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BIO_F_BUFFER(3)			    OpenSSL		       BIO_F_BUFFER(3)

NAME
       BIO_get_buffer_num_lines, BIO_set_read_buffer_size,
       BIO_set_write_buffer_size, BIO_set_buffer_size,
       BIO_set_buffer_read_data, BIO_f_buffer -	buffering BIO

SYNOPSIS
	#include <openssl/bio.h>

	const BIO_METHOD *BIO_f_buffer(void);

	long BIO_get_buffer_num_lines(BIO *b);
	long BIO_set_read_buffer_size(BIO *b, long size);
	long BIO_set_write_buffer_size(BIO *b, long size);
	long BIO_set_buffer_size(BIO *b, long size);
	long BIO_set_buffer_read_data(BIO *b, void *buf, long num);

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
       These functions,	other than BIO_f_buffer(), are implemented as macros.

       Buffering BIOs implement	BIO_read_ex() and BIO_gets() by	using
       BIO_read_ex() operations	on the next BIO	in the chain and storing the
       result in an internal buffer, from which	bytes are given	back to	the
       caller as appropriate for the call; a BIO_gets()	is guaranteed to give
       the caller a whole line,	and BIO_read_ex() is guaranteed	to give	the
       caller the number of bytes it asks for, unless there's an error or end
       of communication	is reached in the next BIO.  By	prepending a buffering
       BIO to a	chain it is therefore possible to provide BIO_gets() or	exact
       size BIO_read_ex() functionality	if the following BIOs do not support
       it.

       Do not add more than one	BIO_f_buffer() to a BIO	chain.	The result of
       doing so	will force a full read of the size of the internal buffer of
       the top BIO_f_buffer(), which is	4 KiB at a minimum.

       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(7), BIO_reset(3), BIO_flush(3), BIO_pop(3), BIO_ctrl(3).

COPYRIGHT
       Copyright 2000-2020 The OpenSSL Project Authors.	All Rights Reserved.

       Licensed	under the OpenSSL license (the "License").  You	may not	use
       this file except	in compliance with the License.	 You can obtain	a copy
       in the file LICENSE in the source distribution or at
       <https://www.openssl.org/source/license.html>.

1.1.1h				  2020-09-22		       BIO_F_BUFFER(3)

NAME | SYNOPSIS | DESCRIPTION | NOTES | RETURN VALUES | SEE ALSO | COPYRIGHT

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