Description:
------------
it seems that the pointer returned by php_stream_fopen_temporary_file / php_stream_fopen_tmpfile is not validated prior to use in memory.c in the case where a script is executed in an environment  where the TMPDIR is not writable to the user, it will cause a SIGSEGV.

from the script side any code that utilize php://temp with 2MB+ buffer with the above condition will encounter this issue.


i have fixed the problem on all the calling code in memory.c using php_error_docref, i see that in phar they have handled the condition with zend_throw_exception_ex. i am not in a position to decide which one is best at this time. i think a friendly warning is better than a SIGSEGV at this point :)

i have validated this problem exists on github-master and releases 5.4.37, 5.4.17 

i will post my pull-request in a comment 

Test script:
---------------
#mkdir /tmp/x
#chmod 444 /tmp/x
#export TMPDIR=/tmp/x

$fp = fopen('php://temp', 'r+');
$data = implode('', array_fill(0, (1024 * 1024 * 2), 'A'));
fwrite($fp, $data);