/usr/lib/python3/dist-packages/bmaptools/TransRead.py is in bmap-tools 3.4-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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# vim: ts=4 sw=4 et ai si
#
# Copyright (c) 2012-2014 Intel, Inc.
# License: GPLv2
# Author: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License, version 2,
# as published by the Free Software Foundation.
#
# This program is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
# General Public License for more details.
"""
This module allows opening and reading local and remote files and decompress
them on-the-fly if needed. Remote files are read using urllib2 (except of
"ssh://" URLs, which are handled differently). Supported file extentions are:
'bz2', 'gz', 'xz', 'lzo' and a "tar" version of them: 'tar.bz2', 'tbz2', 'tbz',
'tb2', 'tar.gz', 'tgz', 'tar.xz', 'txz', 'tar.lzo', 'tzo', 'tar.lz4', 'tlz4'.
This module uses the following system programs for decompressing: pbzip2, bzip2,
gzip, pigz, xz, lzop, lz4, tar and unzip.
"""
import os
import errno
import sys
if sys.version[0] == '2':
import urlparse
else:
import urllib.parse as urlparse
import logging
import threading
import subprocess
from bmaptools import BmapHelpers
_log = logging.getLogger(__name__) # pylint: disable=C0103
# Disable the following pylint errors and recommendations:
# * Instance of X has no member Y (E1101), because it produces
# false-positives for many of 'subprocess' class members, e.g.
# "Instance of 'Popen' has no 'wait' member".
# * Too many instance attributes (R0902)
# * Too many branches (R0912)
# * Too many local variables (R0914)
# * Too many statements (R0915)
# pylint: disable=E1101
# pylint: disable=R0902
# pylint: disable=R0912
# pylint: disable=R0914
# pylint: disable=R0915
# A list of supported compression types
SUPPORTED_COMPRESSION_TYPES = ('bz2', 'gz', 'xz', 'lzo', 'lz4', 'tar.gz',
'tar.bz2', 'tar.xz', 'tar.lzo', 'tar.lz4',
'zip')
def _fake_seek_forward(file_obj, cur_pos, offset, whence=os.SEEK_SET):
"""
This function implements the 'seek()' method for file object 'file_obj'.
Only seeking forward and is allowed, and 'whence' may be either
'os.SEEK_SET' or 'os.SEEK_CUR'.
"""
if whence == os.SEEK_SET:
new_pos = offset
elif whence == os.SEEK_CUR:
new_pos = cur_pos + offset
else:
raise Error("'seek()' method requires the 'whence' argument "
"to be %d or %d, but %d was passed"
% (os.SEEK_SET, os.SEEK_CUR, whence))
if new_pos < cur_pos:
raise Error("''seek()' method supports only seeking forward, "
"seeking from %d to %d is not allowed"
% (cur_pos, new_pos))
length = new_pos - cur_pos
to_read = length
while to_read > 0:
chunk_size = min(to_read, 1024 * 1024)
buf = file_obj.read(chunk_size)
if not buf:
break
to_read -= len(buf)
if to_read < 0:
raise Error("seeked too far: %d instead of %d"
% (new_pos - to_read, new_pos))
return new_pos - to_read
class Error(Exception):
"""
A class for exceptions generated by this module. We currently support only
one type of exceptions, and we basically throw human-readable problem
description in case of errors.
"""
pass
def _decode_sshpass_exit_code(code):
"""
A helper function which converts "sshpass" command-line tool's exit code
into a human-readable string. See "man sshpass".
"""
if code == 1:
result = "invalid command line argument"
elif code == 2:
result = "conflicting arguments given"
elif code == 3:
result = "general run-time error"
elif code == 4:
result = "unrecognized response from ssh (parse error)"
elif code == 5:
result = "invalid/incorrect password"
elif code == 6:
result = "host public key is unknown. sshpass exits without " \
"confirming the new key"
elif code == 255:
# SSH result =s 255 on any error
result = "ssh error"
else:
result = "unknown"
return result
class TransRead(object):
"""
This class implement the transparent reading functionality. Instances of
this class are file-like objects which you can read and seek only forward.
"""
def __init__(self, filepath):
"""
Class constructor. The 'filepath' argument is the full path to the file
to read transparently.
