Req #69175 [Opn]: posix_strerror is not thread-safe
Edit report at https://bugs.php.net/bug.php?id=69175&edit=1
ID: 69175
Updated by: cmb@php.net
Reported by: james at jamesreno dot com
Summary: posix_strerror is not thread-safe
Status: Open
Type: Feature/Change Request
Package: POSIX related
Operating System: Linux
PHP Version: 5.6.6
Block user comment: N
Private report: N
New Comment:
Seems like a good idea, but would require to check whether
strerror_r(3) is available at build time.
PRs welcome!
Previous Comments:
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[2015-03-03 18:33:50] james at jamesreno dot com
Description:
------------
As with alot of the PHP extensions some are not thread-safe by nature however posix_strerror could
easily be thread-safe by making a small change to the way it operates and as such is fully capable
of becoming thread-safe. It is my impression that this use is not thread-safe (I could be wrong).
The problem is that posix_strerror makes a call to strerror() which returns a pointer to the string
which may *not* be modified as it is reused and overwritten by the next call to strerror. Instead
posix_strerror should call strerror_r which accepts a buffer and buffer length and writes the data
there instead.
Granted that PHP seems to be making a copy of the output for its own use there is a possibility of a
race condition occurring with other threads. This is just a small potential improvement that
shouldnt take much time to implement and would be a a step forward for thread-safety.
There may be other cases of thread-safety issues in the posix extension but those can be tackled one
at a time. This is just a very limited and specific report for one use case. If someone wants to
scan the entire extension for said issues more power to them but I am just requesting this
particular case be resolved.
Test script:
---------------
<?php
echo posix_strerror(110);
?>
Expected result:
----------------
No corruption should ever be possible to occur.
Actual result:
--------------
Corruption could possibly occur in a build utilizing multiple threads.
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Edit this bug report at https://bugs.php.net/bug.php?id=69175&edit=1
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