progression bar."""
        self._current += 1
        progress = int((float(self._current)/float(self._total))*self._size)
        if progress > self._progress:
            self._progress = progress
            self.refresh()

    def refresh(self):
        """Refresh the progression bar display."""
        self._stream.write(self._fstr % ('.' * min(self._progress, self._size)) )
        self._stream.flush()