QFile::write() does not report errors

QFile::write() returns always success (the number of bytes that should be written) regardless whether the write actually succeeds or not. See the attached error case example for a proof.

How to run it:

1.  Compile the test kernel module, that creates a sysfs file that always returns EBUSY on write.
2. Load the module. A "/sys/devices/qfile/ebusy" file should appear in the filesystem.
3. Try "echo test > /sys/devices/qfile/ebusy". You will get an error from the shell.
4. Compile the test application.
5. Run the test application. You will get no error from QFile::write().