/Lib/plat-os2emx/grp.py

  1# this module is an OS/2 oriented replacement for the grp standard
  2# extension module.
  3
  4# written by Andrew MacIntyre, April 2001.
  5# updated July 2003, adding field accessor support
  6
  7# note that this implementation checks whether ":" or ";" as used as
  8# the field separator character.
  9
 10"""Replacement for grp standard extension module, intended for use on
 11OS/2 and similar systems which don't normally have an /etc/group file.
 12
 13The standard Unix group database is an ASCII text file with 4 fields per
 14record (line), separated by a colon:
 15  - group name (string)
 16  - group password (optional encrypted string)
 17  - group id (integer)
 18  - group members (comma delimited list of userids, with no spaces)
 19
 20Note that members are only included in the group file for groups that
 21aren't their primary groups.
 22(see the section 8.2 of the Python Library Reference)
 23
 24This implementation differs from the standard Unix implementation by
 25allowing use of the platform's native path separator character - ';' on OS/2,
 26DOS and MS-Windows - as the field separator in addition to the Unix
 27standard ":".
 28
 29The module looks for the group database at the following locations
 30(in order first to last):
 31  - ${ETC_GROUP}              (or %ETC_GROUP%)
 32  - ${ETC}/group              (or %ETC%/group)
 33  - ${PYTHONHOME}/Etc/group   (or %PYTHONHOME%/Etc/group)
 34
 35Classes
 36-------
 37
 38None
 39
 40Functions
 41---------
 42
 43getgrgid(gid) -  return the record for group-id gid as a 4-tuple
 44
 45getgrnam(name) - return the record for group 'name' as a 4-tuple
 46
 47getgrall() -     return a list of 4-tuples, each tuple being one record
 48                 (NOTE: the order is arbitrary)
 49
 50Attributes
 51----------
 52
 53group_file -     the path of the group database file
 54
 55"""
 56
 57import os
 58
 59# try and find the group file
 60__group_path = []
 61if os.environ.has_key('ETC_GROUP'):
 62    __group_path.append(os.environ['ETC_GROUP'])
 63if os.environ.has_key('ETC'):
 64    __group_path.append('%s/group' % os.environ['ETC'])
 65if os.environ.has_key('PYTHONHOME'):
 66    __group_path.append('%s/Etc/group' % os.environ['PYTHONHOME'])
 67
 68group_file = None
 69for __i in __group_path:
 70    try:
 71        __f = open(__i, 'r')
 72        __f.close()
 73        group_file = __i
 74        break
 75    except:
 76        pass
 77
 78# decide what field separator we can try to use - Unix standard, with
 79# the platform's path separator as an option.  No special field conversion
 80# handlers are required for the group file.
 81__field_sep = [':']
 82if os.pathsep:
 83    if os.pathsep != ':':
 84        __field_sep.append(os.pathsep)
 85
 86# helper routine to identify which separator character is in use
 87def __get_field_sep(record):
 88    fs = None
 89    for c in __field_sep:
 90        # there should be 3 delimiter characters (for 4 fields)
 91        if record.count(c) == 3:
 92            fs = c
 93            break
 94    if fs:
 95        return fs
 96    else:
 97        raise KeyError, '>> group database fields not delimited <<'
 98
 99# class to match the new record field name accessors.
100# the resulting object is intended to behave like a read-only tuple,
101# with each member also accessible by a field name.
102class Group:
103    def __init__(self, name, passwd, gid, mem):
104        self.__dict__['gr_name'] = name
105        self.__dict__['gr_passwd'] = passwd
106        self.__dict__['gr_gid'] = gid
107        self.__dict__['gr_mem'] = mem
108        self.__dict__['_record'] = (self.gr_name, self.gr_passwd,
109                                    self.gr_gid, self.gr_mem)
110
111    def __len__(self):
112        return 4
113
114    def __getitem__(self, key):
115        return self._record[key]
116
117    def __setattr__(self, name, value):
118        raise AttributeError('attribute read-only: %s' % name)
119
120    def __repr__(self):
121        return str(self._record)
122
123    def __cmp__(self, other):
124        this = str(self._record)
125        if this == other:
126            return 0
127        elif this < other:
128            return -1
129        else:
130            return 1
131
132
133# read the whole file, parsing each entry into tuple form
134# with dictionaries to speed recall by GID or group name
135def __read_group_file():
136    if group_file:
137        group = open(group_file, 'r')
138    else:
139        raise KeyError, '>> no group database <<'
140    gidx = {}
141    namx = {}
142    sep = None
143    while 1:
144        entry = group.readline().strip()
145        if len(entry) > 3:
146            if sep is None:
147                sep = __get_field_sep(entry)
148            fields = entry.split(sep)
149            fields[2] = int(fields[2])
150            fields[3] = [f.strip() for f in fields[3].split(',')]
151            record = Group(*fields)
152            if not gidx.has_key(fields[2]):
153                gidx[fields[2]] = record
154            if not namx.has_key(fields[0]):
155                namx[fields[0]] = record
156        elif len(entry) > 0:
157            pass                         # skip empty or malformed records
158        else:
159            break
160    group.close()
161    if len(gidx) == 0:
162        raise KeyError
163    return (gidx, namx)
164
165# return the group database entry by GID
166def getgrgid(gid):
167    g, n = __read_group_file()
168    return g[gid]
169
170# return the group database entry by group name
171def getgrnam(name):
172    g, n = __read_group_file()
173    return n[name]
174
175# return all the group database entries
176def getgrall():
177    g, n = __read_group_file()
178    return g.values()
179
180# test harness
181if __name__ == '__main__':
182    getgrall()