[Development] [QLockFile] Whether it is reasonable to use 0644 permission ?

[Denis Shienkov]

>> Currently this problem belongs to QSerialPort which internally uses
QLockFile to indication of employment of the /dev/ttyXYZ resources.> is this still a problem on modern unixes?

 > is this still a problem on modern unixes?

Yes, of course, it still is a problem...

There are one TIOCEXCL flag to make 'exclusive' access, but this flag 
does not work if the root
user want to open an already 'locked' device, because the root ignores 
TIOCEXCL..

So, stays one adequate way, it is use  the lock files, where even root 
won't be able to open an
already locked device (of course, if root's software parses lock-files, 
and if looks for these lock-files in necessary directory).. :)

PS: So, Unix in this case is a ZOO of different solutions, which do not 
work, IMHO...