discover/grub2: Populate $prefix from config file location

Rather than always using the default prefix, we should determine it from
the location of the grub2 config file.

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

4 files changed, 24 insertions, 5 deletions

diff --git a/discover/grub2/grub2.c b/discover/grub2/grub2.c
index ffb6ece..7f63c35 100644
--- a/discover/grub2/grub2.c
+++ b/discover/grub2/grub2.c
@@ -103,7 +103,7 @@ static int grub2_parse(struct discover_context *dc)
 			continue;
 
 		parser = grub2_parser_create(dc);
-		grub2_parser_parse(parser, buf, len);
+		grub2_parser_parse(parser, *filename, buf, len);
 		talloc_free(buf);
 		talloc_free(parser);
 		break;
diff --git a/discover/grub2/grub2.h b/discover/grub2/grub2.h
index 1515d69..6166289 100644
--- a/discover/grub2/grub2.h
+++ b/discover/grub2/grub2.h
@@ -89,6 +89,7 @@ struct grub2_script {
 	struct list			symtab;
 	struct discover_context		*ctx;
 	struct discover_boot_option	*opt;
+	const char			*filename;
 	unsigned int			n_options;
 };
 
@@ -176,6 +177,7 @@ bool resolve_grub2_resource(struct device_handler *handler,
 
 /* external parser api */
 struct grub2_parser *grub2_parser_create(struct discover_context *ctx);
-void grub2_parser_parse(struct grub2_parser *parser, char *buf, int len);
+void grub2_parser_parse(struct grub2_parser *parser, const char *filename,
+		char *buf, int len);
 #endif /* GRUB2_H */
 
diff --git a/discover/grub2/parser.y b/discover/grub2/parser.y
index a3473ca..5a4d4f8 100644
--- a/discover/grub2/parser.y
+++ b/discover/grub2/parser.y
@@ -303,11 +303,14 @@ struct grub2_parser *grub2_parser_create(struct discover_context *ctx)
 	return parser;
 }
 
-void grub2_parser_parse(struct grub2_parser *parser, char *buf, int len)
+void grub2_parser_parse(struct grub2_parser *parser, const char *filename,
+		char *buf, int len)
 {
 	YY_BUFFER_STATE bufstate;
 	int rc;
 
+	parser->script->filename = filename;
+
 	bufstate = yy_scan_bytes(buf, len - 1, parser->scanner);
 	yyset_lineno(1, parser->scanner);
 
diff --git a/discover/grub2/script.c b/discover/grub2/script.c
index e29d437..a58f1a0 100644
--- a/discover/grub2/script.c
+++ b/discover/grub2/script.c
@@ -400,12 +400,26 @@ int statement_function_execute(struct grub2_script *script,
 static void init_env(struct grub2_script *script)
 {
 	struct env_entry *env;
+	char *prefix, *sep;
 
 	list_init(&script->environment);
 
+	/* use location of the parsed config file to determine the prefix */
 	env = talloc(script, struct env_entry);
+
+	prefix = NULL;
+	if (script->filename) {
+		sep = strrchr(script->filename, '/');
+		if (sep)
+			prefix = talloc_strndup(env, script->filename,
+					sep - script->filename);
+	}
+
 	env->name = talloc_strdup(env, "prefix");
-	env->value = talloc_strdup(env, default_prefix);
+	if (prefix)
+		env->value = prefix;
+	else
+		env->value = talloc_strdup(env, default_prefix);
 
 	list_add(&script->environment, &env->list);
 }
@@ -426,6 +440,7 @@ void script_register_function(struct grub2_script *script,
 
 void script_execute(struct grub2_script *script)
 {
+	init_env(script);
 	statements_execute(script, script->statements);
 }
 
@@ -436,7 +451,6 @@ struct grub2_script *create_script(struct grub2_parser *parser,
 
 	script = talloc_zero(parser, struct grub2_script);
 
-	init_env(script);
 	script->ctx = ctx;
 
 	list_init(&script->symtab);