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  man pages->NetBSD man pages -> BIO_f_buffer (3)              



NAME    [Toc]    [Back]

       BIO_f_buffer - buffering BIO

LIBRARY    [Toc]    [Back]

       libcrypto, -lcrypto

SYNOPSIS    [Toc]    [Back]

        #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    [Toc]    [Back]

       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

       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 1024. 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    [Toc]    [Back]

       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    [Toc]    [Back]

       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    [Toc]    [Back]


2001-04-12                    0.9.6g              BIO_f_buffer(3)
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