WordPress unzip_file() results in mkdir_failed (permissions)

Question

I am creating a WordPress framework that has an auto update facility. When the system updates the framework, it downloads a .zip file (works ok, stored in a temp folder), and afterwards tries to extract that zip file to a place within the theme. When unzipping, it throws an error complaining about not being able to create a directory ("mkdir_failed").

The parent of target folder has permission "775" for user "bitnami" and group "bitnami";

root@linux:/home/bitnami# ls -al /opt/bitnami/apps/wordpress/htdocs/wp-content/themes/nexus ... drwxrwxr-x 6 bitnami bitnami 4096 Oct 23 14:02 nexusframework ...

And I tried to put the "daemon" user in the "bitnami" group;

usermod -a -G bitnami daemon

Which indeed is assigned correctly I would say, as i see:

root@linux:/home/bitnami# id daemon uid=1(daemon) gid=1(daemon) groups=1(daemon),1000(bitnami)

So; if the "daemon" user is in the "bitnami" group and the folder has 775 access rights, then why does it fail with "mkdir_failed"?

(note; assigning "777" to the parent folder solves the problem, but this is not an option because of security).

Thanks! - Gert-Jan

update;

After doing more investigation on Linux in general, I read that Linux automatically creates a 'private' group for each user (so bitnami group for the bitnami user, etc.). I don't know if the problem is caused by the fact that I was trying (and apparently succeeded?) to add other users to the same group or not.

update;

See my answer below on how I resolved my issue.

Very strange. Are you sure all the parent directories have +x for group bitnami? — Tim Lamballais
thanks for your comments. @alan978: i think i have, since my kernel is 3.2.0-27virtual (i read selinux is enabled since 2.6 or so) — barkgj
@TimLamballais: re: +x > not sure, unable to test now since i went on 'hacking', same for your question re: 'id bitnami'. — barkgj

barkgj barkgj · Accepted Answer · 2012-10-24T15:45:04

Ok, thanks for all the comments. I eventually decided not to continu my investigation but to head for another direction, as having to rely on the container's folder to have "775" permission would be unwise for the framework (many clients would have 755 instead, so getting this to work for a group is nice but would eventually not solve my problem).

Instead I further investigated how WordPress themselves download and unzip themes and decided to follow that route.

The key problem i was trying to tackle, was to not have the unzipped files be owned by the 'daemon' user, but by the 'bitnami' user. The reason why it "impersonated" to the daemon user, was because i manually told the code to use the "direct" fs_method (as it appears, WP offers various ways to interact with the filesystem, where the easiest one is 'direct', see here). However, using the 'direct' FS_METHOD is the core reason why I have this problem, as that one will use the credentials of the webserver (the 'daemon' user in my case). So by using a different FS_METHOD, I know am able to unzip the files in the folder, using the correct 'bitnami' user (since the container is owner and has permissions (775, or 755 wouldn't matter) now my problem is solved. Note that instead of writing directly to the filesystem, now PHP will use FTP (see here).

WordPress unzip_file() results in mkdir_failed (permissions)

2 Answers