COMMON: Add strnlen for safer C string length reads

This API is intended for use in cases where C strings come
from untrusted sources like game files, where malformed data
missing the null terminator would cause strlen to read out of
bounds.

1 files changed, 11 insertions, 0 deletions

diff --git a/common/str.h b/common/str.h
index d55ba072a9..ba1e0b8341 100644
--- a/common/str.h
+++ b/common/str.h
@@ -445,6 +445,17 @@ size_t strlcpy(char *dst, const char *src, size_t size);
 size_t strlcat(char *dst, const char *src, size_t size);
 
 /**
+ * Determine the length of a string up to a maximum of `maxSize` characters.
+ * This should be used instead of `strlen` when reading the length of a C string
+ * from potentially unsafe or corrupt sources, like game assets.
+ *
+ * @param src The source string.
+ * @param maxSize The maximum size of the string.
+ * @return The length of the string.
+ */
+size_t strnlen(const char *src, size_t maxSize);
+
+/**
  * Convenience wrapper for tag2string which "returns" a C string.
  * Note: It is *NOT* safe to do anything with the return value other than directly
  * copying or printing it.