NAME

Data::Embed - embed arbitrary data in a file

VERSION

This document describes Data::Embed version 0.32.

SYNOPSIS

   use Data::Embed qw< embed embedded >;

   # this is the file where thing will be embedded, at the end
   my $container = '/path/to/some/file';

   # first of all we embed an external file
   my $datafile  = '/path/to/data.tar.gz';
   embed($container, name => 'data.tar.gz', filename => $datafile);

   # we can also embed some data, directly
   use Data::Dumper;
   my $conf = { ... };
   embed($container, name => 'config.yml', data => Dumper($conf));

   # if the data is in a scalar but it's huge, use filename and
   # pass a reference to the scalar so no copy will happen
   my $huge_png = ...;
   embed($container, name => 'image.png', filename => \$huge_png);

   # to retrieve the stuff, use embedded()
   my @files = embedded($container);

   # each item in @files is a Data::Embed::File object

   # get whole contents of file
   my $config_text = $files[1]->contents();

   # otherwise, you can get a filehandle and use it, e.g. to
   # dump it on standard output
   my $data_fh = $files[0]->fh();
   binmode STDOUT;
   print {*STDOUT} <$data_fh>;

   # or save the file back, using the available name
   open my $ofh, '>:raw', $file[2]->name(); # well, do your checks!
   my $ifh = $files[2]->fh();
   while (! eof $ifh) {
      read $ifh, my $buffer, 4096
         or last; # do proper checks in production!
      print {$ofh} $buffer;
   }

DESCRIPTION

This module allows you to manage embedding data at the end of other files, providing both means for embedding the data ("embed" and "writer") and accessing them ("embedded" and "reader").

How can this be helpful? For example, suppose that you want to bring some data along with your perl script, some of which might be binary (e.g. an image, or a tar archive), you can embed these data inside the perl and then retrieve them. For example, this can be the basis for an installer.

For embedding data, you can use the "embed" function. See the relevant documentation or the examples in the "SYNOPSYS" to use it properly.

For extracting the embedded data, you can use the "embedded" function and access each embedded file as a Data::Embed::File object. You can then use its methods contents for accessing the whole data, or get a filehandle through fh and avoid getting the whole data in memory at once.

Note: the filehandle provided by the fh method of Data::Embed::File is actually a IO::Slice object, so it might not support all the functions/methods of a regular filehandle.

You can also access the lower level interface through the two functions "reader" and "writer". See the documentation for Data::Embed::Reader and Data::Embed::Writer.

FUNCTIONS

embed

   embed($hashref); # OR
   embed(%keyvalue_pairs);

Embed new data inside a container file.

Parameters can be passed as key-value pairs either directly or through a hash reference. The following keys are supported:

container

shortcut to specifying the same input and output, i.e. the value will be replicated both on the input and output keys below. Caller still has to ensure that the two are compatible. Provision of a filehandle is currently not supported.

input

any previous container file to use as base for the generated container. If missing, no previous data will be considered (like starting from an empty file). Can be:

  • the - string in a plain scalar, in which case standard input is considered

  • any other string in a plain scalar, considered to be a file name

  • a plain reference to a scalar, considered to hold the input data

  • something that supports the filehandle interface for reading

output

the target container for the newly generated archive. Might be the same as the input or different; in the latter case, the input will be copied over the output, apart from the bits regarding the management of the inclusions. Can be:

  • missing/undefined or the - string in a plain scalar, in which case standard output is used

  • any other string in a plain scalar, considered to be a file name

  • a plain reference to a scalar, considered to be the target scalar to hold the data

  • something that supports the filehandle interface for printing. You should not provide the same filehandle for both input and output, even if you opened it in read-write mode. This limitation might be removed in the future.

name

the name to associate to the section, optionally. If missing it will be set to the empty string

fh

the filehandle from where data should be taken. The filehandle will be exausted starting from its current position

filename

a filename or a reference to a scalar where data will be read from

data

a scalar from where data will be read. If you have a huge amount of data, it's better to use the filename key above passing a reference to the scalar holding the data.

Options fh, filename and data are exclusive and will be considered in the order above (first come, first served).

This function does not return anything.

embedded

Get a list of the embedded files inside a target container. The calling syntax is as follows:

   my $arrayref = embedded($container); # scalar context, OR
   my @files    = embedded($container); # list context

The only input parameter is the $container to use as input. It can be either a real filename, or a filehandle.

Depending on the context, a list will be returned (in list context) or an array reference holding the list.

Whatever the context, each item in the list is a Data::Embed::File object that you can use to access the embedded file data (most notably, you'll be probably using its contents or fh methods).

generate_module_from_file

   # when %args includes details for an output channel
   generate_module_from_file(%args);

   # in case no output is provided in %args:
   my $text = generate_module_from_file(%args);

Generate a module's file contents from a file. The module contains code of a package that has code to read the included data. Arguments are:

package

the name of the package that will be put into the module. This is a mandatory parameter.

output

the output channel. If not present, the output will be provided as a string returned by the function, otherwise you can provide

  • a filehandle where the output will be printed

  • a reference to a scalar (it will be filled with the contents)

  • the - string, in which case the output will be printed to STDOUT

  • a filename

output_from_package

if this key is present and true, the output parameters is overridden and generated automatically from the package name provided in key package. The generated file will assume that the file is contained in the normal path under a lib directory, e.g. if the package name is Some::Module then the generated filename will be lib/Some/Module.pm.

fh

a filehandle where data will be read from

filename

the input will be taken from the provided filename

dataref

the input will be taken from the scalar pointed by the reference

data

the input is taken from the scalar provided with the data key

Input keys are fh, filename, dataref and data. In case multiple of them are present, they will be considered in the order specified.

reader

This is a convenience wrapper around the constructor for Data::Embed::Reader.

reassemble

   # when %args includes details for an output channel
   reassemble(%args);

Reassemble a target container fitting new input sequence. The available arguments are:

sequence

the sequence of items that have to be embedded. Each item can be:

target

the target container. It can be:

  • a filehandle

  • a filename (including -, that does what you mean)

  • a reference to a scalar

If the file or reference to a scalar are used, it will make sure to avoid clobbering. In particular, the prefix data (i.e. data that is not part of the list of files) will be preserved.

writer

This is a convenience wrapper around the constructor for Data::Embed::Writer.

BUGS AND LIMITATIONS

Report bugs either through RT or GitHub (patches welcome).

Passing the same filehandle for both input and output in "embed" is not supported. This applies to container too.

SEE ALSO

Data::Section covers a somehow similar need but differently. In particular, you should look at it if you want to be able to modify the data you want to embed directly, e.g. if you are embedding some textual templates that you want to tweak.

AUTHOR

Flavio Poletti <polettix@cpan.org>

COPYRIGHT AND LICENSE

Copyright (C) 2014-2016 by Flavio Poletti <polettix@cpan.org>

This module is free software. You can redistribute it and/or modify it under the terms of the Artistic License 2.0.

This program is distributed in the hope that it will be useful, but without any warranty; without even the implied warranty of merchantability or fitness for a particular purpose.