Please try using this CVS snapshot:

  http://snaps.php.net/php5.2-latest.tar.gz
 
For Windows:
 
  http://snaps.php.net/win32/php5.2-win32-latest.zip

Correction to prevois post:
Reading the documentation I noticed "If accessing the filename image is impossible, or if it isn't a valid picture, getimagesize() will generate an error of level E_WARNING", meaning the expected result should be an error of level E_WARNING in any case of the file not being an image.

No bug -> bogus.

Same thing happens using the latest CVS Snapshot. "Read error!" on getimagesize() on a textfile containing less than 12 characters. No warning on getimagesize() on the same file containing 13 characters.

Why did you reopen? You get a warning, just like the docs say...

Am I missing something? The docs says "If accessing the filename image is impossible, or if it isn't a valid picture, getimagesize() will generate an error of level E_WARNING". Using getimagesize on a textfile  containing 12 or more characters or any other file not being a valid picture, say a pdf-document, does not produce a warning? The only time I get a warning is using a textfile containing less than 12 characters.

code
----

file_put_contents("test", "123456789012");
echo "12 chars:\n";
var_dump(getimagesize("test"));
file_put_contents("test", "1234567890");
echo "10 chars:\n";
var_dump(getimagesize("test"));


output
------

12 chars:
bool(false)
10 chars:
Warning: getimagesize(): Read error! in /home/user/test.php on line 8
bool(false)

The same thing happens to me on a linux box with 5.2.2.
The problem is not that an error appears, but that it only appears when you use the function on a very small file. According to the docs the error should appear on all invalid files. 

I do prefer that it doesn't give off any warnings tho as the function is a nice way to check for invalid images. I just use an extra check for the length of the file to avoid the error altogether since no image files get as small as just a couple of bytes.

"I do prefer that it doesn't give off any warnings tho as the function is a nice way to check for invalid images."

I agree, such functions should be quiet unless something critical for php happened, invalid images do not fit in this category.

This bug has been fixed in CVS.

Snapshots of the sources are packaged every three hours; this change
will be in the next snapshot. You can grab the snapshot at
http://snaps.php.net/.
 
Thank you for the report, and for helping us make PHP better.

Read errors have been downgraded to E_NOTICE.

Re-open as documentation problem (see Ilias comment)

This bug has been fixed in the documentation's XML sources. Since the
online and downloadable versions of the documentation need some time
to get updated, we would like to ask you to be a bit patient.

Thank you for the report, and for helping us make our documentation better.

Re-opening as getimagesize-related as bug was not fixed in HEAD.

This bug has been fixed in CVS.

Snapshots of the sources are packaged every three hours; this change
will be in the next snapshot. You can grab the snapshot at
http://snaps.php.net/.
 
Thank you for the report, and for helping us make PHP better.

Thanks for the head up!

I am using the following code with PHP 5.3.3
--
<?php

file_put_contents('abc', '12345678901');

$v = getimagesize('abc');

unlink('abc')

?>
--
and I get the notice "getimagesize(): Read error!". Therefore I would say that this is a regression? Do note that with the text '123456789012' I do not get the notice. So it is exactly as the bug opener described it and the bug is not fixed. Please reopen.