Utils.py

## Amazon S3 manager
## Author: Michal Ludvig <michal@logix.cz>
##         http://www.logix.cz/michal
## License: GPL Version 2
## Copyright: TGRMN Software and contributors

import datetime
import os
import sys
import time
import re
import string
import random
import rfc822
import errno
import urllib
from calendar import timegm
from logging import debug, info, warning, error
from ExitCodes import EX_OSFILE
try:
    import dateutil.parser
except ImportError:
    sys.stderr.write(u"""
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
ImportError trying to import dateutil.parser.
Please install the python dateutil module:
$ sudo apt-get install python-dateutil
  or
$ sudo yum install python-dateutil
  or
$ pip install python-dateutil
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
""")
    sys.stderr.flush()
    sys.exit(EX_OSFILE)

import Config
import Exceptions

# hashlib backported to python 2.4 / 2.5 is not compatible with hmac!
if sys.version_info[0] == 2 and sys.version_info[1] < 6:
    from md5 import md5
    import sha as sha1
else:
    from hashlib import md5, sha1

try:
    import xml.etree.ElementTree as ET
except ImportError:
    # xml.etree.ElementTree was only added in python 2.5
    import elementtree.ElementTree as ET

__all__ = []
def parseNodes(nodes):
    ## WARNING: Ignores text nodes from mixed xml/text.
    ## For instance <tag1>some text<tag2>other text</tag2></tag1>
    ## will be ignore "some text" node
    retval = []
    for node in nodes:
        retval_item = {}
        for child in node.getchildren():
            name = child.tag
            if child.getchildren():
                retval_item[name] = parseNodes([child])
            else:
                retval_item[name] = node.findtext(".//%s" % child.tag)
        retval.append(retval_item)
    return retval
__all__.append("parseNodes")

def stripNameSpace(xml):
    """
    removeNameSpace(xml) -- remove top-level AWS namespace
    """
    r = re.compile('^(<?[^>]+?>\s*)(<\w+) xmlns=[\'"](http://[^\'"]+)[\'"](.*)', re.MULTILINE)
    if r.match(xml):
        xmlns = r.match(xml).groups()[2]
        xml = r.sub("\\1\\2\\4", xml)
    else:
        xmlns = None
    return xml, xmlns
__all__.append("stripNameSpace")

def getTreeFromXml(xml):
    xml, xmlns = stripNameSpace(xml)
    try:
        tree = ET.fromstring(xml)
        if xmlns:
            tree.attrib['xmlns'] = xmlns
        return tree
    except Exception, e:
        error("Error parsing xml: %s", e)
        error(xml)
        raise

__all__.append("getTreeFromXml")

def getListFromXml(xml, node):
    tree = getTreeFromXml(xml)
    nodes = tree.findall('.//%s' % (node))
    return parseNodes(nodes)
__all__.append("getListFromXml")

def getDictFromTree(tree):
    ret_dict = {}
    for child in tree.getchildren():
        if child.getchildren():
            ## Complex-type child. Recurse
            content = getDictFromTree(child)
        else:
            content = child.text
        if ret_dict.has_key(child.tag):
            if not type(ret_dict[child.tag]) == list:
                ret_dict[child.tag] = [ret_dict[child.tag]]
            ret_dict[child.tag].append(content or "")
        else:
            ret_dict[child.tag] = content or ""
    return ret_dict
__all__.append("getDictFromTree")

def getTextFromXml(xml, xpath):
    tree = getTreeFromXml(xml)
    if tree.tag.endswith(xpath):
        return tree.text
    else:
        return tree.findtext(xpath)
__all__.append("getTextFromXml")

def getRootTagName(xml):
    tree = getTreeFromXml(xml)
    return tree.tag
__all__.append("getRootTagName")

def xmlTextNode(tag_name, text):
    el = ET.Element(tag_name)
    el.text = unicode(text)
    return el
__all__.append("xmlTextNode")

