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Re: Checking if file is an image [message #170870 is a reply to message #170857]

Sat, 04 December 2010 11:39

Michael Fesser
Messages: 215
Registered: September 2010

Karma:

Senior Member

.oO(jwcarlton)

> I have a section that shows an uploaded image. I was doing this:
>
> list($width, $height, $type, $attr) = @getimagesize("/path/to/
> $image");
>
> if (!$width) {
> $image = "noimage.gif";
> $width = "75";
> $height = "95";
> }
>
> I understand that error suppression has a bit of a performance hit,

Not really, it's just ugly.

> though, so I'm curious if either of these would be better:
>
> if (is_readable("/path/to/$image"))
> list($width, $height, $type, $attr) = @getimagesize("/path/to/
> $image");

if (is_readable("/path/to/$image"))
list($width, $height, $type, $attr) = getimagesize("/path/to/
$image");

> Either would still be followed with "if (!$width)...". I know that
> neither are fool-proof because they don't check that someone didn't
> rename an .xls or .exe to .jpg

They do, because non-image files won't have valid 'width' and 'height'
values.

> but I can probably control that better
> on the upload side than checking here on every page load.

The check that an uploaded file is a valid image would still have to be
done with getimagesize(), because you can't rely on filename and content
type.

> Here, I'm
> more concerned with speed

Do you have a real performance issue? Most likely not.

> and not showing any error messages for
> faulty images.

Simply disable errors on the production system (not on the development
system, though) and check the return values of getimagesize().

Micha

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[Message index]

		Checking if file is an image By: jwcarlton on Sat, 04 December 2010 01:37
		Re: Checking if file is an image By: Magno on Sat, 04 December 2010 02:06
		Re: Checking if file is an image By: jwcarlton on Sat, 04 December 2010 02:38
		Re: Checking if file is an image By: Michael Fesser on Sat, 04 December 2010 11:39
		Re: Checking if file is an image By: Magno on Sat, 04 December 2010 15:10
		Re: Checking if file is an image By: Jerry Stuckle on Sat, 04 December 2010 03:34
		Re: Checking if file is an image By: Michael Fesser on Sat, 04 December 2010 11:39
		Re: Checking if file is an image By: The Natural Philosoph on Sat, 04 December 2010 19:19

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