Perl Net::SSH2 scp_put puts file and then hangs - windows

Question

I'm using Net::SSH2's scp_put method to place one file in my home directory on a Unix server from a Windows box. I am using Strawberry Perl 5.12 (portable version). I installed the libssh2 1.2.5 binaries and then Net::SSH2 from cpan.
Here's my code snippet:
sub uploadToHost{
my $file=#_[0];
my $host=#_[1];
my $user=#_[2];
my $pass=#_[3];
my $remotelocation=#_[4];
#makes a new SSH2 object
my $ssh=Net::SSH2->new() or die "couldn't make SSH object\n";
#prints proper error messages
$ssh->debug(1);
#nothing works unless I explicitly set blocking on
$ssh->blocking(1);
print "made SSH object\n";
#connect to host; this always works
$ssh->connect($host) or die "couldn't connect to host\n";
print "connected to host\n";
#authenticates with password
$ssh->auth_password($user, $pass) or die "couldn't authenticate $user\n";
print "authenticated $user\n";
#this is the tricky bit that hangs
$ssh->scp_put($file, $remotelocation") or die "couldn't put file in $remotelocation\n";
print "uploaded $file successfully\n";
$ssh->disconnect or die "couldn't disconnect\n";
} #ends sub
Output (edited for anonymity):
made SSH object\n
connected to host\n
authenticated \n
libssh2_scp_send_ex(ss->session, path, mode, size, mtime, atime) -> 0x377e61c\n
Net::SSH2::Channel::read(size = 1, ext = 0)\n
It then hangs forever (>40 minutes in one test) and needs to be killed.
What's strange is that it actually does scp the file to the remote server! It only hangs after it should have completed. I couldn't find references to this curious problem elsewhere on StackOverflow or elsewhere.
Can anyone point me in the right direction to either 1) stop it from hanging, or 2) implement (as a workaround) a timer that kills this one command after a few seconds, which is enough time to scp the file?
Thanks, everyone!

Answer 1

You can try using alarm() to prod your process into behaving, if you save this example as 'alarm.pl' you can see how it works:
use strict;
use warnings;
use 5.10.0;
# pretend to be a slow process if run as 'alarm.pl s'
if (#ARGV && $ARGV[0] eq 's') {
sleep(30);
exit();
}
# Otherwise set an alarm, then run myself with 's'
eval {
local $SIG{ALRM} = sub {die "alarmed\n"};
alarm(5);
system("perl alarm.pl s");
};
if ($#) {
die $# unless $# eq "alarmed\n";
say "Timed out slow process";
}
else {
say "Slow process finished";
}

Answer 2

Use Net::SFTP::Foreign with the Net::SSH2 backend, Net::SFTP::Foreign::Backend::Net_SSH2:
use Net::SFTP::Foreign;
my $sftp = Net::SFTP::Foreign->new($host, user => $user, password => $password, backend => Net_SSH2);
$sftp->die_on_error("Unable to connect to remote host");
$sftp->put($file, $remotelocation);
$sftp->die_on_error("Unable to copy file");
If that doesn't work either, you can try using plink (from the PuTTY project) instead of the Net::SSH2 backend.

Answer 3

I don't think it is hanging it is just REALLY SLOW. 10x slower than what it should be. The reason the file would appear to be there is that it allocates the file before it has finished transferring. This isn't really too unexpected, Perl finds new ways to disappoint and frustrate programmers on a daily basis. Sometimes I think I spend more time working around Perl's idiosyncrasies and learning 10 slightly different ways to do the same thing than doing real work.