discover/grub2: Add initial command execution

.. with a simple 'set' command to update the environment

Signed-off-by: Jeremy Kerr <jk@ozlabs.org>

3 files changed, 144 insertions, 5 deletions

diff --git a/discover/grub2/builtins.c b/discover/grub2/builtins.c
new file mode 100644
index 0000000..379e870
--- /dev/null
+++ b/discover/grub2/builtins.c
@@ -0,0 +1,47 @@
+
+#include <stdio.h>
+#include <string.h>
+
+#include <talloc/talloc.h>
+#include <array-size/array-size.h>
+
+#include "grub2.h"
+
+
+static int builtin_set(struct grub2_script *script, int argc, char *argv[])
+{
+	char *name, *value, *p;
+	int i;
+
+	if (argc < 2)
+		return -1;
+
+	p = strchr(argv[1], '=');
+	if (!p)
+		return -1;
+
+	name = talloc_strndup(script, argv[1], p - argv[1]);
+	value = talloc_strdup(script, p+1);
+
+	for (i = 2; i < argc; i++)
+		value = talloc_asprintf_append(value, " %s", argv[i]);
+
+	script_env_set(script, name, value);
+
+	return 0;
+}
+
+static struct grub2_command commands[] = {
+	{
+		.name = "set",
+		.exec = builtin_set
+	},
+};
+
+void register_builtins(struct grub2_script *script)
+{
+	unsigned int i;
+
+	for (i = 0; i < ARRAY_SIZE(commands); i++)
+		script_register_command(script, &commands[i]);
+}
diff --git a/discover/grub2/grub2.h b/discover/grub2/grub2.h
index de74fa5..60a5734 100644
--- a/discover/grub2/grub2.h
+++ b/discover/grub2/grub2.h
@@ -25,6 +25,11 @@ struct grub2_word {
 
 struct grub2_argv {
 	struct list		words;
+
+	/* postprocessing (with process_expansions) populates these to hand to
+	 * the grub2_command callbacks */
+	char			**argv;
+	int			argc;
 };
 
 struct grub2_statements {
@@ -66,9 +71,18 @@ struct grub2_statement_block {
 	struct grub2_statements	*statements;
 };
 
+struct grub2_command {
+	const char		*name;
+	int			(*exec)(struct grub2_script *script,
+					int argc, char *argv[]);
+	struct list_item	list;
+};
+
 struct grub2_script {
 	struct grub2_statements	*statements;
 	struct list		environment;
+	struct list		commands;
+	struct list		symtab;
 };
 
 struct grub2_parser {
@@ -119,5 +133,17 @@ int statement_menuentry_execute(struct grub2_script *script,
 
 struct grub2_script *create_script(void *ctx);
 
+const char *script_env_get(struct grub2_script *script, const char *name);
+
+void script_env_set(struct grub2_script *script,
+		const char *name, const char *value);
+
+void script_register_command(struct grub2_script *script,
+		struct grub2_command *command);
+
+struct grub2_command *script_lookup_command(struct grub2_script *script,
+		const char *name);
+
+void register_builtins(struct grub2_script *script);
 #endif /* GRUB2_H */
 
diff --git a/discover/grub2/script.c b/discover/grub2/script.c
index 568e250..fce4f0a 100644
--- a/discover/grub2/script.c
+++ b/discover/grub2/script.c
@@ -19,8 +19,7 @@ struct env_entry {
 	struct list_item	list;
 };
 
-static const char *env_lookup(struct grub2_script *script,
-		const char *name)
+const char *script_env_get(struct grub2_script *script, const char *name)
 {
 	struct env_entry *entry;
 
@@ -31,11 +30,32 @@ static const char *env_lookup(struct grub2_script *script,
 	return NULL;
 }
 
+void script_env_set(struct grub2_script *script,
+		const char *name, const char *value)
+{
+	struct env_entry *e, *entry = NULL;
+
+	list_for_each_entry(&script->environment, e, list) {
+		if (!strcmp(e->name, name)) {
+			entry = e;
+			break;
+		}
+	}
+
+	if (!entry) {
+		entry = talloc(script, struct env_entry);
+		entry->name = name;
+		list_add(&script->environment, &entry->list);
+	}
+
+	entry->value = value;
+}
+
 static bool expand_var(struct grub2_script *script, struct grub2_word *word)
 {
 	const char *val;
 
-	val = env_lookup(script, word->var.name);
+	val = script_env_get(script, word->var.name);
 	if (!val)
 		val = "";
 
@@ -45,7 +65,8 @@ static bool expand_var(struct grub2_script *script, struct grub2_word *word)
 	return true;
 }
 
-/* iterate through the words in an argv, looking for GRUB2_WORD_VAR expansions.
+/* iterate through the words in an argv_list, looking for GRUB2_WORD_VAR
+ * expansions.
  *
  * Once that's done, we may (if split == true) have to split the word to create
  * new argv items
@@ -54,8 +75,13 @@ static void process_expansions(struct grub2_script *script,
 		struct grub2_argv *argv)
 {
 	struct grub2_word *top_word, *word;
+	int i;
+
+	argv->argc = 0;
 
 	list_for_each_entry(&argv->words, top_word, argv_list) {
+		argv->argc++;
+
 		/* expand vars and squash the list of words into the top struct.
 		 * todo: splitting
 		 */
@@ -71,6 +97,12 @@ static void process_expansions(struct grub2_script *script,
 		}
 		top_word->next = NULL;
 	}
+
+	argv->argv = talloc_array(script, char *, argv->argc);
+	i = 0;
+
+	list_for_each_entry(&argv->words, word, argv_list)
+		argv->argv[i++] = word->text;
 }
 
 int statements_execute(struct grub2_script *script,
@@ -90,13 +122,26 @@ int statement_simple_execute(struct grub2_script *script,
 		struct grub2_statement *statement)
 {
 	struct grub2_statement_simple *st = to_stmt_simple(statement);
+	struct grub2_command *cmd;
+	int rc;
 
 	if (!st->argv)
 		return 0;
 
 	process_expansions(script, st->argv);
 
-	return 0;
+	if (!st->argv->argc)
+		return 0;
+
+	cmd = script_lookup_command(script, st->argv->argv[0]);
+	if (!cmd) {
+		fprintf(stderr, "undefined command '%s'\n", st->argv->argv[0]);
+		return 0;
+	}
+
+	rc = cmd->exec(script, st->argv->argc, st->argv->argv);
+
+	return rc;
 }
 
 int statement_if_execute(struct grub2_script *script,
@@ -145,6 +190,25 @@ static void init_env(struct grub2_script *script)
 	list_add(&script->environment, &env->list);
 }
 
+struct grub2_command *script_lookup_command(struct grub2_script *script,
+		const char *name)
+{
+	struct grub2_command *command;
+
+	list_for_each_entry(&script->commands, command, list) {
+		if (!strcmp(command->name, name))
+			return command;
+	}
+
+	return NULL;
+}
+
+void script_register_command(struct grub2_script *script,
+		struct grub2_command *command)
+{
+	list_add(&script->commands, &command->list);
+}
+
 
 void script_execute(struct grub2_script *script)
 {
@@ -158,6 +222,8 @@ struct grub2_script *create_script(void *ctx)
 	script = talloc(ctx, struct grub2_script);
 
 	init_env(script);
+	list_init(&script->commands);
+	register_builtins(script);
 
 	return script;
 }