/
utils.py
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/
utils.py
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# vim: tabstop=4 shiftwidth=4 softtabstop=4
# Copyright 2010 United States Government as represented by the
# Administrator of the National Aeronautics and Space Administration.
# All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.
"""
System-level utilities and helper functions.
"""
import datetime
import errno
import logging
import os
import platform
import subprocess
import sys
import uuid
import iso8601
from glance.common import exception
logger = logging.getLogger(__name__)
TIME_FORMAT = "%Y-%m-%dT%H:%M:%S"
def chunkreadable(iter, chunk_size=65536):
"""
Wrap a readable iterator with a reader yielding chunks of
a preferred size, otherwise leave iterator unchanged.
:param iter: an iter which may also be readable
:param chunk_size: maximum size of chunk
"""
return chunkiter(iter, chunk_size) if hasattr(iter, 'read') else iter
def chunkiter(fp, chunk_size=65536):
"""
Return an iterator to a file-like obj which yields fixed size chunks
:param fp: a file-like object
:param chunk_size: maximum size of chunk
"""
while True:
chunk = fp.read(chunk_size)
if chunk:
yield chunk
else:
break
def image_meta_to_http_headers(image_meta):
"""
Returns a set of image metadata into a dict
of HTTP headers that can be fed to either a Webob
Request object or an httplib.HTTP(S)Connection object
:param image_meta: Mapping of image metadata
"""
headers = {}
for k, v in image_meta.items():
if v is not None:
if k == 'properties':
for pk, pv in v.items():
if pv is not None:
headers["x-image-meta-property-%s"
% pk.lower()] = unicode(pv)
else:
headers["x-image-meta-%s" % k.lower()] = unicode(v)
return headers
def add_features_to_http_headers(features, headers):
"""
Adds additional headers representing glance features to be enabled.
:param headers: Base set of headers
:param features: Map of enabled features
"""
if features:
for k, v in features.items():
if v is not None:
headers[k.lower()] = unicode(v)
def get_image_meta_from_headers(response):
"""
Processes HTTP headers from a supplied response that
match the x-image-meta and x-image-meta-property and
returns a mapping of image metadata and properties
:param response: Response to process
"""
result = {}
properties = {}
if hasattr(response, 'getheaders'): # httplib.HTTPResponse
headers = response.getheaders()
else: # webob.Response
headers = response.headers.items()
for key, value in headers:
key = str(key.lower())
if key.startswith('x-image-meta-property-'):
field_name = key[len('x-image-meta-property-'):].replace('-', '_')
properties[field_name] = value or None
elif key.startswith('x-image-meta-'):
field_name = key[len('x-image-meta-'):].replace('-', '_')
result[field_name] = value or None
result['properties'] = properties
if 'size' in result:
try:
result['size'] = int(result['size'])
except ValueError:
raise exception.Invalid
for key in ('is_public', 'deleted', 'protected'):
if key in result:
result[key] = bool_from_header_value(result[key])
return result
def bool_from_header_value(value):
"""
Returns True if value is a boolean True or the
string 'true', case-insensitive, False otherwise
"""
if isinstance(value, bool):
return value
elif isinstance(value, (basestring, unicode)):
if str(value).lower() == 'true':
return True
return False
def bool_from_string(subject):
"""
Interpret a string as a boolean.
Any string value in:
('True', 'true', 'On', 'on', '1')
is interpreted as a boolean True.
Useful for JSON-decoded stuff and config file parsing
"""
if isinstance(subject, bool):
return subject
elif isinstance(subject, int):
return subject == 1
if hasattr(subject, 'startswith'): # str or unicode...
if subject.strip().lower() in ('true', 'on', '1'):
return True
return False
def import_class(import_str):
"""Returns a class from a string including module and class"""
mod_str, _sep, class_str = import_str.rpartition('.')
