5 BIO_ctrl, BIO_callback_ctrl, BIO_ptr_ctrl, BIO_int_ctrl, BIO_reset,
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
12 #include <openssl/bio.h>
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));
16 char * BIO_ptr_ctrl(BIO *bp,int cmd,long larg);
17 long BIO_int_ctrl(BIO *bp,int cmd,long larg,int iarg);
19 int BIO_reset(BIO *b);
20 int BIO_seek(BIO *b, int ofs);
22 int BIO_flush(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);
31 int BIO_get_info_callback(BIO *b,bio_info_cb **cbp);
32 int BIO_set_info_callback(BIO *b,bio_info_cb *cb);
34 typedef void bio_info_cb(BIO *b, int oper, const char *ptr, int arg1, long arg2, long arg3);
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
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
50 BIO_seek() resets a file related BIO's file position pointer to B<ofs>
51 bytes from start of file.
53 BIO_tell() returns the current file position of a file related BIO.
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.
58 BIO_eof() returns 1 if the BIO has read EOF, the precise meaning of
59 "EOF" varies according to the BIO type.
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.
66 BIO_get_close() returns the BIOs close flag.
68 BIO_pending(), BIO_ctrl_pending(), BIO_wpending() and BIO_ctrl_wpending()
69 return the number of pending characters in the BIOs read and write buffers.
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().
76 BIO_reset() returns 1 for success and 0 for failure.
78 BIO_seek() and BIO_tell() both return the current file position on success
81 BIO_flush() returns 1 for success and 0 or -1 for failure.
83 BIO_eof() returns 1 if EOF has been reached 0 otherwise.
85 BIO_set_close() always returns 1.
87 BIO_get_close() returns the close flag value: BIO_CLOSE or BIO_NOCLOSE.
89 BIO_pending(), BIO_ctrl_pending(), BIO_wpending() and BIO_ctrl_wpending()
90 return the amount of pending data.
94 BIO_flush(), because it can write data may return 0 or -1 indicating
95 that the call should be retried later in a similar manner to BIO_write().
96 The BIO_should_retry() call should be used and appropriate action taken
99 The return values of BIO_pending() and BIO_wpending() may not reliably
100 determine the amount of pending data in all cases. For example in the
101 case of a file BIO some data may be available in the FILE structures
102 internal buffers but it is not possible to determine this in a
103 portably way. For other types of BIO they may not be supported.
105 Filter BIOs if the do not internally handle a particular BIO_ctrl()
106 operation usually pass the operation to the next BIO in the chain.
107 This often means there is no need to locate the required BIO for
108 a particular operation, it can be called on a chain and it will
109 be automatically passed to the relevant BIO.
111 Source/sink BIOs will return an error if the do not recognize the
112 BIO_ctrl() operation.