John Topley John Topley - 1 year ago 147
PHP Question

PHP is_writable() function always returns false for a writable directory

I'm trying to install a PHP-based software package in a Red Hat 7 Amazon EC2 instance (ami-8cff51fb) that has had Apache 2.4.6 and PHP 5.4.16 installed on it using yum. The installation fails because it says a particular directory needs to be writable by the webserver with 0755 or 0775 permissions.

The directory in question has 0775 permissions with

ownership. I have verified that the httpd process is being run by the apache user and that the apache user is a member of the apache group.

If I edit
to temporarily give the apache user a login shell and then
to that account, I am able to manually create files as the apache user within the directory using the

I took a look at the source code of the installer script and identified that it's failing because PHP's
function is returning false for the directory in question. I created a separate test PHP script to isolate and verify the behaviour I'm seeing:

$dir = '/var/www/html/limesurvey/tmp';
if (is_writable($dir)) {
echo $dir, ' is writable';
} else {
echo $dir, ' is NOT writable';

This outputs the NOT writable message. If I change
above to be
then it correctly outputs that
is writable.

If I change the directory permissions to 0777 and/or change the ownership to
then PHP still reports that the directory isn't writable. I even tried creating a
directory set up with the same permissions and ownership and my test script still reports it as not writable.

I'm really at a loss as to explain this behaviour, so any ideas would be welcome!

Thanks in advance.

The directory listing for
is given below. The
directories have 0775 permissions as per Lime Survey's installation instructions.
is my test script mentioned above.

[ec2-user@ip-xx-x-x-xxx limesurvey]$ pwd
[ec2-user@ip-xx-x-x-xxx limesurvey]$ ls -al
total 80
drwxr-xr-x. 20 root apache 4096 Mar 30 11:25 .
drwxr-xr-x. 3 root root 23 Mar 25 14:41 ..
drwxr-xr-x. 2 root apache 38 Mar 10 12:56 admin
drwxr-xr-x. 16 root apache 4096 Mar 10 12:56 application
drwxr-xr-x. 3 root apache 4096 Mar 10 12:56 docs
drwxr-xr-x. 2 root apache 4096 Mar 10 12:56 fonts
drwxr-xr-x. 19 root apache 4096 Mar 10 12:56 framework
-rw-r--r--. 1 root apache 429 Mar 10 12:56 .gitattributes
-rw-r--r--. 1 root apache 399 Mar 10 12:56 .gitignore
-rw-r--r--. 1 root apache 296 Mar 10 12:56 .htaccess
drwxr-xr-x. 4 root apache 4096 Mar 10 12:56 images
-rw-r--r--. 1 root apache 6652 Mar 10 12:56 index.php
drwxr-xr-x. 5 root apache 39 Mar 10 12:56 installer
drwxr-xr-x. 89 root apache 4096 Mar 10 12:56 locale
drwxrwxr-x. 2 root apache 39 Mar 25 14:41 logs
drwxr-xr-x. 4 root apache 49 Mar 10 12:56 plugins
-rw-r--r--. 1 root apache 61 Mar 10 12:56 README
drwxr-xr-x. 4 root apache 4096 Mar 10 12:56 scripts
-rw-r--r--. 1 root apache 380 Mar 10 12:56 .scrutinizer.yml
drwxr-xr-x. 5 root apache 4096 Mar 10 12:56 styles
drwxr-xr-x. 5 root apache 4096 Mar 10 12:56 styles-public
drwxr-xr-x. 12 root apache 4096 Mar 10 12:56 templates
-rw-r--r--. 1 root apache 159 Mar 30 11:11 test.php
drwxr-xr-x. 3 root apache 20 Mar 10 12:56 themes
drwxr-xr-x. 26 root apache 4096 Mar 10 12:56 third_party
drwxrwxr-x. 5 root apache 80 Mar 26 13:45 tmp
drwxrwxr-x. 6 root apache 79 Mar 10 12:57 upload

namei -l /var/www/html/limesurvey/tmp

[ec2-user@ip-x-x-x-xxx ~]$ namei -l /var/www/html/limesurvey/tmp
f: /var/www/html/limesurvey/tmp
drwxr-xr-x root root /
drwxr-xr-x root root var
drwxr-xr-x root root www
drwxr-xr-x root root html
drwxr-xr-x root apache limesurvey
drwxrwxr-x root apache tmp

Answer Source

After much head-scratching, it transpired that SELinux was preventing the directory from being written to. I found a good tutorial that explains what's going on. I was able to fix it by running this command:

sudo chcon -R -t httpd_sys_rw_content_t tmp