TarArchiveReader.php in Backup and Migrate 8.4

Namespace

BackupMigrate\Core\Service

File

lib/backup_migrate_core/src/Service/TarArchiveReader.php

<?php

namespace BackupMigrate\Core\Service;

use BackupMigrate\Core\Exception\BackupMigrateException;
use BackupMigrate\Core\File\BackupFileReadableInterface;

/**
 * Class TarArchiveReader.
 *
 * @package BackupMigrate\Core\Service
 */
class TarArchiveReader implements ArchiveReaderInterface {

  /**
   * @var BackupFileReadableInterface
   */
  protected $archive;

  /**
   * Get the file extension for this archiver. For a tarball writer this would
   * be 'tar'. For a Zip file writer this would be 'zip'.
   *
   * @return string
   */
  public function getFileExt() {
    return 'tar';
  }

  /**
   * {@inheritdoc}
   */
  public function setArchive(BackupFileReadableInterface $out) {
    $this->archive = $out;
  }

  /**
   * Extract all files to the given directory.
   *
   * @param $directory
   *
   * @return mixed
   */
  public function extractTo($directory) {
    $this->archive
      ->openForRead(TRUE);
    $result = $this
      ->extractAllToDirectory($directory);
    $this->archive
      ->close();
    return $result;
  }

  /**
   * @param $directory
   *  The directory to extract the files to.
   * @return bool
   * @throws \BackupMigrate\Core\Exception\BackupMigrateException
   */
  private function extractAllToDirectory($directory) {
    clearstatcache();

    // Read a header block.
    while (strlen($block = $this->archive
      ->readBytes(512)) != 0) {
      $header = $this
        ->readHeader($block);
      if (!$header) {
        return FALSE;
      }
      if ($header['filename'] == '') {
        continue;
      }

      // Check for potentially malicious files (containing '..' etc.).
      if ($this
        ->maliciousFilename($header['filename'])) {
        throw new BackupMigrateException('Malicious .tar detected, file %filename. Will not install in desired directory tree', [
          '%filename' => $header['filename'],
        ]);
      }

      // ignore extended / pax headers.
      if ($header['typeflag'] == 'x' || $header['typeflag'] == 'g') {
        $this->archive
          ->seekBytes(ceil($header['size'] / 512));
        continue;
      }

      // Add the destination directory to the path.
      if (substr($header['filename'], 0, 1) == '/') {
        $header['filename'] = $directory . $header['filename'];
      }
      else {
        $header['filename'] = $directory . '/' . $header['filename'];
      }

      // If the file already exists, make sure we can overwrite it.
      if (file_exists($header['filename'])) {

        // Cannot overwrite a directory with a file.
        if (@is_dir($header['filename']) && $header['typeflag'] == '') {
          throw new BackupMigrateException('File %filename already exists as a directory', [
            '%filename' => $header['filename'],
          ]);
        }

        // Cannot overwrite a file with a directory.
        if (@is_file($header['filename']) && !@is_link($header['filename']) && $header['typeflag'] == "5") {
          throw new BackupMigrateException('Directory %filename already exists as file', [
            '%filename' => $header['filename'],
          ]);
        }

        // Cannot overwrite a read-only file.
        if (!is_writeable($header['filename'])) {
          throw new BackupMigrateException('File %filename already exists and is write protected', [
            '%filename' => $header['filename'],
          ]);
        }
      }

      // Extract a directory.
      if ($header['typeflag'] == "5") {
        if (!$this
          ->createDir($header['filename'])) {
          throw new BackupMigrateException('Unable to create directory %filename', [
            '%filename' => $header['filename'],
          ]);
        }
      }
      else {
        if (!$this
          ->createDir(dirname($header['filename']))) {
          throw new BackupMigrateException('Unable to create directory for %filename', [
            '%filename' => $header['filename'],
          ]);
        }

        // Symlink.
        if ($header['typeflag'] == "2") {
          if (@file_exists($header['filename'])) {
            @unlink($header['filename']);
          }
          if (!@symlink($header['link'], $header['filename'])) {
            throw new BackupMigrateException('Unable to extract symbolic link: %filename', [
              '%filename' => $header['filename'],
            ]);
          }
        }
        else {

          // Open the file for writing.
          if (($dest_file = @fopen($header['filename'], "wb")) == 0) {
            throw new BackupMigrateException('Error while opening %filename in write binary mode', [
              '%filename' => $header['filename'],
            ]);
          }

          // Write the file.
          $n = floor($header['size'] / 512);
          for ($i = 0; $i < $n; $i++) {
            $content = $this->archive
              ->readBytes(512);
            fwrite($dest_file, $content, 512);
          }
          if ($header['size'] % 512 != 0) {
            $content = $this->archive
              ->readBytes(512);
            fwrite($dest_file, $content, $header['size'] % 512);
          }
          @fclose($dest_file);

          // Change the file mode, mtime.
          @touch($header['filename'], $header['mtime']);
          if ($header['mode'] & 0111) {

            // make file executable, obey umask.
            $mode = fileperms($header['filename']) | ~umask() & 0111;
            @chmod($header['filename'], $mode);
          }
          clearstatcache();

          // Check if the file exists.
          if (!is_file($header['filename'])) {
            throw new BackupMigrateException('Extracted file %filename does not exist. Archive may be corrupted.', [
              '%filename' => $header['filename'],
            ]);
          }

