Bug #79691 [Fbk->Opn]: Lack of error checking in `posix_kill`

Edit report at https://bugs.php.net/bug.php?id=79691&edit=1 ID: 79691 User updated by: srivas41 at purdue dot edu Reported by: srivas41 at purdue dot edu Summary: Lack of error checking in posix_kill -Status: Feedback +Status: Open Type: Bug Package: POSIX related Operating System: Ubuntu 16.04 PHP Version: 7.4.7 Block user comment: N Private report: N New Comment: Could you specify which set of configuration flags enables PHP to warn about the undefined variable in this specific case? I built with ./buildconf && ./configure --enable-werror && make -jnproc`. No error or warning was emitted while running the test script. Previous Comments: ------------------------------------------------------------------------ [2020-06-11 23:02:23] requinix@php.net PHP does warn about the undefined variable. If you can't see the warning then you don't have the appropriate error settings enabled. ------------------------------------------------------------------------ [2020-06-11 22:48:43] srivas41 at purdue dot edu Description: ------------ Posix_kill lacks error checking for undefined variables passed and instead gets typecasted to 0 somehow owing to the internal implementation. As specified in the kill(2) manpage, If pid equals 0, then sig is sent to every process in the process group of the calling process. Therefore, posix_kill will incorrectly send the signal to all processes in the process group which includes the interpreter itself. This behavior can be detrimental if a developer mistakingly passes an undefined variable to posix_kill. This behavior is reproducible with the script specified below. The script sends SIGHUP to the interpreter and exits prematurely due to lack of error checking for undefined variables in posix_kill. Therefore, before printing the last echo statement, posix_kill passes SIGHUP to the interpreter itself exiting prematurely. Test script: --------------- <?php echo "Testing Posix kill\n"; $signal_number=1; //SIGHUP=1 posix_kill($DUMMY, $signal_number); // $DUMMY is undefined echo "Posix kill can error check for undefined variables!"; ?> Expected result: ---------------- Ideally, PHP interpreter should raise an error for an undefined variable for the above test script instead of just weakly typing the undefined variable to 0. Actual result: -------------- The message displayed would be something like: ``` Testing Posix kill [2] <PHP Interpreter PID> hangup ./sapi/cli/php -f test.php ``` ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=79691&edit=1