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d572cb6c DSH |
1 | =pod |
2 | ||
3 | =head1 NAME | |
4 | ||
8eec1389 | 5 | BIO_ctrl, BIO_callback_ctrl, BIO_ptr_ctrl, BIO_int_ctrl, BIO_reset, |
93fe6e13 RL |
6 | BIO_seek, BIO_tell, BIO_flush, BIO_eof, BIO_set_close, BIO_get_close, |
7 | BIO_pending, BIO_wpending, BIO_ctrl_pending, BIO_ctrl_wpending, | |
9058d9bc BP |
8 | BIO_get_info_callback, BIO_set_info_callback, BIO_info_cb, BIO_get_ktls_send, |
9 | BIO_get_ktls_recv | |
121677b4 | 10 | - BIO control operations |
d572cb6c DSH |
11 | |
12 | =head1 SYNOPSIS | |
13 | ||
14 | #include <openssl/bio.h> | |
15 | ||
fce78bd4 | 16 | typedef int BIO_info_cb(BIO *b, int state, int res); |
91da5e77 RS |
17 | |
18 | long BIO_ctrl(BIO *bp, int cmd, long larg, void *parg); | |
fce78bd4 | 19 | long BIO_callback_ctrl(BIO *b, int cmd, BIO_info_cb *cb); |
91da5e77 RS |
20 | char *BIO_ptr_ctrl(BIO *bp, int cmd, long larg); |
21 | long BIO_int_ctrl(BIO *bp, int cmd, long larg, int iarg); | |
d572cb6c DSH |
22 | |
23 | int BIO_reset(BIO *b); | |
93fe6e13 RL |
24 | int BIO_seek(BIO *b, int ofs); |
25 | int BIO_tell(BIO *b); | |
d572cb6c DSH |
26 | int BIO_flush(BIO *b); |
27 | int BIO_eof(BIO *b); | |
91da5e77 | 28 | int BIO_set_close(BIO *b, long flag); |
d572cb6c DSH |
29 | int BIO_get_close(BIO *b); |
30 | int BIO_pending(BIO *b); | |
31 | int BIO_wpending(BIO *b); | |
32 | size_t BIO_ctrl_pending(BIO *b); | |
33 | size_t BIO_ctrl_wpending(BIO *b); | |
34 | ||
fce78bd4 BE |
35 | int BIO_get_info_callback(BIO *b, BIO_info_cb **cbp); |
36 | int BIO_set_info_callback(BIO *b, BIO_info_cb *cb); | |
d572cb6c | 37 | |
50ec7505 | 38 | int BIO_get_ktls_send(BIO *b); |
9058d9bc | 39 | int BIO_get_ktls_recv(BIO *b); |
50ec7505 | 40 | |
d572cb6c DSH |
41 | =head1 DESCRIPTION |
42 | ||
43 | BIO_ctrl(), BIO_callback_ctrl(), BIO_ptr_ctrl() and BIO_int_ctrl() | |
44 | are BIO "control" operations taking arguments of various types. | |
45 | These functions are not normally called directly, various macros | |
46 | are used instead. The standard macros are described below, macros | |
47 | specific to a particular type of BIO are described in the specific | |
48 | BIOs manual page as well as any special features of the standard | |
49 | calls. | |
50 | ||
93fe6e13 RL |
51 | BIO_reset() typically resets a BIO to some initial state, in the case |
52 | of file related BIOs for example it rewinds the file pointer to the | |
53 | start of the file. | |
54 | ||
3b2cbbcb DSH |
55 | BIO_seek() resets a file related BIO's (that is file descriptor and |
56 | FILE BIOs) file position pointer to B<ofs> bytes from start of file. | |
93fe6e13 RL |
57 | |
58 | BIO_tell() returns the current file position of a file related BIO. | |
d572cb6c DSH |
59 | |
60 | BIO_flush() normally writes out any internally buffered data, in some | |
61 | cases it is used to signal EOF and that no more data will be written. | |
62 | ||
63 | BIO_eof() returns 1 if the BIO has read EOF, the precise meaning of | |
64 | "EOF" varies according to the BIO type. | |
65 | ||
66 | BIO_set_close() sets the BIO B<b> close flag to B<flag>. B<flag> can | |
67 | take the value BIO_CLOSE or BIO_NOCLOSE. Typically BIO_CLOSE is used | |
68 | in a source/sink BIO to indicate that the underlying I/O stream should | |
69 | be closed when the BIO is freed. | |
70 | ||
71 | BIO_get_close() returns the BIOs close flag. | |
72 | ||
73 | BIO_pending(), BIO_ctrl_pending(), BIO_wpending() and BIO_ctrl_wpending() | |
1e4e5492 | 74 | return the number of pending characters in the BIOs read and write buffers. |
d572cb6c DSH |
75 | Not all BIOs support these calls. BIO_ctrl_pending() and BIO_ctrl_wpending() |
76 | return a size_t type and are functions, BIO_pending() and BIO_wpending() are | |
77 | macros which call BIO_ctrl(). | |
78 | ||
9058d9bc | 79 | BIO_get_ktls_send() returns 1 if the BIO is using the Kernel TLS data-path for |
50ec7505 | 80 | sending. Otherwise, it returns zero. |
