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Doc Bug #79389 ftell retruns false on linux for STDIN
Submitted: 2020-03-17 14:00 UTC Modified: 2020-03-18 08:06 UTC
From: mail at ahmd dot io Assigned:
Status: Verified Package: Streams related
PHP Version: 7.4.3 OS: linux
Private report: No CVE-ID: None
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 [2020-03-17 14:00 UTC] mail at ahmd dot io 
Description:
------------
Hi

ftell php function returns false for STDIN on Linux with all php 7.4 versions 
https://3v4l.org/LTbpu

The related commit seems to be this one 
https://github.com/php/php-src/commit/c1a6f2b9ccd2f022b8b0a056030a287748e98eaa#diff-093fc4d3c1dfbb6819809690e36128d7L246

Test script:
---------------
<?php
var_dump(ftell(STDIN));


Expected result:
----------------
int(0)

Actual result:
--------------
bool(false)

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 [2020-03-17 18:28 UTC] cmb@php.net
-Assigned To: +Assigned To: nikic
 [2020-03-17 18:28 UTC] cmb@php.net 
Well, the behavior depends on which kind of file stdin refers to.
If it is a pipe, the PHP 7.4 behavior makes more sense to me.
Anyhow, the mentioned commit is not the cause of that behavioral
change (it is not even contained in PHP 7.4.0).

@nikic, is this indeed intended behavior?
 [2020-03-17 18:54 UTC] nikic@php.net 
@cmb: Yes, character devices are not seekable, so ftell should return false.
 [2020-03-18 08:06 UTC] cmb@php.net
-Status: Assigned +Status: Verified -Type: Bug +Type: Documentation Problem -Assigned To: nikic +Assigned To:
 [2020-03-18 08:06 UTC] cmb@php.net 
ftell() for character devices already returned false in earlier
PHP versions; the behavioral change reported by the OP appears to
be related to pipes.  Anyhow, not seekable => ftell() returns
false, makes perfect sense to me.
 [2020-03-20 16:00 UTC] mail at ahmd dot io 
Got it now, thanks for clarifying 

I tried to amend ftell docs in the manual using edit.php.net
but it's my first time to touch php docs, hopefully, I did it correctly and did not miss anything :)
 
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