Extracting a TAR-archive

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

• Unix V7
• Ustar
• POSIX
• Gnu

Each format can be extracted from the archive. Appending entries to the archive is only available for Unix V7 and Ustar format.

Extracting an Archive comes in two flavors:

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

The Archive can be treated like an iterator. After opening the archive, it points to the first entry. The iterator can be moved using the 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:

1. <?php
3. include( "tutorial_autoload.php" );
4. date_default_timezone_set( "UTC" );
6. // Open the gzipped TAR archive.
7. $archive = ezcArchive::open( "compress.zlib:///tmp/my_archive.tar.gz" );
9. while( $archive->valid() )
10. {
11. // Returns the current entry (ezcArchiveEntry).
12. $entry = $archive->current();
14. // ezcArchiveEntry has an __toString() method.
15. echo $entry, "\n";
17. // Extract the current archive entry to /tmp/target_location/
18. $archive->extractCurrent( "/tmp/target_location/" );
20. $archive->next();
21. }
23. ?>

First the 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 uses some date functions and without a time zone PHP may show some warnings.

The gzipped TAR archive is opened using the zlib stream. The while() method iterates over each entry, shows the name, and extracts the entry itself.

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

1. <?php
3. include( "tutorial_autoload.php" );
4. date_default_timezone_set( "UTC" );
6. $archive = ezcArchive::open( "compress.zlib:///tmp/my_archive.tar.gz" );
8. // The foreach method calls internally the iterator methods.
9. foreach( $archive as $entry )
10. {
11. echo $entry, "\n";
13. $archive->extractCurrent( "/tmp/target_location/" );
14. }
16. ?>

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 library 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 also the first file, the ezcArchive->truncate() should be used. The next example replaces all entries from an existing Zip archive with the files file1.txt and file2.txt:

1. <?php
3. include( "tutorial_autoload.php" );
4. date_default_timezone_set( "UTC" );
6. $archive = ezcArchive::open( "/tmp/my_archive.zip" );
7. $archive->truncate();
9. $filesToAppend[] = "/tmp/file1.txt";
10. $filesToAppend[] = "/tmp/file2.txt";
12. // The second parameter specifies prefix. The prefix is normally not included
13. // in the archive.
14. $archive->appendToCurrent( $filesToAppend, "/tmp/" );
16. ?>