"""
self.name = filepath
# Size of the file (in uncompressed form), may be 'None' if the size is
# unknown
self.size = None
# Type of the compression of the file
self.compression_type = 'none'
# Whether the 'bz2file' PyPI module was found
self.bz2file_found = False
# Whether the file is behind an URL
self.is_url = False
# List of child processes we forked
self._child_processes = []
# The reader thread
self._rthread = None
# This variable becomes 'True' when the instance of this class is not
# usable any longer.
self._done = False
# There may be a chain of open files, and we save the intermediate file
# objects in the 'self._f_objs' list. The final file object is stored
# in th elast element of the list.
#
# For example, when the path is an URL to a bz2 file, the chain of
# opened file will be:
# o self._f_objs[0] is the liburl2 file-like object
# o self._f_objs[1] is the stdout of the 'bzip2' process
self._f_objs = []
self._force_fake_seek = False
self._pos = 0
try:
self._f_objs.append(open(self.name, "rb"))
except IOError as err:
if err.errno == errno.ENOENT:
# This is probably an URL
self._open_url(filepath)
else:
raise Error("cannot open file '%s': %s" % (filepath, err))
self._open_compressed_file()
def __del__(self):
"""The class destructor which closes opened files."""
self._done = True
for child in self._child_processes:
child.kill()
if self._rthread:
self._rthread.join()
for file_obj in self._f_objs:
file_obj.close()
def _read_thread(self, f_from, f_to):
"""
This function is used when reading compressed files. It runs in a
spearate thread, reads data from the 'f_from' file-like object, and
writes them to the 'f_to' file-like object. 'F_from' may be a urllib2
object, while 'f_to' is usually stdin of the decompressor process.
"""
chunk_size = 1024 * 1024
while not self._done:
buf = f_from.read(chunk_size)
if not buf:
break
f_to.write(buf)
# This will make sure the process decompressor gets EOF and exits, as
# well as ublocks processes waiting on decompressor's stdin.
f_to.close()
def _open_compressed_file(self):
"""
Detect file compression type and open it with the corresponding
compression module, or just plain 'open() if the file is not
compressed.
"""
def is_gzip(name):
"""Returns 'True' if file 'name' is compressed with 'gzip'."""
if name.endswith('.gzip') or \
(name.endswith('.gz') and not name.endswith('.tar.gz')):
return True
return False
def is_bzip2(name):
"""Returns 'True' if file 'name' is compressed with 'bzip2'."""
if name.endswith('.bz2') and not name.endswith('.tar.bz2'):
return True
return False
def is_xz(name):
"""Returns 'True' if file 'name' is compressed with 'xz'."""
if name.endswith('.xz') and not name.endswith('.tar.xz'):
return True
return False
def is_lzop(name):
"""Returns 'True' if file 'name' is compressed with 'lzop'."""
if name.endswith('.lzo') and not name.endswith('.tar.lzo'):
return True
return False
def is_lz4(name):
"""Returns 'True' if file 'name' is compressed with 'lz4'."""
if name.endswith('.lz4') and not name.endswith('.tar.lz4'):
return True
return False
def is_tar_gz(name):
"""
Returns 'True' if file 'name' is a tar archive compressed with
'gzip'.
"""
if name.endswith('.tar.gz') or name.endswith('.tgz'):
return True
return False
def is_tar_bz2(name):
"""
Returns 'True' if file 'name' is a tar archive compressed with
'bzip2'.
"""
if name.endswith('.tar.bz2') or name.endswith('.tbz') or \
name.endswith('.tbz2') or name.endswith('.tb2'):
return True
return False
def is_tar_xz(name):
"""
Returns 'True' if file 'name' is a tar archive compressed with 'xz'.
"""
if name.endswith('.tar.xz') or name.endswith('.txz'):
return True
return False
def is_tar_lzo(name):
"""
Returns 'True' if file 'name' is a tar archive compressed with
'lzop'.
"""
if name.endswith('.tar.lzo') or name.endswith('.tzo'):
return True
return False
def is_tar_lz4(name):
"""
Returns 'True' if file 'name' is a tar archive compressed with
'lz4'.
