txt: ## dist_cpan-FRITH-Archive-Libarchive.md
  ## Archive::Libarchive
  
  Archive::Libarchive - OO interface to libarchive.
  
  ## Build Status
  
  [![Actions Status](https://github.com/frithnanth/perl6-Archive-Libarchive/workflows/test/badge.svg)](https://github.com/frithnanth/perl6-Archive-Libarchive/actions)
  
  ## Example
  
  ```
  use v6;
  
  use Archive::Libarchive;
  use Archive::Libarchive::Constants;
  
  sub MAIN(:$file! where { .IO.f // die "file '$file' not found" })
  {
    my Archive::Libarchive $a .= new:
        operation => LibarchiveExtract,
        file => $file,
        flags => ARCHIVE_EXTRACT_TIME +| ARCHIVE_EXTRACT_PERM +| ARCHIVE_EXTRACT_ACL +| ARCHIVE_EXTRACT_FFLAGS;
    try {
      $a.extract: sub (Archive::Libarchive::Entry $e --> Bool) { $e.pathname eq 'test2' };
      CATCH {
        say "Can't extract files: $_";
      }
    }
    $a.close;
  }
  
  ```
  
  For more examples see the `example` directory.
  
  ## Description
  
  Archive::Libarchive provides an OO interface to libarchive using Archive::Libarchive::Raw.
  
  As the Libarchive site (<http://www.libarchive.org/>) states, its implementation is able to:
  
  * Read a variety of formats, including tar, pax, cpio, zip, xar, lha, ar, cab, mtree, rar, and ISO images.
  * Write tar, pax, cpio, zip, xar, ar, ISO, mtree, and shar archives.
  * Handle automatically archives compressed with gzip, bzip2, lzip, xz, lzma, or compress.
  
  ## Documentation
  
  #### new(LibarchiveOp :$operation!, Any :$file?, Int :$flags?, Str :$format?, :@filters?)
  
  Creates an Archive::Libarchive object. It takes one **mandatory** argument:
  `operation`, what kind of operation will be performed.
  
  The list of possible operations is provided by the `LibarchiveOp` enum:
  
  * `LibarchiveRead`: open the archive to list its content.
  * `LibarchiveWrite`: create a new archive. The file must not be already present.
  * `LibarchiveOverwrite`: create a new archive. The file will be overwritten if present.
  * `LibarchiveExtract`: extract the archive content.
  
  When extracting one can specify some options to be applied to the newly created files. The default options are:
  
  `ARCHIVE_EXTRACT_TIME +| ARCHIVE_EXTRACT_PERM +| ARCHIVE_EXTRACT_ACL +| ARCHIVE_EXTRACT_FFLAGS`
  
  Those constants are defined in Archive::Libarchive::Constants, part of the Archive::Libarchive::Raw
  distribution.
  More details about those operation modes can be found on the libarchive site: <http://www.libarchive.org/>
  
  If the optional argument `$file` is provided, then it will be opened; if not provided
  during the initialization, the program must call the `open` method later.
  
  If the optional `$format` argument is provided, then the object will select that specific format
  while dealing with the archive.
  
  List of possible read formats:
  
  * 7zip
  * ar
  * cab
  * cpio
  * gnutar
  * iso9660
  * lha
  * mtree
  * rar
  * raw
  * tar
  * warc
  * xar
  * zip
  
  List of possible write formats:
  
  * 7zip
  * ar
  * cpio
  * gnutar
  * iso9660
  * mtree
  * pax
  * raw
  * shar
  * ustar
  * v7tar
  * warc
  * xar
  * zip
  
  If the optional `@filters` parameter is provided, then the object will add those filter to the archive.
  Multiple filters can be specified, so a program can manage a file.tar.gz.uu for example.
  The order of the filters is significant, in order to correctly deal with such files as file.tar.uu.gz and
  file.tar.gz.uu .
  
  List of possible read filters:
  
  * bzip2
  * compress
  * gzip
  * grzip
  * lrzip
  * lz4
  * lzip
  * lzma
  * lzop
  * none
  * rpm
  * uu
  * xz
  
  List of possible write filters:
  
  * b64encode
  * bzip2
  * compress
  * grzip
  * gzip
  * lrzip
  * lz4
  * lzip
  * lzma
  * lzop
  * none
  * uuencode
  * xz
  
  ##### Note
  
  Recent versions of libarchive implement an automatic way to determine the best mix of format and filters.
  If one is using a pretty recent libarchive, both $format and @filters may be omitted: the `new` method will
  determine automatically the right combination of parameters.
  Older versions though don't have that capability and the programmer has to define explicitly both parameters.
  
  #### open(Str $filename!, Int :$size?, :$format?, :@filters?)
  
  #### open(Buf $data!)
  
  Opens an archive; the first form is used on files, while the second one is used to open an archive that
  resides in memory.
  The first argument is always mandatory, while the other ones might been omitted.
  `$size` is the size of the internal buffer and defaults to 10240 bytes.
  
  `Note:` this module does't apply `$*CWD` to the file name under the hood, so this will create a file in the
  original directory.
  
  ```
  use Archive::Libarchive;
  
  my Archive::Libarchive $a .= new: operation => LibarchiveWrite;
  chdir 'subdir';
  $a.open: 'file.tar.gz', format => 'gnutar', filters => ['gzip'];
  …
  
  ```
  
  #### close
  
  Closes the internal archive object, frees the memory and cleans up.
  
