libei: add a backend to work off a single fd

For the case where someone else opens the sockets for us - like a test suite
or eventually the portal.

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>

meson.build

@@ -38,6 +38,7 @@ src_libei = [
     'src/libei.c',
     'src/libei-device.c',
     'src/libei-socket.c',
+    'src/libei-fd.c',
     proto_headers,
 ]
 

src/libei-fd.c

@@ -0,0 +1,90 @@
+/*
+ * Copyright © 2020 Red Hat, Inc.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ */
+
+#include "config.h"
+
+#include <fcntl.h>
+#include <stdlib.h>
+#include <sys/socket.h>
+#include <sys/un.h>
+#include <unistd.h>
+
+
+#include "util-logger.h"
+#include "util-mem.h"
+#include "util-macros.h"
+#include "util-sources.h"
+#include "util-strings.h"
+#include "util-object.h"
+
+#include "libei.h"
+#include "libei-private.h"
+
+/**
+ * This is the simplest backend: the caller prepares a socket and we just
+ * take that and use it.
+ */
+struct ei_fd {
+	struct object object;
+};
+
+static inline struct ei_fd *
+ei_fd(struct ei *ei)
+{
+	return ei->backend;
+}
+
+static inline void
+ei_fd_destroy(struct ei_fd *backend)
+{
+	/* nothing to do here */
+}
+
+OBJECT_IMPLEMENT_CREATE(ei_fd);
+static
+OBJECT_IMPLEMENT_UNREF(ei_fd);
+
+static void
+interface_fd_destroy(struct ei *ei, void *backend)
+{
+	struct ei_fd *ei_fd = backend;
+	ei_fd_unref(ei_fd);
+}
+
+static const struct ei_backend_interface interface = {
+	.destroy = interface_fd_destroy,
+};
+
+_public_ int
+ei_setup_backend_fd(struct ei *ei, int fd)
+{
+	assert(ei);
+	assert(!ei->backend);
+
+	struct ei_fd *ei_fd = ei_fd_create(&ei->object);
+
+	ei->backend = ei_fd;
+	ei->backend_interface = interface;
+
+	return ei_set_connection(ei, fd);
+}

src/libei.h

@@ -114,6 +114,12 @@ ei_configure_name(struct ei * ei, const char *name);
 int
 ei_setup_backend_socket(struct ei *ei, const char *socketpath);
 
+/**
+ * Initialize the ei context on the given socket
+ */
+int
+ei_setup_backend_fd(struct ei *ei, int fd);
+
 struct ei *
 ei_ref(struct ei *ctx);