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, cur-
       rently 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 fol-
       lowing 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)

1.0.2t                            2019-09-10                   BIO_f_buffer(3)