Applications may end up allocating a bunch of shmfence objects, each
of which uses a file descriptor, which must be kept open lest some
other client ask for a copy of it later on.
Lacking an API that can turn a memory mapping back into a file
descriptor, about the best we can do is push the file descriptors out
of the way of other X clients so that we don't run out of the ability
to accept new connections.
This uses fcntl F_GETFD to push the FD up above MAXCLIENTS.
Signed-off-by: Keith Packard <keithp@keithp.com>
Reviewed-by: Julien Cristau <jcristau@debian.org>
extern _X_EXPORT void
xorg_backtrace(void);
+extern _X_EXPORT int
+os_move_fd(int fd);
+
#endif /* OS_H */
#include "pixmapstr.h"
#include <sys/mman.h>
#include <unistd.h>
+#include <fcntl.h>
#include <X11/xshmfence.h>
static DevPrivateKeyRec syncShmFencePrivateKey;
miSyncInitFence(pScreen, pFence, initially_triggered);
+ fd = os_move_fd(fd);
pPriv->fence = xshmfence_map_shm(fd);
if (pPriv->fence) {
pPriv->fd = fd;
pPriv->fd = xshmfence_alloc_shm();
if (pPriv->fd < 0)
return -1;
+ pPriv->fd = os_move_fd(pPriv->fd);
pPriv->fence = xshmfence_map_shm(pPriv->fd);
if (!pPriv->fence) {
close (pPriv->fd);
string[len] = '\0';
}
+
+/* Move a file descriptor out of the way of our select mask; this
+ * is useful for file descriptors which will never appear in the
+ * select mask to avoid reducing the number of clients that can
+ * connect to the server
+ */
+int
+os_move_fd(int fd)
+{
+ int newfd;
+
+#ifdef F_DUPFD_CLOEXEC
+ newfd = fcntl(fd, F_DUPFD_CLOEXEC, MAXCLIENTS);
+#else
+ newfd = fcntl(fd, F_DUPFD, MAXCLIENTS);
+#endif
+ if (newfd < 0)
+ return fd;
+#ifndef F_DUPFD_CLOEXEC
+ fcntl(newfd, F_SETFD, FD_CLOEXEC);
+#endif
+ close(fd);
+ return newfd;
+}