zlib streams should support locking

[githubyiti]

Description

The following code:

<?php
			$gz = gzopen($cachefileb,'w9');
			gzwrite($gz, $towrite);
			gzclose($gz);

Resulted in this output:
Current function caused disk error while multiple sessions is writing to the same file.

But I expected this output instead:
can the file be locked while the file is being written?

### PHP Version

PHP 7.4

### Operating System

Almalinux

[cmb69]

https://www.php.net/flock

[githubyiti]

Thanks for the response!
Yes, someone is reporting the same problem on exactly the page you gave, has the issue been solved?
https://www.php.net/flock#111443

[cmb69]

No, that issue still persists. From a quick look at the implementation, the actual file stream is an "inner stream".

Workaround: use fopen() instead of gzopen() (and use ini_set("zlib.output_compression", 9")).

PS: probably better anyway: use a separate lock file (.lck).

[githubyiti]

Thanks.

The old code in use has already created a lot of data, fear rewriting the old code may unexpectly corrupt the old data.
new scripts are using the way you suggested.

Hope if can have something like gz_lock to patch to the old code.

Regards,

[cmb69]

This cannot be implemented for PHP < 8.5, and I would assume that upgrading to PHP 8 already requires quite some changes to your code base, so possibly tough luck.

Anyway, let's turn this into a proper feature request, since it generally makes sense to be able to lock zlib streams.

[cmb69]

Implementation would need to start at

php-src/ext/zlib/zlib_fopen_wrapper.c

Line 105 in ff80ec7

NULL /* set_option */

[githubyiti]

Thanks for moderating the title.
Hope will have gz_lock in the future.

[cmb69]

Hope will have gz_lock in the future.

Well, you would rather be able to use flock().