#include <openssl/bio.h> BIO *BIO_push(BIO *b, BIO *append); BIO *BIO_pop(BIO *b); void BIO_set_next(BIO *b, BIO *next);
BIO_pop() removes the BIO b from a chain and returns the next BIO in the chain, or NULL if there is no next BIO. The removed BIO then becomes a single BIO with no association with the original chain, it can thus be freed or attached to a different chain.
BIO_set_next() replaces the existing next BIO in a chain with the BIO pointed to by next. The new chain may include some of the same BIOs from the old chain or it may be completely different.
The process of calling BIO_push() and BIO_pop() on a BIO may have additional consequences (a control call is made to the affected BIOs) any effects will be noted in the descriptions of individual BIOs.
BIO_pop() returns the next BIO in the chain, or NULL if there is no next BIO.
If the call:
is made then the new chain will be b64-f. After making the calls
BIO_push(md2, b64); BIO_push(md1, md2);
the new chain is md1-md2-b64-f. Data written to md1 will be digested by md1 and md2, base64 encoded and written to f.
It should be noted that reading causes data to pass in the reverse direction, that is data is read from f, base64 decoded and digested by md1 and md2. If the call:
The call will return b64 and the new chain will be md1-b64-f data can be written to md1 as before.
Licensed under the OpenSSL license (the "License"). You may not use this file except in compliance with the License. You can obtain a copy in the file LICENSE in the source distribution or at https://www.openssl.org/source/license.html.