1lfc_python(3) Python Reference lfc_python(3)
2
6 lfc - Python interface to the LFC
7 lfcthr - Thread enabled version of Python interface to the LFC
8
10 import lfc
11 import lfcthr
13 lfcthr.init()
14
17 The lfc module permits you to access the LFC client interface from
18 python programs. The lfc module is a swig wrapping of the standard C
19 interface. For detailed descriptions of each function see the individ‐
20 ual man page of each function.
21 The lfcthr module is a version of the lfc module supporting multi-
23 threaded Python clients. Its usage is similar to the usage of the lfc
24 module except the obligatory initialisation call lfcthr.init() in the
25 main program before threads are started.
26 There follows a series of examples of how to use selected functions and
28 how to retrieve the information returned by them: Examples are finding
29 the GUID of an existing entry, listing the replicas of a given GUID and
30 setting and retrieving the comment associated with an entry.
31
33 #!/usr/bin/python
34 import sys
36 import lfc
37 """
39 # stat an existing entry in the LFC and print the GUID
40 """
41 name = "/grid/dteam/my.test"
43 stat = lfc.lfc_filestatg()
45 res = lfc.lfc_statg(name,"",stat)
46 if res == 0:
48 guid = stat.guid
49 print "The GUID for " + name + " is " + guid
50 else:
51 err_num = lfc.cvar.serrno
52 err_string = lfc.sstrerror(err_num)
53 print "There was an error while looking for " + name + ": Error " + str(err_num) \
54 + " (" + err_string + ")"
55 sys.exit(1)
56
58 #!/usr/bin/python
59 import lfc
61 """
63 # list the replicas of a given entry, starting from the GUID
64 """
65 guid = "6a3164e0-a4d7-4abe-9f76-e3b8882735d1"
67 listp = lfc.lfc_list()
69 flag = lfc.CNS_LIST_BEGIN
70 print "Listing replicas for GUID " + guid
72 num_replicas=0
74 while(1):
76 res = lfc.lfc_listreplica("",guid,flag,listp)
77 flag = lfc.CNS_LIST_CONTINUE
78 if res == None:
80 break
81 else:
82 rep_name = res.sfn
83 print "Replica: " + rep_name
84 num_replicas = num_replicas + 1
85 lfc.lfc_listreplica("",guid,lfc.CNS_LIST_END,listp)
87 print "Found " + str(num_replicas) + " replica(s)"
88
90 #!/usr/bin/python
91 import sys
93 import lfc
94 import re
95 """
97 # setting and retrieving a comment on a file
98 """
99 file = "/grid/dteam/my.test"
101 comment = "MyComment"
103 res = lfc.lfc_setcomment(file,comment)
104 if res != 0:
106 err_num = lfc.cvar.serrno
107 err_string = lfc.sstrerror(err_num)
108 print "Problem while setting comment for " + file + ": Error " + str(err_num) \
109 + " (" + err_string + ")"
110 sys.exit(1)
111 buffer=""
113 for i in range(0,lfc.CA_MAXCOMMENTLEN+1):
114 buffer=buffer + " "
115 res = lfc.lfc_getcomment(file,buffer)
117 if res != 0:
119 err_num = lfc.cvar.serrno
120 err_string = lfc.sstrerror(err_num)
121 print "Problem while reading the comment for " + file + ": Error " + str(err_num) \
122 + " (" + err_string + ")"
123 sys.exit(1)
124 r = re.compile("(.*?) ", re.DOTALL)
126 comment = r.findall(buffer)[0]
127 print "Read back comment " + comment
129
132 #!/usr/bin/python
133 """
135 # Using the lfc_readdirxr method
136 """
137 import sys
139 import lfc
140 name = "/grid/dteam/my.test"
142 dir = lfc.lfc_opendirg(name,"")
144 if (dir == None) or (dir == 0):
145 err_num = lfc.cvar.serrno
146 err_string = lfc.sstrerror(err_num)
147 print "Error while looking for " + name + ": Error " + str(err_num) \
148 + " (" + err_string + ")"
149 sys.exit(1)
150 while 1:
152 read_pt = lfc.lfc_readdirxr(dir,"")
153 if (read_pt == None) or (read_pt == 0):
154 break
155 entry, list = read_pt
156 print entry.d_name
157 try:
158 for i in range(len(list)):
159 print " ==> %s" % list[i].sfn
160 except TypeError, x:
161 print " ==> None"
162 lfc.lfc_closedir(dir)
164
167 #!/usr/bin/python
168 import lfc
170 """
172 # Using the lfc_getlinks method
173 """
