=encoding utf8

=head1 NAME

Crypt::PKCS11 - Mutex Callbacks

=head1 WARNING

Untested code and unknown affect to the Perl VM.

=head1 SYNPOSIS

  use threads;
  use threads::shared;
  use Crypt::PKCS11;

  my %mutex :shared;
  my $mutexCounter :shared;
  $mutexCounter = 0;

  my $pkcs11 = Crypt::PKCS11->new;
  $pkcs11->load(...);
  $pkcs11->Initialize({
      CreateMutex => sub {
          my $mutexID = $mutexCounter++;
          my $lock = 0;

          $mutex{$mutexID} = shared_clone($lock);

          return $mutexID;
      },
      DestroyMutex => sub {
          my ($mutexID) = @_;
          my $mutex = $mutex{$mutexID};

          if (defined $mutex) {
              lock($mutex);
              delete $mutex{$mutexID};
          }

          return defined $mutex ? CKR_OK : CKR_GENERAL_ERROR;
      },
      LockMutex => sub {
          my ($mutexID) = @_;
          my $mutex = $mutex{$mutexID};

          if (defined $mutex) {
              lock($mutex);
              while ($mutex) {
                  cond_wait($mutex);
              }
              $mutex = threads->tid;
          }

          return defined $mutex ? CKR_OK : CKR_GENERAL_ERROR;
      },
      UnlockMutex => sub {
          my ($mutexID) = @_;
          my $mutex = $mutex{$mutexID};

          if (defined $mutex) {
              unless ($mutex == threads->tid) {
                  return CKR_GENERAL_ERROR;
              }
              lock($mutex);
              $mutex = 0;
              cond_signal($mutex);
          }

          return defined $mutex ? CKR_OK : CKR_GENERAL_ERROR;
      }
  });
  ...

=head1 DESCRIPTION

PKCS #11 supports setting callbacks for handling mutex and in the C library they
can be set per loaded PKCS #11 library but there is no context pointer supplied
to the C callback functions so there is no portable way to related to the
relevant Perl callbacks and therefor all these callbacks are global. Setting
them once will affect all loaded PKCS #11 libraries.

=head1 CALLBACKS

=over 4

=item $mutexID = CreateMutex

A callback to a function to use for creating mutex objects which must return a
numeric scalar with an unique ID for the mutex. This will be used to refer to
the mutex in the other callbacks.

=item DestroyMutex ($mutexID)

A callback to a function to use for destroying mutex objects.

=over 4

=item $mutexID

The unique mutex ID of the mutex to destroy.

=back

=item LockMutex ($mutexID)

A callback to a function to use for locking mutex objects.

=over 4

=item $mutexID

The unique mutex ID of the mutex to lock.

=back

=item UnlockMutex ($mutexID)

A callback to a function to use for unlocking mutex objects.

=over 4

=item $mutexID

The unique mutex ID of the mutex to unlock.

=back

=back

=head1 NOTE

Derived from the RSA Security Inc. PKCS #11 Cryptographic Token Interface (Cryptoki)

=head1 AUTHOR

Jerry Lundström <lundstrom.jerry@gmail.com>

=head1 REPORTING BUGS

Report bugs at https://github.com/dotse/p5-Crypt-PKCS11/issues .

=head1 LICENSE

  Copyright (c) 2015 Jerry Lundström <lundstrom.jerry@gmail.com>
  Copyright (c) 2015 .SE (The Internet Infrastructure Foundation)
  All rights reserved.

  Redistribution and use in source and binary forms, with or without
  modification, are permitted provided that the following conditions
  are met:
  1. Redistributions of source code must retain the above copyright
     notice, this list of conditions and the following disclaimer.
  2. Redistributions in binary form must reproduce the above copyright
     notice, this list of conditions and the following disclaimer in the
     documentation and/or other materials provided with the distribution.

  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
