1=pod
2
3=head1 NAME
4
5BIO_f_buffer - buffering BIO
6
7=head1 SYNOPSIS
8
9 #include <openssl/bio.h>
10
11 BIO_METHOD * BIO_f_buffer(void);
12
13 #define BIO_get_buffer_num_lines(b)	BIO_ctrl(b,BIO_C_GET_BUFF_NUM_LINES,0,NULL)
14 #define BIO_set_read_buffer_size(b,size) BIO_int_ctrl(b,BIO_C_SET_BUFF_SIZE,size,0)
15 #define BIO_set_write_buffer_size(b,size) BIO_int_ctrl(b,BIO_C_SET_BUFF_SIZE,size,1)
16 #define BIO_set_buffer_size(b,size)	BIO_ctrl(b,BIO_C_SET_BUFF_SIZE,size,NULL)
17 #define BIO_set_buffer_read_data(b,buf,num) BIO_ctrl(b,BIO_C_SET_BUFF_READ_DATA,num,buf)
18
19=head1 DESCRIPTION
20
21BIO_f_buffer() returns the buffering BIO method.
22
23Data written to a buffering BIO is buffered and periodically written
24to the next BIO in the chain. Data read from a buffering BIO comes from
25an internal buffer which is filled from the next BIO in the chain.
26Both BIO_gets() and BIO_puts() are supported.
27
28Calling BIO_reset() on a buffering BIO clears any buffered data.
29
30BIO_get_buffer_num_lines() returns the number of lines currently buffered.
31
32BIO_set_read_buffer_size(), BIO_set_write_buffer_size() and BIO_set_buffer_size()
33set the read, write or both read and write buffer sizes to B<size>. The initial
34buffer size is DEFAULT_BUFFER_SIZE, currently 4096. Any attempt to reduce the
35buffer size below DEFAULT_BUFFER_SIZE is ignored. Any buffered data is cleared
36when the buffer is resized.
37
38BIO_set_buffer_read_data() clears the read buffer and fills it with B<num>
39bytes of B<buf>. If B<num> is larger than the current buffer size the buffer
40is expanded.
41
42=head1 NOTES
43
44Buffering BIOs implement BIO_gets() by using BIO_read() operations on the
45next BIO in the chain. By prepending a buffering BIO to a chain it is therefore
46possible to provide BIO_gets() functionality if the following BIOs do not
47support it (for example SSL BIOs).
48
49Data is only written to the next BIO in the chain when the write buffer fills
50or when BIO_flush() is called. It is therefore important to call BIO_flush()
51whenever any pending data should be written such as when removing a buffering
52BIO using BIO_pop(). BIO_flush() may need to be retried if the ultimate
53source/sink BIO is non blocking.
54
55=head1 RETURN VALUES
56
57BIO_f_buffer() returns the buffering BIO method.
58
59BIO_get_buffer_num_lines() returns the number of lines buffered (may be 0).
60
61BIO_set_read_buffer_size(), BIO_set_write_buffer_size() and BIO_set_buffer_size()
62return 1 if the buffer was successfully resized or 0 for failure.
63
64BIO_set_buffer_read_data() returns 1 if the data was set correctly or 0 if
65there was an error.
66
67=head1 SEE ALSO
68
69L<BIO(3)|BIO(3)>,
70L<BIO_reset(3)|BIO_reset(3)>,
71L<BIO_flush(3)|BIO_flush(3)>,
72L<BIO_pop(3)|BIO_pop(3)>,
73L<BIO_ctrl(3)|BIO_ctrl(3)>,
74L<BIO_int_ctrl(3)|BIO_ctrl(3)>
75