Append *len* bytes from *buf* into the *oid* object. The value of
*len* must be <= UINT_MAX/2.
@param io the context to operate in
@param oid the name of the object
@param buf the data to append
@param len length of buf (in bytes)
@returns 0 on success, negative error code on failure
Append *len* bytes from *buf* into the *oid* object. The value of *len* must be <= UINT_MAX/2.
@param io the context to operate in @param oid the name of the object @param buf the data to append @param len length of buf (in bytes) @returns 0 on success, negative error code on failure