def appendXmlTextNode(tag_name, text, parent):
    """
    Creates a new <tag_name> Node and sets
    its content to 'text'. Then appends the
    created Node to 'parent' element if given.
    Returns the newly created Node.
    """
    el = xmlTextNode(tag_name, text)
    parent.append(el)
    return el
__all__.append("appendXmlTextNode")

def dateS3toPython(date):
    # Reset milliseconds to 000
    date = re.compile('\.[0-9]*(?:[Z\\-\\+]*?)').sub(".000", date)
    return dateutil.parser.parse(date, fuzzy=True)
__all__.append("dateS3toPython")

def dateS3toUnix(date):
    ## NOTE: This is timezone-aware and return the timestamp regarding GMT
    return timegm(dateS3toPython(date).utctimetuple())
__all__.append("dateS3toUnix")

def dateRFC822toPython(date):
    return dateutil.parser.parse(date, fuzzy=True)
__all__.append("dateRFC822toPython")

def dateRFC822toUnix(date):
    return timegm(dateRFC822toPython(date).utctimetuple())
__all__.append("dateRFC822toUnix")

def formatSize(size, human_readable = False, floating_point = False):
    size = floating_point and float(size) or int(size)
    if human_readable:
        coeffs = ['k', 'M', 'G', 'T']
        coeff = ""
        while size > 2048:
            size /= 1024
            coeff = coeffs.pop(0)
        return (size, coeff)
    else:
        return (size, "")
__all__.append("formatSize")

def formatDateTime(s3timestamp):
    date_obj = dateutil.parser.parse(s3timestamp, fuzzy=True)
    return date_obj.strftime("%Y-%m-%d %H:%M")
__all__.append("formatDateTime")

def convertTupleListToDict(list):
    retval = {}
    for tuple in list:
        retval[tuple[0]] = tuple[1]
    return retval
__all__.append("convertTupleListToDict")

_rnd_chars = string.ascii_letters+string.digits
_rnd_chars_len = len(_rnd_chars)
def rndstr(len):
    retval = ""
    while len > 0:
        retval += _rnd_chars[random.randint(0, _rnd_chars_len-1)]
        len -= 1
    return retval
__all__.append("rndstr")

def mktmpsomething(prefix, randchars, createfunc):
    old_umask = os.umask(0077)
    tries = 5
    while tries > 0:
        dirname = prefix + rndstr(randchars)
        try:
            createfunc(dirname)
            break
        except OSError, e:
            if e.errno != errno.EEXIST:
                os.umask(old_umask)
                raise
        tries -= 1

    os.umask(old_umask)
    return dirname
__all__.append("mktmpsomething")

def mktmpdir(prefix = os.getenv('TMP','/tmp') + "/tmpdir-", randchars = 10):
    return mktmpsomething(prefix, randchars, os.mkdir)
__all__.append("mktmpdir")

def mktmpfile(prefix = os.getenv('TMP','/tmp') + "/tmpfile-", randchars = 20):
    createfunc = lambda filename : os.close(os.open(filename, os.O_CREAT | os.O_EXCL))
    return mktmpsomething(prefix, randchars, createfunc)
__all__.append("mktmpfile")

def hash_file_md5(filename):
    h = md5()
    f = open(filename, "rb")
    while True:
        # Hash 32kB chunks
        data = f.read(32*1024)
        if not data:
            break
        h.update(data)
    f.close()
    return h.hexdigest()
__all__.append("hash_file_md5")

def mkdir_with_parents(dir_name):
    """
    mkdir_with_parents(dst_dir)

