Manual Pages for UNIX Operating System command usage for man BIO_push

OpenSSL                                        BIO_push(3openssl)



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     BIO_push, BIO_pop - add and remove BIOs from a chain.

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      #include 

      BIO *  BIO_push(BIO *b,BIO *append);
      BIO *  BIO_pop(BIO *b);


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     The BIO_push() function appends the BIO aaaappppppppeeeennnndddd to bbbb, it
     returns bbbb.

     BIO_pop() removes the BIO bbbb 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.

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     The names of these functions are perhaps a little
     misleading. BIO_push() joins two BIO chains whereas
     BIO_pop() deletes a single BIO from a chain, the deleted BIO
     does not need to be at the end of a chain.

     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.

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     For these examples suppose mmmmdddd1111 and mmmmdddd2222 are digest BIOs, bbbb66664444
     is a base64 BIO and ffff is a file BIO.

     If the call:

      BIO_push(b64, f);

     is made then the new chain will be bbbb66664444---ccchhhhaaaaiiiinnnn. After making
     the calls

      BIO_push(md2, b64);
      BIO_push(md1, md2);

     the new chain is mmmmdddd1111---mmmdddd2222---bbb66664444---fff. Data written to mmmmdddd1111 will be
     digested by mmmmdddd1111 and mmmmdddd2222, bbbbaaaasssseeee66664444 encoded and written to ffff.

     It should be noted that reading causes data to pass in the
     reverse direction, that is data is read from ffff, base64
     ddddeeeeccccooooddddeeeedddd and digested by mmmmdddd1111 and mmmmdddd2222. If the call:




14/Sep/2000            Last change: 0.9.8o                      1






OpenSSL                                        BIO_push(3openssl)



      BIO_pop(md2);

     The call will return bbbb66664444 and the new chain will be mmmmdddd1111---bbb66664444---fff
     data can be written to mmmmdddd1111 as before.

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     BIO_push() returns the end of the chain, bbbb.

     BIO_pop() returns the next BIO in the chain, or NULL if
     there is no next BIO.

SSSSEEEEEEEE AAAALLLLSSSSOOOO
     TBA










































14/Sep/2000            Last change: 0.9.8o                      2