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+# Wallet::Object::File -- File object implementation for the wallet.
+# $Id$
+#
+# Written by Russ Allbery <rra@stanford.edu>
+# Copyright 2008 Board of Trustees, Leland Stanford Jr. University
+#
+# See LICENSE for licensing terms.
+
+##############################################################################
+# Modules and declarations
+##############################################################################
+
+package Wallet::Object::File;
+require 5.006;
+
+use strict;
+use vars qw(@ISA $VERSION);
+
+use Digest::MD5 qw(md5_hex);
+use Wallet::Config ();
+use Wallet::Object::Base;
+
+@ISA = qw(Wallet::Object::Base);
+
+# This version should be increased on any code change to this module.  Always
+# use two digits for the minor version with a leading zero if necessary so
+# that it will sort properly.
+$VERSION = '0.01';
+
+##############################################################################
+# File naming
+##############################################################################
+
+# Returns the path into which that file object will be stored or undef on
+# error.  On error, sets the internal error.
+sub file_path {
+    my ($self) = @_;
+    my $name = $self->{name};
+    unless ($Wallet::Config::FILE_BUCKET) {
+        $self->error ('file support not configured');
+        return;
+    }
+    unless ($name) {
+        $self->error ('file objects may not have empty names');
+        return;
+    }
+    my $hash = substr (md5_hex ($name), 0, 2);
+    $name =~ s/([^\w-])/sprintf ('%%%02X', ord ($1))/ge;
+    my $parent = "$Wallet::Config::FILE_BUCKET/$hash";
+    unless (-d $parent || mkdir ($parent, 0700)) {
+        $self->error ("cannot create file bucket $hash: $!");
+        return;
+    }
+    return "$Wallet::Config::FILE_BUCKET/$hash/$name";
+}
+
+##############################################################################
+# Core methods
+##############################################################################
+
+# Override destroy to delete the file as well.
+sub destroy {
+    my ($self, $user, $host, $time) = @_;
+    my $id = $self->{type} . ':' . $self->{name};
+    my $path = $self->file_path;
+    if (defined ($path) && -f $path && !unlink ($path)) {
+        $self->error ("cannot delete $id: $!");
+        return;
+    }
+    return $self->SUPER::destroy ($user, $host, $time);
+}
+
+# Return the contents of the file.
+sub get {
+    my ($self, $user, $host, $time) = @_;
+    $time ||= time;
+    my $id = $self->{type} . ':' . $self->{name};
+    if ($self->flag_check ('locked')) {
+        $self->error ("cannot get $id: object is locked");
+        return;
+    }
+    my $path = $self->file_path;
+    return unless $path;
+    unless (open (FILE, '<', $path)) {
+        $self->error ("cannot get $id: object has not been stored");
+        return;
+    }
+    local $/;
+    my $data = <FILE>;
+    unless (close FILE) {
+        $self->error ("cannot get $id: $!");
+        return;
+    }
+    $self->log_action ('get', $user, $host, $time);
+    return $data;
+}
+
+# Store the file on the wallet server.
+sub store {
+    my ($self, $data, $user, $host, $time) = @_;
+    $time ||= time;
+    my $id = $self->{type} . ':' . $self->{name};
+    if ($self->flag_check ('locked')) {
+        $self->error ("cannot store $id: object is locked");
+        return;
+    }
+    my $path = $self->file_path;
+    return unless $path;
+    unless (open (FILE, '>', $path)) {
+        $self->error ("cannot store $id: $!");
+        return;
+    }
+    unless (print FILE ($data) and close FILE) {
+        $self->error ("cannot store $id: $!");
+        close FILE;
+        return;
+    }
+    $self->log_action ('store', $user, $host, $time);
+    return 1;
+}
+
+1;
+__END__
+
+##############################################################################
+# Documentation
+##############################################################################
+
+=head1 NAME
+
+Wallet::Object::File - File object implementation for wallet
+
+=head1 SYNOPSIS
+
+    my @name = qw(file mysql-lsdb)
+    my @trace = ($user, $host, time);
+    my $object = Wallet::Object::Keytab->create (@name, $dbh, @trace);
+    unless ($object->store ("the-password\n")) {
+        die $object->error, "\n";
+    }
+    my $password = $object->get (@trace);
+    $object->destroy (@trace);
+
+=head1 DESCRIPTION
+
+Wallet::Object::File is a representation of simple file objects in the
+wallet.  It implements the wallet object API and provides the necessary
+glue to store a file on the wallet server, retrieve it later, and delete
+it when the file object is deleted.  A file object must be stored before
+it can be retrieved with get.
+
+To use this object, the configuration option specifying where on the
+wallet server to store file objects must be set.  See Wallet::Config(3)
+for details on this configuration parameter and information about how to
+set wallet configuration.
+
+=head1 METHODS
+
+This object mostly inherits from Wallet::Object::Base.  See the
+documentation for that class for all generic methods.  Below are only those
+methods that are overridden or behave specially for this implementation.
+
+=over 4
+
+=item destroy(PRINCIPAL, HOSTNAME [, DATETIME])
+
+Destroys a file object by removing it from the database and deleting the
+corresonding file on the wallet server.  Returns true on success and false
+on failure.  The caller should call error() to get the error message after
+a failure.  PRINCIPAL, HOSTNAME, and DATETIME are stored as history
+information.  PRINCIPAL should be the user who is destroying the object.
+If DATETIME isn't given, the current time is used.
+
+=item get(PRINCIPAL, HOSTNAME [, DATETIME])
+
+Retrieves the current contents of the file object or undef on error.
+store() must be called before get() will be successful.  The caller should
+call error() to get the error message if get() returns undef.  PRINCIPAL,
+HOSTNAME, and DATETIME are stored as history information.  PRINCIPAL
+should be the user who is downloading the keytab.  If DATETIME isn't
+given, the current time is used.
+
+=item store(DATA, PRINCIPAL, HOSTNAME [, DATETIME])
+
+Store DATA as the current contents of the file object.  Any existing data
+will be overwritten.  Returns true on success and false on failure.  The
+caller should call error() to get the error message after a failure.
+PRINCIPAL, HOSTNAME, and DATETIME are stored as history information.
+PRINCIPAL should be the user who is destroying the object.  If DATETIME
+isn't given, the current time is used.
+
+If FILE_MAX_SIZE is set in the wallet configuration, a store() of DATA
+larger than that configuration setting will be rejected.
+
+=back
+
+=head1 FILES
+
+=over 4
+
+=item FILE_BUCKET/<hash>/<file>
+
+Files are stored on the wallet server under the directory FILE_BUCKET as
+set in the wallet configuration.  <hash> is the first two characters of
+the hex-encoded MD5 hash of the wallet file object name, used to not put
+too many files in the same directory.  <file> is the name of the file
+object with all characters other than alphanumerics, underscores, and
+dashes replaced by C<%> and the hex code of the character.
+
+=back
+
+=head1 LIMITATIONS
+
+The wallet implementation itself can handle arbitrary file object names
+and arbitrary content.  However, due to limitations in the B<remctld>
+server usually used to run B<wallet-backend>, file object names and
+contents containing nul characters (ASCII 0) may not be permitted.  The
+file system used for storing file objects may impose a length limitation
+on the file object name.
+
+=head1 SEE ALSO
+
+remctld(8), Wallet::Config(3), Wallet::Object::Base(3), wallet-backend(8)
+
+This module is part of the wallet system.  The current version is
+available from L<http://www.eyrie.org/~eagle/software/wallet/>.
+
+=head1 AUTHOR
+
+Russ Allbery <rra@stanford.edu>
+
+=cut