    Create directory 'dir_name' with all parent directories

    Returns True on success, False otherwise.
    """
    pathmembers = dir_name.split(os.sep)
    tmp_stack = []
    while pathmembers and not os.path.isdir(os.sep.join(pathmembers)):
        tmp_stack.append(pathmembers.pop())
    while tmp_stack:
        pathmembers.append(tmp_stack.pop())
        cur_dir = os.sep.join(pathmembers)
        try:
            debug("mkdir(%s)" % cur_dir)
            os.mkdir(cur_dir)
        except (OSError, IOError), e:
            warning("%s: can not make directory: %s" % (cur_dir, e.strerror))
            return False
        except Exception, e:
            warning("%s: %s" % (cur_dir, e))
            return False
    return True
__all__.append("mkdir_with_parents")

def unicodise(string, encoding = None, errors = "replace"):
    """
    Convert 'string' to Unicode or raise an exception.
    """

    if not encoding:
        encoding = Config.Config().encoding

    if type(string) == unicode:
        return string
    debug("Unicodising %r using %s" % (string, encoding))
    try:
        return string.decode(encoding, errors)
    except UnicodeDecodeError:
        raise UnicodeDecodeError("Conversion to unicode failed: %r" % string)
__all__.append("unicodise")

def deunicodise(string, encoding = None, errors = "replace"):
    """
    Convert unicode 'string' to <type str>, by default replacing
    all invalid characters with '?' or raise an exception.
    """

    if not encoding:
        encoding = Config.Config().encoding

    if type(string) != unicode:
        return str(string)
    debug("DeUnicodising %r using %s" % (string, encoding))
    try:
        return string.encode(encoding, errors)
    except UnicodeEncodeError:
        raise UnicodeEncodeError("Conversion from unicode failed: %r" % string)
__all__.append("deunicodise")

def unicodise_safe(string, encoding = None):
    """
    Convert 'string' to Unicode according to current encoding
    and replace all invalid characters with '?'
    """

    return unicodise(deunicodise(string, encoding), encoding).replace(u'\ufffd', '?')
__all__.append("unicodise_safe")

def replace_nonprintables(string):
    """
    replace_nonprintables(string)

    Replaces all non-printable characters 'ch' in 'string'
    where ord(ch) <= 26 with ^@, ^A, ... ^Z
    """
    new_string = ""
    modified = 0
    for c in string:
        o = ord(c)
        if (o <= 31):
            new_string += "^" + chr(ord('@') + o)
            modified += 1
        elif (o == 127):
            new_string += "^?"
            modified += 1
        else:
            new_string += c
    if modified and Config.Config().urlencoding_mode != "fixbucket":
        warning("%d non-printable characters replaced in: %s" % (modified, new_string))
    return new_string
__all__.append("replace_nonprintables")

def time_to_epoch(t):
    """Convert time specified in a variety of forms into UNIX epoch time.
    Accepts datetime.datetime, int, anything that has a strftime() method, and standard time 9-tuples
    """
    if isinstance(t, int):
        # Already an int
        return t
    elif isinstance(t, tuple) or isinstance(t, time.struct_time):
        # Assume it's a time 9-tuple
        return int(time.mktime(t))
    elif hasattr(t, 'timetuple'):
        # Looks like a datetime object or compatible
        return int(time.mktime(t.timetuple()))
    elif hasattr(t, 'strftime'):
        # Looks like the object supports standard srftime()
        return int(t.strftime('%s'))
    elif isinstance(t, str) or isinstance(t, unicode):
        # See if it's a string representation of an epoch
        try:
            # Support relative times (eg. "+60")
            if t.startswith('+'):
                return time.time() + int(t[1:])
            return int(t)
        except ValueError:
            # Try to parse it as a timestamp string
            try:
                return time.strptime(t)
            except ValueError, ex:
                # Will fall through
                debug("Failed to parse date with strptime: %s", ex)
                pass
    raise Exceptions.ParameterError('Unable to convert %r to an epoch time. Pass an epoch time. Try `date -d \'now + 1 year\' +%%s` (shell) or time.mktime (Python).' % t)


