Bug #53061 [Opn->Wfx]: filesystem functions deal poorly with out of disk space conditions
Edit report at http://bugs.php.net/bug.php?id=53061&edit=1
ID: 53061
Updated by: cataphract@php.net
Reported by: crrodriguez at opensuse dot org
Summary: filesystem functions deal poorly with out of disk
space conditions
-Status: Open
+Status: Wont fix
Type: Bug
Package: Filesystem function related
Operating System: *nix
PHP Version: 5.3SVN-2010-10-14 (SVN)
Block user comment: N
Private report: N
New Comment:
Closeing as Wont Fix per the exposed reasons.
Previous Comments:
------------------------------------------------------------------------
[2010-10-16 02:18:04] cataphract@php.net
Well, there's the hint that the return value is smaller than
strlen(str_repeat("fail", 1024000)) = 4096000.
I'm not sure if adding a warning here is appropriate, we try to avoid
warnings in correct scripts so that programmers don't have to use "@" to
have notice/warning free code. Even if we consider a disk full an
exceptional circumstance that merited breaking this guideline, a warning
would be of little use; unless the logs are in a separate filesystems,
the warning message would not be able to be logged.
So:
* We can't return false, because a part of the data may have been
written and we need to return how much.
* A warning would be of no use in most circumstances.
Maybe we could return a false+warning if no data has been written, but
it seems dangerous because sometimes programmers would be warned of an
out-of-disk-space conditional and other times they wouldn't.
------------------------------------------------------------------------
[2010-10-15 02:47:11] crrodriguez at opensuse dot org
A liltte bit better test case:
# dd if=/dev/zero of=/tmp/vfs bs=1024 count=1024
# losetup /dev/loop0 /tmp/vfs
# mkfs -t ext2 -m 1 -v /dev/loop0
# mkdir /mnt/vfs
# mount -t ext2 /dev/loop0 /mnt/vfs
<?php
$fp = fopen('/mnt/vfs/foo.txt', 'wb');
var_dump(fwrite($fp, str_repeat("fail", 1024000)));
var_dump(fflush($fp));
var_dump(fclose($fp));
?>
int(1003520)
bool(true)
bool(true)
ls -l /mnt/vfs/foo.txt
-rw-r--r-- 1 root root 1003520 oct 14 21:43 /mnt/vfs/foo.txt
Partial data on disk, no warning or return values hinting the problem.
------------------------------------------------------------------------
[2010-10-14 07:00:13] cataphract@php.net
Why would fflush return false? Nothing was written by fwrite, so the
flush is a no-op.
------------------------------------------------------------------------
[2010-10-14 06:35:11] crrodriguez at opensuse dot org
Description:
------------
Filesystem functions have IMHO the wrong behaviuor on disk-full
conditions
Test script:
---------------
<?php
$fp = fopen('/dev/full', 'wb');
var_dump(fwrite($fp, "fail"));
var_dump(fflush($fp));
var_dump(fclose($fp));
Expected result:
----------------
bool(false) and "warning ...No space left on device.. (aka, handle
ENOSPC)
bool(false)
bool(true)
Actual result:
--------------
int(0)
bool(true)
bool(true)
------------------------------------------------------------------------
--
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