"""
if name.endswith('.tar.lz4') or name.endswith('.tlz4'):
return True
return False
archiver = None
if is_tar_gz(self.name) or is_gzip(self.name):
self.compression_type = 'gzip'
if BmapHelpers.program_is_available("pigz"):
decompressor = "pigz"
else:
decompressor = "gzip"
if is_gzip(self.name):
args = "-d -c"
else:
archiver = "tar"
args = "-x -z -O"
elif is_tar_bz2(self.name) or is_bzip2(self.name):
self.compression_type = 'bzip2'
if BmapHelpers.program_is_available("pbzip2"):
decompressor = "pbzip2"
else:
decompressor = "bzip2"
if is_bzip2(self.name):
args = "-d -c"
else:
archiver = "tar"
args = "-x -j -O"
elif is_tar_xz(self.name) or is_xz(self.name):
self.compression_type = 'xz'
decompressor = "xz"
if is_xz(self.name):
args = "-d -c"
else:
archiver = "tar"
args = "-x -J -O"
elif is_tar_lzo(self.name) or is_lzop(self.name):
self.compression_type = 'lzo'
decompressor = "lzop"
if is_lzop(self.name):
args = "-d -c"
else:
archiver = "tar"
args = "-x --lzo -O"
elif self.name.endswith(".zip"):
self.compression_type = 'zip'
decompressor = "funzip"
args = ""
elif is_tar_lz4(self.name) or is_lz4(self.name):
self.compression_type = 'lz4'
decompressor = "lz4"
if is_lz4(self.name):
args = "-d -c"
else:
archiver = "tar"
args = "-x -Ilz4 -O"
else:
if not self.is_url:
self.size = os.fstat(self._f_objs[-1].fileno()).st_size
return
# Make sure decompressor and the archiver programs are available
if not BmapHelpers.program_is_available(decompressor):
raise Error("the \"%s\" program is not available but it is "
"required decompressing \"%s\""
% (decompressor, self.name))
if archiver and not BmapHelpers.program_is_available(archiver):
raise Error("the \"%s\" program is not available but it is "
"required reading \"%s\"" % (archiver, self.name))
# Start the decompressor process. We'll send the data to its stdin and
# read the decompressed data from its stdout.
if archiver:
args = archiver + " " + args
else:
args = decompressor + " " + args
if hasattr(self._f_objs[-1], 'fileno'):
child_stdin = self._f_objs[-1].fileno()
else:
child_stdin = subprocess.PIPE
child_process = subprocess.Popen(args, shell=True,
bufsize=1024 * 1024,
stdin=child_stdin,
stdout=subprocess.PIPE,
stderr=subprocess.PIPE)
if child_stdin == subprocess.PIPE:
args = (self._f_objs[-1], child_process.stdin, )
self._rthread = threading.Thread(target=self._read_thread, args=args)
self._rthread.daemon = True
self._rthread.start()
self._force_fake_seek = True
self._f_objs.append(child_process.stdout)
self._child_processes.append(child_process)
def _open_url_ssh(self, parsed_url):
"""
This function opens a file on a remote host using SSH. The URL has to
have this format: "ssh://username@hostname:path". Currently we only
support password-based authentication.
"""
username = parsed_url.username
password = parsed_url.password
path = parsed_url.path
hostname = parsed_url.hostname
if username:
hostname = username + "@" + hostname
# Make sure the ssh client program is installed
if not BmapHelpers.program_is_available("ssh"):
raise Error("the \"ssh\" program is not available but it is "
"required for downloading over the ssh protocol")
# Prepare the commands that we are going to run
if password:
# In case of password we have to use the sshpass tool to pass the
# password to the ssh client utility
popen_args = ["sshpass",
"-p" + password,
"ssh",
"-o StrictHostKeyChecking=no",
"-o PubkeyAuthentication=no",
"-o PasswordAuthentication=yes",
hostname]
# Make sure the sshpass program is installed
if not BmapHelpers.program_is_available("ssh"):
raise Error("the \"sshpass\" program is not available but it "
"is required for password-based SSH authentication")
else:
popen_args = ["ssh",
"-o StrictHostKeyChecking=no",
"-o PubkeyAuthentication=yes",
"-o PasswordAuthentication=no",
"-o BatchMode=yes",
hostname]
# Test if we can successfully connect
child_process = subprocess.Popen(popen_args + ["true"])
child_process.wait()
retcode = child_process.returncode
if retcode != 0:
decoded = _decode_sshpass_exit_code(retcode)
raise Error("cannot connect to \"%s\": %s (error code %d)"
% (hostname, decoded, retcode))
# Test if file exists by running "test -f path && test -r path" on the
# host
command = "test -f " + path + " && test -r " + path
child_process = subprocess.Popen(popen_args + [command],
bufsize=1024 * 1024,
stdout=subprocess.PIPE)
child_process.wait()
if child_process.returncode != 0:
raise Error("\"%s\" on \"%s\" cannot be read: make sure it "
"exists, is a regular file, and you have read "
"permissions" % (path, hostname))
# Read the entire file using 'cat'
child_process = subprocess.Popen(popen_args + ["cat " + path],
stdout=subprocess.PIPE)
# Now the contents of the file should be available from sub-processes
# stdout
self._f_objs.append(child_process.stdout)
self._child_processes.append(child_process)
self.is_url = True
self._force_fake_seek = True
def _open_url(self, url):
"""
Open an URL 'url' and return the file-like object of the opened URL.
