Update bbox_lib.cpp

src/gausskernel/cbb/bbox/bbox_lib.cpp

@@ -51,8 +51,16 @@ struct PIPE_IDS {
 static struct PIPE_IDS astPipeIds[BBOX_MAX_PIDS];
 
 /*
- * compare string pszSrc and pszTarget
- */
+function name: bbox_strncmp
+description: compare two strings, the pointer pszSrc and pszTarget store their addresses.
+arguments: Two pointers of type const char*, pointing to two strings needed to be compared.
+return value: s32, an interger.
+					 If it's zero, then string pszSrc and pszTarget are same,
+                     else it indicates the position of the first character that
+                     these two strings can't match.
+note：The two pointers shouldn't be null.
+date: 2022/8/2
+*/
 s32 bbox_strncmp(const char* pszSrc, const char* pszTarget, s32 count)
 {
     signed char cRes = 0;