1lfc_python(3)                           Python          Reference
2lfc_python(3)
3
4
5
6[1mNAME[0m
7       lfc ‐ Python interface to the LFC
8       lfcthr ‐ Thread enabled version of Python interface to the
9LFC
10
11[1mSYNOPSIS[0m
12       [1mimport lfc[0m
13
14       [1mimport lfcthr[0m
15       [1mlfcthr.init()[0m
16
17
18[1mDESCRIPTION[0m
19       The   lfc   module  permits  you  to access the LFC client
20interface from
21       python programs. The lfc module is a swig wrapping of  the
22standard  C
23       interface.  For detailed descriptions of each function see
24the individ‐
25       ual man page of each function.
26
27       The lfcthr module is a version of  the  lfc  module   sup‐
28porting  multi‐
29       threaded  Python  clients. Its usage is similar to the us‐
30age of the lfc
31       module except  the  obligatory  initialisation  call  lfc‐
32thr.init()  in  the
33       main program before threads are started.
34
35       There  follows a series of examples of how to use selected
36functions and
37       how to retrieve the information returned by them: Examples
38are  finding
39       the  GUID  of an existing entry, listing the replicas of a
40given GUID and
41       setting and retrieving the comment associated with an  en‐
42try.
43
44[1mEXAMPLE[0m
45       #!/usr/bin/python
46
47       import sys
48       import lfc
49
50       """
51       # stat an existing entry in the LFC and print the GUID
52       """
53
54       name = "/grid/dteam/my.test"
55
56       stat = lfc.lfc_filestatg()
57       res = lfc.lfc_statg(name,"",stat)
58
59       if res == 0:
60          guid = stat.guid
61          print "The GUID for " + name + " is " + guid
62       else:
63          err_num = lfc.cvar.serrno
64          err_string = lfc.sstrerror(err_num)
65          print  "There was an error while looking for " + name +
66": Error " + str(err_num)                  + " (" + err_string  +
67")"
68          sys.exit(1)
69
70[1mEXAMPLE[0m
71       #!/usr/bin/python
72
73       import lfc
74
75       """
76       #  list  the  replicas of a given entry, starting from the
77GUID
78       """
79
80       guid = "6a3164e0‐a4d7‐4abe‐9f76‐e3b8882735d1"
81
82       listp = lfc.lfc_list()
83       flag = lfc.CNS_LIST_BEGIN
84
85       print "Listing replicas for GUID " + guid
86
87       num_replicas=0
88
89       while(1):
90          res = lfc.lfc_listreplica("",guid,flag,listp)
91          flag = lfc.CNS_LIST_CONTINUE
92
93          if res == None:
94             break
95          else:
96             rep_name = res.sfn
97             print "Replica: " + rep_name
98             num_replicas = num_replicas + 1
99
100       lfc.lfc_listreplica("",guid,lfc.CNS_LIST_END,listp)
101       print "Found " + str(num_replicas) + " replica(s)"
102
103[1mEXAMPLE[0m
104       #!/usr/bin/python
105
106       import sys
107       import lfc
108       import re
109
110       """
111       # setting and retrieving a comment on a file
112       """
113
114       file = "/grid/dteam/my.test"
115
116       comment = "MyComment"
117       res = lfc.lfc_setcomment(file,comment)
118
119       if res != 0:
120          err_num = lfc.cvar.serrno
121          err_string = lfc.sstrerror(err_num)
122          print "Problem while setting comment for " + file +  ":
123Error " + str(err_num)                  + " (" + err_string + ")"
124          sys.exit(1)
125
126       buffer=""
127       for i in range(0,lfc.CA_MAXCOMMENTLEN+1):
128         buffer=buffer + " "
129
130       res = lfc.lfc_getcomment(file,buffer)
131
132       if res != 0:
133          err_num = lfc.cvar.serrno
134          err_string = lfc.sstrerror(err_num)
135          print "Problem while reading the comment for " + file +
136": Error " + str(err_num)                  + " (" + err_string  +
137")"
138          sys.exit(1)
139
140       r = re.compile("(.*?) ", re.DOTALL)
141       comment = r.findall(buffer)[0]
142
143       print "Read back comment " + comment
144
145
146[1mEXAMPLE[0m
147       #!/usr/bin/python
148
149       """
150       # Using the lfc_readdirxr method
151       """
152
153       import sys
154       import lfc
155
156       name = "/grid/dteam/my.test"
157
158       dir = lfc.lfc_opendirg(name,"")
159       if (dir == None) or (dir == 0):
160               err_num = lfc.cvar.serrno
161               err_string = lfc.sstrerror(err_num)
162               print "Error while looking for " + name + ": Error
163" + str(err_num)                       + " (" + err_string + ")"
164               sys.exit(1)
165
166       while 1:
167               read_pt = lfc.lfc_readdirxr(dir,"")
168               if (read_pt == None) or (read_pt == 0):
169                       break
170               entry, list = read_pt
171               print entry.d_name
172               try:
173                       for i in range(len(list)):
174                               print " ==> %s" % list[i].sfn
175               except TypeError, x:
176                       print " ==> None"
177
178       lfc.lfc_closedir(dir)
179
180
181[1mEXAMPLE[0m
182       #!/usr/bin/python
183
184       import lfc
185
186       """
187       # Using the lfc_getlinks method
188       """
189
190       result, list = lfc.lfc_getlinks("/grid/dteam/antotests/ex‐
191tratests/dir2/f105", "")
192       print result
193       print len(list)
194       if (result == 0):
