Maybe fix for a couple of bugs in write descriptors:

[kwikius]

1. In the read_write example, in a write to descriptor, the buffer is never written with the value to write.

2. In /bluez/gattlib_read_write.c the sizeof the pointer is used rather than the length of the buffer when writing the descriptor

I think there may still be problems in the read write example with regard to the type of the value you wish to write. In my case it is a uint8_t. I used the example here https://github.com/sandeepmistry/arduino-BLEPeripheral/blob/master/examples/led/led.ino

Anyway with the version in my branch I can now write the value correctly, but probably needs work to be generic.