xquartz: Add a launch trampoline to better integrate with modern versions of macOS

Fixes: https://github.com/XQuartz/XQuartz/issues/6
Signed-off-by: Jeremy Huddleston Sequoia <jeremyhu@apple.com>

hw/xquartz/bundle/mk_bundke.sh

@@ -24,7 +24,7 @@ install -m 644 ${BUILDDIR}/Info.plist ${BUNDLE_ROOT}/Contents
 install -m 644 ${SRCDIR}/PkgInfo ${BUNDLE_ROOT}/Contents
 
 mkdir -p ${BUNDLE_ROOT}/Contents/MacOS
-install -m 755 ${SRCDIR}/X11.sh ${BUNDLE_ROOT}/Contents/MacOS/X11
+install -m 755 ${SRCDIR}/X11.sh ${BUNDLE_ROOT}/Contents/MacOS
 
 if [[ $(id -u) == 0 ]] ; then
 	chown -R root:admin ${BUNDLE_ROOT}

hw/xquartz/mach-startup/Makefile.am

@@ -7,11 +7,14 @@ AM_CPPFLAGS = \
 AM_CFLAGS = $(DIX_CFLAGS)
 
 x11appdir = $(APPLE_APPLICATIONS_DIR)/$(APPLE_APPLICATION_NAME).app/Contents/MacOS
-x11app_PROGRAMS = X11.bin
+x11app_PROGRAMS = X11.bin X11
 
 dist_X11_bin_SOURCES = \
 	bundle-main.c
 
+dist_X11_SOURCES = \
+	bundle_trampoline.c
+
 # strndup(3) was added in Mac OS X 10.7, but we do this unconditionally to deal
 # with the case where we build on Lion but target Snow Leopard as the minimum
 # OS version.

hw/xquartz/mach-startup/bundle_trampoline.c

@@ -0,0 +1,87 @@
+/* Copyright (c) 2021 Apple 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 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 ABOVE LISTED COPYRIGHT
+ * HOLDER(S) 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.
+ *
+ * Except as contained in this notice, the name(s) of the above
+ * copyright holders shall not be used in advertising or otherwise to
+ * promote the sale, use or other dealings in this Software without
+ * prior written authorization.
+ */
+
+#include <assert.h>
+#include <mach-o/dyld.h>
+#include <libgen.h>
+#include <spawn.h>
+#include <sys/syslimits.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+/* We wnt XQuartz.app to inherit a login shell environment.  This is handled by the X11.sh
+ * script which re-execs the main binary from a login shell environment.  However, recent
+ * versions of macOS require that the main executable of an app be Mach-O for full system
+ * fidelity.
+ *
+ * Failure to do so results in two problems:
+ *    1) bash is seen as the responsible executable for Security & Privacy, and the user doesn't
+ *       get prompted to allow filesystem access (https://github.com/XQuartz/XQuartz/issues/6).
+ *    2) The process is launched under Rosetta for compatability, which results in
+ *       the subsequent spawn of the real executable under Rosetta rather than natively.
+ *
+ * This trampoline provides the mach-o needed by LaunchServices and TCC to satisfy those
+ * needs and simply execs the startup script which then execs the main binary.
+ */
+
+static char *executable_path() {
+    uint32_t bufsize = PATH_MAX;
+    char *buf = calloc(1, bufsize);
+
+    if (_NSGetExecutablePath(buf, &bufsize) == -1) {
+        free(buf);
+        buf = calloc(1, bufsize);
+        assert(_NSGetExecutablePath(buf, &bufsize) == 0);
+    }
+
+    return buf;
+}
+
+int main(int argc, char **argv, char **envp) {
+    char const * const executable_directory = dirname(executable_path());
+    char *executable = NULL;
+
+    asprintf(&executable, "%s/X11.sh", executable_directory);
+    if (access(executable, X_OK) == -1) {
+        free(executable);
+        asprintf(&executable, "%s/X11", executable_directory);
+    }
+    assert(access(executable, X_OK) == 0);
+
+    argv[0] = executable;
+
+    posix_spawnattr_t attr;
+    assert(posix_spawnattr_init(&attr) == 0);
+    assert(posix_spawnattr_setflags(&attr, POSIX_SPAWN_SETEXEC) == 0);
+
+    pid_t child_pid;
+    assert(posix_spawn(&child_pid, executable, NULL, &attr, argv, envp) == 0);
+
+    return EXIT_FAILURE;
+}