kconfig: add 'filename' and 'lineno' built-in variables

The special variables, $(filename) and $(lineno), are expanded to a
file name and its line number being parsed, respectively.
Suggested-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Kees Cook <keescook@chromium.org>

scripts/kconfig/preprocess.c

@@ -114,6 +114,11 @@ static char *do_error_if(int argc, char *argv[])
 	return NULL;
 }
 
+static char *do_filename(int argc, char *argv[])
+{
+	return xstrdup(current_file->name);
+}
+
 static char *do_info(int argc, char *argv[])
 {
 	printf("%s\n", argv[0]);
@@ -121,6 +126,15 @@ static char *do_info(int argc, char *argv[])
 	return xstrdup("");
 }
 
+static char *do_lineno(int argc, char *argv[])
+{
+	char buf[16];
+
+	sprintf(buf, "%d", yylineno);
+
+	return xstrdup(buf);
+}
+
 static char *do_shell(int argc, char *argv[])
 {
 	FILE *p;
@@ -173,7 +187,9 @@ static char *do_warning_if(int argc, char *argv[])
 static const struct function function_table[] = {
 	/* Name		MIN	MAX	Function */
 	{ "error-if",	2,	2,	do_error_if },
+	{ "filename",	0,	0,	do_filename },
 	{ "info",	1,	1,	do_info },
+	{ "lineno",	0,	0,	do_lineno },
 	{ "shell",	1,	1,	do_shell },
 	{ "warning-if",	2,	2,	do_warning_if },
 };