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WordPress

Parser::parse_ftyp(): bool

Source
wp-includes/class-avif-info.php:734
Parses a file stream.

Description

The file type is checked through the "ftyp" box.

Compatibility

WordPress
core
PHP
7.4–8.6-dev
  • 6.7.7
  • 6.8.8
  • 6.9.7
  • 7.0.4
  • 7.1.0

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

Return value

bool
True if the input stream is an AVIF bitstream or false.

Performance profile

How much work a call to Parser::parse_ftyp() 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
Light

Touches nothing outside its own arguments.

Scaling
Scales with input

The body loops, so the work grows with how much data it finds.

Instructions
16–55

Executed per call on PHP 8.5, depending on the branch taken. The body compiles to 64.

Plugin surface
None

Nothing here hands control to plugin code.

Called by
0

Nothing in core calls this; the cost is only what you spend yourself.

What one call costs · 3 distinct outcomes

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

WhenInstructionsCalls it makes
always16–28->parse()
$status == false36–48->parse(), read()
$status == false && $i != 451–55->parse(), read(), skip()

Across PHP versions

PHPCompiledExecutedBranchesNotes
8.6-dev6416–559
8.56416–559
8.46416–5596 fewer instructions than PHP 8.3
8.37016–619
8.27016–619
8.17016–619
7.47016–619

An instruction is not a fixed amount of time, so a matching count is not necessarily the same speed; what it rules out is a difference in the work itself.

Uses · 3

  • read()Reads bytes and advances the stream position by the same count.
  • skip()Advances the stream position by the given offset.
  • \Avifinfo\Box::__construct()

Source code

View on Trac View on GitHub 

  public function parse_ftyp() {    $box    = new Box();    $status = $box->parse( $this->handle, $this->num_parsed_boxes );    if ( $status != FOUND ) {      return false;    }     if ( $box->type != 'ftyp' ) {      return false;    }    // Iterate over brands. See ISO/IEC 14496-12:2012(E) 4.3.1    if ( $box->content_size < 8 ) {      return false;    }    for ( $i = 0; $i + 4 <= $box->content_size; $i += 4 ) {      if ( !( $data = read( $this->handle, 4 ) ) ) {        return false;      }      if ( $i == 4 ) {        continue; // Skip minor_version.      }      if ( substr( $data, 0, 4 ) == 'avif' || substr( $data, 0, 4 ) == 'avis' ) {        return skip( $this->handle, $box->content_size - ( $i + 4 ) );      }      if ( $i > 32 * 4 ) {        return false; // Be reasonable.      }     }    return false; // No AVIF brand no good.  }

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-includes/class-avif-info.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.
Corrections
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