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BIO_F_BUFFER(3) | Library Functions Manual | BIO_F_BUFFER(3) |
NAME
BIO_f_buffer
,
BIO_get_buffer_num_lines
,
BIO_set_read_buffer_size
,
BIO_set_write_buffer_size
,
BIO_set_buffer_size
,
BIO_set_buffer_read_data
—
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);
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(3) and
BIO_puts(3) are
supported.
Calling
BIO_reset(3) 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.
Except BIO_f_buffer
(), these functions are
implemented as macros.
Buffering BIOs implement
BIO_gets(3) by
using BIO_read(3)
operations on the next BIO in the chain. By prepending a buffering BIO to a
chain it is therefore possible to provide the functionality of
BIO_gets(3) 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(3)
is called. It is therefore important to call
BIO_flush(3)
whenever any pending data should be written such as when removing a buffering
BIO using
BIO_pop(3).
BIO_flush(3) 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_ctrl(3), BIO_flush(3), BIO_new(3), BIO_pop(3), BIO_reset(3)HISTORY
BIO_f_buffer
() first appeared in SSLeay
0.6.0. BIO_get_buffer_num_lines
() and
BIO_set_buffer_size
() first appeared in
SSLeay 0.6.5. BIO_set_read_buffer_size
()
and BIO_set_write_buffer_size
() first
appeared in SSLeay 0.8.0.
BIO_set_buffer_read_data
() first appeared
in SSLeay 0.9.0. All these functions have been available since
OpenBSD 2.4.March 31, 2022 | Debian |