open(2) can return EBUSY

[Mats Erik Andersson]

Hello,

when a character device like /dev/cua00 is locked using fcntl(2)
with F_SETLK in one application, a second desire to open the same
device in a second application: 

    open("/dev/cua00", O_RDWR | O_NOCTTY | O_NONBLOCK)

will return an error with "errno == EBUSY". This happens at least
with OpenBSD 4.6.

This possibility is not documented in the manual page open(2),
neither in 4.6, nor in 4.7.


Best regards,

Mats Erik Andersson, fil. dr