Update bbox_lib.cpp

src/gausskernel/cbb/bbox/bbox_lib.cpp

@@ -248,6 +248,18 @@ char* bbox_strstr(const char* s1, const char* s2)
 /*
  * make a directory
  */
+/*
+function name: bbox_mkdir
+description: We distinguish parent directory and child directory through character '/',
+					normally through a for loop, we can make sure all directories above the directory
+                    we want to creat exist, finally we will creat the flag directory after its parent.
+arguments: A pointers of type const char*, pointing to one strings, which indicates the filename and its full path.
+return value: An integer of type s32, if it's RET_ERR, then we fail to make a directory, else if it's RET_OK then we succeed.
+note: Take care the last non-null character of the string needed to be '/', and once if flag directory's
+		 ancestors aren't exist, the function return RET_ERR.
+date: 2022/8/2
+contact tel: same
+*/
 s32 bbox_mkdir(const char* pszDir)
 {
     char szDirName[BBOX_TMP_LEN_32 * 16];