os: wrap socket(SOCK_CLOEXEC) calls

Some system C libraries do not offer SOCK_CLOEXEC flag.

Add a new header for OS compatibility wrappers. Wrap socket() calls into
wl_os_socket_cloexec() which makes sure the O_CLOEXEC flag gets set on
the file descriptor.

On systems having SOCK_CLOEXEC this uses the old socket() call, and
falls back if it fails due to the flag (kernel not supporting it).

wayland-os.h is private and not exported.

Add close-on-exec tests for both normal and forced fallback paths.

Signed-off-by: Pekka Paalanen <ppaalanen@gmail.com>

src/Makefile.am

@@ -14,6 +14,8 @@ libwayland_util_la_SOURCES =			\
 	connection.c				\
 	wayland-util.c				\
 	wayland-util.h				\
+	wayland-os.c				\
+	wayland-os.h				\
 	wayland-private.h
 
 libwayland_server_la_LIBADD = $(FFI_LIBS) libwayland-util.la -lrt

src/wayland-client.c

@@ -36,6 +36,7 @@
 #include <sys/poll.h>
 
 #include "wayland-util.h"
+#include "wayland-os.h"
 #include "wayland-client.h"
 #include "wayland-private.h"
 
@@ -307,7 +308,7 @@ connect_to_socket(struct wl_display *display, const char *name)
 	const char *runtime_dir;
 	size_t name_size;
 
-	display->fd = socket(PF_LOCAL, SOCK_STREAM | SOCK_CLOEXEC, 0);
+	display->fd = wl_os_socket_cloexec(PF_LOCAL, SOCK_STREAM, 0);
 	if (display->fd < 0)
 		return -1;
 

src/wayland-os.c

@@ -0,0 +1,69 @@
+/*
+ * Copyright © 2012 Collabora, Ltd.
+ *
+ * Permission to use, copy, modify, distribute, and sell this software and its
+ * documentation for any purpose is hereby granted without fee, provided that
+ * the above copyright notice appear in all copies and that both that copyright
+ * notice and this permission notice appear in supporting documentation, and
+ * that the name of the copyright holders not be used in advertising or
+ * publicity pertaining to distribution of the software without specific,
+ * written prior permission.  The copyright holders make no representations
+ * about the suitability of this software for any purpose.  It is provided "as
+ * is" without express or implied warranty.
+ *
+ * THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
+ * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
+ * EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
+ * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
+ * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
+ * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
+ * OF THIS SOFTWARE.
+ */
+
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <errno.h>
+
+#include "wayland-os.h"
+
+static int
+set_cloexec_or_close(int fd)
+{
+	long flags;
+
+	if (fd == -1)
+		return -1;
+
+	flags = fcntl(fd, F_GETFD);
+	if (flags == -1)
+		goto err;
+
+	if (fcntl(fd, F_SETFD, flags | FD_CLOEXEC) == -1)
+		goto err;
+
+	return fd;
+
+err:
+	close(fd);
+	return -1;
+}
+
+int
+wl_os_socket_cloexec(int domain, int type, int protocol)
+{
+	int fd;
+
+#ifdef SOCK_CLOEXEC
+	errno = 0;
+	fd = socket(domain, type | SOCK_CLOEXEC, protocol);
+	if (fd >= 0)
+		return fd;
+	if (errno != EINVAL)
+		return -1;
+#endif
+
+	fd = socket(domain, type, protocol);
+	return set_cloexec_or_close(fd);
+}

src/wayland-os.h

@@ -0,0 +1,29 @@
+/*
+ * Copyright © 2012 Collabora, Ltd.
+ *
+ * Permission to use, copy, modify, distribute, and sell this software and its
+ * documentation for any purpose is hereby granted without fee, provided that
+ * the above copyright notice appear in all copies and that both that copyright
+ * notice and this permission notice appear in supporting documentation, and
+ * that the name of the copyright holders not be used in advertising or
+ * publicity pertaining to distribution of the software without specific,
+ * written prior permission.  The copyright holders make no representations
+ * about the suitability of this software for any purpose.  It is provided "as
+ * is" without express or implied warranty.
+ *
+ * THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
+ * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
+ * EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
+ * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
+ * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
+ * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
+ * OF THIS SOFTWARE.
+ */
+
+#ifndef WAYLAND_OS_H
+#define WAYLAND_OS_H
+
+int
+wl_os_socket_cloexec(int domain, int type, int protocol);
+
+#endif

src/wayland-server.c

@@ -44,6 +44,7 @@
 #include "wayland-private.h"
 #include "wayland-server.h"
 #include "wayland-server-protocol.h"
+#include "wayland-os.h"
 
 struct wl_socket {
 	int fd;
@@ -970,7 +971,7 @@ wl_display_add_socket(struct wl_display *display, const char *name)
 	if (s == NULL)
 		return -1;
 
