How to not have tmpfile() be deleted when out of the scope of the method that it was created by?

Question

I'm on [email protected]. When I have one method both creating and reading from a tmpfile, everything works as expected:

class TmpFileReadRightAway
{
    public function storeToTempFileAndReadRightAway(string $content): string
    {
        $fh = tmpfile();
        $path = stream_get_meta_data($fh)['uri'];
        fwrite($fh, $content);

        return file_get_contents($path);
    }
}

echo (new TmpFileReadRightAway())->storeToTempFileAndReadRightAway('this works as expected');

Yet when I split the method into multiple methods, the tempfile() is deleted after the method in which it was created returns.

This is not at all what I expected as I wanted to keep the file around. I would expect the tmpfile to be deleted at termination of the php code at the very end, not after it exits the method.

class TmpFileStoreButReadLater
{

    public function storeButReadLater(string $content): string
    {
        $path = $this->getPath($content);

        return file_get_contents($path); // file at path doesn't exist anymore here, why?
    }

    private function getPath($content): string
    {
        $fh = tmpfile();
        $path = stream_get_meta_data($fh)['uri'];
        fwrite($fh, $content);

        return $path;
    }
}

This would throw

PHP Warning:  file_get_contents(/tmp/phpQsUdA5): Failed to open stream: No such file or directory

Why is the file being deleted in this case and how do I ensure it exists during the runtime of my code?

Answer 1

Use class property.

The tmpfile() document said.

The file is automatically removed when closed (for example, by calling fclose(), or when there are no remaining references to the file handle returned by tmpfile()), or when the script ends.

So, I assume that when method exits, the fclose() is called automatically.

The error about failed to open stream is not just occur in PHP 8.1 but all version since PHP 7.0 to 8.1. (I don't have PHP 5.x to test with.)

To prevent that, set the $fh to class property instead.

class TmpFileStoreButReadLater
{

    protected $fh;

    public function storeButReadLater(string $content): string
    {
        $path = $this->getPath($content);

        return file_get_contents($path); // file at path doesn't exist anymore here, why?
    }

    private function getPath($content): string
    {
        $this->fh = tmpfile();
        $path = stream_get_meta_data($this->fh)['uri'];
        fwrite($this->fh, $content);


        return $path;
    }
}


echo (new TmpFileStoreButReadLater())->storeButReadLater('this works as expected');

Tested on PHP 7.0 - 8.1.3 but no errors now.