1 files changed, 159 insertions, 0 deletions
diff --git a/libbuild2/config/init.cxx b/libbuild2/config/init.cxx
new file mode 100644
index 0000000..73275c6
--- /dev/null
+++ b/libbuild2/config/init.cxx
@@ -0,0 +1,159 @@
+// file      : libbuild2/config/init.cxx -*- C++ -*-
+// copyright : Copyright (c) 2014-2019 Code Synthesis Ltd
+// license   : MIT; see accompanying LICENSE file
+
+#include <libbuild2/config/init.hxx>
+
+#include <libbuild2/file.hxx>
+#include <libbuild2/rule.hxx>
+#include <libbuild2/scope.hxx>
+#include <libbuild2/context.hxx>
+#include <libbuild2/filesystem.hxx>  // exists()
+#include <libbuild2/diagnostics.hxx>
+
+#include <libbuild2/config/module.hxx>
+#include <libbuild2/config/utility.hxx>
+#include <libbuild2/config/operation.hxx>
+
+using namespace std;
+using namespace butl;
+
+namespace build2
+{
+  namespace config
+  {
+    bool
+    boot (scope& rs, const location&, unique_ptr<module_base>& mod)
+    {
+      tracer trace ("config::boot");
+
+      l5 ([&]{trace << "for " << rs;});
+
+      const string& mname (current_mname);
+      const string& oname (current_oname);
+
+      // Only create the module if we are configuring or creating. This is a
+      // bit tricky since the build2 core may not yet know if this is the
+      // case. But we know.
+      //
+      if ((                   mname == "configure" || mname == "create") ||
+          (mname.empty () && (oname == "configure" || oname == "create")))
+      {
+        unique_ptr<module> m (new module);
+
+        // Adjust priority for the import pseudo-module so that
+        // config.import.* values come first in config.build.
+        //
+        m->save_module ("import", INT32_MIN);
+
+        mod = move (m);
+      }
+
+      // Register meta-operations. Note that we don't register create_id
+      // since it will be pre-processed into configure.
+      //
+      rs.insert_meta_operation (configure_id, mo_configure);
+      rs.insert_meta_operation (disfigure_id, mo_disfigure);
+
+      return true; // Initialize first (load config.build).
+    }
+
+    bool
+    init (scope& rs,
+          scope&,
+          const location& l,
+          unique_ptr<module_base>&,
+          bool first,
+          bool,
+          const variable_map& config_hints)
+    {
+      tracer trace ("config::init");
+
+      if (!first)
+      {
+        warn (l) << "multiple config module initializations";
+        return true;
+      }
+
+      const dir_path& out_root (rs.out_path ());
+      l5 ([&]{trace << "for " << out_root;});
+
+      assert (config_hints.empty ()); // We don't known any hints.
+
+      auto& vp (var_pool.rw (rs));
+
+      // Load config.build if one exists (we don't need to worry about
+      // disfigure since we will never be init'ed).
+      //
+      const variable& c_v (vp.insert<uint64_t> ("config.version", false));
+
+      {
+        path f (config_file (rs));
+
+        if (exists (f))
+        {
+          // Check the config version. We assume that old versions cannot
+          // understand new configs and new versions are incompatible with old
+          // configs.
+          //
+          // We extract the value manually instead of loading and then
+          // checking in order to be able to fixup/migrate the file which we
+          // may want to do in the future.
+          //
+          {
+            // Assume missing version is 0.
+            //
+            auto p (extract_variable (f, c_v));
+            uint64_t v (p.second ? cast<uint64_t> (p.first) : 0);
+
+            if (v != module::version)
+              fail (l) << "incompatible config file " << f <<
+                info << "config file version   " << v
+                         << (p.second ? "" : " (missing)") <<
+                info << "config module version " << module::version <<
+                info << "consider reconfiguring " << project (rs) << '@'
+                         << out_root;
+          }
+
+          source (rs, rs, f);
+        }
+      }
+
+      // Register alias and fallback rule for the configure meta-operation.
+      //
+      // We need this rule for out-of-any-project dependencies (e.g.,
+      // libraries imported from /usr/lib). We are registring it on the
+      // global scope similar to builtin rules.
+      //
+      {
+        auto& r (rs.global ().rules);
+        r.insert<mtime_target> (
+          configure_id, 0, "config.file", file_rule::instance);
+      }
+      {
+        auto& r (rs.rules);
+
+        //@@ outer
+        r.insert<alias> (configure_id, 0, "config.alias", alias_rule::instance);
+
+        // This allows a custom configure rule while doing nothing by default.
+        //
+        r.insert<target> (configure_id, 0, "config", noop_rule::instance);
+        r.insert<file> (configure_id, 0, "config.file", noop_rule::instance);
+      }
+
+      return true;
+    }
+
+    module_functions
+    build2_config_load ()
+    {
+      // Initialize the config entry points in the build system core.
+      //
+      config_save_variable = &config::save_variable;
+      config_preprocess_create = &config::preprocess_create;
+
+      return module_functions {&boot, &init};
+    }
+  }
+}