[avrdude-dev] [patch #4328] Device locking for Linux

[Joerg Wunsch]

Update of patch #4328 (project avrdude):

                  Status:                    None => Wont Do                
             Assigned to:                    None => joerg_wunsch           
             Open/Closed:                    Open => Closed                 

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Follow-up Comment #1:

I hesitate to apply that patch, for the following reasons:

. it is (Redhat?) Linux-only, so only covers parts of the environments
  we want to support

. it calls an external program (quite some overhead)

. /usr/sbin/lockdev comes with zero documentation, not even the exit
  codes are documented

. /usr/sbin/lockdev is setgid lock, and has had security
  vulnerabilities in the past

. The entire idea of /usr/sbin/lockdev is IMHO bogus: why introduce a
  separate group for the locks, so you could successfully lock a
  device which you then are unable to open?  Having the lock directory
  owned by the same group as the tty devices would be much better (you
  need access permissions to the tty anyway).  As there is no
  documentation for it, I'd also fear it can lead to DoS situations.

If at all, I'd rather support lockdev(3) functions under Linux, or
uu_lock(3) under FreeBSD.  (No idea whether Solaris or MacOS X also
have a library interface for that.  Hand-crafting a proper UUCP lock
is a dreadful amount of work, so I'd rather avoid it.)  However, those
systems that enjoy /usr/sbin/lockdev will fail then unless the caller
itself is member of group lock.  Thus, we probably need a
configuration option whether UUCP-style lock support is to be enabled
on systems where the respective library functions are available.


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