          // Check the file size.
          $file_size = filesize($header['filename']);
          if ($file_size != $header['size']) {
            throw new BackupMigrateException('Extracted file %filename does not have the correct file size. File is %actual bytes (%expected bytes expected). Archive may be corrupted', [
              '%filename' => $header['filename'],
              '%expected' => (int) $header['size'],
              (int) '%actual' => $file_size,
            ]);
          }
        }
      }
    }
    return TRUE;
  }

  /**
   * Create a directory or return true if it already exists.
   *
   * @param $directory
   *
   * @return boolean
   */
  private function createDir($directory) {
    if (@is_dir($directory) || $directory == '') {
      return TRUE;
    }
    $parent = dirname($directory);
    if ($parent != $directory && $parent != '' && !$this
      ->createDir($parent)) {
      return FALSE;
    }
    if (@(!mkdir($directory, 0777))) {
      return FALSE;
    }
    return TRUE;
  }

  /**
   * Read a tar file header block.
   *
   * @param $block
   * @param array $header
   *
   * @return array
   *
   * @throws \BackupMigrate\Core\Exception\BackupMigrateException
   */
  private function readHeader($block, $header = []) {
    if (strlen($block) == 0) {
      $header['filename'] = '';
      return TRUE;
    }
    if (strlen($block) != 512) {
      $header['filename'] = '';
      throw new BackupMigrateException('Invalid block size: %size bytes', [
        '%size' => strlen($block),
      ]);
    }
    if (!is_array($header)) {
      $header = [];
    }

    // Calculate the checksum.
    $checksum = 0;

    // First part of the header.
    for ($i = 0; $i < 148; $i++) {
      $checksum += ord(substr($block, $i, 1));
    }

    // Ignore the checksum value and replace it by ' ' (space).
    for ($i = 148; $i < 156; $i++) {
      $checksum += ord(' ');
    }

    // Last part of the header.
    for ($i = 156; $i < 512; $i++) {
      $checksum += ord(substr($block, $i, 1));
    }
    if (version_compare(PHP_VERSION, "5.5.0-dev") < 0) {
      $fmt = "a100filename/a8mode/a8uid/a8gid/a12size/a12mtime/" . "a8checksum/a1typeflag/a100link/a6magic/a2version/" . "a32uname/a32gname/a8devmajor/a8devminor/a131prefix";
    }
    else {
      $fmt = "Z100filename/Z8mode/Z8uid/Z8gid/Z12size/Z12mtime/" . "Z8checksum/Z1typeflag/Z100link/Z6magic/Z2version/" . "Z32uname/Z32gname/Z8devmajor/Z8devminor/Z131prefix";
    }
    $data = unpack($fmt, $block);
    if (strlen($data["prefix"]) > 0) {
      $data["filename"] = "{$data['prefix']}/{$data['filename']}";
    }

    // Extract the checksum.
    $header['checksum'] = octdec(trim($data['checksum']));
    if ($header['checksum'] != $checksum) {
      $header['filename'] = '';

      // Look for last block (empty block).
      if ($checksum == 256 && $header['checksum'] == 0) {
        return $header;
      }
      throw new BackupMigrateException('Invalid checksum for file %filename', [
        '%filename' => $data['filename'],
      ]);
    }

    // Extract the properties.
    $header['filename'] = rtrim($data['filename'], "\0");
    $header['mode'] = octdec(trim($data['mode']));
    $header['uid'] = octdec(trim($data['uid']));
    $header['gid'] = octdec(trim($data['gid']));
    $header['size'] = octdec(trim($data['size']));
    $header['mtime'] = octdec(trim($data['mtime']));
    if (($header['typeflag'] = $data['typeflag']) == "5") {
      $header['size'] = 0;
    }
    $header['link'] = trim($data['link']);

    // Look for long filename.
    if ($header['typeflag'] == 'L') {
      $header = $this
        ->readLongHeader($header);
    }
    return $header;
  }

  /**
   * Read a tar file header block for files with long names.
   *
   * @param $header
   *
   * @return array
   *
   * @throws \BackupMigrate\Core\Exception\BackupMigrateException
   */
  private function readLongHeader($header) {
    $filename = '';
    $filesize = $header['size'];
    $n = floor($header['size'] / 512);
    for ($i = 0; $i < $n; $i++) {
      $content = $this->archive
        ->readBytes(512);
      $filename .= $content;
    }
    if ($header['size'] % 512 != 0) {
      $content = $this->archive
        ->readBytes(512);
      $filename .= $content;
    }
    $filename = rtrim(substr($filename, 0, $filesize), "\0");

    // Read the next header.
    $data = $this->archive
      ->readBytes(512);
    $header = $this
      ->readHeader($data, $header);
    $header['filename'] = $filename;
    return $header;
  }

  /**
   * Detect and report a malicious file name.
   *
   * @param string $file
   *
   * @return bool
   */
  private function maliciousFilename($file) {
    if (strpos($file, '/../') !== FALSE) {
      return TRUE;
    }
    if (strpos($file, '../') === 0) {
      return TRUE;
    }
    return FALSE;
  }

  /**
   * This will be called when all files have been added. It gives the implementation
   * a chance to clean up and commit the changes if needed.
   *
   * @return mixed
   */
  public function closeArchive() {
    if ($this->archive) {
      $this->archive
        ->close();
    }
  }

}

Classes

Name	Description
TarArchiveReader	Class TarArchiveReader.