5 files changed, 88 insertions, 1 deletions

diff --git a/discover/grub2/grub2.h b/discover/grub2/grub2.h
index 0a89324..68176fb 100644
--- a/discover/grub2/grub2.h
+++ b/discover/grub2/grub2.h
@@ -98,6 +98,7 @@ struct grub2_script {
 	struct discover_boot_option	*opt;
 	const char			*filename;
 	unsigned int			n_options;
+	struct list			options;
 };
 
 struct grub2_parser {
diff --git a/discover/grub2/script.c b/discover/grub2/script.c
index 36f73b2..f521681 100644
--- a/discover/grub2/script.c
+++ b/discover/grub2/script.c
@@ -364,7 +364,7 @@ int statement_menuentry_execute(struct grub2_script *script,
 
 	opt->option->is_default = option_is_default(script, opt, id);
 
-	discover_context_add_boot_option(script->ctx, opt);
+	list_add_tail(&script->options, &opt->list);
 	script->n_options++;
 	script->opt = NULL;
 
@@ -463,11 +463,43 @@ void script_register_function(struct grub2_script *script,
 	list_add(&script->symtab, &entry->list);
 }
 
+static void set_fallback_default(struct grub2_script *script)
+{
+	struct discover_boot_option *opt, *first = NULL;
+	bool have_default = false;
+
+	list_for_each_entry(&script->options, opt, list) {
+		if (!first)
+			first = opt;
+		have_default = have_default || opt->option->is_default;
+	}
+
+	if (!have_default && first) {
+		const char *env = script_env_get(script, "default");
+
+		pb_log("grub: no explicit default (env default=%s), "
+				"falling back to first option (%s)\n",
+				env ?: "unset", first->option->name);
+
+		first->option->is_default = true;
+	}
+}
 
 void script_execute(struct grub2_script *script)
 {
+	struct discover_boot_option *opt, *tmp;
+
 	init_env(script);
 	statements_execute(script, script->statements);
+
+	set_fallback_default(script);
+
+	list_for_each_entry_safe(&script->options, opt, tmp, list)
+		discover_context_add_boot_option(script->ctx, opt);
+
+	/* Our option list will be invalid, as we've added all options to the
+	 * discover context */
+	list_init(&script->options);
 }
 
 struct grub2_script *create_script(struct grub2_parser *parser,
@@ -480,6 +512,7 @@ struct grub2_script *create_script(struct grub2_parser *parser,
 	script->ctx = ctx;
 
 	list_init(&script->symtab);
+	list_init(&script->options);
 	register_builtins(script);
 
 	return script;
diff --git a/test/parser/Makefile.am b/test/parser/Makefile.am
index 1bb45e8..d69ca7f 100644
--- a/test/parser/Makefile.am
+++ b/test/parser/Makefile.am
@@ -21,6 +21,8 @@ parser_TESTS = \
 	test/parser/test-grub2-if-formats \
 	test/parser/test-grub2-default-index \
 	test/parser/test-grub2-default-multiword \
+	test/parser/test-grub2-implicit-default-unset \
+	test/parser/test-grub2-implicit-default-invalid \
 	test/parser/test-grub2-multiple-resolve \
 	test/parser/test-grub2-multiple-id \
 	test/parser/test-grub2-single-line-if \
diff --git a/test/parser/test-grub2-implicit-default-invalid.c b/test/parser/test-grub2-implicit-default-invalid.c
new file mode 100644
index 0000000..72902db
--- /dev/null
+++ b/test/parser/test-grub2-implicit-default-invalid.c
@@ -0,0 +1,26 @@
+
+#include "parser-test.h"
+
+#if 0 /* PARSER_EMBEDDED_CONFIG */
+default=missing
+menuentry 'test.1' {
+	linux   /vmlinux
+}
+menuentry 'test.2' {
+	linux   /vmlinux
+}
+#endif
+
+void run_test(struct parser_test *test)
+{
+	struct discover_boot_option *opt;
+
+	test_read_conf_embedded(test, "/grub2/grub.cfg");
+	test_run_parser(test, "grub2");
+
+	check_boot_option_count(test->ctx, 2);
+	opt = get_boot_option(test->ctx, 0);
+
+	check_name(opt, "test.1");
+	check_is_default(opt);
+}
diff --git a/test/parser/test-grub2-implicit-default-unset.c b/test/parser/test-grub2-implicit-default-unset.c
new file mode 100644
index 0000000..ecc4c00
--- /dev/null
+++ b/test/parser/test-grub2-implicit-default-unset.c
@@ -0,0 +1,25 @@
+
+#include "parser-test.h"
+
+#if 0 /* PARSER_EMBEDDED_CONFIG */
+menuentry 'test.1' {
+	linux   /vmlinux
+}
+menuentry 'test.2' {
+	linux   /vmlinux
+}
+#endif
+
+void run_test(struct parser_test *test)
+{
+	struct discover_boot_option *opt;
+
+	test_read_conf_embedded(test, "/grub2/grub.cfg");
+	test_run_parser(test, "grub2");
+
+	check_boot_option_count(test->ctx, 2);
+	opt = get_boot_option(test->ctx, 0);
+
+	check_name(opt, "test.1");
+	check_is_default(opt);
+}