NAME¶

lfc - Perl interface to the LFC

SYNOPSIS¶

use lfc;
printf "CNS_LIST_BEGIN is %d\n", $lfc::CNS_LIST_BEGIN;

DESCRIPTION¶

The lfc module permits you to access the LFC client interface from perl programs. The lfc module is a swig wrapping of the standard C interface. For detailed descriptions of each function see the individual man page of each function.

There follows a series of examples of how to use selected functions and how to retrieve the information returned by them: Examples are finding the GUID of an existing entry, listing the replicas of a given GUID and setting and retrieving the comment associated with an entry.

EXAMPLE¶

#!/usr/bin/perl -w
use strict;
use lfc;
# stat an existing entry in the LFC and print the GUID
my ($name,$stat,$guid,$res);
$name = "/grid/dteam/my.test";
$stat = lfcc::new_lfc_filestatg();
$res = lfc::lfc_statg($name,undef,$stat);
if ($res == 0) {


  $guid = lfcc::lfc_filestatg_guid_get($stat);


  print "The GUID for $name is $guid\n";
} else {


  my $err_num = $lfc::serrno;


  my $err_string = lfc::sstrerror($err_num);


  print "There was an error while looking for $name: Error $err_num ($err_string)\n";


  exit(1);
}
lfcc::delete_lfc_filestatg($stat);

EXAMPLE¶

#!/usr/bin/perl -w
use strict;
use lfc;
# list the replicas of a given entry, starting from the GUID
my ($guid,$listp,$flag,$num_replicas);
$guid = "6a3164e0-a4d7-4abe-9f76-e3b8882735d1";
$listp = lfcc::new_lfc_list();
$flag =  $lfc::CNS_LIST_BEGIN;
print "Listing replicas for GUID $guid:\n";
$num_replicas=0;
while(1) {


  my $res = lfc::lfc_listreplica(undef,$guid,$flag,$listp);


  $flag = $lfc::CNS_LIST_CONTINUE;


  if (!defined $res) {


    last;


  } else {


    my $rep_name = lfcc::lfc_filereplica_sfn_get($res);


    print "Replica: $rep_name\n";


    $num_replicas++;


  }
}
lfc::lfc_listreplica(undef,$guid,$lfc::CNS_LIST_END,$listp);
lfcc::delete_lfc_list($listp);
print "Found $num_replicas replica(s)\n";

EXAMPLE¶

#!/usr/bin/perl -w
use strict;
use lfc;
# setting and retrieving a comment on a file
my ($file,$res,$bufspec,$buffer,$comment);
$file = "/grid/dteam/my.test";
$comment = "MyComment";
$res = lfc::lfc_setcomment($file,$comment);
if ($res != 0) {


  my $err_num = $lfc::serrno;


  my $err_string = lfc::sstrerror($err_num);


  print "Problem while setting comment for $file: Error $err_num ($err_string)\n";


  exit(1);
}


  
$bufspec =  "x".($lfc::CA_MAXCOMMENTLEN+1);
$buffer = pack($bufspec);
$res = lfc::lfc_getcomment($file,$buffer);
if ($res != 0) {


  my $err_num = $lfc::serrno;


  my $err_string = lfc::sstrerror($err_num);


  print "Problem while reading the comment for $file: Error $err_num ($err_string)\n";


  exit(1);
}
$comment = unpack("Z*", $buffer);
print "Read back comment $comment\n";

NOTES¶

The current interface to the lfc_getcomment(3), lfc_getcwd(3), lfc_readlink(3), lfc_seterrbuf(3) requires the passing of a suitably allocated buffer (in a similar way to the C functions). However this is rather non standard in PERL. A future version of lfc perl interface may do away with the need to setup the buffer before the call and to explicitly unpack the result afterwards.

SEE ALSO¶

LFC C interface man pages