From: wharmby at uk dot ibm dot com
Operating system: Linux RHEL4
PHP version: 5CVS-2006-11-27 (snap)
PHP Bug Type: Unknown/Other Function
Bug description: Implementation of PHP functions chown() and chgrp() not
thread safe.
Description:
------------
The current implementation of the chown() and chgrp()
functions on Linux use the non-reentrant getpwnam() and
getgrnam() C library calls respectively rather than the
reentrant getpwnam_r() and getgrnam_r(). Therefore using
either chown() or chgrp() on Linux in a ZTS enabled build
could lead to unpredictable/undesirable results.
The following patch, which was built against the latest snapshot (Nov
27th, 2006, 0730 GMT) modifies the code in
ext/standard/filestat.c to use the reentrant versions of
these functions and so make these 2 functions thread safe:
http://pastebin.ca/259657
However, I am concerned that this patch relies on the C
library supporting the POSIX.1 functions getpwnam_r(),
getgrnam_r() and sysconf(). These are all implemented by
GNU libc but are there other C libraries used to build PHP
which may not have the necessary support ? Or is it
reasonable to assume that all C libraries used when buiding
PHP will be POSIX.1 compliant ?
N.B There are other uses of these non-reentrant functions in
the PHP code base (e.g posix.c and fopen_wrappers.c) and I
m happy to produce the necessary patches to fix these uses
if this fix proves satisfactory.
Andy Wharmby
IBM United Kingdom Limited
Reproduce code:
---------------
---------------
Problem found by code inspection. As with most thread safety issues
difficult to produce a simple testcase which will show a reproducible
crash but current Linux executable is clearly
not reentrant.
Expected result:
----------------
N/A
Actual result:
--------------
N/A
--
Edit bug report at http://bugs.php.net/?id=39648&edit=1
--
Try a CVS snapshot (PHP 4.4):
http://bugs.php.net/fix.php?id=39648&r=trysnapshot44
Try a CVS snapshot (PHP 5.2):
http://bugs.php.net/fix.php?id=39648&r=trysnapshot52
Try a CVS snapshot (PHP 6.0):
http://bugs.php.net/fix.php?id=39648&r=trysnapshot60
Fixed in CVS: http://bugs.php.net/fix.php?id=39648&r=fixedcvs
Fixed in release:
http://bugs.php.net/fix.php?id=39648&r=alreadyfixed
Need backtrace: http://bugs.php.net/fix.php?id=39648&r=needtrace
Need Reproduce Script: http://bugs.php.net/fix.php?id=39648&r=needscript
Try newer version: http://bugs.php.net/fix.php?id=39648&r=oldversion
Not developer issue: http://bugs.php.net/fix.php?id=39648&r=support
Expected behavior: http://bugs.php.net/fix.php?id=39648&r=notwrong
Not enough info:
http://bugs.php.net/fix.php?id=39648&r=notenoughinfo
Submitted twice:
http://bugs.php.net/fix.php?id=39648&r=submittedtwice
register_globals: http://bugs.php.net/fix.php?id=39648&r=globals
PHP 3 support discontinued: http://bugs.php.net/fix.php?id=39648&r=php3
Daylight Savings: http://bugs.php.net/fix.php?id=39648&r=dst
IIS Stability: http://bugs.php.net/fix.php?id=39648&r=isapi
Install GNU Sed: http://bugs.php.net/fix.php?id=39648&r=gnused
Floating point limitations: http://bugs.php.net/fix.php?id=39648&r=float
No Zend Extensions: http://bugs.php.net/fix.php?id=39648&r=nozend
MySQL Configuration Error: http://bugs.php.net/fix.php?id=39648&r=mysqlcfg
