Dimensions rule fails to correctly check ratio 1/1 when height equals to width + 1

[OrkhanAlikhanov]

• Laravel Version: 5.4 onwards ([5.4] Ratio validation - allow precision to be based on size of image #19542), 6.x, 7.x
• PHP Version: 7.4.2
• Database Driver & Version: N/A

Description:

Dimensions rule fails to correctly check ratio 1/1 when height equals to width + 1. Following case passes validation while it should not:

width: n
height: n + 1
ratio: 1/1

Here is the code:

framework/src/Illuminate/Validation/Concerns/ValidatesAttributes.php

Lines 556 to 569 in 8f22cab

	protected function failsRatioCheck($parameters, $width, $height)
	{
	if (! isset($parameters['ratio'])) {
	return false;
	}
	[$numerator, $denominator] = array_replace(
	[1, 1], array_filter(sscanf($parameters['ratio'], '%f/%d'))
	);
	$precision = 1 / max($width, $height);
	return abs($numerator / $denominator - $width / $height) > $precision;
	}

What it simplifies to:

  $precision = 1 / max($width, $height);
  $precision = 1 / (n + 1)

  $leftCalc = abs($numerator / $denominator - $width / $height)
  $leftCalc = 1 - n / (n + 1)
  $leftCalc = 1 / (n + 1) (became same as $precision)

check for fail:
  $leftCalc > $precision (which returns false, meaning it did not fail)

Steps To Reproduce:

use Illuminate\Http\UploadedFile;

$n = 64;

Validator::make([
	'image' => UploadedFile::fake()->image('image.png', $n, $n + 1),
], ['image' => 'dimensions:ratio=1'])
  ->errors()
  ->all()

[driesvints]

This seems to be a bug specifically with the faking of images because when I write a test for this scenario in the framework with a real image it behaves as expected. I'm not sure what's going on here. Afaik the faked file's dimensions are passed correctly but the validator isn't behaving as expected.

[brettwhiteman]

It's a float comparison issue and it only happens with certain values of $n in the example above. For example validation passes with $n=64 but not with $n=72

I will submit a PR for this shortly.

[driesvints]

Sent in #34003 for this.