Bug #69963 [Asn->Fbk]: fgets reads EOF if there is nothing on the PIPE to read for a short period
Edit report at https://bugs.php.net/bug.php?id=69963&edit=1
ID: 69963
Updated by: ab@php.net
Reported by: poonam dot chawla at mathworks dot com
Summary: fgets reads EOF if there is nothing on the PIPE to
read for a short period
-Status: Assigned
+Status: Feedback
Type: Bug
Package: Streams related
Operating System: Windows
PHP Version: 5.6.10
Assigned To: ab
Block user comment: N
Private report: N
New Comment:
Hi,
could you please check the build http://windows.php.net/downloads/snaps/ostc/69900/
which is linked in this mail http://news.php.net/php.internals/86976 ? Please
be aware that you'll need add a stream context. The patch is unlikely to appear in PHP5, but in
PHP7.
Though be aware that forcing blocking reads on pipes, you're putting yourself under the risk to
experience dead locks, see #64438. When used carefully, it still can work and be useful.
Thanks.
Previous Comments:
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[2015-06-30 13:27:18] poonam dot chawla at mathworks dot com
My apologies. That is correct.
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[2015-06-30 11:30:05] ab@php.net
@poonam, you obviously meant feof, not fgets?
Thanks.
------------------------------------------------------------------------
[2015-06-29 21:17:42] poonam dot chawla at mathworks dot com
Hi,
Thanks for an early response. It is a WINDOWS ONLY issue but unfortunately not the same one.
69900 : The issue/bug is that for every fgets call process hangs for 100ms.
However, in the issue I am experiencing there is no delay/hang on fgets.
Thanks,
Poonam
------------------------------------------------------------------------
[2015-06-29 20:57:34] cmb@php.net
If that is a Windows only issue, it might be somehow related to
bug #69900.
------------------------------------------------------------------------
[2015-06-29 20:21:01] poonam dot chawla at mathworks dot com
Description:
------------
I am using PHP to read from STDIN and write to a log file. The PHP process is spawned by another
process (for the example sake, I am attaching a python script that spawns a new PHP process).
I observed that if there is nothing to read on the STDIN for a short period of time, PHP behaves
unexpectedly (reads EOF and exits).It was interesting to find out that PHP 5.4 exhibhits the correct
behavior, however both PHP 5.5 and 5.6 behave unexpectedly.
Test script:
---------------
PHP:
<?php
$in = fopen("php://stdin", "rb");
$out = fopen('C:/Users/pchawla/php_test/log_file.txt', 'w');
while ( ! feof($in) ) {
$line = fgets($in);
fwrite($out, $line);
}
?>
import subprocess
import sys
Python:
import subprocess
import sys
def log():
proc = subprocess.Popen(['php',
'C:/Users/pchawla/php_test/log_handler.php'], stdin=subprocess.PIPE)
while True:
line = sys.stdin.readline();
proc.stdin.write(line)
if __name__ == "__main__":
log()
Expected result:
----------------
fgets() should return FALSE only when there is an error or it reads EOF from the PIPE.
Actual result:
--------------
fgets() returns FALSE when there is nothing to read from the PIPE for a short period of time (~20
seconds).
------------------------------------------------------------------------
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Edit this bug report at https://bugs.php.net/bug.php?id=69963&edit=1
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