174 result, list = lfc.lfc_getlinks("/grid/dteam/antotests/extratests/dir2/f105", "")
176 print result
177 print len(list)
178 if (result == 0):
179 for i in list:
180 print i.path
181
184 #!/usr/bin/python
185 import lfc
187 """
189 # Using the lfc_getreplica method
190 """
191 result, list = lfc.lfc_getreplica("/grid/dteam/antotests/extratests/dir2/f105", "", "")
193 print result
194 print len(list)
195 if (result == 0):
196 for i in list:
197 print i.host
198 print i.sfn
199
202 #!/usr/bin/python
203 import lfc
205 """
207 # Using the lfc_getacl and lfc_setacl methods to add a user ACL
208 """
209 nentries, acls_list = lfc.lfc_getacl("/grid/dteam/tests_sophie3", lfc.CA_MAXACLENTRIES)
211 print nentries
213 print len(acls_list)
214 for i in acls_list:
216 print i.a_type
217 print i.a_id
218 print i.a_perm
219 # When adding a first ACL for a given user, you also need to add the mask
221 # When adding the second user ACL, it is not necessary anymore
222 acl_user = lfc.lfc_acl()
224 acl_mask = lfc.lfc_acl()
225 acl_user.a_type=2 # 2 corresponds to CNS_ACL_USER
227 acl_user.a_id=18701 # user id
228 acl_user.a_perm=5
229 acl_mask.a_type=5 # 5 corresponds to CNS_ACL_MASK
231 acl_mask.a_id=0 # no user id specified
232 acl_mask.a_perm=5
233 acls_list.append(acl_user)
235 acls_list.append(acl_mask)
236 res = lfc.lfc_setacl("/grid/dteam/tests_sophie3", acls_list)
238 if res == 0:
240 print "OK"
241 else:
242 err_num = lfc.cvar.serrno
243 err_string = lfc.sstrerror(err_num)
244 print "There was an error : Error " + str(err_num) + " (" + err_string + ")"
245 sys.exit(1)
246
249 #!/usr/bin/python
250 import lfc
252 """
254 # Using the lfc_getacl and lfc_setacl methods to remove a user ACL
255 """
256 nentries, acls_list = lfc.lfc_getacl("/grid/dteam/tests_sophie3", lfc.CA_MAXACLENTRIES)
258 # Note : you cannot remove the owner ACL (i.e. for CNS_ACL_USER_OBJ type) if ACLs
260 # ====== for other users exist. Ff all the other user ACLs are deleted, the owner
261 # ====== ACL is automatically removed.
262 for i in acls_list:
264 print i.a_type
265 print i.a_id
266 print i.a_perm
267 del acls_list[1] # delete a given user ACL from the list of ACLs
269 res = lfc.lfc_setacl("/grid/dteam/tests_sophie3", acls_list)
271 if res == 0:
273 print "OK"
274 else:
275 err_num = lfc.cvar.serrno
276 err_string = lfc.sstrerror(err_num)
277 print "There was an error : Error " + str(err_num) + " (" + err_string + ")"
278 sys.exit(1)
279
282 #!/usr/bin/env python
283 import lfcthr
284 import os
285 from threading import Thread
286 class slave(Thread):
288 def __init__ (self):
290 Thread.__init__(self)
291 def run(self):
293 ....
294 result = lfcthr.lfc_getreplica("", guid, "")
295 ....
296 return
297 if __name__ == '__main__':
299 os.environ['LFC_HOST'] = 'my_lfc.cern.ch'
301 # Threaded library initialisation
303 lfcthr.init()
304 ....
306 # Start up of threads
307 for i in xrange(totalNumberOfSlaves):
308 slv = slave(i)
309 slv.start()
310 ....
312
316 #!/usr/bin/python
317 import lfc
319 """
321 # Using the lfc_getusrmap method
322 """
323 result, list = lfc.lfc_getusrmap()
325 print result
326 print len(list)
327 if (result == 0):
328 for i in list:
329 print i.userid + " " + i.username
330
333 #!/usr/bin/python
334 import lfc
336 """
338 # Using the lfc_getgrpmap method
339 """
340 result, list = lfc.lfc_getgrpmap()
342 print result
343 print len(list)
344 if (result == 0):
345 for i in list:
346 print i.gid + " " + i.groupname
347
350 The current interface to the lfc_getcomment(3), lfc_getcwd(3),
351 lfc_readlink(3), lfc_seterrbuf(3) requires the passing of str object
352 which is modified to contain the result (in a similar way to the C
353 functions, which accept a buffer). However this breaks the immutabil‐
354 ity of python str. This will be changed in the future.
355
357 LFC C interface man pages
358LFC $Date: 2010-02-04 13:08:39 +0100 (Thu, 04 Feb 2010) $lfc_python(3)