[gtk+] wayland: use memfd_create instead of open in tmpdir

[Ray Strode <halfline src gnome org>]

commit df70e28d92e7c1d95f25120bdf059c07c211f083
Author: Ray Strode <rstrode redhat com>
Date:   Mon Jan 25 11:41:23 2016 -0500

    wayland: use memfd_create instead of open in tmpdir
    
    The tmpdir is used for a wide assortment of things, and
    can easily fill up. If it fills then desktop will start
    crashing with SIGBUS errors.
    
    This commit changes the shm pool allocation code, to use
    memfd_create, instead, so the shared memory files will
    be anonymous and not associated with /tmp
    
    https://bugzilla.gnome.org/show_bug.cgi?id=761095

 gdk/wayland/gdkdisplay-wayland.c |   28 ++++++++++++----------------
 1 files changed, 12 insertions(+), 16 deletions(-)
---
diff --git a/gdk/wayland/gdkdisplay-wayland.c b/gdk/wayland/gdkdisplay-wayland.c
index 5e88d96..360c489 100644
--- a/gdk/wayland/gdkdisplay-wayland.c
+++ b/gdk/wayland/gdkdisplay-wayland.c
@@ -22,7 +22,9 @@
 #include <errno.h>
 #include <unistd.h>
 #include <fcntl.h>
+#include <linux/memfd.h>
 #include <sys/mman.h>
+#include <sys/syscall.h>
 
 #include <glib.h>
 #include "gdkwayland.h"
@@ -928,27 +930,24 @@ create_shm_pool (struct wl_shm  *shm,
                  size_t         *buf_length,
                  void          **data_out)
 {
-  char *filename;
   struct wl_shm_pool *pool;
-  int fd;
+  int ret, fd;
   void *data;
 
-  filename = g_strconcat (g_get_tmp_dir (), G_DIR_SEPARATOR_S, "wayland-shm-XXXXXX", NULL);
-  fd = mkstemp (filename);
-  if (fd < 0)
+  ret = syscall (SYS_memfd_create, "gdk-wayland", MFD_CLOEXEC);
+
+  if (ret < 0)
     {
-      g_critical (G_STRLOC ": Unable to create temporary file (%s): %s",
-                  filename, g_strerror (errno));
-      g_free (filename);
+      g_critical (G_STRLOC ": creating shared memory file failed: %s",
+                  g_strerror (-ret));
       return NULL;
     }
-  unlink (filename);
+
+  fd = ret;
 
   if (ftruncate (fd, size) < 0)
     {
-      g_critical (G_STRLOC ": Truncating temporary file (%s) failed: %s",
-                  filename, g_strerror (errno));
-      g_free (filename);
+      g_critical (G_STRLOC ": Truncating shared memory file failed: %m");
       close (fd);
       return NULL;
     }
@@ -957,9 +956,7 @@ create_shm_pool (struct wl_shm  *shm,
 
   if (data == MAP_FAILED)
     {
-      g_critical (G_STRLOC ": mmap'ping temporary file (%s) failed: %s",
-                  filename, g_strerror (errno));
-      g_free (filename);
+      g_critical (G_STRLOC ": mmap'ping shared memory file failed: %m");
       close (fd);
       return NULL;
     }
@@ -967,7 +964,6 @@ create_shm_pool (struct wl_shm  *shm,
   pool = wl_shm_create_pool (shm, fd, size);
 
   close (fd);
-  g_free (filename);
 
   *data_out = data;
   *buf_length = size;