xref: /freebsd/crypto/openssl/doc/man3/BIO_f_buffer.pod (revision 2f513db72b034fd5ef7f080b11be5c711c15186a)
1=pod
2
3=head1 NAME
4
5BIO_get_buffer_num_lines,
6BIO_set_read_buffer_size,
7BIO_set_write_buffer_size,
8BIO_set_buffer_size,
9BIO_set_buffer_read_data,
10BIO_f_buffer
11- buffering BIO
12
13=head1 SYNOPSIS
14
15 #include <openssl/bio.h>
16
17 const BIO_METHOD *BIO_f_buffer(void);
18
19 long BIO_get_buffer_num_lines(BIO *b);
20 long BIO_set_read_buffer_size(BIO *b, long size);
21 long BIO_set_write_buffer_size(BIO *b, long size);
22 long BIO_set_buffer_size(BIO *b, long size);
23 long BIO_set_buffer_read_data(BIO *b, void *buf, long num);
24
25=head1 DESCRIPTION
26
27BIO_f_buffer() returns the buffering BIO method.
28
29Data written to a buffering BIO is buffered and periodically written
30to the next BIO in the chain. Data read from a buffering BIO comes from
31an internal buffer which is filled from the next BIO in the chain.
32Both BIO_gets() and BIO_puts() are supported.
33
34Calling BIO_reset() on a buffering BIO clears any buffered data.
35
36BIO_get_buffer_num_lines() returns the number of lines currently buffered.
37
38BIO_set_read_buffer_size(), BIO_set_write_buffer_size() and BIO_set_buffer_size()
39set the read, write or both read and write buffer sizes to B<size>. The initial
40buffer size is DEFAULT_BUFFER_SIZE, currently 4096. Any attempt to reduce the
41buffer size below DEFAULT_BUFFER_SIZE is ignored. Any buffered data is cleared
42when the buffer is resized.
43
44BIO_set_buffer_read_data() clears the read buffer and fills it with B<num>
45bytes of B<buf>. If B<num> is larger than the current buffer size the buffer
46is expanded.
47
48=head1 NOTES
49
50These functions, other than BIO_f_buffer(), are implemented as macros.
51
52Buffering BIOs implement BIO_gets() by using BIO_read_ex() operations on the
53next BIO in the chain. By prepending a buffering BIO to a chain it is therefore
54possible to provide BIO_gets() functionality if the following BIOs do not
55support it (for example SSL BIOs).
56
57Data is only written to the next BIO in the chain when the write buffer fills
58or when BIO_flush() is called. It is therefore important to call BIO_flush()
59whenever any pending data should be written such as when removing a buffering
60BIO using BIO_pop(). BIO_flush() may need to be retried if the ultimate
61source/sink BIO is non blocking.
62
63=head1 RETURN VALUES
64
65BIO_f_buffer() returns the buffering BIO method.
66
67BIO_get_buffer_num_lines() returns the number of lines buffered (may be 0).
68
69BIO_set_read_buffer_size(), BIO_set_write_buffer_size() and BIO_set_buffer_size()
70return 1 if the buffer was successfully resized or 0 for failure.
71
72BIO_set_buffer_read_data() returns 1 if the data was set correctly or 0 if
73there was an error.
74
75=head1 SEE ALSO
76
77L<bio(7)>,
78L<BIO_reset(3)>,
79L<BIO_flush(3)>,
80L<BIO_pop(3)>,
81L<BIO_ctrl(3)>.
82
83=head1 COPYRIGHT
84
85Copyright 2000-2016 The OpenSSL Project Authors. All Rights Reserved.
86
87Licensed under the OpenSSL license (the "License").  You may not use
88this file except in compliance with the License.  You can obtain a copy
89in the file LICENSE in the source distribution or at
90L<https://www.openssl.org/source/license.html>.
91
92=cut
93