diff options
Diffstat (limited to 'lib/libsys')
| -rw-r--r-- | lib/libsys/kqueue.2 | 29 |
1 files changed, 28 insertions, 1 deletions
diff --git a/lib/libsys/kqueue.2 b/lib/libsys/kqueue.2 index 96c9b0222a37..a8ebabf02cf7 100644 --- a/lib/libsys/kqueue.2 +++ b/lib/libsys/kqueue.2 @@ -97,10 +97,37 @@ system call also creates a new kernel event queue, and additionally takes a .Fa flags argument, which is a bitwise-inclusive OR of the following flags: -.Bl -tag -width "KQUEUE_CLOEXEC" +.Bl -tag -width "KQUEUE_CPONFORK" .It Dv KQUEUE_CLOEXEC The returned file descriptor is automatically closed on .Xr execve 2 +.It Dv KQUEUE_CPONFORK +When this flag is set, the created kqueue is copied into +the child process on +.Xr fork 2 +calls. +The kqueue descriptor index of the new kqueue will be inherited by the child, +that is, the numeric value of the descriptor will remain the same. +.Pp +Copying is deep, that is, each registered event in the original kqueue is +copied (and not shared) into the new kqueue. +This is contrary to how other descriptor types are handled upon +.Xr fork 2 , +where the copied file descriptor references the same file object +as the source descriptor (shallow copy). +.Pp +By default, in other words, when the flag is not set, kqueues from +the parent are not copied on fork to the child process. +The corresponding file descriptor indeces are unused in the child. +.Pp +Registered events that reference file descriptors which are not +duplicated on fork, are not copied into the new kqueue. +For instance, if the event references a file descriptor opened with the +.Dv O_CLOEXEC +flag set, it is not copied. +Similarly, if event references a kqueue opened without the +.Dv KQUEUE_CPONFORK +flag, the event is not copied. .El .Pp The |