[libvirt] [PATCH glib] Fix event loop implementation on win32
Libvirt uses gnulib for making winsock look like POSIX sockets. This means that in the libvirt event handle callbacks the application will be given a file descriptor rather than a winsock HANDLE object. The g_io_channel_unix_new method will detect that it is an FD and delegate to the g_io_channel_win32_new_fd method. Unfortunately the glib Win32 event loop impl is not very good at dealing with FD objects, simulating poll() by doing a read() on the FD :-( The API docs for g_io_channel_win32_new_fd say "All reads from the file descriptor should be done by this internal GLib thread. Your code should call only g_io_channel_read()." This isn't going to fly for libvirt, since it has zero knowledge of glib at all, so is just doing normal read(). Fortunately we can work around this problem by turning the FD we get from libvirt back into a HANDLE using the _get_osfhandle() method. Signed-off-by: Daniel P. Berrange <berrange@redhat.com> --- libvirt-glib/libvirt-glib-event.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/libvirt-glib/libvirt-glib-event.c b/libvirt-glib/libvirt-glib-event.c index 87019b5..826db2d 100644 --- a/libvirt-glib/libvirt-glib-event.c +++ b/libvirt-glib/libvirt-glib-event.c @@ -31,6 +31,10 @@ #include "libvirt-glib/libvirt-glib.h" +#ifdef G_OS_WIN32 +#include <io.h> +#endif + /** * SECTION:libvirt-glib-event * @short_description: Integrate libvirt with the GMain event framework @@ -164,7 +168,7 @@ gvir_event_handle_add(int fd, data->events = events; data->cb = cb; data->opaque = opaque; - data->channel = g_io_channel_unix_new(fd); + data->channel = g_io_channel_unix_new(_get_osfhandle(fd)); data->ff = ff; g_debug("Add handle %p %d %d %d %p\n", data, data->watch, data->fd, events, data->opaque); -- 1.8.4.2
On Fri, Jan 24, 2014 at 05:04:31PM +0000, Daniel P. Berrange wrote:
Libvirt uses gnulib for making winsock look like POSIX sockets. This means that in the libvirt event handle callbacks the application will be given a file descriptor rather than a winsock HANDLE object. The g_io_channel_unix_new method will detect that it is an FD and delegate to the g_io_channel_win32_new_fd method. Unfortunately the glib Win32 event loop impl is not very good at dealing with FD objects, simulating poll() by doing a read() on the FD :-(
The API docs for g_io_channel_win32_new_fd say
"All reads from the file descriptor should be done by this internal GLib thread. Your code should call only g_io_channel_read()."
This isn't going to fly for libvirt, since it has zero knowledge of glib at all, so is just doing normal read().
Fortunately we can work around this problem by turning the FD we get from libvirt back into a HANDLE using the _get_osfhandle() method.
Signed-off-by: Daniel P. Berrange <berrange@redhat.com> --- libvirt-glib/libvirt-glib-event.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/libvirt-glib/libvirt-glib-event.c b/libvirt-glib/libvirt-glib-event.c index 87019b5..826db2d 100644 --- a/libvirt-glib/libvirt-glib-event.c +++ b/libvirt-glib/libvirt-glib-event.c @@ -31,6 +31,10 @@
#include "libvirt-glib/libvirt-glib.h"
+#ifdef G_OS_WIN32 +#include <io.h> +#endif + /** * SECTION:libvirt-glib-event * @short_description: Integrate libvirt with the GMain event framework @@ -164,7 +168,7 @@ gvir_event_handle_add(int fd, data->events = events; data->cb = cb; data->opaque = opaque; - data->channel = g_io_channel_unix_new(fd); + data->channel = g_io_channel_unix_new(_get_osfhandle(fd));
Doesn't this need to be #ifdef G_OS_WIN32 ? Christophe
On Mon, Jan 27, 2014 at 11:48:16AM +0100, Christophe Fergeau wrote:
On Fri, Jan 24, 2014 at 05:04:31PM +0000, Daniel P. Berrange wrote:
Libvirt uses gnulib for making winsock look like POSIX sockets. This means that in the libvirt event handle callbacks the application will be given a file descriptor rather than a winsock HANDLE object. The g_io_channel_unix_new method will detect that it is an FD and delegate to the g_io_channel_win32_new_fd method. Unfortunately the glib Win32 event loop impl is not very good at dealing with FD objects, simulating poll() by doing a read() on the FD :-(
The API docs for g_io_channel_win32_new_fd say
"All reads from the file descriptor should be done by this internal GLib thread. Your code should call only g_io_channel_read()."
This isn't going to fly for libvirt, since it has zero knowledge of glib at all, so is just doing normal read().
Fortunately we can work around this problem by turning the FD we get from libvirt back into a HANDLE using the _get_osfhandle() method.
Signed-off-by: Daniel P. Berrange <berrange@redhat.com> --- libvirt-glib/libvirt-glib-event.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/libvirt-glib/libvirt-glib-event.c b/libvirt-glib/libvirt-glib-event.c index 87019b5..826db2d 100644 --- a/libvirt-glib/libvirt-glib-event.c +++ b/libvirt-glib/libvirt-glib-event.c @@ -31,6 +31,10 @@
#include "libvirt-glib/libvirt-glib.h"
+#ifdef G_OS_WIN32 +#include <io.h> +#endif + /** * SECTION:libvirt-glib-event * @short_description: Integrate libvirt with the GMain event framework @@ -164,7 +168,7 @@ gvir_event_handle_add(int fd, data->events = events; data->cb = cb; data->opaque = opaque; - data->channel = g_io_channel_unix_new(fd); + data->channel = g_io_channel_unix_new(_get_osfhandle(fd));
Doesn't this need to be #ifdef G_OS_WIN32 ?
Doh. Don't know what I was thinking here. Daniel -- |: http://berrange.com -o- http://www.flickr.com/photos/dberrange/ :| |: http://libvirt.org -o- http://virt-manager.org :| |: http://autobuild.org -o- http://search.cpan.org/~danberr/ :| |: http://entangle-photo.org -o- http://live.gnome.org/gtk-vnc :|
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