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BIO(3)		      DragonFly Library Functions Manual		BIO(3)


NAME

     BIO -- I/O abstraction


SYNOPSIS

     #include <openssl/bio.h>


DESCRIPTION

     A BIO is an I/O abstraction, it hides many of the underlying I/O details
     from an application.  If an application uses a BIO for its I/O, it can
     transparently handle SSL connections, unencrypted network connections and
     file I/O.

     There are two types of BIO, a source/sink BIO and a filter BIO.

     As its name implies, a source/sink BIO is a source and/or sink of data,
     examples include a socket BIO and a file BIO.

     A filter BIO takes data from one BIO and passes it through to another, or
     to the application.  The data may be left unmodified (for example a mes-
     sage digest BIO) or translated (for example an encryption BIO).  The
     effect of a filter BIO may change according to the I/O operation it is
     performing: for example an encryption BIO will encrypt data if it is
     being written to and decrypt data if it is being read from.

     BIOs can be joined together to form a chain (a single BIO is a chain with
     one component).  A chain normally consist of one source/sink BIO and one
     or more filter BIOs.  Data read from or written to the first BIO then
     traverses the chain to the end (normally a source/sink BIO).


SEE ALSO

     BIO_ctrl(3), BIO_f_base64(3), BIO_f_buffer(3), BIO_f_cipher(3),
     BIO_f_md(3), BIO_f_null(3), BIO_f_ssl(3), BIO_find_type(3), BIO_new(3),
     BIO_new_bio_pair(3), BIO_push(3), BIO_read(3), BIO_s_accept(3),
     BIO_s_bio(3), BIO_s_connect(3), BIO_s_fd(3), BIO_s_file(3), BIO_s_mem(3),
     BIO_s_null(3), BIO_s_socket(3), BIO_set_callback(3), BIO_should_retry(3)

DragonFly 4.7			 July 17, 2014			 DragonFly 4.7
BIO_f_buffer(3)                     OpenSSL                    BIO_f_buffer(3)


NAME

       BIO_f_buffer - buffering BIO


SYNOPSIS

        #include <openssl/bio.h>

        BIO_METHOD * BIO_f_buffer(void);

        #define BIO_get_buffer_num_lines(b)    BIO_ctrl(b,BIO_C_GET_BUFF_NUM_LINES,0,NULL)
        #define BIO_set_read_buffer_size(b,size) BIO_int_ctrl(b,BIO_C_SET_BUFF_SIZE,size,0)
        #define BIO_set_write_buffer_size(b,size) BIO_int_ctrl(b,BIO_C_SET_BUFF_SIZE,size,1)
        #define BIO_set_buffer_size(b,size)    BIO_ctrl(b,BIO_C_SET_BUFF_SIZE,size,NULL)
        #define BIO_set_buffer_read_data(b,buf,num) BIO_ctrl(b,BIO_C_SET_BUFF_READ_DATA,num,buf)


DESCRIPTION

       BIO_f_buffer() returns the buffering BIO method.

       Data written to a buffering BIO is buffered and periodically written to
       the next BIO in the chain. Data read from a buffering BIO comes from an
       internal buffer which is filled from the next BIO in the chain.  Both
       BIO_gets() and BIO_puts() are supported.

       Calling BIO_reset() on a buffering BIO clears any buffered data.

       BIO_get_buffer_num_lines() returns the number of lines currently
       buffered.

       BIO_set_read_buffer_size(), BIO_set_write_buffer_size() and
       BIO_set_buffer_size() set the read, write or both read and write buffer
       sizes to size. The initial buffer size is DEFAULT_BUFFER_SIZE,
       currently 4096. Any attempt to reduce the buffer size below
       DEFAULT_BUFFER_SIZE is ignored. Any buffered data is cleared when the
       buffer is resized.

       BIO_set_buffer_read_data() clears the read buffer and fills it with num
       bytes of buf. If num is larger than the current buffer size the buffer
       is expanded.


NOTES

       Buffering BIOs implement BIO_gets() by using BIO_read() operations on
       the next BIO in the chain. By prepending a buffering BIO to a chain it
       is therefore possible to provide BIO_gets() functionality if the
       following BIOs do not support it (for example SSL BIOs).

       Data is only written to the next BIO in the chain when the write buffer
       fills or when BIO_flush() is called. It is therefore important to call
       BIO_flush() whenever any pending data should be written such as when
       removing a buffering BIO using BIO_pop(). BIO_flush() may need to be
       retried if the ultimate source/sink BIO is non blocking.


RETURN VALUES

       BIO_f_buffer() returns the buffering BIO method.

       BIO_get_buffer_num_lines() returns the number of lines buffered (may be
       0).

       BIO_set_read_buffer_size(), BIO_set_write_buffer_size() and
       BIO_set_buffer_size() return 1 if the buffer was successfully resized
       or 0 for failure.

       BIO_set_buffer_read_data() returns 1 if the data was set correctly or 0
       if there was an error.


SEE ALSO

       BIO(3), BIO_reset(3), BIO_flush(3), BIO_pop(3), BIO_ctrl(3),
       BIO_int_ctrl(3)

1.0.2h                            2016-05-03                   BIO_f_buffer(3)

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