def check_bucket_name(bucket, dns_strict = True):
    if dns_strict:
        invalid = re.search("([^a-z0-9\.-])", bucket)
        if invalid:
            raise Exceptions.ParameterError("Bucket name '%s' contains disallowed character '%s'. The only supported ones are: lowercase us-ascii letters (a-z), digits (0-9), dot (.) and hyphen (-)." % (bucket, invalid.groups()[0]))
    else:
        invalid = re.search("([^A-Za-z0-9\._-])", bucket)
        if invalid:
            raise Exceptions.ParameterError("Bucket name '%s' contains disallowed character '%s'. The only supported ones are: us-ascii letters (a-z, A-Z), digits (0-9), dot (.), hyphen (-) and underscore (_)." % (bucket, invalid.groups()[0]))

    if len(bucket) < 3:
        raise Exceptions.ParameterError("Bucket name '%s' is too short (min 3 characters)" % bucket)
    if len(bucket) > 255:
        raise Exceptions.ParameterError("Bucket name '%s' is too long (max 255 characters)" % bucket)
    if dns_strict:
        if len(bucket) > 63:
            raise Exceptions.ParameterError("Bucket name '%s' is too long (max 63 characters)" % bucket)
        if re.search("-\.", bucket):
            raise Exceptions.ParameterError("Bucket name '%s' must not contain sequence '-.' for DNS compatibility" % bucket)
        if re.search("\.\.", bucket):
            raise Exceptions.ParameterError("Bucket name '%s' must not contain sequence '..' for DNS compatibility" % bucket)
        if not re.search("^[0-9a-z]", bucket):
            raise Exceptions.ParameterError("Bucket name '%s' must start with a letter or a digit" % bucket)
        if not re.search("[0-9a-z]$", bucket):
            raise Exceptions.ParameterError("Bucket name '%s' must end with a letter or a digit" % bucket)
    return True
__all__.append("check_bucket_name")

def check_bucket_name_dns_conformity(bucket):
    try:
        return check_bucket_name(bucket, dns_strict = True)
    except Exceptions.ParameterError:
        return False
__all__.append("check_bucket_name_dns_conformity")

def check_bucket_name_dns_support(bucket_host, bucket_name):
    """
    Check whether either the host_bucket support buckets and
    either bucket name is dns compatible
    """
    if "%(bucket)s" not in bucket_host:
        return False

    try:
        return check_bucket_name(bucket_name, dns_strict = True)
    except Exceptions.ParameterError:
        return False
__all__.append("check_bucket_name_dns_support")

def getBucketFromHostname(hostname):
    """
    bucket, success = getBucketFromHostname(hostname)

    Only works for hostnames derived from bucket names
    using Config.host_bucket pattern.

    Returns bucket name and a boolean success flag.
    """

    # Create RE pattern from Config.host_bucket
    pattern = Config.Config().host_bucket % { 'bucket' : '(?P<bucket>.*)' }
    m = re.match(pattern, hostname)
    if not m:
        return (hostname, False)
    return m.groups()[0], True
__all__.append("getBucketFromHostname")

def getHostnameFromBucket(bucket):
    return Config.Config().host_bucket % { 'bucket' : bucket }
__all__.append("getHostnameFromBucket")


def calculateChecksum(buffer, mfile, offset, chunk_size, send_chunk):
    md5_hash = md5()
    size_left = chunk_size
    if buffer == '':
        mfile.seek(offset)
        while size_left > 0:
            data = mfile.read(min(send_chunk, size_left))
            md5_hash.update(data)
            size_left -= len(data)
    else:
        md5_hash.update(buffer)

    return md5_hash.hexdigest()


__all__.append("calculateChecksum")


# Deal with the fact that pwd and grp modules don't exist for Windows
try:
    import pwd
    def getpwuid_username(uid):
        """returns a username from the password databse for the given uid"""
        return pwd.getpwuid(uid).pw_name
except ImportError:
    import getpass
    def getpwuid_username(uid):
        return getpass.getuser()
__all__.append("getpwuid_username")

try:
    import grp
    def getgrgid_grpname(gid):
        """returns a groupname from the group databse for the given gid"""
        return  grp.getgrgid(gid).gr_name
except ImportError:
    def getgrgid_grpname(gid):
        return "nobody"

__all__.append("getgrgid_grpname")



# vim:et:ts=4:sts=4:ai