try:
__import__(mod_str)
return getattr(sys.modules[mod_str], class_str)
except (ImportError, ValueError, AttributeError), e:
raise exception.ImportFailure(import_str=import_str,
reason=e)
def import_object(import_str):
"""Returns an object including a module or module and class"""
try:
__import__(import_str)
return sys.modules[import_str]
except ImportError:
cls = import_class(import_str)
return cls()
def generate_uuid():
return str(uuid.uuid4())
def is_uuid_like(value):
try:
uuid.UUID(value)
return True
except Exception:
return False
def isotime(at=None):
"""Stringify time in ISO 8601 format"""
if not at:
at = datetime.datetime.utcnow()
str = at.strftime(TIME_FORMAT)
tz = at.tzinfo.tzname(None) if at.tzinfo else 'UTC'
str += ('Z' if tz == 'UTC' else tz)
return str
def parse_isotime(timestr):
"""Parse time from ISO 8601 format"""
try:
return iso8601.parse_date(timestr)
except iso8601.ParseError as e:
raise ValueError(e.message)
except TypeError as e:
raise ValueError(e.message)
def normalize_time(timestamp):
"""Normalize time in arbitrary timezone to UTC"""
offset = timestamp.utcoffset()
return timestamp.replace(tzinfo=None) - offset if offset else timestamp
def safe_mkdirs(path):
try:
os.makedirs(path)
except OSError, e:
if e.errno != errno.EEXIST:
raise
def safe_remove(path):
try:
os.remove(path)
except OSError, e:
if e.errno != errno.ENOENT:
raise
class PrettyTable(object):
"""Creates an ASCII art table for use in bin/glance
Example:
ID Name Size Hits
--- ----------------- ------------ -----
122 image 22 0
"""
def __init__(self):
self.columns = []
def add_column(self, width, label="", just='l'):
"""Add a column to the table
:param width: number of characters wide the column should be
:param label: column heading
:param just: justification for the column, 'l' for left,
'r' for right
"""
self.columns.append((width, label, just))
def make_header(self):
label_parts = []
break_parts = []
for width, label, _ in self.columns:
# NOTE(sirp): headers are always left justified
label_part = self._clip_and_justify(label, width, 'l')
label_parts.append(label_part)
break_part = '-' * width
break_parts.append(break_part)
label_line = ' '.join(label_parts)
break_line = ' '.join(break_parts)
return '\n'.join([label_line, break_line])
def make_row(self, *args):
row = args
row_parts = []
for data, (width, _, just) in zip(row, self.columns):
row_part = self._clip_and_justify(data, width, just)
row_parts.append(row_part)
row_line = ' '.join(row_parts)
return row_line
@staticmethod
def _clip_and_justify(data, width, just):
# clip field to column width
clipped_data = str(data)[:width]
if just == 'r':
# right justify
justified = clipped_data.rjust(width)
else:
# left justify
justified = clipped_data.ljust(width)
return justified
def get_terminal_size():
def _get_terminal_size_posix():
import fcntl
import struct
import termios
height_width = None
try:
height_width = struct.unpack('hh', fcntl.ioctl(sys.stderr.fileno(),
termios.TIOCGWINSZ,
struct.pack('HH', 0, 0)))
except:
pass
if not height_width:
try:
p = subprocess.Popen(['stty', 'size'],
shell=False,
stdout=subprocess.PIPE)
result = p.communicate()
if p.returncode == 0:
return tuple(int(x) for x in result[0].split())
except:
pass
return height_width
def _get_terminal_size_win32():
try:
from ctypes import windll, create_string_buffer
handle = windll.kernel32.GetStdHandle(-12)
csbi = create_string_buffer(22)
res = windll.kernel32.GetConsoleScreenBufferInfo(handle, csbi)
except:
return None
if res:
import struct
unpack_tmp = struct.unpack("hhhhHhhhhhh", csbi.raw)
(bufx, bufy, curx, cury, wattr,
left, top, right, bottom, maxx, maxy) = unpack_tmp
height = bottom - top + 1
width = right - left + 1
return (height, width)
else:
return None
def _get_terminal_size_unknownOS():
raise NotImplementedError
func = {'posix': _get_terminal_size_posix,
'win32': _get_terminal_size_win32}
height_width = func.get(platform.os.name, _get_terminal_size_unknownOS)()
if height_width == None:
raise exception.Invalid()
for i in height_width:
if not isinstance(i, int) or i <= 0:
raise exception.Invalid()
return height_width[0], height_width[1]