main: Move usroverlay parsing back to C++ consistently

Otherwise, we end up segfaulting because
`rpm-ostree -h usroverlay` confuses things.

Unfortunately, if we expose it publicly in our help text
it needs to have a C++ trampoline.

rpmostree-cxxrs.cxx

@@ -2027,6 +2027,9 @@ extern "C"
   rpmostreecxx$cxxbridge1$Bubblewrap$run (::rpmostreecxx::Bubblewrap &self,
                                           const ::rpmostreecxx::GCancellable &cancellable) noexcept;
 
+  ::rust::repr::PtrLen
+  rpmostreecxx$cxxbridge1$usroverlay_entrypoint (const ::rust::Vec< ::rust::String> &args) noexcept;
+
   ::rust::repr::PtrLen
   rpmostreecxx$cxxbridge1$applylive_entrypoint (const ::rust::Vec< ::rust::String> &args) noexcept;
 
@@ -3534,6 +3537,16 @@ Bubblewrap::run (const ::rpmostreecxx::GCancellable &cancellable)
     }
 }
 
+void
+usroverlay_entrypoint (const ::rust::Vec< ::rust::String> &args)
+{
+  ::rust::repr::PtrLen error$ = rpmostreecxx$cxxbridge1$usroverlay_entrypoint (args);
+  if (error$.ptr)
+    {
+      throw ::rust::impl< ::rust::Error>::error (error$);
+    }
+}
+
 void
 applylive_entrypoint (const ::rust::Vec< ::rust::String> &args)
 {

rpmostree-cxxrs.h

@@ -1741,6 +1741,8 @@ ::rust::Box< ::rpmostreecxx::Bubblewrap>
 bubblewrap_new_with_mutability (::std::int32_t rootfs_fd,
                                 ::rpmostreecxx::BubblewrapMutability mutability);
 
+void usroverlay_entrypoint (const ::rust::Vec< ::rust::String> &args);
+
 void applylive_entrypoint (const ::rust::Vec< ::rust::String> &args);
 
 void applylive_finish (const ::rpmostreecxx::OstreeSysroot &sysroot);

rust/src/builtins/usroverlay.rs

@@ -7,7 +7,7 @@ use clap::Command;
 use std::os::unix::prelude::CommandExt;
 
 /// Directly exec(ostree admin unlock) - does not return on success.
-pub fn entrypoint(args: &[&str]) -> Result<()> {
+pub fn usroverlay_entrypoint(args: &Vec<String>) -> Result<()> {
     let cmd = cli_cmd();
     cmd.get_matches_from(args.iter().skip(1));
 

rust/src/lib.rs

@@ -152,6 +152,7 @@ pub mod ffi {
 
     // builtins/apply_live.rs
     extern "Rust" {
+        fn usroverlay_entrypoint(args: &Vec<String>) -> Result<()>;
         fn applylive_entrypoint(args: &Vec<String>) -> Result<()>;
         fn applylive_finish(sysroot: &OstreeSysroot) -> Result<()>;
     }
@@ -898,6 +899,7 @@ pub mod ffi {
 }
 
 pub mod builtins;
+pub(crate) use crate::builtins::usroverlay::usroverlay_entrypoint;
 pub(crate) use crate::builtins::apply_live::*;
 pub(crate) use crate::builtins::compose::commit::*;
 pub(crate) use crate::builtins::compose::*;

rust/src/main.rs

@@ -30,8 +30,6 @@ async fn inner_async_main(args: Vec<String>) -> Result<i32> {
                 // Add custom Rust commands here, and also in `libmain.cxx` if user-visible.
                 "countme" => rpmostree_rust::countme::entrypoint(args).map(|_| 0),
                 "cliwrap" => rpmostree_rust::cliwrap::entrypoint(args).map(|_| 0),
-                // The `unlock` is a hidden alias for "ostree CLI compatibility"
-                "usroverlay" | "unlock" => builtins::usroverlay::entrypoint(args).map(|_| 0),
                 // A hidden wrapper to intercept some binaries in RPM scriptlets.
                 "scriptlet-intercept" => builtins::scriptlet_intercept::entrypoint(args).map(|_| 0),
                 // This is a deprecated entrypoint

src/app/libmain.cxx

@@ -38,6 +38,17 @@
 
 #include "libglnx.h"
 
+static gboolean
+dispatch_usroverlay (int argc, char **argv, RpmOstreeCommandInvocation *invocation,
+                     GCancellable *cancellable, GError **error)
+{
+  rust::Vec<rust::String> rustargv;
+  for (int i = 0; i < argc; i++)
+    rustargv.push_back (std::string (argv[i]));
+  CXX_TRY (rpmostreecxx::usroverlay_entrypoint (rustargv), error);
+  return TRUE;
+}
+
 static RpmOstreeCommand commands[] = {
   { "compose",
     static_cast<RpmOstreeBuiltinFlags> (RPM_OSTREE_BUILTIN_FLAG_LOCAL_CMD
@@ -91,7 +102,12 @@ static RpmOstreeCommand commands[] = {
   { "scriptlet-intercept", static_cast<RpmOstreeBuiltinFlags> (RPM_OSTREE_BUILTIN_FLAG_HIDDEN),
     "Intercept some commands used by RPM scriptlets", NULL },
   { "usroverlay", static_cast<RpmOstreeBuiltinFlags> (RPM_OSTREE_BUILTIN_FLAG_REQUIRES_ROOT),
-    "Apply a transient overlayfs to /usr", NULL },
+    "Apply a transient overlayfs to /usr", dispatch_usroverlay },
+  // Alias for ostree compatibility
+  { "unlock",
+    static_cast<RpmOstreeBuiltinFlags> (RPM_OSTREE_BUILTIN_FLAG_REQUIRES_ROOT
+                                        | RPM_OSTREE_BUILTIN_FLAG_HIDDEN),
+    "Apply a transient overlayfs to /usr", dispatch_usroverlay },
   /* Legacy aliases */
   { "pkg-add", static_cast<RpmOstreeBuiltinFlags> (RPM_OSTREE_BUILTIN_FLAG_HIDDEN), NULL,
     rpmostree_builtin_install },