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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, | |
8 | BIO_get_info_callback, BIO_set_info_callback - BIO control operations | |
d572cb6c DSH |
9 | |
10 | =head1 SYNOPSIS | |
11 | ||
12 | #include <openssl/bio.h> | |
13 | ||
14 | long BIO_ctrl(BIO *bp,int cmd,long larg,void *parg); | |
15 | long BIO_callback_ctrl(BIO *b, int cmd, void (*fp)(struct bio_st *, int, const char *, int, long, long)); | |
1bc74519 | 16 | char * BIO_ptr_ctrl(BIO *bp,int cmd,long larg); |
d572cb6c DSH |
17 | long BIO_int_ctrl(BIO *bp,int cmd,long larg,int iarg); |
18 | ||
19 | int BIO_reset(BIO *b); | |
93fe6e13 RL |
20 | int BIO_seek(BIO *b, int ofs); |
21 | int BIO_tell(BIO *b); | |
d572cb6c DSH |
22 | int BIO_flush(BIO *b); |
23 | int BIO_eof(BIO *b); | |
24 | int BIO_set_close(BIO *b,long flag); | |
25 | int BIO_get_close(BIO *b); | |
26 | int BIO_pending(BIO *b); | |
27 | int BIO_wpending(BIO *b); | |
28 | size_t BIO_ctrl_pending(BIO *b); | |
29 | size_t BIO_ctrl_wpending(BIO *b); | |
30 | ||
31 | int BIO_get_info_callback(BIO *b,bio_info_cb **cbp); | |
32 | int BIO_set_info_callback(BIO *b,bio_info_cb *cb); | |
33 | ||
34 | typedef void bio_info_cb(BIO *b, int oper, const char *ptr, int arg1, long arg2, long arg3); | |
35 | ||
36 | =head1 DESCRIPTION | |
37 | ||
38 | BIO_ctrl(), BIO_callback_ctrl(), BIO_ptr_ctrl() and BIO_int_ctrl() | |
39 | are BIO "control" operations taking arguments of various types. | |
40 | These functions are not normally called directly, various macros | |
41 | are used instead. The standard macros are described below, macros | |
42 | specific to a particular type of BIO are described in the specific | |
43 | BIOs manual page as well as any special features of the standard | |
44 | calls. | |
45 | ||
93fe6e13 RL |
46 | BIO_reset() typically resets a BIO to some initial state, in the case |
47 | of file related BIOs for example it rewinds the file pointer to the | |
48 | start of the file. | |
49 | ||
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50 | BIO_seek() resets a file related BIO's (that is file descriptor and |
51 | FILE BIOs) file position pointer to B<ofs> bytes from start of file. | |
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52 | |
53 | BIO_tell() returns the current file position of a file related BIO. | |
d572cb6c DSH |
54 | |
55 | BIO_flush() normally writes out any internally buffered data, in some | |
56 | cases it is used to signal EOF and that no more data will be written. | |
57 | ||
58 | BIO_eof() returns 1 if the BIO has read EOF, the precise meaning of | |
59 | "EOF" varies according to the BIO type. | |
60 | ||
61 | BIO_set_close() sets the BIO B<b> close flag to B<flag>. B<flag> can | |
62 | take the value BIO_CLOSE or BIO_NOCLOSE. Typically BIO_CLOSE is used | |
63 | in a source/sink BIO to indicate that the underlying I/O stream should | |
64 | be closed when the BIO is freed. | |
65 | ||
66 | BIO_get_close() returns the BIOs close flag. | |
67 | ||
68 | BIO_pending(), BIO_ctrl_pending(), BIO_wpending() and BIO_ctrl_wpending() | |
1e4e5492 | 69 | return the number of pending characters in the BIOs read and write buffers. |
d572cb6c DSH |
70 | Not all BIOs support these calls. BIO_ctrl_pending() and BIO_ctrl_wpending() |
71 | return a size_t type and are functions, BIO_pending() and BIO_wpending() are | |
72 | macros which call BIO_ctrl(). | |
73 | ||
74 | =head1 RETURN VALUES | |
75 | ||
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76 | BIO_reset() normally returns 1 for success and 0 or -1 for failure. File |
77 | BIOs are an exception, they return 0 for success and -1 for failure. | |
d572cb6c | 78 | |
93fe6e13 | 79 | BIO_seek() and BIO_tell() both return the current file position on success |
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80 | and -1 for failure, except file BIOs which for BIO_seek() always return 0 |
81 | for success and -1 for failure. | |
93fe6e13 | 82 | |
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83 | BIO_flush() returns 1 for success and 0 or -1 for failure. |
84 | ||
85 | BIO_eof() returns 1 if EOF has been reached 0 otherwise. | |
86 | ||
87 | BIO_set_close() always returns 1. | |
88 | ||
89 | BIO_get_close() returns the close flag value: BIO_CLOSE or BIO_NOCLOSE. | |
90 | ||
91 | BIO_pending(), BIO_ctrl_pending(), BIO_wpending() and BIO_ctrl_wpending() | |
92 | return the amount of pending data. | |
93 | ||
94 | =head1 NOTES | |
95 | ||
96 | BIO_flush(), because it can write data may return 0 or -1 indicating | |
1bc74519 | 97 | that the call should be retried later in a similar manner to BIO_write(). |
d572cb6c DSH |
98 | The BIO_should_retry() call should be used and appropriate action taken |
99 | is the call fails. | |
100 | ||
101 | The return values of BIO_pending() and BIO_wpending() may not reliably | |
102 | determine the amount of pending data in all cases. For example in the | |
103 | case of a file BIO some data may be available in the FILE structures | |
104 | internal buffers but it is not possible to determine this in a | |
105 | portably way. For other types of BIO they may not be supported. | |
106 | ||
3b2cbbcb | 107 | Filter BIOs if they do not internally handle a particular BIO_ctrl() |
32751b8a DSH |
108 | operation usually pass the operation to the next BIO in the chain. |
109 | This often means there is no need to locate the required BIO for | |
110 | a particular operation, it can be called on a chain and it will | |
3b2cbbcb DSH |
111 | be automatically passed to the relevant BIO. However this can cause |
112 | unexpected results: for example no current filter BIOs implement | |
113 | BIO_seek(), but this may still succeed if the chain ends in a FILE | |
114 | or file descriptor BIO. | |
32751b8a | 115 | |
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116 | Source/sink BIOs return an 0 if they do not recognize the BIO_ctrl() |
117 | operation. | |
118 | ||
119 | =head1 BUGS | |
120 | ||
121 | Some of the return values are ambiguous and care should be taken. In | |
122 | particular a return value of 0 can be returned if an operation is not | |
123 | supported, if an error occurred, if EOF has not been reached and in | |
1bc74519 | 124 | the case of BIO_seek() on a file BIO for a successful operation. |
32751b8a | 125 | |
d572cb6c DSH |
126 | =head1 SEE ALSO |
127 | ||
128 | TBA | |
99ec4fdb RS |
129 | |
130 | =cut | |
e2f92610 RS |
131 | |
132 | =head1 COPYRIGHT | |
133 | ||
134 | Copyright 2000-2016 The OpenSSL Project Authors. All Rights Reserved. | |
135 | ||
136 | Licensed under the OpenSSL license (the "License"). You may not use | |
137 | this file except in compliance with the License. You can obtain a copy | |
138 | in the file LICENSE in the source distribution or at | |
139 | L<https://www.openssl.org/source/license.html>. | |
140 | ||
141 | =cut |