9058d9bc BP |
81 | BIO_get_ktls_recv() returns 1 if the BIO is using the Kernel TLS data-path for |
82 | receiving. Otherwise, it returns zero. | |
50ec7505 | 83 | |
d572cb6c DSH |
84 | =head1 RETURN VALUES |
85 | ||
3b2cbbcb DSH |
86 | BIO_reset() normally returns 1 for success and 0 or -1 for failure. File |
87 | BIOs are an exception, they return 0 for success and -1 for failure. | |
d572cb6c | 88 | |
93fe6e13 | 89 | BIO_seek() and BIO_tell() both return the current file position on success |
3b2cbbcb DSH |
90 | and -1 for failure, except file BIOs which for BIO_seek() always return 0 |
91 | for success and -1 for failure. | |
93fe6e13 | 92 | |
d572cb6c DSH |
93 | BIO_flush() returns 1 for success and 0 or -1 for failure. |
94 | ||
95 | BIO_eof() returns 1 if EOF has been reached 0 otherwise. | |
96 | ||
97 | BIO_set_close() always returns 1. | |
98 | ||
99 | BIO_get_close() returns the close flag value: BIO_CLOSE or BIO_NOCLOSE. | |
100 | ||
101 | BIO_pending(), BIO_ctrl_pending(), BIO_wpending() and BIO_ctrl_wpending() | |
102 | return the amount of pending data. | |
103 | ||
9058d9bc | 104 | BIO_get_ktls_send() returns 1 if the BIO is using the Kernel TLS data-path for |
50ec7505 | 105 | sending. Otherwise, it returns zero. |
9058d9bc BP |
106 | BIO_get_ktls_recv() returns 1 if the BIO is using the Kernel TLS data-path for |
107 | receiving. Otherwise, it returns zero. | |
50ec7505 | 108 | |
d572cb6c DSH |
109 | =head1 NOTES |
110 | ||
111 | BIO_flush(), because it can write data may return 0 or -1 indicating | |
b055fceb | 112 | that the call should be retried later in a similar manner to BIO_write_ex(). |
d572cb6c DSH |
113 | The BIO_should_retry() call should be used and appropriate action taken |
114 | is the call fails. | |
115 | ||
116 | The return values of BIO_pending() and BIO_wpending() may not reliably | |
117 | determine the amount of pending data in all cases. For example in the | |
118 | case of a file BIO some data may be available in the FILE structures | |
119 | internal buffers but it is not possible to determine this in a | |
120 | portably way. For other types of BIO they may not be supported. | |
121 | ||
3b2cbbcb | 122 | Filter BIOs if they do not internally handle a particular BIO_ctrl() |
32751b8a DSH |
123 | operation usually pass the operation to the next BIO in the chain. |
124 | This often means there is no need to locate the required BIO for | |
125 | a particular operation, it can be called on a chain and it will | |
8c1cbc72 | 126 | be automatically passed to the relevant BIO. However, this can cause |
3b2cbbcb DSH |
127 | unexpected results: for example no current filter BIOs implement |
128 | BIO_seek(), but this may still succeed if the chain ends in a FILE | |
129 | or file descriptor BIO. | |
32751b8a | 130 | |
3b2cbbcb DSH |
131 | Source/sink BIOs return an 0 if they do not recognize the BIO_ctrl() |
132 | operation. | |
133 | ||
134 | =head1 BUGS | |
135 | ||
136 | Some of the return values are ambiguous and care should be taken. In | |
137 | particular a return value of 0 can be returned if an operation is not | |
138 | supported, if an error occurred, if EOF has not been reached and in | |
1bc74519 | 139 | the case of BIO_seek() on a file BIO for a successful operation. |
32751b8a | 140 | |
50ec7505 BP |
141 | =head1 HISTORY |
142 | ||
9058d9bc | 143 | The BIO_get_ktls_send() and BIO_get_ktls_recv() functions were added in |
4674aaf4 | 144 | OpenSSL 3.0. |
50ec7505 | 145 | |
e2f92610 RS |
146 | =head1 COPYRIGHT |
147 | ||
e39e295e | 148 | Copyright 2000-2020 The OpenSSL Project Authors. All Rights Reserved. |
e2f92610 | 149 | |
4746f25a | 150 | Licensed under the Apache License 2.0 (the "License"). You may not use |
e2f92610 RS |
151 | this file except in compliance with the License. You can obtain a copy |
152 | in the file LICENSE in the source distribution or at | |
153 | L<https://www.openssl.org/source/license.html>. | |
154 | ||
155 | =cut |