Is there any way to open a file inside kext

Question

I'm writing a kext and

My requirement is to load the configuration during the runtime, when it is triggered from userspace or within the kext

Is it possible to open a file inside kext and perform read operation inside kext,

or can you suggest any alternatives for this!!

Thanks

Venkat

507

Posted by

vereddy

Reply

Answer 1

You can do this using various vnode KPIs. Start with

vnode_open

in

<sys/vnode.h>

in the Kernel framework.

However, there are some things to consider here:

We generally recommend that kernel code not read configuration files directly. Rather, it should start with a default configuration and then allow for dynamic reconfiguration based from a daemon as the system boots.
For large read-only files, like firmware images, you can load the file using OSKextRequestResource (
```
<libkern/OSKextLib.h>
```
).
If your KEXT is on the boot path — and Ethernet drivers can be on the boot path when the system is configured to netboot — you have to avoid deadlocking. In that case you want to get your configuration from NVRAM, using
```
IODTNVRAM
```
.

Share and Enjoy
—
Quinn “The Eskimo!”
Apple Developer Relations, Developer Technical Support, Core OS/Hardware

let myEmail = "eskimo" + "1" + "@apple.com"

Posted by

eskimo

Answer 2

You can do this using various vnode KPIs. Start with

vnode_open

in

<sys/vnode.h>

in the Kernel framework.

However, there are some things to consider here:

We generally recommend that kernel code not read configuration files directly. Rather, it should start with a default configuration and then allow for dynamic reconfiguration based from a daemon as the system boots.
For large read-only files, like firmware images, you can load the file using OSKextRequestResource (
```
<libkern/OSKextLib.h>
```
).
If your KEXT is on the boot path — and Ethernet drivers can be on the boot path when the system is configured to netboot — you have to avoid deadlocking. In that case you want to get your configuration from NVRAM, using
```
IODTNVRAM
```
.

Share and Enjoy
—
Quinn “The Eskimo!”
Apple Developer Relations, Developer Technical Support, Core OS/Hardware

let myEmail = "eskimo" + "1" + "@apple.com"

Posted by

eskimo

Accepted Reply