Description:
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PHP's is_readable function seems to always return false for a file that has been made available offline using the Windows Offline Files functionality (http://windows.microsoft.com/en-us/windows/understanding-offline-files#1TC=windows-7) in offline mode, even if the file can be read using fread and related functions. If the offline share is put back into online mode, is_readable returns true again.

I experience this problem both for shares hosted on Windows and on Linux (using Samba).

Test script:
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<?php
// 'U:' is network share that has been made 'Always available' using Windows Offline Files
// 'test.txt' is an existing file that can be read and written by the user running PHP
var_dump(is_readable('U:/test.txt'));
$fp = fopen('U:/test.txt', 'r');
var_dump($fp);


Expected result:
----------------
bool(true)
resource(#) of type (stream)

Actual result:
--------------
// When the share is in offline mode ('Work offline')
bool(false)
resource(5) of type (stream)

// When the share is in online mode ('Work online')
bool(true)
resource(5) of type (stream)