195            for i in list:
196                 print i.path
197
198
199[1mEXAMPLE[0m
200       #!/usr/bin/python
201
202       import lfc
203
204       """
205       # Using the lfc_getreplica method
206       """
207
208       result,    list    =   lfc.lfc_getreplica("/grid/dteam/an‐
209totests/extratests/dir2/f105", "", "")
210       print result
211       print len(list)
212       if (result == 0):
213            for i in list:
214                 print i.host
215                 print i.sfn
216
217
218[1mEXAMPLE[0m
219       #!/usr/bin/python
220
221       import lfc
222
223       """
224       # Using the lfc_getacl and lfc_setacl methods to add a us‐
225er ACL
226       """
227
228       nentries,         acls_list         =        lfc.lfc_geta‐
229cl("/grid/dteam/tests_sophie3", lfc.CA_MAXACLENTRIES)
230
231       print nentries
232       print len(acls_list)
233
234       for i in acls_list:
235               print i.a_type
236               print i.a_id
237               print i.a_perm
238
239       # When adding a first ACL for a given user, you also  need
240to add the mask
241       #  When  adding  the  second user ACL, it is not necessary
242anymore
243
244       acl_user = lfc.lfc_acl()
245       acl_mask = lfc.lfc_acl()
246
247       acl_user.a_type=2        # 2 corresponds to CNS_ACL_USER
248       acl_user.a_id=18701      # user id
249       acl_user.a_perm=5
250
251       acl_mask.a_type=5        # 5 corresponds to CNS_ACL_MASK
252       acl_mask.a_id=0               # no user id specified
253       acl_mask.a_perm=5
254
255       acls_list.append(acl_user)
256       acls_list.append(acl_mask)
257
258       res     =      lfc.lfc_setacl("/grid/dteam/tests_sophie3",
259acls_list)
260
261       if res == 0:
262               print "OK"
263       else:
264               err_num = lfc.cvar.serrno
265               err_string = lfc.sstrerror(err_num)
266               print "There was an error : Error " + str(err_num)
267+ " (" + err_string + ")"
268               sys.exit(1)
269
270
271[1mEXAMPLE[0m
272       #!/usr/bin/python
273
274       import lfc
275
276       """
277       # Using the lfc_getacl and lfc_setacl methods to remove  a
278user ACL
279       """
280
281       nentries,         acls_list         =        lfc.lfc_geta‐
282cl("/grid/dteam/tests_sophie3", lfc.CA_MAXACLENTRIES)
283
284       # Note :  you  cannot  remove  the  owner  ACL  (i.e.  for
285CNS_ACL_USER_OBJ type) if ACLs
286       # ====== for other users exist. Ff all the other user ACLs
287are deleted, the owner
288       # ====== ACL is automatically removed.
289
290       for i in acls_list:
291               print i.a_type
292               print i.a_id
293               print i.a_perm
294
295       del acls_list[1]    # delete a given  user  ACL  from  the
296list of ACLs
297
298       res      =     lfc.lfc_setacl("/grid/dteam/tests_sophie3",
299acls_list)
300
301       if res == 0:
302               print "OK"
303       else:
304               err_num = lfc.cvar.serrno
305               err_string = lfc.sstrerror(err_num)
306               print "There was an error : Error " + str(err_num)
307+ " (" + err_string + ")"
308               sys.exit(1)
309
310
311[1mEXAMPLE[0m
312       #!/usr/bin/env python
313       import lfcthr
314       import os
315       from threading import Thread
316
317       class slave(Thread):
318
319          def __init__ (self):
320             Thread.__init__(self)
321
322          def run(self):
323               ....
324               result = lfcthr.lfc_getreplica("", guid, "")
325               ....
326               return
327
328       if __name__ == ’__main__’:
329
330           os.environ[’LFC_HOST’] = ’my_lfc.cern.ch’
331
332           #     Threaded library initialisation
333           lfcthr.init()
334
335           ....
336           #     Start up of threads
337           for i in xrange(totalNumberOfSlaves):
338               slv = slave(i)
339               slv.start()
340
341           ....
342
343
344
345[1mEXAMPLE[0m
346       #!/usr/bin/python
347
348       import lfc
349
350       """
351       # Using the lfc_getusrmap method
352       """
353
354       result, list = lfc.lfc_getusrmap()
355       print result
356       print len(list)
357       if (result == 0):
358            for i in list:
359                 print i.userid + " " + i.username
360
361
362[1mEXAMPLE[0m
363       #!/usr/bin/python
364
365       import lfc
366
367       """
368       # Using the lfc_getgrpmap method
369       """
370
371       result, list = lfc.lfc_getgrpmap()
372       print result
373       print len(list)
374       if (result == 0):
375            for i in list:
376                 print i.gid + " " + i.groupname
377
378
379[1mKNOWN BUGS[0m
380       The    current    interface    to    the    [1mlfc_getcom‐
381ment(3)[22m,   [1mlfc_getcwd(3)[22m,
382       [1mlfc_readlink(3)[22m,  [1mlfc_seterrbuf(3)  [22mrequires
383the passing of str object
384       which  is  modified  to  contain the result (in a  similar
385way  to  the  C
386       functions,  which accept a buffer).  However  this  breaks
387the immutabil‐
388       ity of python str. This will be changed in the future.
389
390[1mSEE ALSO[0m
391       [1mLFC C interface man pages[0m
392
393
394
395LFC           $Date: 2010‐02‐04 12:08:39 +0000 (Thu, 04 Feb 2010)
396$lfc_python(3)