PclZip::privReadEndCentralDir( $p_central_dir )

Compatibility

Present in every tracked release (6.7.7 to 7.1.0), and compiles on PHP 7.4 through 8.6-dev.

Parameters

$p_central_dir

Performance profile

How much work a call to PclZip::privReadEndCentralDir() does, and what it touches: the algorithmic scaling, the Zend instruction count per call across PHP versions, the hooks it hands control to, and the core code that calls it. Measured from the compiled opcodes, not a stopwatch, so every number is identical on any machine running the same PHP version, and every function in core is ranked by cost.

Cost class

Heavy

Reads or writes the filesystem via filesize().

Scaling

Scales with input

The body loops, so the work grows with what you pass in.

Instructions

31–160

Executed per call on PHP 8.5, depending on the branch taken. The body compiles to 214.

Plugin surface

None

Nothing here hands control to plugin code.

Called by

6

6 places in core call this, so the cost is paid more often than your own code shows.

What it touches

• filesystemfilesystem accessfilesize()called directly

What one call costs · 25 distinct outcomes

One number would be a lie: the work depends on which branch runs. These are every distinct cost PclZip::privReadEndCentralDir() can have, taken from its control-flow graph on PHP 8.5.

Uses · 2

• PclZip::privErrorLog()
• PclZip::errorCode()

Used by · 6

• PclZip::privAdd()
• PclZip::privDeleteByRule()
• PclZip::privExtractByRule()
• PclZip::privList()
• PclZip::privMerge()
• PclZip::properties()

Source code

View on Trac ↗View on GitHub ↗

4553  function privReadEndCentralDir(&$p_central_dir)4554  {4555    $v_result=1;4556 4557    // ----- Go to the end of the zip file4558    $v_size = filesize($this->zipname);4559    @fseek($this->zip_fd, $v_size);4560    if (@ftell($this->zip_fd) != $v_size)4561    {4562      // ----- Error log4563      PclZip::privErrorLog(PCLZIP_ERR_BAD_FORMAT, 'Unable to go to the end of the archive \''.$this->zipname.'\'');4564 4565      // ----- Return4566      return PclZip::errorCode();4567    }4568 4569    // ----- First try : look if this is an archive with no commentaries (most of the time)4570    // in this case the end of central dir is at 22 bytes of the file end4571    $v_found = 0;4572    if ($v_size > 26) {4573      @fseek($this->zip_fd, $v_size-22);4574      if (($v_pos = @ftell($this->zip_fd)) != ($v_size-22))4575      {4576        // ----- Error log4577        PclZip::privErrorLog(PCLZIP_ERR_BAD_FORMAT, 'Unable to seek back to the middle of the archive \''.$this->zipname.'\'');4578 4579        // ----- Return4580        return PclZip::errorCode();4581      }4582 4583      // ----- Read for bytes4584      $v_binary_data = @fread($this->zip_fd, 4);4585      $v_data = @unpack('Vid', $v_binary_data);4586 4587      // ----- Check signature4588      if ($v_data['id'] == 0x06054b50) {4589        $v_found = 1;4590      }4591 4592      $v_pos = ftell($this->zip_fd);4593    }4594 4595    // ----- Go back to the maximum possible size of the Central Dir End Record4596    if (!$v_found) {4597      $v_maximum_size = 65557; // 0xFFFF + 22;4598      if ($v_maximum_size > $v_size)4599        $v_maximum_size = $v_size;4600      @fseek($this->zip_fd, $v_size-$v_maximum_size);4601      if (@ftell($this->zip_fd) != ($v_size-$v_maximum_size))4602      {4603        // ----- Error log4604        PclZip::privErrorLog(PCLZIP_ERR_BAD_FORMAT, 'Unable to seek back to the middle of the archive \''.$this->zipname.'\'');4605 4606        // ----- Return4607        return PclZip::errorCode();4608      }4609 4610      // ----- Read byte per byte in order to find the signature4611      $v_pos = ftell($this->zip_fd);4612      $v_bytes = 0x00000000;4613      while ($v_pos < $v_size)4614      {4615        // ----- Read a byte4616        $v_byte = @fread($this->zip_fd, 1);4617 4618        // -----  Add the byte4619        //$v_bytes = ($v_bytes << 8) | ord($v_byte);4620        // Note we mask the old value down such that once shifted we can never end up with more than a 32bit number4621        // Otherwise on systems where we have 64bit integers the check below for the magic number will fail.4622        $v_bytes = ( ($v_bytes & 0xFFFFFF) << 8) | ord($v_byte);4623 4624        // ----- Compare the bytes4625        if ($v_bytes == 0x504b0506)4626        {4627          $v_pos++;4628          break;4629        }4630 4631        $v_pos++;4632      }

Changelog

Unchanged from 6.7.7 through 7.1.0.

1. 6.7.7
2. 6.8.8
3. 6.9.7
4. 7.0.4
5. 7.1.0

Signature, return type and hooks compared across 5 parsed releases.

About this page

Parsed data

Generated from the wordpress-develop 7.1.0 tag, from src/wp-admin/includes/class-pclzip.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.

Corrections

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