Text input to file upload - php

Question

I have a form:
<form method="POST" action="">
<textarea id="input_text" name="input_text"></textarea>
<input type="submit" name="decrypt" value="sm">
</form>
now I submit it, php is try to write $_POST['input_text'] to a file then do another action, after complete action, php 'll delete the file created.
<?php
$Path = dirname(__FILE__).'/temp/';
$File_NAME = time().'.txt';
$input_text = stripslashes($_POST['input_text']);
$fp=fopen($Path.$File_NAME,'w');
fwrite($fp,$input_text);
fclose($fp);
//do some curl action with the file, then delete the file
if(file_exists($Path.$File_NAME))
unlink($Path.$File_NAME);
but if the text too strong, user submit the form, then they abort the page, so the file doesn't delete.
I want to direct change the $_POST['input_text'] to type='file', but user also can use it such as a textarea. so php don't need to delete the file because it is a tmp file.

Answer 1

As per your Edit to the question, the possible solution is to first check the $_POST['input_text'] for length before even opening the file. If the text is too long, show an error message.
I don't think that file is even required in that case.
OLD ANSWER:
Fetching the $_POST['input_text], you can :
$txt = $_POST['input_text'];
$file = fopen("file.txt", "w+"); //w+ indicates read + write
fwrite($file,$txt); //to ride the 'input_txt'
Then perform the actions you want and finally delete the file if required using:
fclose($file);
delete("file.txt");
But make sure to grant the PHP page the permissions to Read/Write first.