#32858 [Asn->Fbk]: Bug #25649 has crept back into PHP - Improper feof() handling under FreeBSD

ID: 32858 Updated by: tony2001@php.net Reported By: lew at mailduct dot com -Status: Assigned +Status: Feedback Bug Type: Filesystem function related Operating System: FreeBSD 4.11-REL PHP Version: 5.0.4, 4.3.10 Assigned To: wez New Comment: Please try using this CVS snapshot: http://snaps.php.net/php5-latest.tar.gz For Windows: http://snaps.php.net/win32/php5-win32-latest.zip Previous Comments: ------------------------------------------------------------------------ [2005-05-27 08:40:27] sniper@php.net Assigning to Wez since he fixed it last time.. ------------------------------------------------------------------------ [2005-05-27 00:02:11] lew at mailduct dot com I have now tested this using PHP 5.0.4 (cli), and the bug remains. This bug was fixed by wez@php.net on Sep 2003, but has now crept back in to both versions 4 and 5 of PHP. PHP is failing to clear the EOF indicator when reading a stream that would otherwise BLOCK if read. --- quote (wez@php.net): The PHP streams implementation uses the following logic for determining the EOF status: - after a read attempt, if no bytes were read OR (a read error occurred and the error != EWOULDBLOCK) --> set the EOF indicator otherwise, clear the EOF indicator [1] - after a successful fseek(), clear the EOF indicator. [1] - this step was missing and has just been comitted to the CVS. The feof() function call works like this: - if stream buffer has data, return false - otherwise, return the EOF indicator flag. ---endquote ------------------------------------------------------------------------ [2005-04-27 21:36:47] lew at mailduct dot com Description: ------------ In my prior bug report #25649 from September 2003, I pointed out a serious bug in how PHP handles FEOF under FreeBSD. It was fixed by wez@php.net and committed. This same problem (improper handling of feof() by PHP under FreeBSD) has now crept into current 4.3.X versions of PHP... Problem: Once set, the FEOF indicator is not properly cleared when more data is appended to a file that is opened for read by a PHP application. Example: Suppose I want to "tail" a file using PHP. Once I hit the EOF, I will no longer be able to read data from that file even when another application appends to it. This is not the correct behaviour for feof(), as illustrated by the prior fix done by wez@php.net. Reproduce code: --------------- --- program: $fp = fopen( '/var/log/maillog','r' ); while( TRUE ) { $r = array( $fp ); $n = stream_select( $r,$w=NULL,$e=NULL,30 ); if( $n ) { echo fgets( $fp ); } } --- feeder: echo "This is a test..." >> /var/log/maillog Expected result: ---------------- For as long as PROGRAM is running, each time I run FEEDER I expect to see PROGRAM output "This is a test..." but it does not, because once EOF is reached, it is not properly reset upon more data being appended to the file. See pr #25649 for historical info... Actual result: -------------- PROGRAM will read the contents of /var/log/maillog until it reaches EOF, and will not output anything else, even if new data is appeneded to the file. ------------------------------------------------------------------------ -- Edit this bug report at http://bugs.php.net/?id=32858&edit=1