Bug #46498 [Com]: is_writable() returns invalid result

Edit report at https://bugs.php.net/bug.php?id=46498&edit=1 ID: 46498 Comment by: nick at all-it dot ru Reported by: registrace at koren dot cz Summary: is_writable() returns invalid result Status: No Feedback Type: Bug Package: Filesystem function related Operating System: Linux PHP Version: 5.2.6 Block user comment: N Private report: N New Comment: This bug is 4 years old but nothing done to fix it and use proper functions to check effective access right instead of real... I'm using 5.3 version. Does anybody like to fix it? It is awfully difficult to recompile PHP each time I update it. I can provide patch but not sure whether somebody like to have this bug fixed. Previous Comments: ------------------------------------------------------------------------ [2009-02-20 01:00:00] php-bugs at lists dot php dot net No feedback was provided for this bug for over a week, so it is being suspended automatically. If you are able to provide the information that was originally requested, please do so and change the status of the bug back to "Open". ------------------------------------------------------------------------ [2009-02-13 00:13:49] jani@php.net Please try using this CVS snapshot: http://snaps.php.net/php5.2-latest.tar.gz For Windows: http://windows.php.net/snapshots/ ------------------------------------------------------------------------ [2008-11-05 21:01:31] registrace at koren dot cz Description: ------------ PHP Function is_writable() sometimes reports false results. Requirements: Linux - getuid() != geteuid() After inspection of PHP source, I realized, that is_writable() internally uses syscall access(2). In turn, access(2) man page (on Linux) says: The check is done with the calling process’s real UID and GID, rather than with the effective IDs as is done when actually attempting an operation. This is to allow set-user-ID programs to easily determine the invoking user’s authority. Reproduce code: --------------- <? $file = "testfile.txt"; echo "GetUID: " . posix_getuid() . "/" . posix_geteuid() . "<br />"; echo "file is writable " . (is_writable($file)?"TRUE":"FALSE") . "<br />"; fopen("testfile.txt", 'wt'); echo ("file created"); ?> Expected result: ---------------- Expected result: either: file is writable TRUE file created or file is writable FALSE ERROR Actual result: -------------- GetUID: 933/10099 file is writable FALSE file created ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=46498&edit=1