BIO_f_buffer(3)

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

1.0.2t               Last change: 2019-09-10                    1

BIO_f_buffer(3)              OpenSSL              BIO_f_buffer(3)

     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               Last change: 2019-09-10                    2