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eZ Components - Archive
~~~~~~~~~~~~~~~~~~~~~~~

.. contents:: Table of Contents

Introduction
============

The Archive component provides a generic API for creating and extracting
archives.  Currently, the Archive component supports the Tar and Zip formats.
Compression algorithms, such as GZip or BZip2, are indirectly supported.
The stream wrappers from PHP should be used to handle compressed archives.

Class overview
==============

The following list sums up the most important classes:

ezcArchive
  This class provides the main API for accessing or creating a
  Tar or Zip archive. ezcArchive provides methods for
  extracting entries (files, directories, symbolic links and so on), appending
  entries and removing entries.

ezcArchiveEntry
  The ezcArchiveEntry class is returned when an entry (such as a file or
  directory) is requested from the opened archive. ezcArchiveEntry provides
  entry information about the path, its access rights and whether the entry is
  a directory, a symbolic link, a hard link, a block-file and so on. The owner name, the
  group name and the last access time are also available. 
 
More information about these classes can be found in the documentation of the
class itself.

Usage
=====

The following examples demonstrate how to use the Archive component.

Extracting a Tar-archive
------------------------

The Tar format has more than one standard. The most common formats are:

- Gnu
- POSIX
- Unix V7
- Ustar (The default when creating a tar archive)

The Archive component can extract from any of these formats. Appending entries
to the archive is only available for the Unix V7 and Ustar formats.

Extracting entries can occur in two ways:

- ezcArchive->extract(), extracts all entries from the archive.
- ezcArchive->extractCurrent(), extracts only the current entry.

An ezcArchive object can be used like an iterator. After opening the file, it
points to the first entry. The iterator can be moved using ezcArchive->next()
and ezcArchive->rewind() to move to the next entry or go back to the first
entry.

The next example demonstrates how to extract an entire archive file-by-file:

.. include:: tutorial_extract.php
   :literal:

First, tutorial_autoload.php is included. The included file loads the
correct php files for the Archive package. Hereafter the time zone is set to
"UTC". The Archive component uses some date functions and might therefore
produce warnings if the time zone is not specified.

The gzipped Tar archive is opened using the zlib stream. The while() method
iterates over each entry, showing the name and extracting the entry itself.

The Archive component extends from the PHP Iterator class, thus the above
example can be rewritten as follows:

.. include:: tutorial_iterator.php
   :literal:

Please be aware that by default archive files are opened in read/write mode. In
order to prevent that, you can set an option to open the archive in read-only
mode. This also prevents the modify and create timestamps of the file to be
preserved. The following example shows that:

.. include:: tutorial_read_only.php
   :literal:

Appending files to an archive
-----------------------------

Unfortunately, it is not yet possible to directly append files to a gzipped or
bzipped Tar archive. The ZLib and BZip2 libraries do not support opening a file
for reading and writing.

ezcArchive has two methods for appending files:

- ezcArchive->append(), appends entries to the end of the archive.
- ezcArchive->appendCurrent(), appends entries after the current entry and
  removes the rest of the files from the archive.

To replace the first file as well, use ezcArchive->truncate().  The 
next example replaces all entries from an existing Zip archive with the files
file1.txt and file2.txt:

.. include:: tutorial_replacing.php
   :literal:

Appending directories to an archive
-----------------------------------

You need to append a slash '/' to the end of the directory name that is added
to an archive.

The next example replaces all entries from an existing Zip archive with the
'directory' folder and the 'file.txt' file:

.. include:: tutorial_directories.php
   :literal:

Appending a directory tree to an archive
----------------------------------------

Using the function ezcBase::walkRecursive() a directory tree can be added to
an archive.

The next example shows how to browse a directory tree and add all the files
and directories inside to an archive:

.. include:: tutorial_recursive.php
   :literal:

The **ArchiveContext** class will hold the archive object which is passed to
the callback function *findRecursiveCallback*. The *appendRecursive* function
sets up the context object (of class **ArchiveContext**) and calls the
*findRecursiveCallback* function. In the *findRecursiveCallback* function the
current file or directory is appended to the archive object inside the
context.

More Information
================

For more information, see the ezcArchive API documentation.

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