Archive::Libarchive::ArchiveRead(3)

NAME
Archive::Libarchive::ArchiveRead - Libarchive read archive class

VERSION
version 0.09

SYNOPSIS
 use 5.020;
 use Archive::Libarchive qw( :const );

 my $r = Archive::Libarchive::ArchiveRead->new;
 $r->support_filter_all;
 $r->support_format_all;
 $r->open_filename("archive.tar", 10240) == ARCHIVE_OK
   or die $r->error_string;

 my $e = Archive::Libarchive::Entry->new;
 say $e->pathname while $r->next_header($e) == ARCHIVE_OK;

DESCRIPTION
This class represents an archive instance for reading from archives.

CONSTRUCTOR

  new
 # archive_read_new
 my $r = Archive::Libarchive::ArchiveRead->new;

Create a new archive read object.

METHODS
This is a subset of total list of methods available to all archive classes. For the full list see "Archive::Libarchive::ArchiveRead" in Archive::Libarchive::API.

  open
 # archive_read_open1
 # archive_read_set_callback_data
 # archive_read_set_close_callback
 # archive_read_set_open_callback
 # archive_read_set_read_callback
 # archive_read_set_seek_callback
 # archive_read_set_skip_callback
 $r->open(%callbacks);

This is a basic open method, which relies on callbacks for its implementation. The only callback that is required is the "read" callback. The "open" and "close" callbacks are made available mostly for the benefit of the caller. The "skip" and "seek" callbacks are used if available for some formats like "zip" to improve performance. All callbacks should return a normal status code, which is "ARCHIVE_OK" on success.

Unlike the "libarchive" C-API, this interface doesn't provide a facility for passing in "client" data. In Perl this is implemented using a closure, which should allow you to pass in arbitrary variables via proper scoping.

open
     $r->open(open => sub ($r) {
       ...
     });

    Called immediately when the archive is "opened";

read
     $r->open(read => sub ($r, $ref) {
       $$ref = ...;
       ...
       return $size.
     });

    Called when new data is required. What is passed in is a scalar reference. You should set this scalar to the next block of data. On success you should return the size of the data in bytes, and on failure return a normal status code.

seek
     $r->open(seek => sub ($r, $offset, $whence) {
       ...
     });

    Called to seek to the new location. The $offset and $whence arguments work exactly like the "libc" "fseek" function.

skip
     $r->open(skip => sub ($r, $request) {
       ...
     });

    Called to skip the next $request bytes. Should return the actual number of bytes skipped on success (which can be less than or equal to $request), and on failure return a normal status code.

close
     $r->open(close => sub ($r) {
       ...
     });

    This is called when the archive instance is closed.

  open_memory
 # archive_write_open_memory
 my $code = $r->open_memory(\$buffer);

Open's the in-memory archive.

  open_FILE
 $r->open_FILE($file_pointer);

This takes either a FFI::C::File, or an opaque pointer to a libc file pointer.

  open_perlfile
 $r->open_perlfile(*FILE);

This takes a perl file handle and reads the archive from there.

  open_filename
 # archive_read_open_filename
 my $int = $r->open_filename($string, $size_t);

Open a single-file archive. The $size_t argument is the block size.

  open_filenames
 # archive_read_open_filenames
 my $int = $r->open_filenames(\@filenames, $size_t);

Open a multi-file archive (typically for RAR format). The $size_t argument is the block size.

  next_header
 # archive_read_next_header
 my $code = $r->next_header($e);

Returns the next Archive::Libarchive::Entry object.

  read_data
 # archive_read_data
 my $size_or_code = $r->read_data(\$buffer, $size);
 my $size_or_code = $r->read_data(\$buffer);

Read in data from the content section of the archive entry. The output is written into $buffer. Up to $size bytes will be read. This will return the number of bytes read on success, zero (0) on EOF and a normal status code on error.

  read_data_block
 # archive_read_data_block
 my $int = $r->read_data_block(\$buffer, \$offset);

A zero-copy version of archive_read_data that also exposes the file offset of each returned block. Note that the client has no way to specify the desired size of the block. The API does guarantee that offsets will be strictly increasing and that returned blocks will not overlap.

Gotcha with this method is that it returns "ARCHIVE_EOF" when there is no more data to read instead of the number of bytes. The size can be determined from the length of the newly resized $buffer.

  append_filter
 # archive_read_append_filter
 my $int = $r->append_filter($code);

Append filter to manually specify the order in which filters will be applied. This will accept either a string representation of the filter code, or the constant. The constant prefix is "ARCHIVE_FILTER_". So for a gzipped file this would be either 'gzip' or "ARCHIVE_FILTER_GZIP". For the full list see "CONSTANTS" in Archive::Libarchive::API.

  set_format
 # archive_read_set_format
 my $int = $r->set_format($code);

Set the format manually. This will accept either a string representation of the format, or the constant. The constant prefix is "ARCHIVE_FORMAT_". So for a tar file this would be either 'tar' or "ARCHIVE_FORMAT_TAR".

  set_passphrase_callback
 # archive_read_set_passphrase_callback
 my $int = $r->set_passphrase_callback(sub ($r) {
   ...
   return $passphrase;
 });

Set a callback that will be called when a passphrase is required, for example with a .zip file with encrypted entries.

SEE ALSO

Archive::Libarchive::Peek
    Provides an interface for listing and retrieving entries from an archive without extracting them to the local filesystem.

Archive::Libarchive::Extract
    Provides an interface for extracting arbitrary archives of any format/filter supported by "libarchive".

Archive::Libarchive::Unwrap
    Decompresses / unwraps files that have been compressed or wrapped in any of the filter formats supported by "libarchive"

Archive::Libarchive
    This is the main top-level module for using "libarchive" from Perl. It is the best place to start reading the documentation. It pulls in the other classes and "libarchive" constants so that you only need one "use" statement to effectively use "libarchive".

Archive::Libarchive::API
    This contains the full and complete API for all of the Archive::Libarchive classes. Because "libarchive" has hundreds of methods, the main documentation pages elsewhere only contain enough to be useful, and not to overwhelm.

Archive::Libarchive::Archive
    The base class of all archive classes. This includes some common error reporting functionality among other things.

Archive::Libarchive::ArchiveWrite
    This class is for creating new archives.

Archive::Libarchive::DiskRead
    This class is for reading Archive::Libarchive::Entry objects from disk so that they can be written to Archive::Libarchive::ArchiveWrite objects.

Archive::Libarchive::DiskWrite
    This class is for writing Archive::Libarchive::Entry objects to disk that have been written from Archive::Libarchive::ArchiveRead objects.

Archive::Libarchive::Entry
    This class represents a file in an archive, or on disk.

Archive::Libarchive::EntryLinkResolver
    This class exposes the "libarchive" link resolver API.

Archive::Libarchive::Match
    This class exposes the "libarchive" match API.

Dist::Zilla::Plugin::Libarchive
    Build Dist::Zilla based dist tarballs with libarchive instead of the built in Archive::Tar.

Alien::Libarchive3
    If a suitable system "libarchive" can't be found, then this Alien will be installed to provide it.

libarchive.org <http://libarchive.org/>
    The "libarchive" project home page.

<https://github.com/libarchive/libarchive/wiki>
    The "libarchive" project wiki.

<https://github.com/libarchive/libarchive/wiki/ManualPages>
    Some of the "libarchive" man pages are listed here.

AUTHOR
Graham Ollis <plicease@cpan.org>

COPYRIGHT AND LICENSE
This software is copyright (c) 2021,2022 by Graham Ollis.

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.