  #### extract-opts(Int $flags?)
  
  Sets the options for the files created when extracting files from an archive.
  The default options are:
  
  `ARCHIVE_EXTRACT_TIME +| ARCHIVE_EXTRACT_PERM +| ARCHIVE_EXTRACT_ACL +| ARCHIVE_EXTRACT_FFLAGS`
  
  #### next-header(Archive::Libarchive::Entry:D $e! --> Bool)
  
  When reading an archive this method fills the Entry object and returns True till it reaches the end of the archive.
  
  The Entry object is pubblicly defined inside the Archive::Libarchive module. It's initialized this way:
  
  `my Archive::Libarchive::Entry $e .= new;`
  
  So a complete archive lister can be implemented in few lines:
  
  ```
  use v6;
  use Archive::Libarchive;
  
  sub MAIN(Str :$file! where { .IO.f // die "file '$file' not found" })
  {
    my Archive::Libarchive $a .= new: operation => LibarchiveRead, file => $file;
    my Archive::Libarchive::Entry $e .= new;
    while $a.next-header($e) {
      $e.pathname.say;
      $a.data-skip;
    }
    $a.close;
  }
  
  
  ```
  
  #### data-skip(--> Int)
  
  When reading an archive this method skips file data to jump to the next header.
  It returns `ARCHIVE_OK` or `ARCHIVE_EOF` (defined in Archive::Libarchive::Constants)
  
  #### read-file-content(Archive::Libarchive::Entry $e! --> Buf)
  
  This method reads the content of a file represented by its Entry object and returns it.
  
  #### write-header(Str $file, Str :$pathname?, Int :$size?, Int :$filetype?, Int :$perm?, Int :$atime?, Int :$mtime?, Int :$ctime?, Int :$birthtime?, Int :$uid?, Int :$gid?, Str :$uname?, Str :$gname? --> Bool)
  
  When creating an archive this method writes the header entry for the file being inserted into the archive.
  The only mandatory argument is the file name, every other argument has a reasonable default.
  If the being inserted into the archive is a symbolic link, the target will be composed as a pathname relative to the
  base directory of the file, not as a full pathname.
  More details can be found on the libarchive site.
  
  Each optional argument is available as a method of the Archive::Libarchive::Entry object and it can be set when needed.
  
  Note: `write-header` has a lot of optional arguments whose values are collected from the file one is adding to the
  archive. When using the second form of `write-data` one has to provide at least these arguments:
  
  * $size
  * $atime
  * $mtime
  * $ctime
  
  For example:
  
  ```
  $a.write-header($filename,
                  :size($buffer.bytes),
                  :atime(now.Int),
                  :mtime(now.Int),
                  :ctime(now.Int));
  
  ```
  
  #### write-data(Str $path --> Bool)
  
  #### write-data(Buf $data --> Bool)
  
  When creating an archive this method writes the data for the file being inserted into the archive.
  `$path` is the pathname of the file to be archived, while `$data` is a data buffer.
  
  #### extract(Str $destpath? --> Bool)
  
  #### extract(&callback:(Archive::Libarchive::Entry $e --> Bool)!, Str $destpath? --> Bool)
  
  When extracting files from an archive this method does all the dirty work.
  If used in the first form it extracts all the files.
  The second form takes a callback function, which receives a Archive::Libarchive::Entry object.
  The callback function receives a Archive::Libarchive::Entry object.
  
  For example, this will extract only the file whose name is `test2`:
  
  `$a.extract: sub (Archive::Libarchive::Entry $e --> Bool) { $e.pathname eq 'test2' };`
  
  In both cases one can specify the directory into which the files will be extracted.
  
  #### lib-version
  
  Returns a hash with the version number of libarchive and of each library used internally.
  
  ### Errors
  
  When the underlying library returns an error condition, the methods will return a Failure object, which can
  be trapped and the exception can be analyzed and acted upon.
  
  The exception object has two fields: $errno and $error, and return a message stating the error number and
  the associated message as delivered by libarchive.
  
  ## Prerequisites
  
  This module requires Archive::Libarchive::Raw Raku module and the libarchive library
  to be installed. Please follow the instructions below based on your platform:
  
  ### Debian Linux
  
  ```
  sudo apt-get install libarchive13
  
  ```
  
  The module looks for a library called libarchive.so, or whatever it finds in
  the environment variable `PERL6_LIBARCHIVE_LIB` (provided that the library one
  chooses uses the same API).
  
  ## Installation
  
  To install it using zef (a module management tool):
  
  ```
  $ zef update
  $ zef install Archive::Libarchive
  
  ```
  
  ## Note
  
  Archive::Libarchive::Raw and in turn this module rely on a C library which might not be present in one's
  installation, so it's not a substitute for a pure Raku module.
  
  This is a OO interface to the functions provided by the C library, accessible through the Archive::Libarchive::Raw
  module.
  
  ## Author
  
  Fernando Santagata
  
  ## Contributions
  
  Many thanks to Haythem Elganiny for implementing some multi methods in the `Entry` class.
  
  ## Copyright and license
  
  The Artistic License 2.0
  