#40183 [Bgs]: fopen() for appending does not move position until first I/O

ID: 40183 User updated by: perrog at gmail dot com Reported By: perrog at gmail dot com Status: Bogus Bug Type: Filesystem function related Operating System: Mac OS X 10.4 PHP Version: 5.2.1RC3 New Comment: Yes, you have right. I became aware that even the ISO C Library Standard mentions ftell() immediately after fopen() returns a value that is implementation-defined (17.19.3): "If a file can support positioning requests (such as a disk file, as opposed to a terminal), then a file position indicator associated with the stream is positioned at the start (character number zero) of the file, unless the file is opened with append mode in which case it is implementation-defined whether the file position indicator is initially positioned at the beginning or the end of the file." Previous Comments: ------------------------------------------------------------------------ [2007-01-21 19:01:13] iliaa@php.net Thank you for taking the time to write to us, but this is not a bug. Please double-check the documentation available at http://www.php.net/manual/ and the instructions on how to report a bug at http://bugs.php.net/how-to-report.php The initial position returned is 0 because counting starts from the append position (earlier data does not count). ------------------------------------------------------------------------ [2007-01-21 07:26:48] perrog at gmail dot com Description: ------------ Opening a file for appending does not move the file pointer to the end of file before the first I/O operation is performed. That makes ftell() return zero directly after the fopen() call. The workaround, if you need to call ftell() immediately after the fopen(), is to use a no-operation I/O call fseek() that don't do anything. Thus, the file pointer is updated and returns correct position information. Reproduce code: --------------- // create or open a file, and write some stuff to it. $filename = "/path/to/file.txt"; $fp = fopen($filename, "a+"); fwrite($fp, "Sample text"); fclose($fp); // re-open it and check what ftell() returns $fp = fopen($filename, "a+"); echo " pre-fseek: " . ftell($fp) . "\n"; // ftell returns 0 fseek($fp, 0, SEEK_END); echo "post-fseek: " . ftell($fp) . "\n"; // ftell now ok Expected result: ---------------- The snippet should print the file size of the file: pre-fseek: 11 post-fseek: 11 Actual result: -------------- The snippet should print the correct file size only after the first I/O operation: pre-fseek: 0 post-fseek: 11 ------------------------------------------------------------------------ -- Edit this bug report at http://bugs.php.net/?id=40183&edit=1