utils: Add a hackish "logout" command

utils/CMakeLists.txt

@@ -34,3 +34,4 @@ luna_utility(touch.cpp touch)
 luna_utility(free.cpp free)
 luna_utility(sha256sum.cpp sha256sum)
 luna_utility(arch.cpp arch)
+luna_utility(logout.cpp logout)

utils/logout.cpp

@@ -0,0 +1,28 @@
+#include <errno.h>
+#include <os/ArgumentParser.h>
+#include <signal.h>
+#include <sys/pstat.h>
+
+// Very hackish. Will do for now.
+Result<int> luna_main(int argc, char** argv)
+{
+    os::ArgumentParser parser;
+    parser.add_description("Log out of a GUI session.");
+    parser.add_system_program_info("logout"_sv);
+    parser.parse(argc, argv);
+
+    pid_t last = pstat(-1, nullptr);
+    for (pid_t pid = 1; pid <= last; pid++)
+    {
+        static process ps;
+        if (pstat(pid, &ps) < 0)
+        {
+            if (errno == ESRCH) continue;
+            return err(errno);
+        }
+
+        if (strstr(ps.ps_name, "/usr/bin/launch")) { kill(ps.ps_pid, SIGTERM); }
+    }
+
+    return 0;
+}