Based on Xorg upstream git commit b07602014061cb41540f6a7e74e4132e67aa1117
From: Alan Coopersmith <Alan.Coopersmith@sun.com>
Date: Mon, 22 Aug 2005 21:47:59 +0000

If MAKE_XKM_OUTPUT_DIR is defined, call trans_mkdir to create directory if
it doesn't already exist. (ported from Solaris Xsun bug #5039004)

[Xorg has since dropped upstream, but we still use.]

Updated to include changes to ensure xkb directory & files are writable
by gid 0, to fix bug:
6916317 Changing xkb settings after login not working on snv130

diff --git a/xkb/Makefile.am b/xkb/Makefile.am
index fb3ccbf..5a82e09 100644
--- a/xkb/Makefile.am
+++ b/xkb/Makefile.am
@@ -1,6 +1,7 @@
 noinst_LTLIBRARIES = libxkb.la libxkbstubs.la
 
 AM_CFLAGS = $(DIX_CFLAGS)
+AM_CFLAGS += -DMAKE_XKM_OUTPUT_DIR
 
 DDX_SRCS = \
         ddxBeep.c \
diff --git a/xkb/ddxLoad.c b/xkb/ddxLoad.c
index d462957..9338a1c 100644
--- a/xkb/ddxLoad.c
+++ b/xkb/ddxLoad.c
@@ -68,14 +68,30 @@ THE USE OR PERFORMANCE OF THIS SOFTWARE.
 #define PATHSEPARATOR "/"
 #endif
 
+#ifdef MAKE_XKM_OUTPUT_DIR
+/* Borrow trans_mkdir from Xtransutil.c to more safely make directories */
+# undef X11_t
+# define TRANS_SERVER
+# define prmsg(lvl,...) \
+        if (lvl <= 1) { LogMessage(X_ERROR, __VA_ARGS__); } else ((void)0)
+# include <X11/Xtrans/Xtransutil.c>
+# ifndef XKM_OUTPUT_DIR_MODE
+#  define XKM_OUTPUT_DIR_MODE 0775
+# endif
+#endif
+
 static void
 OutputDirectory(char *outdir, size_t size)
 {
 #ifndef WIN32
+#ifdef MAKE_XKM_OUTPUT_DIR
+    if (geteuid() == 0 && trans_mkdir(XKM_OUTPUT_DIR, XKM_OUTPUT_DIR_MODE) == 0 && (strlen(XKM_OUTPUT_DIR) < size)) {
+#else
     /* Can we write an xkm and then open it too? */
     if (access(XKM_OUTPUT_DIR, W_OK | X_OK) == 0 &&
         (strlen(XKM_OUTPUT_DIR) < size)) {
-        (void) strcpy(outdir, XKM_OUTPUT_DIR);
+#endif
+        (void) strcpy (outdir, XKM_OUTPUT_DIR);
     }
     else
 #else
@@ -113,6 +129,15 @@ XkbDDXCompileKeymapByNames(XkbDescPtr xkb,
     const char *xkmfile = "-";
 #endif
 
+    /* save gid and reset to gid 0 before making xkm_output_dir or
+       running xkbcomp to create the xkm file in it. */
+    gid_t usr_gid = getgid();
+
+    if (setregid(0, usr_gid) < 0)
+        ErrorF("Error in setting regid to 0: %s\n", strerror(errno));
+    if (setegid(0) < 0)
+        ErrorF("Error in setting egid to 0: %s\n", strerror(errno));
+    
     snprintf(keymap, sizeof(keymap), "server-%s", display);
 
     OutputDirectory(xkm_output_dir, sizeof(xkm_output_dir));
@@ -164,6 +189,11 @@ XkbDDXCompileKeymapByNames(XkbDescPtr xkb,
     out = fopen(tmpname, "w");
 #endif
 
+    if (setregid(usr_gid, 0) < 0)
+        ErrorF("Error in resetting regid: %s\n", strerror(errno));
+    if (setegid(usr_gid) < 0)
+        ErrorF("Error in resetting egid: %s\n", strerror(errno));
+
     if (out != NULL) {
 #ifdef DEBUG
         if (xkbDebugFlags) {