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RarEntry::getCrc

(PECL rar >= 0.1)

RarEntry::getCrcGet CRC of the entry

Descrição

public RarEntry::getCrc ( void ) : string

Returns an hexadecimal string representation of the CRC of the archive entry.

Parâmetros

Esta função não possui parâmetros.

Valor Retornado

Returns the CRC of the archive entry or FALSE on error.

Changelog

Versão Descrição
2.0.0 This method now returns correct values for multiple volume archives.

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User Contributed Notes 1 note

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aterlux at mail dot ru
1 year ago
RarEntry::getCrc() returs a lowercase hex-string (e.g. 'bf6fa85c') the same as hash_... functions, using the same polynomial as 'crc32b' algorithm.
So, it can be used to check CRC after a stream unpacking:

<?php
  $archive_name
= 'archive.rar';

 
$entry_name = 'someentry.ext';

 
$rar = RarArchive::open($archive_name) or die("Cannot open archive $archive_name");

  if (
$rar->isBroken()) {
    die(
"The archive is broken!");
  }

 
$entry = $rar->getEntry($entry_name) or die("Cannot find entry $entry_name");

 
$stream = $entry->getStream() or die("Cannot open stream");

 
$crc = hash_init('crc32b'); // Initializing the hash function

 
while (!feof($stream)) {
   
$s = fread($stream, 8192);
    if (
$s === false) {
       
// Error reading (do not use fread(...) or die(...), because fread can return '0'!)
     
die('Error reading the compressed file.');
    }
   
hash_update($crc, $s); // updating the hash

    // ...
    // Do whatever with the $s
 
}

 
fclose($stream);

 
$got_crc = hash_final($crc);
 
$need_crc = $entry->getCrc();

  print(
"Got CRC: $got_crc" . PHP_EOL);
  print(
"Need CRC: $need_crc" . PHP_EOL);

  if (
$got_crc != $need_crc) {
   
// rollback
   
print("Sorry guys, the file was incorrect!" . PHP_EOL);
  } else {
    print(
"Everything is ok" . PHP_EOL);
  }
?>
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