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Request #60938 xp_socket.c functions should respect pcntl signal handlers
Submitted: 2012-01-31 13:41 UTC Modified: 2021-09-05 04:22 UTC
Votes:2
Avg. Score:5.0 ± 0.0
Reproduced:2 of 2 (100.0%)
Same Version:1 (50.0%)
Same OS:2 (100.0%)
From: nasretdinov at gmail dot com Assigned: cmb (profile)
Status: No Feedback Package: PCNTL related
PHP Version: 5.3.9 OS: *nix
Private report: No CVE-ID: None
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 [2012-01-31 13:41 UTC] nasretdinov at gmail dot com
Description:
------------
Socket functions in xp_socket.c read and write indefinitely in case they received  
any 
signal (read/write returned EINTR). Example, from 
php_sock_stream_wait_for_data():

while(1) {
retval = php_pollfd_for(sock->socket, PHP_POLLREADABLE, ptimeout);
if (retval == 0) sock->timeout_event = 1;
if (retval >= 0) break;
if (php_socket_errno() != EINTR) break;
}

The problem here is that this behavior is not compatible with pcntl signal 
handling 
because pcntl signals are implemented using ticks and this code actually does not 
exit 
even if we need to call signal handler.

Suggested fix for read() is to take into account existence of PCNTL and do the 
following check:

if (php_socket_errno() != EINTR) break;
#ifdef PCNTL_G
else if(PCNTL_G(head)) break;
#endif

/* PCNTL_G(head) is pointer to a queue of signals
   that were caught and will be processed after next tick.
   This queue is empty if we do not register handlers for received signal.
*/

This fix (and adding ZEND_EXTERN_MODULE_GLOBALS(pcntl) to pcntl.c) gives the 
expected result below

Test script:
---------------
<?php
declare(ticks = 1);
function sighandler($sig) {
echo "Caught signal $sig, exiting correctly\n";
exit(1);
}

pcntl_signal(SIGINT, 'sighandler', false);
pcntl_signal(SIGHUP, 'sighandler', false);

mysql_connect(); // assumes 'mysqlnd' as MySQL driver
mysql_query('SELECT SLEEP(100)'); // ignores SIGINT and SIGHUP for 100 sec

Expected result:
----------------
$ php test.php
^C
Warning: mysql_query(): MySQL server has gone away in test.php on line 14

Warning: mysql_query(): Error reading result set's header in 
/Users/nasretdinov/test.php on line 14
Caught signal 2, exiting correctly

Actual result:
--------------
$ php
^C
# ...after 100 sec...
Caught signal 2, exiting correctly

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 [2021-08-24 14:18 UTC] cmb@php.net
-Status: Open +Status: Feedback -Assigned To: +Assigned To: cmb
 [2021-08-24 14:18 UTC] cmb@php.net
Isn't this obsolete with the availability of pcntl_async_signals()
as of PHP 7.1.0?
 [2021-09-05 04:22 UTC] php-bugs at lists dot php dot net
No feedback was provided. The bug is being suspended because
we assume that you are no longer experiencing the problem.
If this is not the case and you are able to provide the
information that was requested earlier, please do so and
change the status of the bug back to "Re-Opened". Thank you.
 
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