[php-src] PR #24477: ext/ftp: abort a pending transfer in ftp_nb_put()

Pull Request: https://github.com/php/php-src/pull/24477 Author: kubakozub ### What ftp_nb_get() aborts a pending non-blocking transfer before starting a new one. ftp_nb_put() does not. ftp_getdata() assigns ftp->data unconditionally, so each ftp_nb_put() / ftp_nb_fput() issued while a transfer is pending replaces the pointer to the previous databuf_t, leaking it with its socket, and reads the pending transfer's response as the answer to its own command. The guard was added to the GET path by c962a96c347 (GH-10562, "Memory leak and invalid state with consecutive ftp_nb_fget") and never applied to the PUT path. It is absent there on every branch from PHP-8.2 to master. ### Measured Starting one non-blocking download and then five non-blocking uploads, counting the process's own sockets through /proc/self/fd: ``` before: nb_fput #0..#4 sockets 3,4,5,6,7 (delta +1 +2 +3 +4 +5) after: nb_fput #0..#4 sockets 1,2,1,2,1 (delta -1 +0 -1 +0 -1) ``` The second line is what the guarded sibling ftp_nb_fget() already does with the same server and the same loop. ### Test ext/ftp/tests/ftp_nb_put_during_nb_transfer.phpt leaves a transfer pending with ftp_nb_fget() and then uploads. It fails without the change and passes with it. The full ext/ftp suite is unaffected: 62 passed, 0 failed, 4 skipped. 🤖 Generated with [Claude Code](https://claude.com/claude-code)