From 14b1c4d3dd9ff4e45c305e9ca52a5c19b0fbe475 Mon Sep 17 00:00:00 2001
From: Nils Tonnaett <ntonnatt@ccrma.stanford.edu>
Date: Wed, 13 May 2026 11:53:43 -0700
Subject: [PATCH] module-avb: add zero padding check function

---
 src/modules/module-avb/strings.c | 20 ++++++++++++++++++++
 src/modules/module-avb/strings.h |  2 ++
 2 files changed, 22 insertions(+)

diff --git a/src/modules/module-avb/strings.c b/src/modules/module-avb/strings.c
index 2f680715d..169c745c1 100644
--- a/src/modules/module-avb/strings.c
+++ b/src/modules/module-avb/strings.c
@@ -76,3 +76,23 @@ int validate_utf8(uint8_t *str, size_t len) {
     return 0;
   }
 }
+
+int check_zero_padding(uint8_t const *str, size_t len)
+{
+	size_t str_len = strnlen((char *)str, len);
+	/* String doesn't need to be null-terminated. Return success if there is no null in str */
+	if (str_len == len)
+	{
+		return 0;
+	}
+
+	for (int i = str_len; i < len; ++i)
+	{
+		if (str[i] != 0x00)
+		{
+			return -1;
+		}
+	}
+
+	return 0;
+}
diff --git a/src/modules/module-avb/strings.h b/src/modules/module-avb/strings.h
index 3cdafc303..7c607df09 100644
--- a/src/modules/module-avb/strings.h
+++ b/src/modules/module-avb/strings.h
@@ -6,7 +6,9 @@
 
 #include <stddef.h>
 #include <stdint.h>
+#include <string.h>
 
 int validate_utf8(uint8_t *str, size_t len);
+int check_zero_padding(uint8_t *str, size_t len);
 
 #endif /* AVB_STRINGS_H */