Description:
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It seems that there is a long-lasting bug in PHP that prevents socket_read (called on a server-side socket returned from socket_accept()) to return false when TCP connection is closed (no matter how - gracefully or not).

Here this bug is mention also: http://stackoverflow.com/questions/9085615/php-detecting-remote-host-disconnection

Test script:
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https://github.com/zyura/PHPSrv/blob/master/tcpserver.php

Expected result:
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socket_read() returns FALSE when client disconnects and socket_last_error() returns adequate error code.

Actual result:
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when client disconnects socket_read() always return empty string '' keeping client socket forever...