Run binary application from android source - permission denied

I need to execute a binary from source code of an android application. This binary must be run for a few seconds and I have to capture the standard output during this time. Then I have to kill both processes. The problem is that the binary attempts to access /dev/block/vold/179:1 (sdcard) to read the device and am getting the message "permission denied" or sometimes other error messages. I've no clear what I have to do to run 开发者_开发知识库for 30 seconds and how to solve the "permission denied." I think the problem is not "su" process execution, because the application asks me for root privileges (I put the "process.runtime.getRuntime (). Exec (" su ");)

Please, help me! I've a big headache!!

Thanks.

Did you put this permission in your manifest?

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

Edit: Actually since you mention that it's reading, not writing, this may not be the answer you're looking for :P