CMS streaming filter BIO
NULL if an error occurred. The error can be obtained from ERR_get_error(3).
BIO_flush(3) must be called to finalise the structure.The CMS_STREAM flag must be included in the corresponding flags parameter of the cms creation function.If an application wishes to write additional data to out, BIOs should be removed from the chain using BIO_pop(3) and freed with BIO_free(3) until out is reached. If no additional data needs to be written, BIO_free_all(3) can be called to free up the whole chain.Any content written through the filter is used verbatim: no canonical translation is performed.It is possible to chain multiple BIOs to, for example, create a triple wrapped signed, enveloped, signed structure. In this case it is the application's responsibility to set the inner content type of any outer CMS_ContentInfo structures.Large numbers of small writes through the chain should be avoided as this will produce an output consisting of lots of OCTET STRING structures. Prepending a BIO_f_buffer(3) buffering BIO will prevent this.