-	s->fd = socket(PF_LOCAL, SOCK_STREAM | SOCK_CLOEXEC, 0);
+	s->fd = wl_os_socket_cloexec(PF_LOCAL, SOCK_STREAM, 0);
 	if (s->fd < 0) {
 		free(s);
 		return -1;

tests/Makefile.am

@@ -5,7 +5,8 @@ my_check_programs =				\
 	list-test				\
 	connection-test				\
 	event-loop-test				\
-	client-test
+	client-test				\
+	os-wrappers-test
 
 TESTS = $(my_check_programs)
 
@@ -23,6 +24,11 @@ connection_test_SOURCES = connection-test.c $(test_runner_src)
 event_loop_test_SOURCES = event-loop-test.c $(test_runner_src)
 client_test_SOURCES = client-test.c $(test_runner_src)
 
+os_wrappers_test_SOURCES = 			\
+	os-wrappers-test.c			\
+	../src/wayland-os.c			\
+	$(test_runner_src)
+
 AM_CFLAGS = $(GCC_CFLAGS)
 LDADD = $(top_builddir)/src/libwayland-util.la \
 	$(top_builddir)/src/libwayland-server.la \

tests/os-wrappers-test.c

@@ -0,0 +1,100 @@
+/*
+ * Copyright © 2012 Collabora, Ltd.
+ *
+ * Permission to use, copy, modify, distribute, and sell this software and its
+ * documentation for any purpose is hereby granted without fee, provided that
+ * the above copyright notice appear in all copies and that both that copyright
+ * notice and this permission notice appear in supporting documentation, and
+ * that the name of the copyright holders not be used in advertising or
+ * publicity pertaining to distribution of the software without specific,
+ * written prior permission.  The copyright holders make no representations
+ * about the suitability of this software for any purpose.  It is provided "as
+ * is" without express or implied warranty.
+ *
+ * THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
+ * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
+ * EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
+ * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
+ * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
+ * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
+ * OF THIS SOFTWARE.
+ */
+
+#define _GNU_SOURCE
+
+#include <stdlib.h>
+#include <assert.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <unistd.h>
+#include <dlfcn.h>
+#include <errno.h>
+
+#include "test-runner.h"
+#include "../src/wayland-os.h"
+
+static int fall_back;
+static int wrapped_calls;
+
+static int (*real_socket)(int, int, int);
+
+static void
+init_fallbacks(int do_fallbacks)
+{
+	fall_back = do_fallbacks;
+	real_socket = dlsym(RTLD_NEXT, "socket");
+}
+
+__attribute__ ((visibility("default"))) int
+socket(int domain, int type, int protocol)
+{
+	wrapped_calls++;
+
+#ifdef SOCK_CLOEXEC
+	if (fall_back && (type & SOCK_CLOEXEC)) {
+		errno = EINVAL;
+		return -1;
+	}
+#endif
+
+	return real_socket(domain, type, protocol);
+}
+
+static void
+do_os_wrappers_socket_cloexec(int n)
+{
+	int fd;
+	int nr_fds;
+
+	nr_fds = count_open_fds();
+
+	/* simply create a socket that closes on exec */
+	fd = wl_os_socket_cloexec(PF_LOCAL, SOCK_STREAM, 0);
+
+#ifdef SOCK_CLOEXEC
+	/*
+	 * Must have 2 calls if falling back, but must also allow
+	 * falling back without a forced fallback.
+	 */
+	assert(wrapped_calls > n);
+#else
+	assert(wrapped_calls == 1);
+#endif
+	assert(fd >= 0);
+
+	exec_fd_leak_check(nr_fds);
+}
+
+TEST(os_wrappers_socket_cloexec)
+{
+	/* normal case */
+	init_fallbacks(0);
+	do_os_wrappers_socket_cloexec(0);
+}
+
+TEST(os_wrappers_socket_cloexec_fallback)
+{
+	/* forced fallback */
+	init_fallbacks(1);
+	do_os_wrappers_socket_cloexec(1);
+}