[Ssh-sftp-perl-users] Fix for Net::SFTP 'ls' Math::Pari leak

[David R. <dr...@at...>]

I've been delving into the guts of Net::SFTP, Net::SSH::Perl, and =
Math::Pari to find out why 'ls' overflows the PARI stack (e.g. =
http://www.codecomments.com/message237191.html), and believe I have a =
fix.  The leak is in Net::SSH::Perl::Util::SSH2MP::bin2mp; when it =
creates a Math::Pari 64-bit int for the file size (via =
Net::SFTP::Attributes::init and Net::SFTP::Buffer::get_int64):

  sub bin2mp {
      my $s =3D shift;
      my $p =3D PARI(0);
      for my $b (split //, $s) {
          $p =3D $p * 256 + ord $b;
      }
      $p;
  }

the '256', through no fault of the code, leaks about 12 bytes for each =
file listed (I wrote a Math::Pari::dumpStack to check and then moved the =
256 to a $base =3D PARI(256) outside the loop as is done in mp2bin to =
check this), so it becomes:

  sub bin2mp {
      my $s =3D shift;
      my $p =3D PARI(0);
      my $base =3D PARI(256);
      for my $b (split //, $s) {
          $p =3D $p * $base + ord $b;
      }
      $p;
  }

While this doesn't solve the underlying problem (Math::Pari constants =
shouldn't leak), it's a small patch for a decent gain.  I will continue =
to look into Math::Pari to see if I can fix the underlying problem.  For =
now, if someone's actively having problems, they can apply my fix =
themselves.

Problem is reproducible on perl 5.5.3 and 5.8.5, with a simple =
connection and looped ls, e.g. (*) perl -MNet::SFTP -we =
'$ftp=3DNet::SFTP->new(...connection params...); $ftp->ls("/some/dir") =
while 1' (the more files in the dir, the less iterations it takes).

* NOTE: do NOT use -l, Net::SSH::Perl is sensitive to it for =
transmission - should this be considered a bug?

Should I send a patch to this list?

Thanks,

--=20
Dave
Isa. 40:31