Expose more from treefile via cxx-rs; adapt _install_langs to use it

We only honor `_install_langs` in the compose path, so move the
code to look at the treefile and move the string concatention to
Rust.

rust/src/lib.rs

@@ -255,6 +255,11 @@ pub mod ffi {
         fn get_ostree_override_layers(&self) -> Vec<String>;
         fn get_all_ostree_layers(&self) -> Vec<String>;
         fn get_repos(&self) -> Vec<String>;
+        fn get_packages(&self) -> Vec<String>;
+        fn get_exclude_packages(&self) -> Vec<String>;
+        fn get_install_langs(&self) -> Vec<String>;
+        fn format_install_langs_macro(&self) -> String;
+        fn get_lockfile_repos(&self) -> Vec<String>;
         fn get_ref(&self) -> &str;
         fn get_rojig_spec_path(&self) -> String;
         fn get_rojig_name(&self) -> String;

rust/src/treefile.rs

@@ -537,10 +537,36 @@ impl Treefile {
             .collect()
     }
 
+    pub(crate) fn get_packages(&self) -> Vec<String> {
+        self.parsed.packages.clone().unwrap_or_default()
+    }
+
+    pub(crate) fn get_exclude_packages(&self) -> Vec<String> {
+        self.parsed.exclude_packages.clone().unwrap_or_default()
+    }
+
+    pub(crate) fn get_install_langs(&self) -> Vec<String> {
+        self.parsed.install_langs.clone().unwrap_or_default()
+    }
+
+    /// If install_langs is set, generate a value suitable for the RPM macro `_install_langs`;
+    /// otherwise return the empty string.
+    pub(crate) fn format_install_langs_macro(&self) -> String {
+        if let Some(langs) = self.parsed.install_langs.as_ref() {
+            langs.join(":")
+        } else {
+            "".to_string()
+        }
+    }
+
     pub(crate) fn get_repos(&self) -> Vec<String> {
         self.parsed.repos.clone().unwrap_or_default()
     }
 
+    pub(crate) fn get_lockfile_repos(&self) -> Vec<String> {
+        self.parsed.lockfile_repos.clone().unwrap_or_default()
+    }
+
     pub(crate) fn get_ref(&self) -> &str {
         self.parsed.treeref.as_deref().unwrap_or_default()
     }

src/libpriv/rpmostree-core.cxx

@@ -693,7 +693,6 @@ rpmostree_context_setup (RpmOstreeContext    *self,
                          GError       **error)
 {
   std::string releasever;
-  g_autofree char **instlangs = NULL;
   /* This exists (as a canonically empty dir) at least on RHEL7+ */
   static const char emptydir_path[] = "/usr/share/empty";
 
@@ -726,22 +725,11 @@ rpmostree_context_setup (RpmOstreeContext    *self,
   /* Set the RPM _install_langs macro, which gets processed by librpm; this is
    * currently only referenced in the traditional or non-"unified core" code.
    */
-  if (g_variant_dict_lookup (self->spec->dict, "instlangs", "^a&s", &instlangs))
+  if (!self->is_system && self->treefile_rs)
     {
-      g_autoptr(GString) opt = g_string_new ("");
-
-      gboolean first = TRUE;
-      for (char **iter = instlangs; iter && *iter; iter++)
-        {
-          const char *v = *iter;
-          if (!first)
-            g_string_append_c (opt, ':');
-          else
-            first = FALSE;
-          g_string_append (opt, v);
-        }
-
-      dnf_context_set_rpm_macro (self->dnfctx, "_install_langs", opt->str);
+      auto instlangs = self->treefile_rs->format_install_langs_macro();
+      if (instlangs.length() > 0)
+        dnf_context_set_rpm_macro (self->dnfctx, "_install_langs", instlangs.c_str());
     }
 
   /* This is what we use as default. Note we should be able to drop this in the