[GromNaN]

ext-mongodb 2.5.x crashes on macOS at process shutdown, in about half of the CLI runs, with this stack:

sasl_client_done() -> digestmd5_common_mech_free()
-> _sasl_log() -> _sasl_syslog() -> asl_open() -> strrchr()

The extension calls sasl_client_done() from an atexit() handler. On macOS, Apple's Cyrus SASL logs through ASL, and asl_open() reads the process arguments through _NSGetArgv().

The root cause is in PHP. save_ps_args() installs a copy of argv in _NSGetArgv(), and cleanup_ps_args() frees that copy just before exit() without restoring the pointer. Any atexit() handler that reads _NSGetArgv() after that point reads freed memory. This is not specific to ext-mongodb: another library that logs through ASL from an atexit() handler can hit the same crash. See mongodb/mongo-php-driver#2213, where the extension works around it.

Restore the original argv pointer before freeing the copy, as is already done for environ.

The test adds a zend_test hook that registers an atexit() handler reading _NSGetArgv(), and checks that it no longer sees the freed copy and that argv[0] is readable. ZEND_DONT_UNLOAD_MODULES=1 keeps the extension loaded so the handler runs at process exit, and the test also covers a process title set with cli_set_process_title().

Verified on PHP 8.4 with zend_test built statically: the test passes with the fix, fails without it, and passes with run-tests.php --repeat 2.

This targets PHP 8.4, the oldest branch in active support.