(PHP Extension) Decompress Large Text File in Blocks

Decompresses a large text file in blocks, and compares the restored (decompressed) file with the original to make sure it's correct.

Chilkat PHP Downloads PHP Extension for Windows, Linux, MacOS, Alpine Linux, Solaris

<?php

// The version number (9_5_0) should match version of the Chilkat extension used, omitting the micro-version number.
// For example, if using Chilkat v9.5.0.48, then include as shown here:
include("chilkat_9_5_0.php");

// This example requires the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.

// First, let's compress a text file.
// We'll then decompress in blocks, and compare the decompressed with the original file.

// Compress a text file:
$compress = new CkCompression();
$compress->put_Algorithm('deflate');

$success = $compress->CompressFile('qa_data/hamlet.xml','qa_data/hamlet_compressed.dat');
if ($success != true) {
    print $compress->lastErrorText() . "\n";
    exit;
}

$fac = new CkFileAccess();

// Examine the uncompressed and compressed sizes:
$originalPath = 'qa_data/hamlet.xml';
// Note: The FileSize method returns a signed 32-bit integer.  If the file is potentially larger than 2GB, call FileSizeStr instead to return
// the size of the file as a string, then convert to an integer value.
print 'uncompressed size: ' . $fac->FileSize($originalPath) . "\n";
print 'compressed size: ' . $fac->FileSize('qa_data/hamlet_compressed.dat') . "\n";

// Decompress in blocks..
$facSrc = new CkFileAccess();
$facDest = new CkFileAccess();

$facSrc->OpenForRead('qa_data/hamlet_compressed.dat');

// If we compress in 32K chunks, find out how many blocks there will be.
$blockSize = 32768;
$numBlocks = $facSrc->GetNumBlocks($blockSize);

// Open an output file for the decompressed data.
$restoredPath = 'qa_output/hamlet_restored.xml';
$success = $facDest->OpenForWrite($restoredPath);
if ($success != true) {
    print $facDest->lastErrorText() . "\n";
    exit;
}

$compressedBytes = new CkByteData();

$i = 0;
while ($i < $numBlocks) {
    $success = $facSrc->ReadBlock($i,$blockSize,$compressedBytes);
    if ($i == 0) {
        $decompressedStr = $compress->beginDecompressString($compressedBytes);
    }
    else {
        $decompressedStr = $compress->moreDecompressString($compressedBytes);
    }

    $facDest->AppendText($decompressedStr,'utf-8');

    $i = $i + 1;
}

// At the very end, flush any remaining content, if any.
$decompressedStr = $compress->endDecompressString();
$facDest->AppendText($decompressedStr,'utf-8');

$facSrc->FileClose();
$facDest->FileClose();

// Examine the size of the restored file.
print 'restored size: ' . $fac->FileSize($restoredPath) . "\n";

// Compare the contents of the original with the restored.
$bEqualContents = $fac->FileContentsEqual($restoredPath,$originalPath);
print 'Contents Equal: ' . $bEqualContents . "\n";

?>