PHP: rfc:tempnam-suffix-v2

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====== PHP RFC: Support optional suffix parameter in tempnam ======
  * Version: 1.1
  * Date: 2023-08-02
  * Author: Athos Ribeiro, athoscribeiro@gmail.com
  * Status: Voting
  * First Published at: http://wiki.php.net/rfc/tempnam-suffix-v2
  * Based on work by Stefan Neufeind, neufeind@php.net at https://wiki.php.net/rfc/tempnam-suffix

===== Introduction =====
The **tempnam** function allows users to optionally specify a **prefix** to be prepended to the generated filenames.

It would be useful to allow users to also specify a **suffix** when generating temporary files. For instance, a suffix could provide even more semantic value or context for a user inspecting the generated files, and, in specific situations, could even provide more context for software processing such files.

===== Proposal =====
Add a new optional suffix parameter to the tempnam function, changing its signature from
<code php>
tempnam(string $directory, string $prefix): string|false
</code>
to
<code php>
tempnam(string $directory, string $prefix, string $suffix = ""): string|false
</code>

==== Example ====

<code php>
tempnam("/tmp", "application-");
/* /tmp/application-xxxxxx */

tempnam("/tmp", "", ".pdf");
/* /tmp/xxxxxx.pdf */

tempnam("/tmp", "application-", ".pdf");
/* /tmp/application-xxxxxx.pdf */
</code>

===== Backward Incompatible Changes =====
None with exception of changing the signature of the internal php_do_open_temporary_file function, which is not exported.

===== Proposed PHP Version(s) =====
next PHP 8.x.

===== RFC Impact =====
The suffix-parameter is optional. Thus it is transparent to any existing PHP-code in use.

Only the internal API is affected because of the additional parameter which is added. Still, this only includes the addition of a new function (php_open_temporary_fd_ex2) and changing the signature of the php_do_open_temporary_file function, which is not exported.

===== Open Issues =====


===== Unaffected PHP Functionality =====
All but tempnam and the internal php_do_open_temporary_file function.

===== Future Scope =====

The **tempnam** **prefix** paramter is sanitized through the **basename** function when path separators are present in the provided string, using only the last part of the provided path. For instance, **foo/bar** would become **bar**. We could not find the historical reasons for the **prefix** parameter to behave as described, but for consistency, we are currently using the same approach for the new **suffix** parameter.

Moreover,o nly the 63 first characters passed to the **prefix** paramter are used. Although we could not find the historical reasons behind this decision, we are currently replicating the behavior for the new **suffix** parameter.

Finally, **In windows systems**, none of the characters passed as a suffix will be appended to the file name (i.e., **the suffix parameter will be ignored**). This is due to the underlying function (and API) used to generate temporary files, which do not provide means to set a suffix. While we could provide a custom implementation, the current windows API being used includes a .TMP extension to the generated files, which AFAICT, does matter in windows systems. I also found a related discussion in an old bug at https://bugs.php.net/bug.php?id=44222. Changing such behaviors would require a different RFC.

Therefore, the following changes are left for future work:

* Re-visit tempnam's implementation to verify the need to truncate the prefix/suffix params at 64 characters.
* Re-visit tempnam's implementation to verify the need to modify the prefix/suffix params thorugh the basename function.
* Re-work tempnam's windows implementation to match the default non-windows behaviors.

The first two could be part of a minor refactoring effort for tempnam. The last one, however, should be part of a major refactoring effort for tempnam.

===== Proposed Voting Choices =====
Accept this RFC and accept an optional **suffix** parameter in the **tempnam** function? Yes / No

===== Patches and Tests =====
The following is a candidate for this proposal, which includes the assumptions presented in the Open Issues section above.

https://github.com/php/php-src/pull/11685

===== Implementation =====
As linked above

===== Vote =====

<doodle title="Support optional suffix parameter in tempnam" auth="athos" voteType="single" closed="false" closeon="2023-09-10T00:00:00Z">
   * Yes
   * No
</doodle>

===== References =====
  * Original RFC by Stefan Neufeind: https://wiki.php.net/rfc/tempnam-suffix
  * First discussion started by Stefan: https://marc.info/?l=php-internals&m=138946779304541
  * First implementation proposal by Stefan: https://github.com/php/php-src/pull/575
  * Old bug requesting related feature: https://bugs.php.net/bug.php?id=37613
  * Old bug requesting related feature: https://bugs.php.net/bug.php?id=43898
  * Current implementation proposal: https://github.com/php/php-src/pull/11685
  * Old bug with discussion on differences in tempnam's windows implementation: https://bugs.php.net/bug.php?id=44222
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