"""
def _print_warning(timeout):
"""
This is a small helper function for printing a warning if we cannot
open the URL for some time.
"""
_log.warning("failed to open the URL with %d sec timeout, is the "
"proxy configured correctly? Keep trying ..." %
timeout)
import socket
if sys.version[0] == '2':
import httplib
import urllib2
else:
import http.client as httplib
import urllib.request as urllib2
parsed_url = urlparse.urlparse(url)
if parsed_url.scheme == "ssh":
# Unfortunately, liburl2 does not handle "ssh://" URLs
self._open_url_ssh(parsed_url)
return
username = parsed_url.username
password = parsed_url.password
if username and password:
# Unfortunately, in order to handle URLs which contain user name
# and password (e.g., http://user:password@my.site.org), we need to
# do few extra things.
new_url = list(parsed_url)
if parsed_url.port:
new_url[1] = "%s:%s" % (parsed_url.hostname, parsed_url.port)
else:
new_url[1] = parsed_url.hostname
url = urlparse.urlunparse(new_url)
# Build an URL opener which will do the authentication
password_manager = urllib2.HTTPPasswordMgrWithDefaultRealm()
password_manager.add_password(None, url, username, password)
auth_handler = urllib2.HTTPBasicAuthHandler(password_manager)
opener = urllib2.build_opener(auth_handler)
else:
opener = urllib2.build_opener()
opener.addheaders = [('User-Agent', 'Mozilla/5.0')]
urllib2.install_opener(opener)
# Open the URL. First try with a short timeout, and print a message
# which should supposedly give the a clue that something may be going
# wrong.
# The overall purpose of this is to improve user experience. For
# example, if one tries to open a file but did not setup the proxy
# environment variables propely, there will be a very long delay before
# the failure message. And it is much nicer to pre-warn the user early
# about something possibly being wrong.
for timeout in (10, None):
try:
f_obj = opener.open(url, timeout=timeout)
# Handling the timeout case in Python 2.7
except socket.timeout as err:
if timeout is not None:
_print_warning(timeout)
else:
raise Error("cannot open URL '%s': %s" % (url, err))
except urllib2.URLError as err:
# Handling the timeout case in Python 2.6
if timeout is not None and \
isinstance(err.reason, socket.timeout):
_print_warning(timeout)
else:
raise Error("cannot open URL '%s': %s" % (url, err))
except (IOError, ValueError, httplib.InvalidURL) as err:
raise Error("cannot open URL '%s': %s" % (url, err))
except httplib.BadStatusLine:
raise Error("cannot open URL '%s': server responds with an "
"HTTP status code that we don't understand" % url)
self.is_url = True
self._f_objs.append(f_obj)
def read(self, size=-1):
"""
Read the data from the file or URL and and uncompress it on-the-fly if
necessary.
"""
if size < 0:
size = 0xFFFFFFFFFFFFFFFF
buf = self._f_objs[-1].read(size)
self._pos += len(buf)
return buf
def seek(self, offset, whence=os.SEEK_SET):
"""The 'seek()' method, similar to the one file objects have."""
if self._force_fake_seek or not hasattr(self._f_objs[-1], "seek"):
self._pos = _fake_seek_forward(self._f_objs[-1], self._pos,
offset, whence)
else:
self._f_objs[-1].seek(offset, whence)
def tell(self):
"""The 'tell()' method, similar to the one file objects have."""
if self._force_fake_seek or not hasattr(self._f_objs[-1], "tell"):
return self._pos
else:
return self._f_objs[-1].tell()
def close(self):
"""Close the file-like object."""
self.__del__()
def __getattr__(self, name):
"""
If we are backed by a local uncompressed file, then fall-back to using
its operations.
"""
if self.compression_type == 'none' and not self.is_url:
return getattr(self._f_objs[-1], name)
else:
raise AttributeError
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