In other words, move_uploaded_file() protects against moving a non-uploaded file or moving one more than once.
So it's for an upload processing code that, at some point, is becoming unsure of what the heck it is doing.
It is a band-aid.
Sure.
> So it's for an upload processing code that, at some point, is becoming unsure of what the heck it is doing.
How do you get to this conclusion from the above?
> It is a band-aid.
Nope. Uploaded file checking would seem to be necessary, though rather than requiring the developer to implement it, there's some lang-sec value in php doing the check automatically with any $_FILES references and instead allowing the developer to suppress it. That's an area where implementation can be refined, but it doesn't make the current solution a band-aid by any stretch.
Edit: as an example, I'd much rather see the example given in php docs actually implemented as part of the framework rather than delegated to the developer. But aside from just dumping all uploaded files in one quarantined location, this solution is a functional pattern. https://www.php.net/manual/en/function.is-uploaded-file.php
(I'm not a php dev, and docs on the relevant functions date back to 2003, so for all I know, this has been rectified in the intervening 17 years)
A resource leak. That's assuming that you are referring to temp files not getting removed once the POST handler exits... which is not how it works.
https://www.php.net/manual/en/features.file-upload.post-meth...
The file will be deleted from the temporary directory
at the end of the request if it has not been moved
away or renamed.
This RFC does not talk about life cycle management of uploaded files at all, leave alone such specifics as hash tables.
Is there a way to call Dang to have a look at those offensive comments? :-)
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It's not a band-aid. When a file is uploaded (see RFC 1867) via HTTP POST, PHP internally allocates a hash table that tracks which files on the filesystem have been uploaded. When the process terminates, it uses that hashtable to remove any remaining uploaded files in the tmp space.
move_uploaded_file() confirms that the filename was indeed created as a result of an upload, and additionally removes that entry from the hash table.