When using GNULIB with Winsock, libvirt will never see the normal HANDLE objects, instead GNULIB guarantees that libvirt gets a C runtime file descriptor. The GNULIB poll impl also expects to get C runtime file descriptors rather than HANDLE objects. Document this behaviour so that it is clear to applications providing event loop implementations if they need Windows portability. Signed-off-by: Daniel P. Berrangé <berrange@redhat.com> --- include/libvirt/libvirt-event.h | 4 ++++ src/util/virevent.c | 7 +++++++ 2 files changed, 11 insertions(+) diff --git a/include/libvirt/libvirt-event.h b/include/libvirt/libvirt-event.h index 734dbdcbc1..facdc3a3ec 100644 --- a/include/libvirt/libvirt-event.h +++ b/include/libvirt/libvirt-event.h @@ -67,6 +67,10 @@ typedef void (*virEventHandleCallback)(int watch, int fd, int events, void *opaq * listen for specific events. The same file handle can be registered * multiple times provided the requested event sets are non-overlapping * + * @fd will always be a C runtime file descriptor. On Windows + * the _get_osfhandle() method can be used if a HANDLE is required + * instead. + * * If the opaque user data requires free'ing when the handle * is unregistered, then a 2nd callback can be supplied for * this purpose. This callback needs to be invoked from a clean stack. diff --git a/src/util/virevent.c b/src/util/virevent.c index f6c797724e..fd5d8f5bf1 100644 --- a/src/util/virevent.c +++ b/src/util/virevent.c @@ -60,6 +60,13 @@ static virEventRemoveTimeoutFunc removeTimeoutImpl; * requires that an event loop has previously been registered with * virEventRegisterImpl() or virEventRegisterDefaultImpl(). * + * @fd must always always be a C runtime file descriptor. On Windows + * if the caller only has a HANDLE, the _open_osfhandle() method can + * be used to open an associated C runtime file descriptor for use + * with this API. After opening a runtime file descriptor, CloseHandle() + * must not be used, instead close() will close the runtime file + * descriptor and its original associated HANDLE. + * * Returns -1 if the file handle cannot be registered, otherwise a handle * watch number to be used for updating and unregistering for events. */ -- 2.21.0