ZipArchive deletes zip file with no contents and doesn't update stat cache

[timint]

Description

There is a problem with ZipArchive deleting empty archives without notice upon successful close. And statcache not updated.

<?php
    $tmp_file = tempnam(sys_get_temp_dir(), '');
    var_dump(is_file($tmp_file)); // returns true

    $zip = new ZipArchive;
    $zip->open($tmp_file, ZipArchive::OVERWRITE);
    $zip->close(); // returns true

    var_dump(is_file($tmp_file)); // returns true
    var_dump(file_get_contents($tmp_file)); // returns error file does not exist

I expected the defined file to remain. If I can't count on that I expected the statcache to be updated.

PHP Version

PHP 8.1.6

Operating System

Windows 11 x64

[remicollet]

Confirmed

I expected the defined file to remain.

This the default behavior of the libzip library, (perhaps since empty file are not valid zip archive), so nothing we can change in php

If I can't count on that I expected the statcache to be updated.

PR pending

[remicollet]

Fixed in standalone pecl extension
pierrejoye/php_zip@fac6809

[remicollet]

See PR #8783

[cmb69]

perhaps since empty file are not valid zip archive

I don't think this is true. On Windows, I can create an empty.zip via the explorer, and the specification says:

4.1.2 ZIP files SHOULD contain at least one file and MAY contain multiple files.

"SHOULD contain" is not "MUST contain".

We may consider to still create such an empty archive, even if libzip would delete the file. Or maybe upstream would reconsider the behavior for empty archives.

[remicollet]

perhaps since empty file are not valid zip archive

I don't think this is true

I mean "empty file" (size=0) are not valid, not about "empty archive" ;)

[cmb69]

Yeah, but this ticket is about empty archives:

    $zip = new ZipArchive;
    $zip->open($tmp_file, ZipArchive::OVERWRITE);
    $zip->close(); // returns true

[remicollet]

Yes, but the example use a "empty file" (tempnam) which is not a valid archive.

And indeed, the library doesn't allow to create an empty archive, but I don't think we can fix this in the extension.

P.S. opening an empty archive works (and it is not deleted during the close)

For memory, upstream code: https://github.com/nih-at/libzip/blob/v1.9.0/lib/zip_close.c#L65

[cmb69]

Yes, but the example use a "empty file" (tempnam) which is not a valid archive.

Oh, right!

And indeed, the library doesn't allow to create an empty archive, but I don't think we can fix this in the extension.

Thinking about it, that should really be fixed upstream. For instance, given that I have an archive, and delete some entries, after ::close() the archive is gone, if there are no more entries. At least that happens with libzip 1.7.3 (I'm feeling bad, because winlibs are so far behind).

[remicollet]

libzip discussion nih-at/libzip#299

[remicollet]

Followup: add documentation of library expected /documented behavior in our documentation
php/doc-en#1628